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Chance of Strong/Severe Storms Today

Posted on May 17, 2012 by SteveSponsler

Fairly Close model consensus so far this mid-morning with surface 'now' data indicating that a weak surface low could form for reasons described below. East coast sea breeze convergence along or even east of I-95 could, if current thinking
holds fast, result in rotation in a few storms from Saint Augustine
to Central Brevard

TODAY: Tricky forecast, but waste not want not. So wasting no time to get this post out as a precautionary measure. Some "scrappy Cu" (cumulus clouds) already forming in thinning early day mid-level clouds over Central and North Florida as sun beams in. Jet stream level winds across the South Half of the state with agreement that Central Florida will be under the right entrance region of those winds. Additionally, latest guidance in two models shows a streak of 20,000 ft. winds at 500 mb (millibars) streaking right across Central Florida later this afternoon right under the divergent winds aloft . Highest convective instability is forecast to exist from Lake Okeechobee and North, due the result of late night through early morning rain activity further south where jet stream cirrus clouds continue to run over that Southward Area now and as it looks, the remainder of the day. Meanwhile, surface boundary to sink into North Central today, with latest surface and low level streamline analysis indicating convergence along that boundary increasing during the day, especially along any sea breeze front resulting in stronger upward vertical velocities.

With those factors in mind 1) Divergence aloft 2) strong 500mb wind core 3) instability and finally, the big question mark, 4) an east coast sea breeze which seems most likely north of St. Lucie County, and 5) coldest temperatures aloft from 10000 ft up are from Brevard and North. South Florida might be contending with outflow backlash from early day activity, but things could change down there quickly, as often seems to be the case. Regardless, without a doubt the region further north, as it stands now at least, holds the better chance of severe weather today . So with those factors in mind:

Questionable activity South Florida. More than likely, this region will see some storms today, but all things considered further north those factors seem to pale in comparison until after 7pm tonight. By that time certainly it could all be a different story. Otherwise, North bound we go where from this image alone one can see the skies have cleared with no high clouds coming in from the west off the Gulf of Mexico.

ADDITIVE FACTOR: Low to mid level helicity values along the coast, especially from Brevard and North are shown to be the most consistent in guidance, with a concerning higher value running from near Southern Volusia toward Cocoa Beach, and again further north toward Ormond Beach give or take 50 miles north/south. Another factor is that latest guidance is showing stronger downdraft CAPE values encroaching in on the entire west side of the state from the Gulf. Downdraft CAPE tends to limit overall coverage, but that which can form , that is to say, can work against the downdraft cape into updrafts, can result in storms that rapidly build vertically, resulting in hail and/or strong downburst winds. Thus the area in red as well. Such downdraft CAPE would also, if it is true to form as a mere 'mortal model' can show, would INHIBIT activity over South Florida already covered in High Clouds.However, guidance is showing rainfall down that way, the type for lightning production. Best best at this point down there would be from Port Charlotte and South inland toward Lake Okeechobee and the Everglades for any potential strong storms,.

THUS: The purple area would be considered for this post to be a zone to watch for rotating thunderstorms and maybe even a brief waterspout or tornado, especially South of St. Augustine and North of Vero Beach, with a possible highlight north 1/2 of Brevard County east of I-95 closest to the boundary, convergence, instability, divergence, and 500mb wind core (IF IT IN FACT WILL EXIST). Any activity especially after 4:30Pm near the coast (if it manifests) is worth monitoring today, especially for deviant right or left moving activity. Storms or showers could continue in isolated fashion after 9pm. toward midnight.

FRIDAY: With today's "Potential Soap Opera Drama" on the line, tomorrow per the latest NAM model shows yet more, thus today / tonight could fold with... "...To Be Continued". Today's boundary gets 'locked up' in the quick upper level winds and has a hard time dropping, at least permanently, much further south than Southern Brevard, if even that. Net result is the same sort of set up on Friday only this time from Brevard County and South toward Palm Beach County. See no reason why high clouds again might not be a factor further south, toward Dade County at least. Otherwise, might need to watch mostly inland toward West Central and SW Florida, as winds gain more of an east ward yet light component in higher levels of the atmosphere.

Beyond Friday is a big TBD, but based on what I'm seeing the previous post looks valid yet still, namely early day activity east side translating toward the interior mid-late afternoon, with activity attempting to migrate back east yet again toward or after sunset through Tuesday.

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Today’s Forecast Picture Says But One Word

Posted on May 16, 2012 by SteveSponsler

CLOUDY
Today: One look outside looks not much different than it does from outer space, other than from there the clouds are white; how interesting of a day that would be to see from the ground and be looking up, nothing but a cloudy white as opposed to grey. The trough shown in purple at the surface and into the upper levels makes slow leeway east and south during the next 48 hours. For today, there are some Florida Oranges drawn in to indicate tangerine dreams thunder at best almost anywhere, but two locations seem to have a best shot though not shown here. One being Dead Central interior very late today toward the east coast southward toward Palm Beach County. The other area is the NE Quadrant of the State as far south as Ormond Beach where thunder has already occurred. There is only two storms state wide even at 220pm in the afternoon, and they are on opposite sides of the state and barely moving. Steering remains weak as does heating due to the cloud cover, and with little sign of a surface boundary and so far no apparent easst coast sea breeze (or barely) forcing should be fairly weak and the surface if there is any boundary interactions at all.

THURSDAY/FRIDAY: Possibly a better chances of storms or rain showers North Central and south of there almost any time, but Thursday and/or Friday might be able to yield a strong storm risk in there. All contingent upon the amount of early morning and overnight Gulf Stream activity which shreds high level clouds across the state when or if they do occur. The GFS is showing reduced high level cloudiness (moisture) overnight later tonight but that could easily change if more storms generate well to the west of the state. If the day dawns sunny, the chance of rain is better.

BEYOND: Really no change to forecast reasoning from yesterday or days before. Boundary will have worked Southward into South Central or South Florida on Saturday with a deeper easterly (but rather light) flow. This could result in early morning to overnight showers close to the east coast progressing inland during the day. The GFS is consistent that this highly unusual May pattern (which is acting more like the middle to late summer minus the warmer surface temperature) could continue to months end. That is a big stretch, but the gist is not expecting any astounding or earth shattering changes in the overall pattern from Friday and beyond, although that shalt change in the days ahead.
Comments are always welcome, especially if they are constructive and/or helpful. Let me know what you need to see!

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"Chance?" of Some Strong Thunderstorms Today and Numerous Showers

Posted on May 15, 2012 by SteveSponsler

Image depicts a fairly deep east coast sea breeze could be forming as of 2pm. Storms
over North East Florida seem to have been triggered by higher low level instability combined with a bubble of upper level divergence aloft resulting in an upward vacuum early this afternoon. Otherwise, it appears all of South Florida will begin to 'fire up' in the next 2 hours, if all holds true to form per model guidance due to greater instability in this area as well

TODAY: A frontal boundary that has been meandering toward the western Florida Panhandle seems to be 'fizzling' a bit, in regard to how well defined it was 2 days ago. Wind fields at all levels below 20,000 ft are 10kts or less, but much stronger higher up. Latest LDIS and guidance shows (and has been showing all day so far) a 'donut hole' of greater stability across Central due to early high level cloudiness that is only now beginning to clear on out. This area remains a bit of "??" this afternoon in regard to 'will storms truly be able to fire there?". It appears that any activity from North Florida as well as South Florida could send outflows into that region, so that storms there will run later in the day after peak heating.

So, with a bit of hesitation, but owing solely on model guidance consistency (other than one of them), willing to hedge in on the storms gathering momentum in number in the next hour or so (currently it is just after 2:25pm) over North and South Florida , but with the strongest of storms forming after 4:30-5:oopm in the 'questionnable zone' of Central and South Central toward Lake Okeechobee southward into Palm Beach County. I see why guidance is heding on the East Central Area being 'out' today for storms based on the morning KSC sounding. It's a matter of whether or not it was a small or large area that showed unfavorable storms as well as whether or not those conditions remain there and all of central all day long, which is a big unknown.

The east coast sea breeze at this hour does not appear to be yet past I-95, and the west coast one has begun as of the last hour per visible satellite image animations. Things can change quickly though, as it has done in the past, with the east coast breeze suddenly gaining momentum after 4pm and pushing well inland.

Otherwise, temperatures aloft are cold enough to result in storms with small hail, and a quick down burst or even microburst of strong winds central, where there is a low level dry layer. ON THE OTHER HAND, that drier layer, should it remain (and at this hour it is shown in short term LDIS, Local Data Integration System as well as the RAP (the new Rapid Refresh model) guidance as a higher Level of Free Convection (LFC) unfavorable for storm formation.

There are times that activity simply cannot manifest in such an environment until after dark or not at all. Giving the models the benefit of the doubt though, should those factors improve, the best chance of those stronger storms will be along the Sea Breeze merger then back eastward in subsequent outflow / post sea breeze environments toward I95 if not US1 from Brevard County Southward.

Activity it appears will be sapped out early on this evening by 8-9pm, wherever that may happen to be...likely South Central or South Florida.

Red is where some of the higher chance of a pulse strong storm could occur, not to discount anywhere else within the orange zone however. Again, The region across all of East Central remains just a bit in question, and therefore remains the 'wild card' out, or Ace of Spades for the Strong Storms winner's circle.

TUESDAY/FRIDAY: Appears that within the time frame of Thursday or Friday the frontal boundary (not shown) remains will work toward Central and become drawn out and possibly dissolve. Much depends on what happens toward the Yucatan Peninsula.

Guidance has been hinting at low pressure forming in that area with an inverted trough forming northward from it, possibly enhanced by the unstable waters of the Loop Current of the eastern Gulf. Should the frontal boundary latch on to that boundary further southward progression of the front should cease, and equally allow moisture from the Caribbean to converge along it resulting in over night toward early day showers and thunder working westward into the interior and west side later in the day. Much to be resolved in those regards.

Otherwise, although it appears this could be a day by day deal to determine if or if not there is a decent shot at storms each day, at time that appears to be the case. The main factors that would negate such chances would be higher level clouds early in the day which would prevent low level instability to mount up for storm developments. On the otherhand, should a scenario as just described formulate, rain chances will remain in the cards for folks somewhere/sometime well into next week. Much depends on the strength of the front and how far south it penetrates...in other words, who knows.

Surface Boundary could be in this area by Friday with mid level moisture being drawn northward

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Strong/Severe Storms Possible ..OR….

Posted on May 10, 2012 by SteveSponsler

Red where possible "hot zone" storms could occur today from WNW of Ft. Pierce to the Coast and South into Broward County mainly near and East of Lake Okeechobee toward Ft. Lauderdale
Frontal boundary, very shallow has reached South Central and dissipated. Mid-Level trough is still to drop south this afternoon. Although there is just enough instability for showers as far north as the Cape, believe any showers to from later today will be along that mid-level trough toward Lake County, if even that.

Otherwise, the region where the boundary at the surface has waned out , is where it got caught up in stacked westerlies, increasing with height. The only down side to the areas shown is this region "could" be on the descending side of an upper level jet streak forecast to cross Central, although model guidance so far do not indicate this to be the case in the precipitation fields. Believe at this point most of Dade and just maybe Southern Broward might eke out on the storms due to forecast warming in the mid-levels, but should a storm punch through that layer they could go gang busters.

Given the forecast vertical helicity, and approaching mid-level lift ahead of the trough to drop through Central, storms could be strong to severe, although 500mb temperatures are not crazy bonker nuts cold, they are sufficient.

***CAVEAT:**** Due to the lack of any low level boundaries, no forecast triggers in the vorticity fields, and if the RAP and SPC MesoAnalysis guidance is correct, the area in question could dry up in the mid levels to quickly after 330pm, which would discount this chance altogether to very little activity at all. Close monitoring thus will be necessary to either confirm either/or/ situation beyond that time frame. In the meanwhile, certainly some storms could manifest, but it is always possible there will not be ample moisture in place at or just after the time of peak storm hours if those two pieces of guidance are correct. Lapse rates that looked tremendous down that way earlier today are not as impressive per latest LDIS/RAP plot from the MLB NWS Office Website. Otherwise,

FRIDAY/SATURDAY: Pleasant and a bit cooler with no rains forecast for the most part except maybe some scant showers south Florida toward the SW Coast.

SUNDAY; Not a significant enough change in guidance to harp on what has already been written here the past two days. Mid level 'warm front' from the trough to pass down the state today lifts back north in response to mid-upper level low pressure across the north Gulf coast region. In doing so, moisture depth increases from south to north. This boundary at the mid-levels should be near Central by mid-afternoon Sunday, with showers reaching as far north as the Cape by near midnight or so Sunday night into Monday. GFS continues to expound a 'shift change', namely that the Brevard Coast area give or take a county could get very wet from post-Sunday Midnight through much of Monday, this will continue to be watched.

MONDAY-THURSDAY: Day by day give or take thunderstorm chances remain in guidance. The GFS and ECMWF appear to pull a cold front through on Thursday, and if so, that will be the end of this pattern on that day after sunset. So far, looks like an early afternoon start to showers and thunder ending after 8pm each evening Monday through Thursday. But, as the story ends, can't count the chickens until they've hatched, otherwise a forecast post for that time frame this far in advance could well be hard-boiled.
Comments are always welcome, especially if they are constructive and/or helpful. Let me know what you need to see!

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Strong Storms "Possible" East of I95 Later This Afternoon

Posted on May 9, 2012 by SteveSponsler

Today's lead off image shows the upper level low over the Desert SW noted yesterday has dropped further south than expected. Meanwhile, in red is shown where the leading edge of upper level winds are estimated to be located earlier today, and in purple where that leading edge is expected to be by late afternoon moving in across the North 1/2 of the state.

TODAY: A front boundary will be entering the NW Panhandle by tonight. Meanwhile, SW flow is expected to increase toward sunset at the surface, but before that time (and here is the clincher of clinchers), the pressure gradient might not be strong enough to offset an east coast sea breeze which would end up pinned close to, if not east of, US 1. for many locations along the entire east coast before the gradient increases toward sunset.

Considering also, good surface heating toward the east coast and inland could provide for the added boost of a temperature (thermal) gradient from the cooler near shore waters to provide for a shallow sea breeze to form or upwind river breeze at least along the Brevard barrier islands. Further South, lake shadow wind effect could enhance storms either side (north of south) of the shadow into Palm Beach County or Martin/St Lucie County. Further north toward JAX, there could also be a sea breeze south toward Northern Ormond Beach. So far, guidance is painting that the area just along or north of I-4 might become 'capped' due to a surge of warmer 850mb air temperatures, although this cannot ever be for certain. For now, the next graphic has made that 'assumption'. Also assumed is "the clincher of clinchers", a sea breeze or side shore component. If this does not form, chances are much lower of anything beyond some storms of generic quality except toward Lake Okeechobee and NE Florida.

Otherwise, although 500mb temperatures are not as cold as two days ago, that aren't far off from yesterday with still cool at 700mbs. Good surface heating, instability (light -mdt), and some upper level energy to trigger showers and storms, especially after 4pm or so. Whether or not this will be of in the form of rain showers over the interior is difficult to pin point, but the best chance of thunder seems to be within 20 miles of the coast except toward NW Florida and the Panhandle as the front moves in. Conditions appear most favorable for any strong to marginal severe storms that might occur to be after 4:45pm today closest to the coast from the Cape and South due to local affects, and near Jax due to the proximity of the approaching frontal boundary, except near Palm Beach County will it looks like more of a low level wind field boundary happen-chance situation. Showers and some thunder could continue in very isolated fashion anywhere along the east coast as late as 11pm in random fashion due to remnant out flow boundaries and residual convective instability.

This image shows a guesstimate for showers (green) to stronger storms (lavender) , although the area near JAX/St. Augustine and in the Panhandle could have easily been included for some 'purpling'. Stronger storms near the coast could contain small hail and wind gusts in excess of 50mph, especially after 4:30pm in a few spots under the premise a sea-breeze or side shore wind can form.

THURSDAY: The Front will glide slowly south over night toward Dead Central by noon time Thursday. At this point, it is becoming just a bit flaky as to how far south and how fast the boundary will continue southward during the first half at least of the afternoon during peak heating. Winds aloft will be paralleling the front, and that factor combined with surfacing heating could slow it down. There is minute indications a weak surface low could try to form near Tampa Bay as well, which would further impede southward progress until after or near sunset. With this in mind, a pre-ump agreement (despite a few model runs showing otherwise) could call for showers or thunder to occur from the Cape south along the east coast on Thursday. Some could be strong as well with colder air aloft, but a seabreeze and thus lack of low level convergence would be a mitigating factor in that regard. Where ever the boundary is stalled or slowly moving will more than likely be the additive factor for stronger activity tomorrow, wherever that might happen to be.

Possible storms on Thursday if low develops. Otherwise, any storms will be relegated a bit further south toward Vero Beach. Some consistency indicates at least showers or something looking like showers no matter
what from the Cape and South

FRIDAY/SATURDAY: The boundary will remain toward far South Florida into the Straits Area but the 700mb trough never really clears Central. This COULD end up acting as a future source of storms by early Next Week, surprise surprise...otherwise, shallow depth easterlies could become a bit gusty on Saturday at 18-25mph, especially due the mid afternoon and into the evening.

As such, showers could re-emerge toward SW Florida on either day, with possibly some light rains South Florida, but clouds seems to be the more prevalent mode south of the mid-level boundary except toward the SW Coast.

SUNDAY/ MONDAY: Upper low shown previously toward the SW U.S. never really clears the SE States but lingers across the Northern Gulf and parts of Florida as anticipated in yesterday's post.

As noted before (yesterday) another upper low fills the void from the Northern Plains states which drops SSE into the 'gap', re-enforcing that trough, while a surface low forms toward Coastal Louisiana and lifts another boundary northward, a part of the old surface front and mid-level boundary. Net affect, we could be seeing more thunderstorm chances as soon as overnight Sunday or early Monday near the East Coast south of the Cape, and much more widespread Monday afternoon and potentially for much of next week. After this point, it gets messier and messier in model inconsistency , at least in regard to climatology.

OVER GULF is what WAS the Desert SW Low. Note the trough
swinging southward from the Plain to fall into the same trough and re-enforce it.
Better YET! Look what is forecast then to approach from the west. Do note though,
this could all change by the next model run.

At this point, this is all a tough call. The extended outlook'd 'pattern' is highly unusual for this time of year. The GFS and another model take it so far as to produce a tropical system over the western Caribbean which drifts north across Cuba in the next 12 days or so, which would be a first in QUITE a number of years this early in the season. If nothing more, the fact that a model (s) is even hinting at the possibility is worth noting at this stage.

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More Showers/Thunder Today, Possibly Strong Thursday

Posted on May 8, 2012 by SteveSponsler

Shower and thunder graphic. See note. Some thunder could move off shore South of Brevard toward Ft. Pierce and maybe West Palm Beach. Storms not expected to become strong/severe except maybe Toward Southern Palm Beach County in from the coast toward Ft Lauderdale/Miami possibly. Temperatures at 500mb not as cold today, but whether or not that will have any bearing on storm strength is hard to say. 700mb remains cool one more day, but that could only mean storms will form quickly but not be strong. Highest instability starts off along the NE Quadrant of state by become state wide by early afternoon.

TODAY: Another day of widespread showers and thunder possible. The only real difference today from yesterday is that 500mb temperatures might not be as cold as yesterday, although, morning sounding has shown no change from yesterday. Additionally, mixing ratios are not as favorable nor are the lifted condensation levels for solid low level storm bases. All models agree that warming is forecast by early afternoon nearly state wide except far SE Florida. The frontal boundary that worked toward South Central is to lift north and dissipate today, making for another day of outflow boundary, Lake Breeze Boundary, and Sea breeze interactions once again...making it quite difficult to pinpoint exactly where any particularly heavier activity will manifest, at least at this early hour of blog posting.

Here is the current upper level situation. NOTE the location of those 500mb winds today. This will be worth noting in latter portions of the post.

Winds aloft continue weak over the state. Steering will be toward the east again, but all depends on how quickly either the east and/or west coast sea breezes move inland as to how far rainfall will reach the east coast toward late day and early evening. So far, indications are that along the east coast it will begin around 12:30pm, upon which time showers and some thunder forms within the first hour or so afterward along or west of US1 to I-95. Thus, expect most areas on the east side or even 1/2 of state today will end up CLOUDY by late afternoon at a minimum.

Again, above is the upper level flow for today high high up there. See the low/trough to the West of Florida by Cali? This low will gradually be moving east, but now guidance shows it never quite clears Florida through mid-month. Instead, NOTE THE NW CORNER of the image. Another Low is moving in.

The low toward the NW U.S., now, is forecast to drop in behind the trail left by the first one, and carve a broad upper level trough along and east of the Mississippi in the next week to 10 days. There will be at least two more frontal boundaries to contend with during this process, the first being late Thursday as the one of today dissolves.

WEDNESDAY: Wednesday looks similar to today, but possibly a bit even warmer aloft in the mid-levels. Coverage difficult to ascertain, but expecting something similar to today, with little chance of severe or even strong storms as it stands now. Today will be a good test to see what does occur in the long run though. Never say never when it comes to boundary collisions is the key.

THURSDAY: As we can see, upper level trough and winds aloft now moving in, with a surface front (not shown) moving down the state. Convergence along that boundary, sea breezes, and cold air aloft could make for another day like Monday was only more active along the immediate East Coast.

Compare image to the one above and note the winds that are stronger are now over the state. Colder aloft as well..but see where the low to the west remains? And see the other Still in the NW States. That one could slowly merge with the southern one carving out a broad path or trough of low pressure east of the Mississippi River going into Next Week.

THURSDAY: Possible stronger to severe storms on Thursday from Volusia and South along the east coast ahead of a frontal boundary.

FRIDAY/SUNDAY: Easterly winds manifest, breezy and dry, but with clouds and possible showers toward the Keys and Southern Dade, but pleasant otherwise. Front will be way south, but remain in the mid-levels. In a sense, so far, it could 're-manifest' by Late Sunday..moving back north..with rain south of Volusia along the coast in doing so.

Monday/Tuesday time frame could be stormy or rainy along the east half of state, with the Latest GFS showing up to 2" of rain if not more in this area. That is a 'new one" though and too far out in time to hold fast on to.

BEYOND: Time will tell, the all in all though is that this pattern for this time of year is fairly rare from my recollections...as the amount of coverage reflects late June, with showers possible toward the third week at various times.

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Reflections of A Summer Like Pattern Through Thursday

Posted on May 7, 2012 by SteveSponsler

Early afternoon severe thunderstorm warning along east coast sea breeze with little steering but cold air aloft, greater moisture in the atmosphere, better mixing ratios along the east coast, as well as better (stronger) atmospheric low level instability in the absence of down draft Convective Available potential energy and almost no inhibition allows early activity.

AT 122 PM EDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR DELTONA...AND MOVING SOUTHEAST AT 10 MPH. (the warning has since been cancelled).

TODAY: Frontal boundary has eked by Central Florida and will linger in the area for several days. Much of today will be quite similar to a summer like regime, with an east coast sea breeze manifesting early afternoon showers and storms along it and sending out flows from said activity every which way, only to merge with the west coast sea breeze over the interior during late day and early evening.

Although storms could form along either sea breeze, the better chance will be along the east coast sea breeze as it progresses inland. Expect we could see yet stronger storms toward Lake County, then sending outflows back eastward late in the day. Other storms though interior Central are entirely possible.. It will all depend on how far inland each breeze progresses as to where the storngest storms are located/
Best regions look just about anywhere away from the coasts near and north of Lake Okeechobee, but showers and some thunder could occur even further south just in from the coasts. Skies becoming mostly cloudy east 1/2 of state by later today due to convective rainshower and storm debris drifting east and off the coast.

LATE TODAY: Expect that showers and some storms, <as noted there is already a severe warning>, will increase after 4pm. There is not a whole lot of cloud cover state wide as of 2pm (see below), and the day is still young. Temperatures aloft, especially down the east side of the state to be the coldest aloft, so would watch near and west of I -95 later today as inland mergers send outflows back and against the east coast sea breeze. Although low level instability is not super impressive at all, most of it seems to be coming off the Atlantic. Additionally, as opposed to yesterday, there is almost no down draft CAPE north of Dade County and across the state. Further south, there might be too much of that factor to allow even a rain shower because that factor acts to suppress activity unless updrafts are stronger than downdrafts...as was the case yesterday. Winds aloft are very weak, so storms will pulse up and down down quickly, spreading collapsing showers and cold air with them out in every direction.

Late afternoon is when outflows collide after heating has built up all day...so would expect this could occur along and west of the east coast sea breeze wherever it happens to be located later today. Some activity could be stronger close to the decaying surface boundary/front across Central and might work eastward along it and offshore Brevard toward Martin County / Ft. Pierce after 7pm and into early evening.

THROUGH THURSDAY: Much of the same completely unforecast-able and unusually early (!)summer like regime in regard to 'most likely' locations in advance beyond the day to day basis routine. Day by day analysis required, although Wednesday seems to be most favorable for much of the east coast to get a shot at rain and/or thunderstorms.

Meanwhile, an upper level trough well to the west near the Desert SW region (see below) will be opening up and traversing across the Deep South. This system will eject upper level energy out in phases too difficult to peg down in timing. It will be a matter of a disturbance traversing over the state coincident with late afternoon peak heating combined with sea breeze/lake breeze/outflow boundary collisions that will be the strong/severe storm determinants today through Thursday. The boundary will sink further South by Friday morning through at least Saturday.

In General, this is the track of the low pressure upper level trough. It will take until early next week to pass near Florida if even at all. So far, this has been the trend in guidance from the GFS model (Global Forecast System). With that, we can see a down trend in activity on Friday through Saturday, but it could pick back up again by late Sunday or Monday.

As noted above captioned image, the frontal boundary near Central will eventually get shoved southward toward the keys area. But, as that upper trough approaches, moist and unstable air will get drawn back northward in advance of that trough. Thus, the frontal boundary to come back north by near the end of the weekend. resulting in another round of summer like weather with highs in the lower 90Fs, although cooler on Friday and Saturday along the east coast under the influence of a predominant easterly sea breeze those day.

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Isolated Thunder East Central, Possible One Stronger Storm Toward Beaches

Posted on May 6, 2012 by SteveSponsler

Isolated Thunder East Central Florida late afternoon into early Evening
Some showers in areas noted into the Everglades and around Lake Okeechobee.
Showers and some thunder near and north of I-10.
TODAY: Will leave this one fairly brief early this Sunday afternoon. Tables have about turned now for the onset of a new weather pattern which showed signs of its arrival late yesterday near Martin County. Expect that today, with precipitable water only around 1.2" (compared to near 1.85" - 2+" in the summer), that any activity will be very isolated with 3 (at most) storms possible Central. Based on trends and guidance since early on, there is a chance that one sole storm could become strong, unusually so once migrating east of I-95 toward US1 and the beaches from near Mims south toward MLB after 6pm. This would only be possible in the presence of a late afternoon sea breeze remaining very close to east of I-95. As has been noted in the past, the sea breeze penetration can be very tricky at best any day, but especially so on days when guidance does not show that one is supposed to even develop at all. For now, if it develops late and/or does develop but makes little inland penetration, a strong storm is possible eastern Brevard mainly. If it develops sooner, a strong storm could form toward Eastern Osceola County after 6pm. Otherwise, sunny and bright with few clouds outside around any activity, especially after 5pm.

MONDAY/TUESDAY: As noted in the above image, more upper level 'wind' energy will be present in days to come, but not so much today. There is not one day that a lot of Convective Available Potential Energy (CAPE) is shown to pop up over the landmass, but moisture is expected to be increased by Monday, so more thunder and showers is possible on that day and Tuesday regardless of the fact the atmosphere is not all that unstable at the surface. The better factors could be colder air aloft, as will be the case today to some degree.

BEYOND: Thunder and shower chances should start to decrease from north to South, especially on Thursday with an end most areas by the weekend. It does not look like after a few day break in the activity the rain chances will be gone for good. An upper level system, slow to get here, will still be on the move from the west along the northern Gulf Coast; so that although we might see a break toward next weekend, there could still be a few days of more hectic weather to come heading toward mid-May.
Comments are always welcome, especially if they are constructive and/or helpful. Let me know what you need to see!

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Pattern Changing – Slow and Steady For Central and South

Posted on May 5, 2012 by SteveSponsler

Forecast Image for Monday where showers and thunder could occur. Weakened
frontal boundary across North Central by Afternoon

WEEKEND OUTLOOK: Diverging from forecast and SPC outlook today (showing thunder most areas), forewarned so could be off. Believe there will be very little rain over the weekend except toward perhaps North Volusia and North and along I-10 on Sunday, with thunder possible toward Gainesville, JAX, and north or toward DAB. Otherwise,
guidance is showing showers toward Orlando late day as a result of sea breeze convergence; however Convective Available Potential Energy for this time of year is barely suitable, and Lifted Indices are not much better than feeble. Can envision some showers at best and maybe only a good cloud deck materializing as inversion from high pressure that has been overhead weakens, with low topped showers as opposed to thunder. We are moving out of what has been a long established pattern while the 'Post big system' resulting in the tornado watch a while back slowly breaks down. Continued warm away from the beaches, reaching some 90Fs inland with light winds, and an overnight onshore wind component maybe one more night well after dark, as has been the case for a few weeks now.

Toward Monday, boundary slides South, with another boundary approaching from the South Central Plains. Southern Branch jet will reside near the depicted Surface low and across the Northern to Central Gulf most of next week in various degrees

MONDAY and BEYOND: The front shown across Central on Monday perhaps drops south a bit overnight but then lifts back north awaiting yet the next boundary. There has been some consistency now for 48 hours in varying degrees in GFS guidance, hence today's post. Showers and Thunder most likely near and north of Lake Okeechobee in days ahead next week, with some showers further south toward SE Florida. The main triggers would be the frontal boundaries resulting in convergence of sea breezes near it. Guidance is also showing that perhaps there will be no sea breeze at all, which would or could taper down the thunder chance; but, upper level temperatures are rather cool upstairs, combined with ample Convective Available Potential Energy CAPE (but not really excitingly so), and guidance rarely handles sea breezes in account of local data density. SPC already has a "See Text" for stronger storms on Monday near and north of the BeachLine (Magic Diving Line as referred to here time and time again)..Monday GFS does show a disturbance and good upward vertical velocities, but such depictions this far out in time are perhaps not worth heeding conclusively as of this time today, but bears watching. If it verifies, strong storms Central on Monday. The only thing that has been constant is the rain chances, and thunder toward the east side of the state through Wednesday, with perhaps a day or two break here and there.

IN CLOSURE: Guidance has shown at some point or another this pattern will continue to varying degrees and locations for the remainder of the state into next weekend, so I expect we will hearing about some sort of rain chance on TV or other media outlets, time and place TBD. It appears after this little dabble with frontal boundaries is over, although not shown, would be the next contender. HEAT...usually the hottest time of year near the East Coast is prior to onset of the Wet Season in Late May toward early to mid June. ..but this may not occur prior to a few days of possible strong storms here and there when all is said and done. Once any heat spell ensues, wet season follows, although there is no set rule I know of that says a heat spell has to occur at all. 3 years in a row there has been one though, lasting anywhere from 2 days to 5 days.

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Complex Lower Latitude Weather Pattern to Persist Through Next Week

Posted on April 28, 2012 by SteveSponsler

South to West Central Showers and Some Thunder, Most likely near Tampa Bay Later Today
TODAY: Latest satellite image shown above. Those high white clouds are shifting north and streaming off toward the east at the same time. Meanwhile, instability to build into South Central toward lower North Central; however, the area north of the Beachline looks to remain 'capped off' for much activity other than a drip at most. Most likely area to get storms today along the west coast near Tampa under better sunshine as the east coast sea-breeze meets the near coast west coast sea breeze.

TOMORROW THROUGH TUESDAY: Same general pattern holds without going into details. It is possible that most rain will fall from Southern Dade and all of the Keys during this time frame. The wild card will be upstream of the Bahamas northward toward Palm Beach county where downstream fo easterlies helicity at low levels and shear across the islands could result in convergent bands moving ashore most anytime . Usually, these patterns fit a mold of 'most likely time it will rain within that zone', but exactly when that time will be is difficult to determine. Often though, it is near sunset or shortly thereafter until late morning.

BEYOND> Upper level and mid level lows seem to be trapped in sort of an eddy bubble, not unlike a twig caught between two rocks in a stream that rotates around in place. Current thinking, which has changed since yesterday, is for increasing rains state wide around Friday, with thunder possible. Will leave it at that for now, since it really is a bit of a waste of time to jump into the nitty gritty ..when the pattern is operating in a random chance roulette wheel fashion.

Comments are always welcome, especially if they are constructive and/or helpful. Let me know what you need to see!

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