"But seeing they could not See; hearing they could not Hear"
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"From its chamber comes the whirlwind, and cold from the scattering winds." - Job 37:9.

"The wind blows to the south and turns to the north; round and round it goes, ever returning on its course".

Saturday, October 29, 2011

Continued Cloudy Through Sunset, Possible Thunder Southeast

915AM Surface chart from Melbourne's Local Data Integration System shows a surface low over North Central Brevard County with a temporarily stationary surface front located as shown. This low is gradually stacking up into the mid-levels through 10,000 and will waver near the location of this low until mid-afternoon. Drizzle could occur over East Central from time to time with a better chance of rain shown in green  and thunder in the white area after noon time through  5pm.   The color coding is surface temperatures with the key shown toward the right side.
At 850mb,   the same low with the fronts shown in black at this level also is noted. The green lines indicating plentiful moisture remaining in the low levels. This moistures will slowly erode from the West later today, with clearing from the NW to ESE during the afternoon. Also noted above is that there was a tornado warning issued around 827AM this morning for a small but rotating storm east of Lake Okeechobee which has since moved offshore. So far, it does not look like a re-occurrence of this type of activity will occur over South Florida later today based on the wind fields taking shape. 

The low over East Central Florida should strengthen a bit more as it moves to the east during the early afternoon, abetted by upper level divergence. This divergence should be able to keep the cloud cover in place as well, especially since PWAT continues over 2" over Central and South Florida, and even where it is not that moist, there is ample moisture in the critical area between the LCL, Lifted Condenstation Level, and LFC, Level of Free Convection,  to generate clouds. These have already formed well to the west and north once the sun came up where it was previously clear.

Latest visible satellite image shows the abundant cloud cover. Most of the region from JAX to Gainvesville should start to clear out later this afternoon after peak heating, with the clearing line making it toward Central by Sunset ..but the areas along US1 from Volusia and South toward Lake Okeechobee and South Florida could remain mostly cloudy at least. 

OVERNIGHT: Big rains with thunder occurred over South Florida as two or more vorticity maxes crossed this area and Central. The one over South Florida had warmer dewpoint air and thus more instability to work with, thus the lightning. Further north toward Central, the air was more stable resulting in more of an over running stratiform type rain. Very early this morning another vort max crossed Central and exited near Port Canaveral, producing a second round of moderate to heavy rainfall in tandem with another further south.

TODAY: Mostly cloudy, with some drizzle possible in isolated fashion with more bona fide showers and possible thunder over SE Florida east and south of Lake Okeechobee and into the Everglades as well as over the Keys. The surface and mid-level low will pull off the east and NE later today. ..meanwhile, a strengthening low off the coast of Maryland will 'bomb out', with increasing winds, moisture, and cold air in place resulting in Snow across Eastern PA, SE NY, and New England with temperatures holding in the 30Fs. This low will parallel the NE coast with snows spreading toward Maine tomorrow. While this low is deepening, the surface front further south will be quasi-stationary until that low further north starts to move north and east a bit.

Meanwhile, the front will clear Central Brevard between the hours of 1:30-300pm in earnest, followed by a burst of NNW wind nearly parallel to the coast running down Flagler, Volusia and North Brevard by late afternoon. This surge could induce another shot of brief rain east of US1 in North Brevard toward far Eastern SE Volusia. Meanwhile, South Florida will be have a chance of thunderstorms about that same time. Highs today remaining in the lower 70Fs falling into the mid-upper 60Fs north of Port Canaveral by mid-afternoon. Highs in South Florida could reach the low 80Fs if there are enough cloud breaks. The front should clear Miami by 7pm give or take an hour, with thunder chances over by 6pm. Rain clears this area for the time being until tomorrow.

SUNDAY: Overnight, winds will remain steady and breezy from the NNW gradually veering to the N to NNE. Moisture could remain in place from Southern Brevard and South to Key Large and the Keys, so cloudy skies could remain a problem. There will still be enough moisture in the lower levels, especially as the wind becomes more NE-ENE later in the day for scattered to broken cloud cover further north toward the Magic Dividing line running form Port Canaveral to Orlando to Tampa as well. .with highs possibly only in the upper 60Fs to lower 70Fs, north of the Beach Line but warming toward the upper 70Fs South Florida with lower to mid-70Fs up and down A1A from Volusia and South, but fingers crossed on that one (fearing upper 60Fs). Only chance of rain on Sunday earlier will be over the Keys but as winds become more NE-ENE during the day some sprinkles could re-emerge under the clouds almost anywhere.

SUNDAY OVERNIGHT/MONDAY:  Thinking cap time once again. Not going to touch on the finer details for this time frame since although model guidance is close on the timing of a retrogression back to Peninsular pattern similar to last night, there are some finer details regarding where the best chance of rain will occur. The GFS is showing an area of rain developing near the SE Coast and working north as another low pressure area develops...with the highest rainfall totals over Martin/St. Lucie/toward Indian River Counties..with a newer run now showing  as far north as extreme eastern Brevard to the Port. The GFS handled the events of last night fairly well, whereas both the short term Rapid Update Cycle model and the NAM showed the highest rainfall to occur over a band across Central Florida. Much of this was likely due to the temperature profiles of the atmosphere, with the latter two stressing isentropic lift whereas the GFS was based more upon thermodynamics, which ended up being the better option. So far, the NAM is again showing Central for the highest rainfall on Monday. and the GFS is playing a repeat of last night. I'm not so sure that will be the case just yet, but chances probably will favor the GFS solution if for no other reason than how well this model has done the past few months over Florida vs. the NAM which I refused to acknowledge once it proved to have a bad track record by Mid-July .  This model did quite well last winter so I keep going back to it to see when it might start to strike gold again.

It did well with all the other features such as wind fields and temperatures, it is the placement of precipitation that has been the bust. It was surprising to the see the short term RUC bust as well, so can't knock it all that had something going, but it never happened in reality.

OTHERWISE: In either case, rain chances increase from south to north over night Sunday, with the bulk of the rainfall on Monday in either case to occur along and South of I-4. Both models now intersect though that the east coast from North Brevard to Miami will have rain in some form or another. Thunder could again come into play (elevated), but low level instability will likely be lacking every where other than in Dade County due to continued cloud cover. This instability would be advected into Dade and perhaps Broward by the closer proximity of the warmer Gulf Stream waters around South Florida. On the other hand, the NAM believes it will be the colder air aloft over Central mixing in the mid-levels along a mid-level boundary that will cause the rains over Central.

BEYOND: Either way, Monday's rain will be a daytime event, ending shortly before dark or toward mid-evening. On shore winds from the NNE-NE following almost immediate with no big cool down except over North Florida. Lows along the East Coast in the mid 60Fs, but upper 60Fs toward Central Brevard and 70Fs further South neat the Coast.  Continued breezy onshore winds gradually veering to ENE through Wednesday into Thursday and 'deceasing'  by Friday with a chance of coastal sprinkles almost anytime after sunrise Wednesday through Friday as temperatures slowly warm, with 70Fs prevalent along the east coast round the 24 hour clock, with lower 80Fs inland and west.  

Rain chances decrease and temperatures warm toward next weekend...
with possible big changes in store, especially toward the Texas Gulf Coast/Eastern Texas/and parts of the Deep South heading into the second week in November. Indicators are pointing toward a potential severe weather event in the next 7-10 days.. 

No big cool downs are shown by the latest GFS way out in dreamland time zone, but that could change. So far, it is showing nothing but warmer air for the Southern 2/3rds of the state heading toward mid-November.   

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