Been a few days since I've posted, as the forecast at that time has remained on track. ..although it has been entertaining to watch each and every model flip flop and disagree between and within themselves in even only the mid-range for a number of days concerning how this week will unfold. The long range has been a comedy, and this will likely continue during the change of seasons. After tiring of watching the flip flops from one extreme to another, decided to post and run with La Nina climatology even though the presentation for today's post could certainly change, will run with the following for the short term with post- and re- flection on past and future trends:
TODAY: Mid Level trough that was in place since our last cold front never cleared the state. That much was correct. A short wave trough that produced severe weather in Oklahoma over the weekend progressed east yesterday and dropped a portion into the mid-level trough over Florida that was already in place overnight completely moisture starved. Although mostly transparent, it did bring the dewpoints up a bit and reflected at the surface with a NW -WNW wind which should continue today toward sunset. The old frontal boundary that was east of the state backed a bit on the southern end toward far SE Florida, whereas the more northern portion has moved on out into the Atlantic. Weak low pressure formed off the SE coast bringing some showers there yesterday, but that too should kick out by afternoon. At time, only clouds are over this area with showers mostly offshore. The clouds could remain a problem for most of the day until the 850mb trough moves out tonight. Otherwise, some high cirrus clouds thinly dispersed could pass over head Central and South Florida today with highs in the mid-70Fs, a bit warmer South Florida, although if the clouds remain near the SE Coast it's debatable.
TONIGHT: Winds become more northerly to NNE overnight as the mid-level troughs finally start to move east of the state and high pressure builds across the Deep South in their wake. Coastal lows might occur within the first two hours of sunset, then level off toward the lower 70Fs if not rise after 3AM as winds blow across sea surface temperatures in the upper 70Fs...inland lows a good 8-12 degrees cooler from US1 and westward. Hey, if one lives along and east of A1A, US1 is inland.
TUESDAY: Shallow NNE-NE wind with a trajectory coming off the Carolina Coast will be moist only in the lowest levels making for another rain free day with perhaps some low topped / flat bottomed stratocumulus clouds with highs again in the 70Fs. Looks like another round of 24 hour 70Fs for the coast, with slightly cooler inland and west coast morning lows.
WEDNESDAY: High pressure at the surface builds further east into the Atlantic and mid-level high pressure finally starts to follow suit with deeper easterly flow although still coming off the Mid-Atlantic coast as opposed to a long easterly trajectory from well out in the Atlantic which otherwise would advect deep moisture across the state, or at least have the potential to. Could be a pocket of moisture convergence that will move across South Central Florida on this day resulting in light low topped showers there, but otherwise continued round the clock 70Fs for the coast, with daybreak and sunset stratocumulus clouds during the diurnal temperature change cycle (as the sun rises and sets).
THURSDAY/SATURDAY: Gets messy. The latest GFS and now the NAM (since it extends toward this time frame) imply that the next frontal boundary which has been delayed a full 48 hours since first portrayed last week will stretch ENE-WSW along the southern branch subtropical jet, leading to passage of a pre-frontal trough with no temperature change associated with it toward Thursday afternoon. This boundary is to eventually align very close to the Florida Straits (the north side of them) by Saturday as the main front skims the North half of the state with a return to 70Fs and increased clouds after a warm Thursday. Timing will remain an issue probably for the next day or so, and impacts of the pre-frontal trough will depend on the time of day it moves through each area. So far, it appears that Thursday will be much warmer with highs in the low-mid 80Fs..with the better chance of rain over South Florida, showers possible almost anywhere until better ironing out of the finer details can be made. But do note, at one time this front has been portrayed to being everything from a squall line with 40Fs to follow, to being completely benign and dry with zero impacts other than a cool down. The morning run is favoring the later, but as a reminder, it could change on the next run.
SATURDAY/SUNDAY: High pressure quickly builds eastward across the Deep South into the SW Atlantic with return onshore flow. Very breezy with more 70Fs round the clock in shallow on shore flow. Any rains to remain south of Florida initially but should retrograde toward the Keys and far South Florida late weekend .
TROPICS/RINA/PATTERN: All in all, the general pattern has been for quick moving systems to skirt across the northern U.S. very progressively with a near neutral to retrograding pattern over the South Florida and the Caribbean . Other than an occasional mid-level trough across the southern tier of states this area has been neutral. Southern Branch Jet Stream across Florida with an impulses being sheared out before dropping into the state as a result, and no impulses on the approach from off the Southern California coast leads to quick and moisture starved Northern Stream impulses since they cannot tap into deep moisture from the south and surface high pressure continuously re-establishing across Texas, the Northern Gulf, and North Florida means quick and ineffective cold frontal passages other than a wind shifts and a shot of showers. Very La Nina like .
Thus, the future of Rina remains problematic. For now, if one assumes the above paragraph, this storm will never pose a problem for Florida...and we'll have
" 'Rinal' Failure". Models that are bringing it to Florida have it doing so by the weekend. For that to occur, they also show it strengthening , significantly at that, and being drawn further north, then being pulled ENE-NE ward ahead of the next front later this week.
Never say never in these cases, so it is worth watching. But, given the trends of the past few days during 'down time', the GFS has not once brought it northward nor strengthened it to the level portrayed by those models that have brought it north. Shear should increase again north of the system tonight, so I'm favoring the idea it will be lingering in the same general area as late as Halloween. We'll know soon enough ...but South Florida residents should at least keep an ear open for any rapid changes in strength and motion through Thursday.