"But seeing they could not See; hearing they could not Hear"
“The views expressed herein are those of the author and do not necessarily represent those of the National Weather Service or affiliate/related organizations. Please consult .gov sites for official information”

"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".

Wednesday, October 26, 2011

Chances of Rain Increase This Weekend

HURRICANE RINA: Rina is in the center of this image. Note that one any northward track it will encounter more and more shear . Additionally, it will begin to interact with land on a continue Westward course of any fashion, and likely begin to entrain the dry air shown in orange over the Yucatan. The storm is best off it were to stay but, it is moving away from the best Ocean Heat Content waters, so expect it to be downgraded today.

TODAY: High pressure has built rapidly eastward since yesterday over the Deep South and into the Atlantic. It is also sinking southward a bit as well as anticipated. Early morning inverted coastal trough set up with the deeper easterly winds, with lows at the coast in the mid-70Fs where as inland temperatures were in the lower to mid 60Fs in north winds on the front side of the inverted trough. With daybreak, the inverted trough washed out and winds subsided as the north half of the state is more entrenched within the high pressure rather than being in gradient flow with low pressure over the Caribbean.  

There is an impressive inversion at all the locations resulting in broad but flat topped stratocumulus clouds resulting in some sprinkles, but heating of the day in an other wise cloud free sky is eroding those away. It appears per satellite imagery that small cumulus clouds are replacing these clouds in many locations. Guidance up until this morning indicated that some showers could occur near coastal Brevard after dark and north into Volusia which looks 'possible', but other wise another mild night in store.

THURSDAY: Much warmer all areas with highs in the low-mid 80Fs and a more southerly surface flow while high pressure persists across the state in the Mid-Levels. Deeper atmospheric moisture from far South Florida should work as far as Dead Central by sunset, but very poor lapse rates seems to inhibit a broad coverage of showers/storms despite ample moisture. Looks more like clouds once again over showers until later in the day working from Southern Portions toward Central Thursday night into Friday.

FRIDAY-SATURDAY Frontal boundary that has emerged from the Rockies is really dragging its "Southern End Heals" as the ridge that has moved into the Atlantic continuously rebuilds back toward the west across Florida and the Gulf. The front gets stretched thin buat manages to slide into North Florida and slowly south to Central where it remains until late Saturday. Best chance of rain for the peninsula on this day, but any Thunder appears to be restricted to far south Florida where low level winds converge more and instability will be the greatest. For good precautionary measure, could through in thunder as far north as Southern Osceola over toward Vero. Otherwise, heading into Saturday it appears the best chance of rain will be on and behind the front due to isentropic lift over Central, with the boundary and moisture from South Florida working South Through the day.

SUNDAY: Boundary appears will get to the frontal graveyard close the Florida Straits, but a secondary (and stronger system and associated jet stream streak now near the Aleutians (Bay of Alaska) will be dropping into the NW U.S. In response, the front buckles and lifts back north toward Dead Central to just south of I-4 by Monday increasing rain chances once again.

HERE is where the first predicament (of several) comes. The 00z ECMWF (European Model) has the developing low (cyclogenesis) from this newer impulse to occur over the Northern Gulf of Mexico south of Pensacola, whereas the 12Z (8am EDT) GFS run reads, "No Dice, the low will from in the Ohio Valley". Big difference as far as Florida is concerned in terms of any potential 'active weather' vs. the continued " status quo benign" pattern over the state per the past week.  For now, I'm hedging more toward the GFS trend since it also is no longer bringing Rita into the state (amongst other reasons such as continuity from the past 8 days, this model's trends in the past 96 hours, and La Nina climatology).  How strong/deep this secondary trough will eventually get is another matter, so Monday has two strikes against it now in regard to how well the weather for this time frame can be predicted.

BEYOND: Latest GFS is running with a very La Nina like pattern with perhaps a bit of a NAO (Negative Atlantic Oscillation) along the  NE U.S. Coast, so this region will be host to a variety of forecast conundrums all their own through the weekend and into next week if the NAO does appear to be developing. Locally, whatever comes out of the next few days and early next week, it appears that the October climatology that I'm most familiar with along coastal East Florida of NNE-ENE winds will prevail other than in the presence of a frontal boundary. This means that cooler ocean temperatures will be drawn down the seaboard, with near shore waters already in the lower 70Fs.  This helps set the stage for inverted coastal troughs with a more direct easterly flow that is at least 8,000 ft deep and not too strong. Thus, coastal cloudiness from time to time and perhaps some very light rainfall with round the clock 70Fs heading to later next week.

HURRICANE RITA: As of noon when I started writing this post, Rita was in a good position to hold its own strength, but was moving toward water of less Heat Energy as well as getting closer to land. Thus, believe the storm will start to weaken. If it weakens too much, it could get steered into the NE Yucatan and be 'gone', at least for a while. It is a very small storm, so it could weaken quickly. Any distance further from the coast could keep Rita alive and well though. Rita is also heading toward drier air to  its north and could start to entrain some of that drier air. Shear lurks just to the storms north as well, and the further north it progresses the stronger it gets. The GFDL run is now the only model taking it to Florida. With plenty of time to spare, and with the chance of Rita being nothing more than a tropical storm if that were to occur..this should not be a 'major' issue, but is worth watching just in case. 

IN SUMMARY: Much of what the weather will be like Friday through at Least Tuesday remains a difficult reading to make...the Crystal Ball remains foggy. Perhaps it's time to resort to a Snow Globe to shake things up a bit, but the Southern Branch Jet  across the Southern Gulf and Florida is not budging, which has been the biggest thorn in the 'forecast' side. Most of the active weather should be under and south of this feature, which means better rain chances for the Keys from time to time in the next few days. So far, the Friday/Saturday/and Sunday look to be the best days for chances of rain..but decreasing from north to south during this time frame.

*** Per The Weather Channel, Rina had been downgraded as I was getting ready to hit the "send" button.

No comments: