MESOSCALE PRECIPITATION DISCUSSION 0525
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
920 AM EDT FRI AUG 05 2016
AREAS AFFECTED...EASTERN FL PANHANDLE/WEST-CENTRAL FL COAST...
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 051320Z - 051750Z
SUMMARY...EARLY MORNING CONVECTION CONTINUES TO FIRE IN RESPONSE
TO A WEAK/PERSISTENT BAND OF MID-LEVEL VORTICITY ACROSS THE
NORTHEASTERN GULF OF MX. DEEP TROPICAL MOISTURE REMAINS OVER THE
REGION WITH PWATS OVER 2.25" ACROSS MUCH OF THE NORTHERN HALF OF
FL. VERY WEAK STEERING FLOWS SHOULD ALLOW FOR SLOW MOVING
CONVECTION WITH CELL MERGERS INCREASING THE RISK FOR FLASH
FLOODING.
DISCUSSION...VISIBLE IMAGERY THIS MORNING SHOWED SEVERAL
CONVECTIVE COMPLEXES ERUPTING ALONG THE NORTHWEST FL COAST. THE
12Z SOUNDING FROM TLH INDICATED DEEP TROPICAL MOISTURE IN PLACE
WITH PWATS NEARING 2.50 INCHES. ADDITIONALLY...TALL/SKINNY CAPE
PROFILES WERE NOTED COUPLED WITH VERY WEAK TROPOSPHERIC FLOW AND
FREEZING LEVELS ABOVE 15 KFT. ALL OF THESE INGREDIENTS SUPPORT
HEAVY RAINFALL ACROSS THE AFFECTED REGION. WHILE MOST OF THE CB
TOWERS WERE LOCATED ALONG THE COAST OR JUST OFFSHORE...VAD WIND
PROFILER DATA SHOWED DECENT LOW-LEVEL WESTERLY FLOW WHICH SHOULD
DRAW SOME OF THESE STORMS INLAND. AS OF 13Z...THE PROFILER DATA
INDICATED 10 TO 15 KNOTS OF WESTERLY FLOW IN THE 3000 TO 6000 FT
LAYER. THERE DOES NOT APPEAR TO BE ANY NOTABLE INHIBITION IN THE
RAP OBJECTIVE ANALYSIS WHICH IS BEING VERIFIED BY THE FREE
CONVECTION OCCURRING OVER MUCH OF THE NORTHEASTERN GULF OF MX.
AS USUAL...THE FLASH FLOOD GUIDANCE VALUES ARE RATHER HIGH OVER
THE REGION WHICH WOULD MAKE EXCEEDANCE OF THESE NUMBERS DIFFICULT.
HOWEVER...ANY ORGANIZED/SLOW-MOVING CELLS WITHIN THIS EXTREMELY
HIGH PWAT/WEAK SHEAR ENVIRONMENT CAN PRODUCE HEAVY DOWNPOURS
CAPABLE OF FLASH FLOODING.
THERE IS A DECENT SIGNAL IN THE CAMS FOR ORGANZED HEAVY RAINFALL
OVER THE REGION...PARTICULARLY ALONG THE COAST WHERE LOW-LEVEL
CONVERGENCE WILL BE MAXIMIZED. THE 00Z NSSL-WRF CONFINES THE
ACTIVITY TOWARD THE SOUTH WHILE THE LATEST HRRR/HRRR-PARALLEL SEEM
TO EVENLY DISTRIBUTE THE CONVECTION ALONG THE COAST.
RUBIN-OSTER
ATTN...WFO...JAX...TAE...TBW...
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey
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The sea breeze has worked its way inland across the TX coastal plains today and is now well inland this evening. The NE GOM will be watched closely this weekend and through next week as there is a potential for tropical development. The current forecast keeps the disturbed weather in the NE GOM. This is a prime example of how close to home development can occur and the GOM waters are very warm.
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Not seeing much development tropical wise for the gulf/Caribbean over the next week or two besides what happens over the northeastern part of the gulf. Rain chances should increase though during the middle/late part of the week as deeper moisture is fetched from the central and eastern part of the gulf/Caribbean. Otherwise expect more of the same, warm and muggy with some isolated afternoon showers possible.
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After a slew of 98°F and 99°F days, tomorrow should reach the Century mark, where the highs will stay for the next week. Slight chance of rain Mon, Tue, Thursday, and Saturday.
There may be a glimmer of hope regarding our rain chances and a break from the heat by next weekend, but I would like to see a bit more consistency in the guidance before buying what the computer models are selling in the Medium Range. The ECMWF is suggesting the unsettled weather to our East over near Northern Florida will meander Westbound across the Northern Gulf Coast throughout the coming workweek and approach our Region next Saturday. The ECMWF Ensembles are in somewhat agreement while the GFS and its Ensembles are less bullish on those modeled rain chances. If the ECMWF is correct, the Upper Ridge would relax over Texas allowing for cooler temperatures and unsettled weather as deep tropical moisture increases along with instability. There are also suggestions of a weak frontal boundary nearing the Red River Valley of North Texas as a vigorous shortwave trough advances East across the United States. Later in the week we will look at the potential of how those re curving Tropical Cyclones in the Western Pacific may influence the Northern Hemisphere upper air pattern and any potential sensible weather impacts for our Region. Fingers crossed that those that have not seen much...if any rainfall since June will get their chance before long.
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Edit to add the morning Updated Super Ensemble Day 8+ Analogs are suggesting a bit of a weakness over Texas as the Upper Ridge shifts both West and East indicated by the "+" signs meaning higher heights, or building High Pressure over the Great Basin and the SE United States. The Super Ensembles are updated each morning around 9:00AM local time, so we will continue to monitor for any subtle changes throughout the coming week.
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the 12Z GFS has trended the way of the 00Z ECMWF suggesting a somewhat complicated forecast challenge as the mid/upper level remnants of Eastern Pacific Tropical Storm Javier turn right or toward the Southern Rockies/Southern Plains with an approach trough and the area of unsettled weather over the Northern/NE Gulf meander Westbound.
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Overall routine summer pattern in place over the region with high pressure aloft and weak high pressure over the NW Gulf keeping temperatures hot and rain chances low.
Overall pattern will slowly change this week as the high pressure ridge over TX begins to break down and shift westward…especially by the end of the week. Edge of the current ridging over central LA early this afternoon depicts the region where thunderstorms have begun to develop (roughly from deep E TX southeast toward the central LA coast). Further east a trough of lower pressure is located over the NE Gulf of Mexico and north FL. Meso scale models show current activity in the Sabine River Valley attempting to move SSW/SW this evening and may impact our far eastern counties with a few storms. Models…especially the TX TECH WRF show an even better chance on Monday with activity approaching from the NE and moving deeper into the area…not sure if the ridge will give as much ground as this model is suggesting, but will need to keep an eye out toward the NE for any organized convection that may attempt to move into the area.
Bigger changes appear at least possible toward the end of the week into next weekend as ridging appears to get broken down by an incoming trough in the Pac NW which appears possibly strong enough to even send a weak frontal boundary into the state. At the same time both the EURO and GFS are starting to trend toward the NE Gulf of Mexico surface trough moving westward as high pressure builds over the SE US. This would allow a significant increase in moisture by next weekend over the region with much lower heights aloft and possibly some sort of frontal boundary somewhere over the state. While confidence is certainly low with regard to any frontal boundary this time of year, the pattern does support cooler temperatures and much better rain chances next weekend into the start of the following week.
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Area Forecast Discussion
National Weather Service Fort Worth TX
1223 PM CDT SUN AUG 7 2016
.AVIATION...
VFR conditions will prevail through the period with winds
fluctuating between SW and SE at 10 kts or less. Scattered showers
and thunderstorms are possible across eastern TX this afternoon
but this activity will be well east of area TAF sites. Additional
thunderstorms are possible on Monday afternoon closer to the DFW
Metroplex, but will refrain from including any mention in the
extended DFW TAF for now as the potential is too low.
-Stalley
&&
.PREV DISCUSSION... /ISSUED 319 AM CDT SUN AUG 7 2016/
The upper level ridge will continue to largely control the
weather this week but a front looks probable by the weekend.
Hot and humid conditions will continue for the next few days
across much of North and Central Texas with highs from 98-104
degrees and overnight lows in the mid to upper 70s in most
places, but in the low 80s in the urban areas of the DFW
Metroplex. Have expanded the Heat Advisory to include Montague,
Wise, Jack, and Young counties, but have decided not to extend
into Monday at this time. While some places may reach Heat
Advisory criteria on Monday, would like to further assess how
widespread 105-108 heat index values will be on Monday. The
reality may be that only isolated locations reach 105-108 degrees
while most of the region remains 100-105 degrees. Either way, it
will be hot again on Monday. This afternoon/evening and Monday
afternoon/evening, there continues a low chance for showers and
isolated thunderstorms across our eastern counties. On Monday
morning, there may be a few showers across our north and northeast
counties.
On Tuesday, most of the models develop a weak upper level low under
the ridge, just northwest of our CWA. This weak low appears to be
a piece of energy that is traveling around the top of the ridge
and breaks off. The models do not explicitly develop convection
across the region, but with this weakness aloft would not be
surprised to see a few showers or storms develop across parts of
the region during the peak afternoon and evening hours. Moisture
will still be the best across our eastern counties on Tuesday, and
forecast soundings still show fairly dry air in the mid levels
indicative of the upper level ridge overhead, but will include a
mention of low chances for isolated convection on Tuesday.
The weak upper level low quickly vacates the area by Wednesday,
and Wednesday and Thursday will be very similar to each other with
hot temperatures and a low chance of rain in the eastern counties.
We may get a break from the heat and a more promising chance for
rain by the weekend as the upper level ridge is squashed south by
a trough moving east across the country. The GFS is stronger with
this trough as it crosses the Plains and develops farther south
into the Southern Plains on Saturday. The ECMWF still has evidence
of this trough sliding into the Southern Plains, but is weaker
and slower with the timing. This pattern change allows a cold
front to slide into our area and with that will come a chance for
rain. Based on the latest guidance, timing of the front is on
Saturday with the best chances for rain that same day.
srainhoutx wrote:the 12Z GFS has trended the way of the 00Z ECMWF suggesting a somewhat complicated forecast challenge as the mid/upper level remnants of Eastern Pacific Tropical Storm Javier turn right or toward the Southern Rockies/Southern Plains with an approach trough and the area of unsettled weather over the Northern/NE Gulf meander Westbound.
Thank you, i have actually followed this forum for many year's as a lurker for great insight on the weather. We are pretty nervious with current long range forcast for Destin area so i thought after all these years i would actually post looking for some specific help. Ill be watching this week
I am a little worried about that low in the NE Gulf. It was my understanding that it was not going to affect SE Texas in any way. Now, it appears that it IS wandering this direction. Though an amateur met by hobby, I am unable to get anymore opinions and data as regards this system. Thus, I have the following questions:
1. Should I count on a tropical threat to SE Texas this coming weekend?
2. Why is this disturbance now seen as a threat to SE Texas?
3. Will this be anything like the April 18 2016 flood event, with one big difference: Higher winds?
Am looking forward to a response. Good evening, everybody.
Skyguy wrote:Dear forum:3. Will this be anything like the April 18 2016 flood event, with one big difference: Higher winds?
I'm not pro like some of the people on here, but I can safely say no. While we may get an uptick in moisture, we should not be directly impacted by this system. The areas that should be more worried is the central Gulf Coast, around NW Florida/AL/MS.
Skyguy wrote:Dear forum:3. Will this be anything like the April 18 2016 flood event, with one big difference: Higher winds?
I'm not pro like some of the people on here, but I can safely say no. While we may get an uptick in moisture, we should not be directly impacted by this system. The areas that should be more worried is the central Gulf Coast, around NW Florida/AL/MS.
If so, then what do our local mets mean by this:
Extended progs continuing to indicate a change in the pattern by
next weekend...but a slightly different one than the one offered
by yesterday`s runs. Instead of a deepening long-wave upper trof
from the west...models are now going with a combination of an
upper trof and an associated frontal boundary from the NNW and
the westward movement of that system that has been lingering in
over the far NERN Gulf. At any rate, trend appears to be going
toward wet by the weekend so no real argument with the CHC POPS
already in the grids for this timeframe. 41
Am I to understand, then, that they do not project a direct hit on SE Texas from this system, but rather the upswing in moisture you mentioned?
Skyguy wrote:Am I to understand, then, that they do not project a direct hit on SE Texas from this system, but rather the upswing in moisture you mentioned?
Indeed. While we change to a wet pattern next weekend, it will not be a direct hit from this system, but rather the cold front coming in from the NNW taking advantage of the tropical moisture that will be in place. Also, that system to our East is likely not going to develop. The only direct impacts will be flooding for the Florida Panhandle.
