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Area Forecast Discussion (AFD)

Issued by Houston/Galveston, TX (HGX)

                            
000
FXUS64 KHGX 230005
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
605 PM CST Fri Feb 22 2019

.AVIATION...
LIFR ceilings and fog will persist overnight and into the morning
hours Saturday. There could be some brief improvement near any
isolated light/moderate showers overnight, but that won't be the
norm and isn't indicated in the TAFs. Cold front and associated
band of shra & embedded tsra should push thru se Tx from northwest
(CLL) to se (GLS) between 13-19Z. Ceilings should gradually lift
into VFR territory a few hours after the front passes and rains
end. Look for wind gusts 15-25kt out of the wnw behind the front.
47

&&

.PREV DISCUSSION... /ISSUED 322 PM CST Fri Feb 22 2019/ 
SHORT TERM [Tonight Through Sunday Night]...

Latest mesoanalysis shows the warm front has moved inland 
basically from north of Palacios to Houston HOU to north of 
Beaumont. T/Td are in the 70s south of the front as we can confirm
here at the office. North of the front temperatures are still in 
the 60s to 50s in the Brazos valley. Temperatures may drop a 
little bit tonight but largely remain steady. If anything 
temperatures may increase a bit as the warm front moves more north
after midnight tonight.

There will continue to be chances of showers and maybe an 
isolated thunderstorm. Jet streak and vorticity max seen on water 
vapor imagery has move into the area but any convection with it is
located north of the area towards the Arklatex. There is a thin 
band of showers from College Station down to Victoria but this 
activity should not develop much more than it has. AMDAR airplane 
soundings show capping at 800-700mb and 700mb temperatures are 
pushing 8C-10C based of this an RAP mesoanalysis data. Cap should 
hold overnight going into tomorrow morning.

Upper level trough over the southern Rockies should rotate east 
into the Plains by mid day Saturday. Surface low should deepen 
near the upper low and push a Pacific cold front into the area. 
Largely this means there will not be much of a temperature 
difference, but the airmass will be significantly drier. WRF model
runs agree with a broken line of convection moving along the 
front from 12Z to 18Z Saturday. A few storms could be strong but 
given the capping, it will be a battle for significant deep 
convection to develop. SPC has most of the area in a marginal risk
and this looks on track. Greatest threat will be east and 
northeast of the area. Storms could still produce gusty winds, 
lightning and brief heavy rainfall. While soils are rather moist, 
flooding should not be a concern with storms moving through the 
area quickly.

Front should be of the coast and east of the area by 18Z to 21Z 
based on WRF model runs along with the NAM/GFS. Airmass should be 
much drier and should cool off overnight. Low temperatures Sunday 
should be in the 40s most areas with a nice warm up into the 60s 
for high temperatures Sunday.

Overpeck

LONG TERM [Monday Through Friday]...

Moisture return looks to set up once again Monday night into 
Tuesday. Forecast will keep an increase in rain chances for the 
Tuesday time period. Beyond Tuesday all of the models really 
struggle with finding a common solution. Best chance of rain next 
week does look to be on Tuesday, but depending upon the model, 
there could be some low end rain chances for much of the week 
after Tuesday. Right now think the ensemble/blended model approach
looks to be best course of action for the forecast. Usually the 
models have had a least some consistency with only some slight 
timing problems, but lately that has not been the case.

Overpeck

MARINE... Will be keeping the Marine Dense Fog Advisory in place 
for the bays and nearshore waters through 9AM Sat morning. Some 
brief periods of slightly improved visibilities are possible the 
rest of this after- noon, but should fall once again this 
evening/overnight. This Advisory may be extended a couple of 
hours tomorrow morning...depending on the timing of the next cold 
front. Per the models...the front is expected to reach the coast 
around noon (Sat), with scattered showers and isolated 
thunderstorms along/ahead of it. Moderate/strong N to NW winds in 
the wake of the front will help clear the fog out of the marine 
areas late Sat afternoon/early evening. SCEC flags could also be 
posted very briefly over the coastal waters Sat night. How- ever, 
with the surface high building in quickly over the region, we will
likely see winds decreasing once again by Sun morning. 

Winds will turn easterly late Sunday and slowly strengthen Mon/Tues 
as the fetch deepens. As a result, tide levels are forecast to rise 
to around 2.5 ft above MLLW. Will have to watch for possible run-up 
issues from mid-week on. Otherwise, unsettled weather should return 
to the coastal waters Tues along with onshore winds. 41

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      55  68  42  64  41 /  50  80   0   0   0 
Houston (IAH)              62  73  47  67  45 /  40  80   0   0   0 
Galveston (GLS)            66  70  53  65  53 /  40  70   0   0   0 

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Dense Fog Advisory until 10 AM CST Saturday for the following 
     zones: Brazoria Islands...Chambers...Coastal Brazoria...
     Coastal Galveston...Coastal Harris...Coastal Jackson...
     Coastal Matagorda...Galveston Island and Bolivar 
     Peninsula...Matagorda Islands.

GM...Dense Fog Advisory until 10 AM CST Saturday for the following 
     zones: Galveston Bay...Matagorda Bay.

     Dense Fog Advisory until noon CST Saturday for the following 
     zones: Coastal waters from Freeport to Matagorda Ship 
     Channel TX out 20 NM...Coastal waters from High Island to 
     Freeport TX out 20 NM.

&&

$$