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Area Forecast Discussion (AFD)

Issued by Houston/Galveston, TX (HGX)

FXUS64 KHGX 212207

Area Forecast Discussion
National Weather Service Houston/Galveston TX
407 PM CST Thu Feb 21 2019

.NEAR TERM [Through Tonight]...

Coastal trough or broad coastal low pressure is still situated 
just east of the 42019 buoy which is clearly in warm sector 
airmass with T/Td in the low 70s and SE wind. Mesoanalysis shows 
LLJ moving right over top the frontal boundary and main moisture 
axis corresponds nicely with axis of shower activity through SE 
Texas. Shower activity has waned this afternoon but still plenty 
of drizzle and light rain to keep PoPs higher than what the radar 
would indicate. Fog has developed as well and should continue to 
spread inland with LIFR ceilings. Overnight it appears these 
trends will continue along with increasing sea fog in the bays and
along the coast.

.SHORT TERM [Friday Through Saturday Night]...

The main concern going for Friday and Saturday will be any severe
weather threat. In short there will be a strong trough that 
develops tomorrow over the southern Rockies. There may be a lead 
vorticity max that could trigger a few storms mainly north of 
Huntsville by afternoon/evening. The trick will be capping that 
develops and if the vorticity advection is enough to erode capping
for a few storms. EML should be spreading over the area overnight
so question of whether there will be enough parameters in place 
to get storms. SPC keeps with a marginal risk on day 2 outlook and
this looks reasonable.

Saturday Pacific front pushes through during the middle of the 
day. Again here, capping will be an issue although jet dynamics 
may be more in phase for storms along the front. That said, 
boundary layer flow is a bit more veered with 925/850mb more from 
the SW ahead of the front. Better dynamics exist north of the area
towards the Arklatex to the Miss River Valley where SPC day 3 has
slight/enhanced risk while leaving a sliver of marginal risk over
SE Texas. Again there are enough conditions out of phase that 
while storms could form, severe thunderstorms may not be a threat.
Front clears through the afternoon with storms pushing east 
fairly quickly. There will be some decent rainfall totals with 
this activity but not enough for flooding concerns.

.LONG TERM [Sunday Through Thursday]...

Models are trying to come into better agreement Tuesday morning 
with another isentropic lift event like we have had today and 
earlier this week. GFS/ECMWF are in a little better agreement with
a cold front pushing through late next week but still some 
substantial differences. Again like yesterday, ensembles and 
blends of models seem to be the best forecast for now until there 
is better consistency.



.AVIATION [18Z TAF Issuance]...

Did not make a lot of changes from previous TAF set as we continue
with this wet/messy pattern. LIFR and IFR CIGS/VIS to persist thru
the afternoon (and overnight) across our central/southern sites as
the warm front slowly moves inland. Sea fog will remain an ongoing
issue at GLS until the next cold front (Sat afternoon). Otherwise,
with short-term models verifying well of late, another round of TS
tomorrow morning along the I-45 corridor near IAH/HOU. 41



Sea fog looks to have returned across the bays/nearshore waters this 
afternoon and should persist through the overnight hours. The Marine 
Dense Fog Advisory issued earlier this afternoon is currently on tap 
through 9 AM tomorrow morning but could be extended. These very fav- 
orable conditions for sea fog will remain in place until the passage 
of the next cold front (Sat afternoon). 

Otherwise, the light to moderate NE/E winds tonight will be shifting 
to the SE tomorrow with the passage of the coastal low and an assoc- 
iated warm front. Deepening moisture and embedded disturbances aloft 
will keep the weather here foggy/drizzly with scattered showers Fri/ 
Fri night. 

The next cold front is still on track to move into the marine waters 
late Saturday afternoon. This should end the fog threat as a strong/ 
moderate offshore flow develops. A brief SCEC may be required across 
the offshore waters in the wake of the front on Sun. Winds will veer 
to the E-NE on Sun night through early Tues as high pressure settles 
over the Plains. This pattern should give us a fairly persistent and 
deep easterly flow early next week...and could help to increase tide 
levels at that time. Stay tuned. 41




College Station (CLL)  51  65  59  70  41 /  30  50  60  60   0 
Houston (IAH)          55  72  67  74  47 /  40  60  50  80   0 
Galveston (GLS)        60  70  65  72  52 /  60  50  30  60   0 



GM...Dense Fog Advisory until 9 AM CST Friday 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...Galveston Bay...Matagorda Bay.

     SMALL CRAFT SHOULD EXERCISE CAUTION through Friday morning 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.

     afternoon for the following zones: Waters from Freeport to 
     Matagorda Ship Channel TX from 20 to 60 NM...Waters from 
     High Island to Freeport TX from 20 to 60 NM.



NEAR TERM...Overpeck
SHORT TERM...Overpeck
LONG TERM...Overpeck