Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 271801

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1201 PM CST Fri Jan 27 2023

...New AVIATION...

(Today through Saturday Night)
Issued at 308 AM CST Fri Jan 27 2023

Another chilly start to end the work week with temperatures from the
upper 20s to upper 30s inland early this morning. Patchy frost will
persist at some locations, mainly north of I-10 through around
daybreak. Otherwise, return flow from the departing surface high is
beginning to set up across the forecast area. It will be another dry
day, but slightly warmer given southerly flow at surface and aloft.
Highs will generally be in the low 60s.

With continued southerly warm and humid air, PWATs will begin to
increase tonight from the south. This is in response to a surface
trough that will develop/move along the TX coast tonight into
Saturday. Latest Nighttime Microphysics satellite imagery shows a
widespread area of mid clouds spreading over South TX/Deep TX coast.
This blanket of clouds will slowly move across SETX today. As we
move into the night hours, isentropic upglide on the 295K surface
will take place, which combined with increased low-level
moisture, light rain/drizzle will be possible.

The best rain chances will be on Saturday throughout the day as the
surface/inverted trough moves along the Upper TX coast and southerly
warm air intensifies. Should not be a total washout, but off and on
showers will persist through the day. The main focus arrives by
Saturday night as a weak surface low develops over north TX,
dragging a cold front on Sunday. Ahead of the front, persistent
southerly flow, deep low-level convergence on the nose of a
southerly LLJ will be enough to produce increasing rain chances and
isolated to scattered thunderstorms throughout the night. With
continued warm southerly flow and abundant cloud cover, temperatures
will remain on the warm side with highs from the upper 60s to low



(Sunday through Thursday)
Issued at 308 AM CST Fri Jan 27 2023

Sunday starts an active period of rain chances for the long term.
Southeast Texas will continue to be in the path of the sub-
tropical jet that`s oriented SW to NE from Mexico to the
Carolinas. This SW flow aloft will continue to send shortwave
troughs that will invigorate showers along the coast and across
Texas. Meanwhile, the polar jet oriented across the northern half
of the US will have several shortwave troughs pushing across The
Rockies and invigorating leeside lows across the Central Plains
that quickly race to the northeast and drag cold fronts through
South CONUS.

This repetitive pattern starts on Sunday with a 30-40kt LLJ
setting up across Southeast Texas ahead of a leeside low emerging
off The Rockies. We can expect scattered streamer showers in the
morning until a cold front arrives in the afternoon that will
slowly make its way towards our coast. WPC has placed areas south
of I-10 in a Slight Risk for excessive rainfall on Sunday given
the fact that the sub-tropical jet overhead will provide ample
diffluence aloft while PWs climb to 1.5-1.7 inches. Forecast
rainfall totals range from 1-3 inches south of Huntsville and east
of Brenham with the highest rainfall totals expected to fall
along our southeastern counties. With the front pushing through a
little slower now and passing through Southeast Texas during the
afternoon with peak daytime heating, instability should be enough
for some of these showers to become strong storms along the front,
so SPC has placed most of our CWA in a Marginal Risk for severe

This front will push offshore by Sunday evening before stalling
in the Gulf. By Monday, a shortwave trough embedded in the SW flow
aloft will invigorate a coastal trough along this stalled frontal
boundary that will push inland into Southeast Texas as a weak low
before racing to the northeast towards the Mid-Atlantic on
Tuesday. Therefore, 30-50% PoPs will remain on Monday and Tuesday
with showers originating along the coast Monday morning and
spreading north by Monday evening and into Tuesday. Relief from
rain will be brief as another stronger shortwave pushing through
the Rockies on Wednesday will sweep a cold front through Southeast
Texas on Wednesday evening/Thursday morning.



(18Z TAF Issuance)
Issued at 1135 AM CST Fri Jan 27 2023

VFR conditions with light southerly flow will continue through
this evening. Increasing southerly flow will bring increased
moisture tonight causing CIGs to lower and scattered light rain
showers by Saturday morning. The lowest CIGs will be across the
north and western parts of the region impacting CLL and UTS where
MVFR conditions with ceilings around 2500ft will develop around 8
to 10z, then down to IFR conditions after 12z with ceilings
between 500 and 700ft. CLL and UTS will also have the chance for
some patchy fog reducing visibility down to 3 to 6 miles
overnight. CXO, IAH, HOU, and SGR will generally stay in MVFR
conditions tonight through Saturday, but there may be a few hours
of IFR conditions between sunrise and noon. Coastal terminals
(LBX and GLS) will not be getting down into the IFR conditions,
but MVFR conditions are still likely by 12z. Ceilings will remain
an aviation concern through the next several days at least.

Some light isolated showers will begin to pop up overnight, but
expect an increase of showers between 12 and 18z with a lull
developing after that. A cold front will approach the area on
Sunday increasing the chances for showers and thunderstorms.



Issued at 308 AM CST Fri Jan 27 2023

Gentle to moderate onshore flow will resume this afternoon as high
pressure begins to push east. Onshore flow quickly strengthens
after sunset tonight with Advisory flags most likely needed shortly
after midnight tonight. Fresh to strong winds and building seas
will persist through most of the day on Saturday and into Sunday
morning until a cold front arrives Sunday afternoon. Scattered
showers expected on Saturday with increasing rain chances
overnight on Saturday and into Sunday morning.



College Station (CLL)  61  48  68  61 /  10  30  30  60
Houston (IAH)  61  52  71  63 /   0  30  40  70
Galveston (GLS)  61  58  69  62 /  10  30  30  70




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