495 
FXUS64 KBRO 191720 AAB
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1120 AM CST Wed Jan 19 2022

.DISCUSSION...Updated for latest aviation discussion below.

&&

.AVIATION...MVFR ceilings at KBRO with low clouds moving north 
along the coast. VFR at KHRL and KMFE. A strong cold front will 
push through the area tonight through Thursday morning. Ceilings 
will lower to MVFR overnight and patchy, MVFR visibility fog may 
develop ahead of the front. TAF sites may experience a shift to 
gusty, strong north winds around dawn Thursday with the arrival 
of the cold front. KMFE could see several hours of 15 to 25G30 
MPH, and KHRL and KBRO could see 20 to 30G35 MPH winds Thursday 
morning.

&&

.PREV DISCUSSION... /issued 539 AM CST Wed Jan 19 2022/ 

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Latest surface observations and satellite images
indicate MVFR conditions at all Rio Grande Valley aerodromes due
to patchy fog and low clouds. VFR conditions are expected to
return around 14Z as winds become moderate to breezy. Winds are 
expected to decrease this evening as a cold front approaches the 
area. Patchy fog and low ceilings are expected to return late 
tonight with MVFR conditions possible by 07Z. A strong cold front 
will surge into the region late in the period. 

PREV DISCUSSION... /issued 359 AM CST Wed Jan 19 2022/ 

SHORT TERM (Now through Thursday): Satellite images and surface 
observations indicate that some patchy fog has developed across 
portions of the Brush Country early this morning. The fog is 
expected to lift and mix out by mid morning as winds increase. 

A nearly zonal flow aloft and a persistent low level southerly flow 
will continue to advect warm and moist air into deep south Texas 
today. Surface low pressure across northern Texas will maintain a 
moderate pressure gradient, resulting breezy southerly winds today, 
especially near the coast. A dry line/prefrontal trough will move 
into the western portions of the CWA this afternoon and shifting 
winds to the northwest. The downsloping winds will lead to very warm 
temperatures, with highs in the 80s, across the area today. No rain 
is expected today or into this evening.

Now the main story! An arctic cold front will surge into deep south 
Texas late tonight. Models remain in good agreement with the timing 
of this front reaching the northern Ranchlands around midnight and 
south of the Rio Grande Valley by daybreak Thursday. Isolated to 
scattered rain showers will develop along and ahead of the front 
with the best rain chances across the eastern portions of the CWA 
and over the Gulf waters. In addition...will mention some patchy fog 
developing ahead of the front late tonight as winds become light. 

Strong cold air advection and overrunning conditions will develop in 
the wake of the front. Low temperatures tonight will be the highs 
for the day on Thursday, as temperatures will significantly fall on 
Thursday in the wake of the front. Thursday will be rather chilly 
with cloudy skies and brisk north winds. Temperatures will drop into 
the 40s in the Brush Country and 50s across the Rio Grande Valley 
Thursday morning. Temperatures will continue to fall further during 
the day with all areas , except for the beaches, dropping into 40s. 
Models guidance continues to indicate the temperatures will struggle 
to get out of the low to mid 40s by afternoon, especially across the 
northern ranchlands. Also, periods of rain and drizzle will develop 
through the day with better rain chances near the coast. Will lean 
towards a blend of the NBM and the colder NAM/MET for temperatures 
Thursday afternoon. 

LONG TERM (Thursday Night through Tuesday):Major Longwave trough 
will be extending from the Canadian Maritime to NW Mexico with 
Arctic air associated with a 1040mb Surface ridge, over Iowa, 
spilling south into Texas Thursday night and Friday.  Model guidance 
continue to trend lower with the overall atmosphere temperature 
regime and are now showing slightly deeper cold air and freezing 
temps at the surface to support better probability of a mix of sleet 
and freezing rain for the western two-thirds of the CWA. 
Collaboration with WPC Winter Wx desk and neighboring NWS CRP 
supports a slew of winter weather highlights for the Thursday night 
and Friday morning period. At this time we will be issuing a Freeze 
Watch, Winter Storm Watch, and a Wind Chill Watch.  Please see the 
Watch/Warning/Advisory section and the individual watch products 
(WSW,NPW) for details on time and zones impacted. Overall, the time 
period for impacts will as early as 10 PM Thursday night through 
Friday morning.  Concerns will be for accumulation of sleet of 
better than one-tenth of an inch and some patches of Freezing rain 
with amounts right now less than one-tenth.  These amounts can 
increase as QPF values from impressive isentropic ascent have been 
increased adding to potential dangerous situation. WPC QPF values 
are close to one quarter inch between Midnight-6 AM Friday which of 
course is when freezing temperatures will occur.  

Upper Trough axis will be slow to move east Friday with cold air 
advection and the thick overcast persisting keeping any appreciable 
warming limited. Rain/winter mix could linger through the morning 
slowly ending west to east with the Lower Valley still seeing light 
rain and drizzle much of the day. Highs on Friday were lowered two 
or three degrees across the board with 40s for all locations. 
Another freeze is probable Friday night into Saturday for all areas 
except the Lower RGV and South Hidalgo as partial clearing takes 
place as the trough axis shifts eastward. Surface winds do turn 
easterly which might allow for some modification of the cold air and 
further adjustments for this time period are likely.  

A brief lull in the rain chances and not as cold temperatures are 
expected Saturday with mid-level ridge building in between the 
exiting trough and an upstream upper low. Highs recover into the 50s 
and may approach 60. The next system is promising to be quite potent 
with models suggesting a quick uptick in isentropic ascent with 
widespread rain developing Saturday night into Sunday and lingering 
Monday as the upper low will be slow in moving east. Rain amounts 
could range from one-quarter to one-half inch possibly more due to 
the slow moving system. This system will not be as cold but still 
temperatures will below normal with lows in the upper 30s and 40s 
and high mainly in the 50s. Warm and drier conditions are expected 
for Tuesday with another potential upper level storm system and 
cold front approaching later Wednesday. 

MARINE:(Now through Thursday): Buoy 42020 reported south winds at 
18 knots with gusts around 21 knots and seas around 5.6 feet with a 
period of 7 seconds at 310 CST/910 UTC. Small Craft Advisory remains 
in effect for the offshore Gulf waters (20-60 NM out) due to strong 
south winds and rough seas. Exercise Caution conditions will prevail 
today along the lower Texas coast today due to elevated southerly 
winds. A strong cold front will move through the waters late tonight 
into early Thursday morning, bringing hazardous marine conditions 
with gusts to gale-force possible. A Gale Watch remains in effect 
for the Gulf waters from 3 AM Thursday until Noon Thursday. 
Confidence remains low at this time that the Gale Watch needs to be 
extended beyond Noon Thursday as 925mb winds may not support sustain 
or frequent gales into the afternoon. 

(Thursday night through Sunday):A tight pressure gradient 
over the Western Gulf of Mexico between a major cold front and 
Arctic high pressure across the Central U.S will continue to drive 
strong north winds over the Lower Texas coastal water through 
Friday. The gradient slackens Friday night and Saturday with the 
ridge shifting east. The approach of an upper level low Sunday and 
Monday will allow for coastal trough development with northeast 
winds increasing once again. Widespread rain and drizzle with very 
cold temperatures are expected Thursday night and Friday with 
another round of rain Sunday and Monday.  

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  79  54  56  36 /   0  20  60  80 
BROWNSVILLE          84  52  55  36 /   0  20  60  70 
HARLINGEN            84  50  54  34 /   0  30  60  80 
MCALLEN              85  51  54  36 /   0  20  50  80 
RIO GRANDE CITY      86  50  51  34 /   0  20  40  70 
SOUTH PADRE ISLAND   74  58  59  42 /   0  20  70  80 

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...High Rip Current Risk through Thursday afternoon for TXZ256-257-
     351.

     Winter Storm Watch from late Thursday night through Friday 
     morning for TXZ248>252-351-353.

     Freeze Watch from Thursday evening through Friday morning for 
     TXZ248>252-254-351-353.

     Wind Chill Watch from late Thursday night through Friday morning 
     for TXZ248>252-254-353.

GM...Small Craft Advisory from 6 AM to noon CST Thursday for GMZ130-
     132-135.

     Gale Warning from 6 AM to noon CST Thursday for GMZ150-155-170-
     175.

&&

$$

This product is also available on the web at:
https://weather.gov/rgv

54-BHM/69-Farris/58-Reese/65-Soria