Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 302338 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
538 PM CST Mon Jan 30 2023

...New AVIATION...

.SHORT TERM...
(Tonight through Tuesday night)
Issued at 231 PM CST Mon Jan 30 2023

A strong cold front will finish making its way through the County
Warning and Forecast Area this afternoon/evening. I continued to
favor the NAM for temps this package. That said, the main impact
will be lower temperatures which will drop into the 30s and 40s
tonight. High temperatures on Tuesday will be 30 degrees colder
than today, settling from the upper 30s across the Northern
Ranchlands to the upper 40s for the Lower Valley. Then, low
temperatures Tuesday night will be mostly in the 30s across the
area except slightly higher for the immediate coast.

A few spots across the Ranchlands could see freezing temperatures
Tuesday night/Wednesday morning. For now, we are also watching the
potential for low wind chill readings. If winds remain strong enough
and also maybe back a bit more to northwest (bringing cold overland
temps into the picture) and temperatures stay low, a case could be
made for a possible wind chill advisory Tuesday night.

Yes, there will also be light rain, but precip accumulation in this
overrunning scenario will remain meager. That said, a tenth of an
inch or two of rain could accumulate Tuesday night. While forecast
soundings from the NAM show a nose of below zero colder temperatures
just above the deck across the northern sections, freezing rain
probability remains low and not enough to justify mention in the
deterministic forecast. It is worth noting that the probability is
not zero, however. Bottom line for the short term forecast? Look for
cold, dreary, gray, and moist (wetting) weather.

&&

.LONG TERM...
(Wednesday through next Monday)
Issued at 231 PM CST Mon Jan 30 2023

Have gone full NAM even into the start of the long term, as it was
the only model with a grip on this arctic air mass. Not too much
of a surprise, as the NAM consistently fairs better in these
shallow cold air masses through South Texas, and it once again has
beat global models or any sort of blended model output. Beyond
the NAMs reach, have essentially mixed NBM and NBM10 into Friday
to help bring temperatures down.

Mid-level flow remains southwesterly into late this week, before
the next shortwave runs from Baja CA through northeast Texas into
Friday, so until then will lean cooler with persistent northerly
flow, low level clouds, and overrunning rain chances. The
approaching mid-level trough axis could enhance rain chances late
Wednesday through Thursday with more showers than light rain or
drizzle, especially along the coast. Total QPF at this time
remains generally a tenth to a quarter of an inch.

Skies finally clear from west to east into Friday, with
radiational cooling bringing another couple cold mornings Friday
and Saturday. Highs over the weekend warm back into the 70s. A
weak frontal boundary is expected on Sunday with little to no
fanfare at this time, potentially even stalling just north of the
CWA. Above normal temperatures return Monday, with 80s possible
across the brush country and upper valley.

&&

.AVIATION...
(00Z TAFS)
Issued at 531 PM CST Mon Jan 30 2023

A cold front currently moving through the Lower Valley will
back southeast winds to northeast and then north. Low clouds will
develop with ceilings lowering from MVFR to IFR this evening,
with LIFR ceilings possible late tonight into Tuesday. Isolated to
scattered light rain and patchy drizzle are expected through the
next 24 hours.

&&

.MARINE...
Issued at 231 PM CST Mon Jan 30 2023

Now through Tuesday Night...Opted to hoist a small craft advisory
for northeast winds behind a strong cold front edging through the
CWA and into the coastal waters this afternoon. The advisory is
posted for all waters through midnight, but could be extended. The
pressure gradient will remain tight through the remainder of the
short term and winds on the Gulf will remain elevated, ranging from
small craft exercise caution to low end small craft advisory
criteria. Seas will also build through the period. Winds on the
Laguna may stay just below advisory criteria after tonight. The
chance for rain will remain high on the waters, especially Tuesday
night as a coastal trough develops.

Wednesday through Monday...Low pressure across the Western Gulf
gradually works northeast as high pressure builds over the
weekend. Expect showers and light rain or drizzle into Friday
before a mostly clear weekend. Moderate to strong northerly flow
brings Small Craft Caution to Small Craft Conditions Thursday
afternoon into Friday afternoon. Onshore flow returns over the
weekend with more favorable marine conditions. A weak frontal
boundary approaches on Sunday, but may stall, with moderate
southeasterly flow expected on Monday driving potential SCEC to
SCA conditions offshore.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             46  48  38  47 /  20  20  60  40
HARLINGEN               43  46  37  46 /  30  30  70  40
MCALLEN                 42  44  38  46 /  30  30  70  40
RIO GRANDE CITY         42  43  38  46 /  40  30  80  30
SOUTH PADRE ISLAND      55  55  44  51 /  30  30  70  50
BAYVIEW/PORT ISABEL     49  49  40  48 /  30  30  70  40

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory until midnight CST tonight for GMZ130-132-
     135-150-155-170-175.

&&

$$

SHORT TERM...54-BHM
LONG TERM....56-Hallman
AVIATION...63-KC


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