Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 142124
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
324 PM CST Sun Jan 14 2018


...Freezing rain possible Tuesday night and Wednesday...
...Very cold temperatures and low wind chills Tuesday night
through Thursday morning...

.SHORT TERM (Tonight through Monday night):
500mb low/trough across the Midwest United States tonight will
deepen across the north- central U.S. Monday into Mon night
allowing a blast of cold Canadian air to move into the northern
plains tonight and into the southern plains Monday before moving
into central Texas Mon night behind a strong cold front. An
onshore flow tonight through Mon night will allow temperatures to
warm to near normal tonight and Monday and slightly above normal
Mon night before the polar airmass arrives Tues morning. In
addition...moisture will increase across the CWA Monday into Mon
night to mention isolated to scattered showers Mon night as the
front approaches from the north.


.LONG TERM (Tuesday through Sunday):Very challenging forecast for
the first half of long term with an Arctic surge to overspread all
of Deep South Texas and the Rio Grand Valley from Tuesday through
Thursday. Latest model package coming in colder as a 1052mb High
pressure area moves out of Canada Monday and spreads into the
Central/Southern Plains and North Texas Tuesday. The cold air will
continue to surge into our CWA through at least Thursday before
the surface ridge moves east and the airmass modifies rather
rapidly for next weekend.

Without much detail expecting the cold front to move through the
region early Tuesday morning but could reach the Northern
Ranchlands after midnight Monday night. In any case, temperatures
will be falling and rain/drizzle chances increasing through the
day and into Wednesday morning. The main issue and impact with
this system will the rapid drop in temperatures, wind chills and
the chance of freezing rain/drizzle. Models temperature guidance
and forecast soundings show surface temperatures dipping below
freezing over the north and west and into portions of Northern
Hidalgo county. Atmosphere becomes saturated from the surface to
around 700mb as the overrunning machine, isentropic lift, turns
on. A reasonable worse case scenario is if models continue to
trend colder, and some ensemble members are colder, freezing
temperatures along with some patches of freezing rain are possible
along the Rio Grande River Wed from McAllen to Brownsville
Wednesday morning. Confidence is increasing that some winter
weather impacts will be felt across portions of DSTX but with
onset still more than 48 hours away winter storm watches or
warning will not issued at this time. Winds chills to drop below
the 30 degrees Tuesday evening and may not rise above 30 until
later Thursday morning.

As drier air moves into the Northern and Western Ranchlands rain
chances may temporary lower Wednesday afternoon and evening but it
will remain very cold with the EC the coldest and will be trending
in this direction. Models suggest a coastal trough to rapidly
develop Wednesday night and strengthen Thursday with the approach
of a moderately strong mid level shortwave trough. Rain and
drizzle to increase with Thursday possibly being the wettest day
of the week. Not expecting winter weather impacts, although a few
patches of freezing rain is still possible across northern
counties Wednesday night/early Thu, but as temperatures trend to
moderate slightly as east/SE winds at 925-850mb increase the
threat of freezing rain lessens. Overall, it will still be a west
raw Wed night and Thursday.


&&

.MARINE:(Tonight through Monday night): Seas were near 3 feet with
east winds near 8 knots at buoy019 early this afternoon. Winds will
veer to the southeast tonight and increase slightly with surface
high pressure across the southeast United States and low pressure
across the Texas panhandle. Moderate southeast winds will prevail
across the coastal waters Monday with a strong cold front moving
into north TX Mon afternoon. The pressure gradient increases across
the lower TX coast Mon night and winds will be moderate to strong
offshore the lower TX coast. May need small craft advisories for the
offshore waters Mon night. The cold front will approach the coastal
bend early Tues morning.


Tuesday through Friday...An extending period of adverse conditions
with a strong cold front passage and high pressure building into
the region. The front surges through Tuesday morning with gale
force gusts developing Tuesday mid to late morning and may last
through early Wednesday morning. Winds may diminish temporarily
later Wednesday but look to increase once again Wednesday night
and Thursday as a coastal trough develops. Strong north-northeast
winds persist through Thursday with hazardous sea lingering into
Friday. very cold temperatures are expected along with rain and
drizzle Tuesday through Thursday.


&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  51  71  55  59 /   0  10  20  50
BROWNSVILLE          50  73  55  62 /   0  10  20  50
HARLINGEN            46  74  52  59 /   0  10  20  40
MCALLEN              52  73  53  58 /   0  10  20  50
RIO GRANDE CITY      50  75  50  52 /   0  10  20  60
SOUTH PADRE ISLAND   55  69  58  60 /   0  10  20  50

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Gale Watch from Tuesday morning through late Tuesday night for
     GMZ150-155-170-175.

&&

$$

This product is also available on the web at:
HTTP://WEATHER.GOV/RGV

61...short term
59...long term



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