Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 162259 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
559 PM CDT Fri Mar 16 2018

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


.AVIATION...VFR conditions now, but as south southeast winds
decrease to light overnight and dew points remain elevated, will
see ceilings come down to MVFR and high IFR. A weak surface based
inversion did develop around 1000 feet this morning, suggesteing
that a repeat will be possible tonight. In addition, patchy fog
will be possible near dawn, but shouldn`t be the limiting
parameter. Saturday morning MVFR ceilings may remain stubborn
with weak winds, but should lift in the afternoon.


.PREV DISCUSSION... /issued 254 PM CDT Fri Mar 16 2018/

SHORT TERM (Now through Saturday night): Under mostly to partly
sunny skies, temperatures have warmed into the 80s and in some cases
lower 90s across the region with the warmest temperatures residing
inland where a dryline is mixing eastward into our region. A broken
low CU deck developed early across interior Cameron and Willacy
Counties, however, as surface heating increased much of this cloud
cover has started to mix out.

Southeasterly surface flow should prevail through the short term
(keeping us above average for temps) as a high pressure system
continues to exit stage east. Moist southeasterly surface flow will
be capped by a strong EML, which should preclude rainfall
development. Though an isolated shower or two late in the period may
be possible, especially close to the coast.

Otherwise cloud cover develops during the night and then mixes out
during the day inland. There is some signal for patchy fog
developing tonight, especially across the Ranchlands. Winds should
remain just high enough to keep dense fog from developing,
especially in the lower valley.

LONG TERM (Sunday through Friday): The beginning of the long term
period will feature a developing mid-level low pressure system
over the High Plains and deepen considerably as it moves across
the Central Plains. A lee surface low will bring a pretty sharp
front through South Texas on Monday.

Temperatures ahead of the front will be well above normal with
highs reaching the low 90s west of Highway 69-E and into the mid
90s near Falcon Dam. Very dry air in the mid levels will keep rain
chances low with the best chance being near the coast and over the
Gulf waters Sunday night into Monday morning. As the front moves
through Monday morning into early afternoon, there will be a small
window of opportunity for a few showers or a thunderstorm, but
model sounding indicate a very strong cap just off the surface,
which will limit chances considerably. Still, with a very sharp
dew point drop behind the front, decided to keep at least a
mention of rain chances east of McAllen and along the coast.
Temperatures behind the front will remain mostly unchanged during
the day, so highs still could reach the upper 80s to low 90s,
especially if the front lags a bit longer than expected. A heat
spike won`t be out of the question Monday with a brief wind shift
to the southwest just off the surface.

The main concern in the long term will be the possibility of
elevated fire spread conditions Monday afternoon. RH values will
quickly drop to the 20s and even the teens, possibly as far east
as the coastal counties. Winds, however, may not reach the
threshold for a Red Flag Warning, but we will continue to keep a
close eye on model trends. Nonetheless, Monday won`t be a day to
do any outdoor burning.

For the rest of the period, above-normal temperatures and dry
conditions are expected through at least Wednesday with moisture
trying to return by the end of the week. Southeast winds will
also strengthen by the end of the week as another storm system
develops in the Northern Plains.

MARINE (Now through Saturday night): Looking offshore, buoy 42020
and TABSK show marine conditions have improved today as high
pressure continues to move eastward allowing the surface pressure
gradient to weaken.

Conditions should stay rather benign (with wave heights generally
less than 5 ft and winds less than 15kt) through the short term
marine period. Warm southerly flow will continue through the weekend
as a warm southeasterly/southerly return flow continues across our
marine zones. Can`t rule out a spotter shower toward the end of the

Sunday through Wednesday: Light southerly winds and low seas will
continue through early Monday ahead of a cold front. Northerly
winds will then increase to around 15 knots with the passage of
the front and then increase with a reinforcing shot of high
pressure on Tuesday. Winds may reach Small Craft Advisory levels
with seas building to 4 to 6 feet through early Wednesday.




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