Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 142358 AAA

Area Forecast Discussion...UPDATED
National Weather Service BROWNSVILLE TX
558 PM CST Sat Jan 14 2017

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


.AVIATION...Clouds and southerly winds will continue across the
region this evening. Cigs will lower to MVFR to possibly IFR or
even lower during the overnight hours as a low level jet increase
moisture across the region. However...winds at the surface may
become weaker allowing for some fog formation. Small shower
chances will possible. Winds will increase on Sunday as a strong
storm system passes across Central TX...with 15 to 20 mph winds
and higher gusts.


.PREV DISCUSSION... /issued 250 PM CST Sat Jan 14 2017/

SHORT TERM (Now through Sunday night): Current precipitation
noted on radar in response to a weak midlevel impulse stretching
northward across Deep South Texas. Most showers have remained
light, but have been enough to completely wet the ground in some
places in the mid- valley. The impulse will pivot to the northeast
this afternoon, with a brief lull this evening. Tonight, the
leading edge of the large- scale negatively-tilted H5 trough will
pivot into West Texas, with our area along the very southern edge.
Lift around the edge will bring some shower activity again into
central Texas, with some activity developing in the western valley
late tonight into Sunday morning. These showers will be similar
to today, with light accumulation. SPC has the line for general
activity thunder right along the northern edge of the CWA, so
thunder is not out of the question for areas near Zapata and
Hebbronville. With increased cloud cover today, highs have not
quite reached the 80s yet, but may add a couple more degrees
before sunset. Similar conditions expected tomorrow, with mostly
cloudy skies holding temps into the lower 80s at best. By tomorrow
evening, the H5 trough is moving into western Oklahoma, taking
midlevel energy with it, and leaving a moist southwesterly Pacific
tap in place. Cannot fully eliminate rain chances after midnight
Sunday night, as the weakened tail-end of a line of thunderstorms
to the north may clip the very northern edge of counties again.

LONG TERM (Monday through Saturday): A 582 dam height center over
Florida will lie over the southern flank of strong but retreating
high pressure area covering the Northeast United States on Mon. A
552 dam ht. center, a mid level low, will be vertically stacked
over a 1009 mb low over Oklahoma, with a sfc. cold front extending
south into the Upper Valley. A positively tilted mid level trough
will extend southwest from the Oklahoma low to over Baja

It should be warm and breezy along the coast Monday due to
moisture pooling ahead of the front, with isolated coastal showers
possible, with weaker winds across the Upper Valley near and
behind the front. Southwest flow aloft ahead of a very elongated
positive tilt mid level trough to the west will offer only
parallel flow and little forward push. Warm moist air will funnel
into the area ahead of the front with highs again in the 80s. A
few more showers may develop Monday night as the front stalls out
over the Upper Valley.

Mid level ridging into the Pacific Northwest will push cP air
south into Texas on Tuesday, and previous solutions did push a
front through the area late in the day, but now it looks like any
front will not have the upper support to support onward movement
through here. Look for cloudier weather with increased rain
chances and slightly cooler temperatures Tuesday and Wednesday as
the frontal boundary adjusts position over the area.

Temperatures will be moderated slightly on Tuesday due to
increased cloud cover (70s), with Tuesday night lows in the 50s
and 60s, and with highs in the lower to mid 70s Wednesday. While
there will be drier air upstream, with the upper trough now
hanging back, the near by surface front will not move far and a
chance of rain will persist into Thursday. A piece of that trough
in the form of a mid level low or open wave may swing far enough
south Thursday through Thursday night, across the Rio Grande
Plains, to support extended and potentially better rain chances.
The GFS and ECMWF seem to be in a little better agreement today
with the Thursday scenario of better rain chances and, due to the
upper support, the possibility of a few general thunderstorms as

Winds and warmth will increase Saturday with return flow as a
storm system deepens in the plains. The long range models hint at
a stronger front moving through the RGV Saturday night into Sunday
morning, right at the end of the extended forecast.

Now through Sunday night: Winds will begin to ramp back upwards
tonight as the next surface low develops across West Texas. Winds
tonight will continue in the 10 to 15 knot range, while the
continued long fetch across the Gulf keeps seas right around 5
feet. As the surface low treks across the Texas High Plains, winds
will shift more to the south during the day and increase to 15 to
20 knots. Small craft will need to exercise caution due to
increased winds, and a Small Craft Advisory may be needed is
forecast winds rise any further. Not much change for the seas
tomorrow into tomorrow night as already agitated conditions
continue. A few streamer showers are possible late tonight into
tomorrow morning right along the coast.

Monday through Thursday: Low end small craft advisory conditions
may linger into Mon morning, but winds and seas will improve
thereafter, with light to moderate winds and mdt. seas holding
through Thursday. Winds will generally be out of the southeast to




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