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Area Forecast Discussion (AFD)

Issued by Brownsville/Rio Grande Valley, TX (BRO)

FXUS64 KBRO 191730 AAB

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1130 AM CST Mon Feb 19 2018

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


.AVIATION...VFR to MVFR conditions expected to continue this
afternoon into early tonight with strong surface winds of 25 to 
30 knots and gusts above 35 knots this afternoon. Winds diminish 
after sunset this evening to 10 to 20 knots through tonight as 
the low level jet moves east. IFR conditions expected early 
tonight with continued southeasterly flow off the Gulf. Increasing
winds and sufficient mixing brings MVFR conditions back by mid 


.PREV DISCUSSION... /issued 540 AM CST Mon Feb 19 2018/ 

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...South Texas wind machine will be in full effect today.
Morning sounding measured low level jet near 50 knots at 2000
feet. Once daytime mixing begins, a good portion of these winds
will mix down to the surface, with winds of 25 to 30 knots
expected areawide today, with gusts above 35kts this afternoon.
Winds will finally relax after sunset as the llvl jet is pushed
well offshore. Winds tonight will still remain elevated in the 10
to 15 knot range.

PREV DISCUSSION... /issued 419 AM CST Mon Feb 19 2018/ 

SHORT TERM (Now through Tuesday): A series of areas of low 
pressure will continue to develop off the lee of the Rockies in 
Colorado and eject to the northeast during the next 36 hours. This
will continue to keep the gradient tightened and keep the low- 
level jet strong through the next 24 hours. Mixing of this jet 
down to the surface today will bring another breezy to windy day 
across the valley. Wind Advisories are in effect for areas east of
US 281 today, with Winds of 30 to 35 mph expected. This will also
continue to keep warm temperatures going in the region, with 
highs today in the upper 80s and lower 90s. Tonight into tomorrow,
the llvl jet will shift further offshore, allowing winds to relax
across the region. This is due to the next sfc low diving 
southward into Texas with the next cold front. Southerly flow will
still continue, but much lighter than Monday. Highs will again 
reach the mid to upper 80s. The approach of the next front will 
bring a small chance for showers Tuesday afternoon for the 
northern ranchlands, but the better rain chances remain beyond the
short-term forecast.

LONG TERM (Tuesday Night through Sunday): 500mb trough across the
western United States Tuesday will continue to provide a southwest
flow aloft across south Texas Wednesday and Thursday. At the
surface...a cold front will move into central TX Wednesday and
stall to the north of the CWA Wed night. The front will provide a
focus for showers and thunderstorms to develop across portions of
south TX Wednesday into Wed night and rain chances will increase
across the CWA Wed night with the best chance of rain across the
northern ranchlands. A southeast flow will prevail across the Rio
Grande valley Wednesday through the rest of the week as the front
weakens and retreats northward Thursday into Thurs night. This
will provide a chance of showers or thunderstorms...mainly across
northern portions of the CWA Thursday. Unseasonably warm 
temperatures will continue on Wednesday before the increase in
clouds and rain chances provide slightly cooler temperatures on
Thursday. Warm and relatively dry conditions will prevail Friday
before a weak cold front moves into south TX Saturday providing a
slight chance to chance of showers or thunderstorms across deep 
south TX for the rest of the forecast period.

MARINE (Now through Tuesday): Marine fog continues right along the 
coast, with visibilities hovering between 1 and 3 miles. Fog should 
thin through the day, as a strong low-level jet brings gusty south 
winds to the region. Small Craft Advisories have been posted for all 
marine zones through the day for winds around 20 knots. This will 
kick seas up to 5 to 8 feet for the Gulf and create choppy to rough 
bay waters. Southeast winds will remain elevated overnight as the
jet shifts further offshore and continues to mix to the surface. 
20 knot winds are still possible for the offshore Gulf waters 
tonight. Improved conditions are expected tomorrow as winds 
decrease to around 15 knots.

Tuesday night through Friday...Moderate southeast winds will
prevail across the coastal waters Tues night before the pressure
gradient weakens across the lower Texas coast Wednesday as a cold
front moves into central Texas. Light to moderate south to
southeast winds should prevail across the western Gulf of Mexico
Wednesday and Thursday as the pressure gradient remains weak 
across the lower TX coast. Winds should increase slightly Thurs 
night into Friday as the pressure gradient increases across the
coastal waters. 


TX...Wind Advisory until 7 PM CST this evening for TXZ250-251-253>257.

GM...Small Craft Advisory for winds until 7 PM CST this evening for 



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