National Weather Service Raw Text Product

Displaying AFOS PIL: AFDBRO Received: 2018-10-12 08:57 UTC

FXUS64 KBRO 120857

Area Forecast Discussion
National Weather Service Brownsville TX
357 AM CDT Fri Oct 12 2018

.SHORT TERM (Today through Saturday):Elongated 500mb ridge across 
central Mexico and the Gulf of Mexico will provide a westerly flow 
aloft across Texas today as Tropical Storm Sergio makes landfall 
across Baja California and moves into northwest Mexico this 
afternoon. Low to mid level moisture will remain high across 
northeast Mexico and northwest Texas today before the remnants of 
Sergio move into west Texas tonight. Moisture will increase across 
west Texas tonight and best rain chances will remain well northwest 
of the CWA today through Saturday even as the 500mb shortwave 
associated with Sergio moves across the southern plains Sat 
afternoon. Will mention isolated showers and thunderstorms across 
the Rio Grande valley and northern ranchlands today as the weak cold 
front across northeast Mexico lifts northward as a warm front before 
dissipating. Will likely see isolated streamer showers overnight 
tonight and isolated showers and thunderstorms Saturday for 
seabreeze convection. Will go with a blend of NAM/GFS MOS guidance 
for temperatures today through Saturday which is near normal to 
above normal.

.LONG TERM (Saturday Night through Thursday):Models continue in
fair agreement with the development of a highly amplified mid 
level pattern over North America and the CONUS. A strong cold 
mid/upper level trough digs through the heart of the country (Sun-
Tue) as strong high pressure builds north along the West Coast 
well into British Columbia, Canada. By the middle of the week a 
winter like trough will be established over the Midwest with an 
upper low settling over the Desert Southwest while a mid level 
ridge builds over the Gulf of Mexico. All this will set up a major
temperature and weather change for the RGV as a much advertised 
cold front surges through Texas Sunday night into Monday. The 
front is still on schedule for a Deep South Texas/RGV passage 
Monday with some differences in timing between the GFS and ECMWF. 
GFS is currently lagging behind the ECMWF and temperatures 
guidance spread between the models shows some differences for days
4-6 (Mon-Wed). With plenty of time to smooth these differences 
out as we approach this event only minor changes to the 
temperature and pops were made in the latest forecast and grid 

Overall, Sunday will be another warm to hot day with a possible 
afternoon shower or thunderstorms. Subsidence ahead of the front 
might be a factor with a potential heat spike. Then we can expect
the front to move through the northern and western Ranchlands 
early in the day Monday with steady falling temperatures. The Mid 
and Lower RGV might not see the front well into Monday afternoon 
and possibly as late as sunset at BRO and SPI. This will allow for
temperatures to approach 90 degrees in the Lower Valley if clouds
and rain hold off. The front should be pushing well offshore 
Monday night with Tuesday and Wednesday being a shock to the 
system with temperatures falling into the 50s and 60s for daytime 
highs and 40s and 50s for overnight lows. Rain chances will be on 
the increase with some widespread rainfall amounts of 1-3 inches
possible (especially near the coast) as isentropic flow maximizes
and mid level instability allows for some elevated convection. 
Models suggest cool temperatures and rain chances to stick around 
Thursday as the upper low over the Desert SW remains in place 
maintaining the warm moisture air overriding the cool surface air.
Not until Friday does the stubborn upper low begin to lift out 
allowing for a slow recovery back to warmer temperatures and for 
some sun to break through the thick overcast. Expect day to day 
changes in temperatures and pops as we get closer to the frontal 
passage and models get a better handle of the rapidly changing 


.MARINE:(Today through Saturday): Seas were near 5 feet with east 
winds near 18 knots at buoy020 early this morning. Light to moderate 
southeast winds will prevail across the coastal waters today with 
surface high pressure across Missouri and Illinois extending 
southward into the Gulf of Mexico. The pressure gradient will 
increase across the lower Texas coast tonight as the remnants of 
Tropical Storm Sergio move across northwest Mexico into west Texas. 
Moderate southeast winds will prevail across the western Gulf of 
Mexico tonight and increase slightly Saturday with low pressure 
across northwest Texas. SCEC conditions will develop across the 
coastal waters Saturday as a result. 

Saturday night through Tuesday...A moderate onshore flow and
moderate sea is expected Sat night through early Monday in advance
of the first strong cold front of the Fall season. The front is
expected to work its way South of Port Mansfield and Port Isabel
Monday afternoon to early Monday evening. North winds to steadily
increase and remain elevated Tuesday through Thursday. An extended
period of small craft advisories are anticipated with very rough
sea as strong high pressure builds in behind the cold front. Rain
chances increase with periods of rain and some thunderstorms
making for a nasty and hazardous conditions for the middle part of
next week. Next Weekend looks to be much improved. 


BAYVIEW/PORT ISABEL  91  80  92  79 /  10  20  20  10 
BROWNSVILLE          92  78  92  79 /  20  20  20  10 
HARLINGEN            92  76  93  77 /  10  20  20  10 
MCALLEN              91  78  93  79 /  20  20  20  10 
RIO GRANDE CITY      92  77  95  77 /  10  20  10  10 
SOUTH PADRE ISLAND   89  82  89  82 /  10  20  20  10 




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61...short term
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