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Area Forecast Discussion (AFD)

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

FXUS64 KBRO 171741 AAC

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1241 PM CDT Mon Jun 17 2019

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


.AVIATION...Convection had developed along an outflow boundary
this morning, affecting mainly BRO and HRL, but is now quickly
waning in both coverage and intensity. Gusty east winds to around
25KT may persist for the next hour or so. After that, a more
typical VFR sky is expected for the remainder of the afternoon
with scattered cumulus and moderate SE winds. Winds become light
overnight as pressure gradient will be weakening. MVFR cloud deck
may develop late tonight, with highest confidence in this at MFE
per SREF probabilities. VFR should return by mid-morning on


.PREV DISCUSSION... /issued 1116 AM CDT Mon Jun 17 2019/ 

DISCUSSION...Updated PoP/Wx grids through 18Z to account for
latest convective trends, per radar. Did not make any changes for
this afternoon, as HRRR pretty insistent that showers/storms
should be winding down by then, but will continue to monitor. Text
products updated and sent.

PREV DISCUSSION... /issued 627 AM CDT Mon Jun 17 2019/ 

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Brownsville radar shows some convection surging south
along the lower Texas coast. Will continue to mention VCTS at 
HRL and BRO this morning as most of the showers and thunderstorms 
are expected to remain over the coastal waters, east of the 
terminals. However, any thunderstorms that develop today should be
isolated. Otherwise, VFR conditions are expected for the next 24 

DISCUSSION...Updated for latest marine discussion below.

MARINE...Brownsville radar indicates a line of convection moving
south into the northern portions of lower Texas Gulf waters. Made
a quick update to increase pops across the Gulf waters this
morning. No other changes are needed at this time. 

PREV DISCUSSION... /issued 436 AM CDT Mon Jun 17 2019/ 

SHORT TERM (Now through Tuesday): A mid-level trough moving over 
north Texas is generating some convection well north of the CWA 
early this morning. Brownsville radar indicates a few streamer 
showers over the lower Texas coastal waters. Some of these showers 
may move inland across the lower Rio Grande Valley through mid 
morning, rainfall amounts will remain light. Model guidance, except 
for the ECMWF and HRRR, continue to indicate very low rain chances 
through the short term. However, outflow boundaries from overnight 
convection north of deep south Texas and daytime heating locally may 
trigger some showers or a thunderstorm later this morning into the 
afternoon. Will mention an isolated chance of convection, mainly 
along the coast. Can not rule out one or two thunderstorms, if they 
develop, producing strong gusty winds and the potential for some 
hail and brief heavy downpours. High temperatures today will range 
from the 80s at the beaches, mid to upper 90s inland and triple 
digits across the west with heat index values generally of 105 to 
110 degrees.

Rain-free conditions and above normal temperatures will prevail 
tonight and Tuesday as 500mb ridging builds over the region. Heat 
index values of 105 to 110 degrees are forecast for Tuesday 
afternoon, with peak values from 111 to 114 degrees possible for an 
hour or so.

LONG TERM (Tuesday Night through Sunday): The main issue in this
portion of the forecast will be heat. Broad 500 mb high pressure
will persist over Deep South Texas and the Rio Grande Valley
throughout the period, essentially preventing any precipitation
and producing limited cloud cover. With well above normal daytime
high temperatures forecast and a relatively moist and humid
atmosphere also in place, the potential for a Heat Advisory and/or
Excessive Heat Warning for portions or all of the BRO CWFA each 
day is high. 

MARINE (Now through Tuesday): The pressure gradient will continue 
to weaken today as low pressure moves northeast. Small craft 
exercise caution conditions will persist this morning with improving 
conditions by this afternoon. Isolated showers and thunderstorms are 
possible today and tonight across the Gulf waters.

Tuesday Night through Sunday: An enhanced pressure gradient is
anticipated for this period with high pressure over the Gulf of
Mexico interacting with thermal low pressure over northern Mexico.
Small Craft Advisory is likely to be needed for the Laguna Madre
beginning on Wednesday, with additional Small Craft Advisories for
the Gulf of Mexico waters likely beginning on Friday. 




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