Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 160854

Area Forecast Discussion
National Weather Service BROWNSVILLE TX
354 AM CDT Sun Oct 16 2016

.SHORT TERM (Today through Monday): Endless summer continues to
close the weekend and start the third full week of October 2016.  In
a typical year where at least one drying and somewhat cooling front
would have arrived by now, we`d be a bit more concerned by forecast
heat index, especially near the coast, over 100 in the second half
of October.  However, since it really hasn`t cooled below 90 for
more than a couple days last weekend toward the coast, there has yet
to be any notable acclimation to more typical October afternoon
temperatures, which by now would range from the mid to upper 80s.

In terms of sensible weather - if you have plans to be at the beach
or the pool today (Sunday), add another day on Monday.
Atmospherically, very big "bubble" of subtropical summer-like high
pressure means more searing heat (see Climate section below for
details) with plenty of sunshine and just a period of quick morning
cumulus that will mix out in the very dry atmospheric air...layer
humidity from 700-300 mb falls to 5 percent or less for much of the
period and with compressional heating some of that air mass will be
tapped each afternoon which should erode any raising clouds by 1 to
3 pm each day.

As for temperatures, the dry adiabatic profile combined with August-
like thicknesses support near-century mark readings in the mid/upper
Valley, with slightly lower readings across the somewhat greener Rio
Grande Plains and toward the coast.  The good news for heat index is
that same dry air will mix toward the surface and should allow dew
points to fall into the upper 50s to lower 60s along and west of US
281, while 65 to 70 degree dewpoints for the populated areas farther
east will keep a bit more discomfort...though freshening afternoon
breezes in these areas will take a bit of the edge off.  Speaking of
the beach...will continue to advertise moderate threat for rips
today into Monday (at least) with the swell period and flow
perpendicular to the beach.

For the overnight, basically carbon copied early Saturday morning
into this morning and again Monday.  That means some fog development
across the ranchlands extending into the rural portions of the
Valley, including areas such as San Manuel, Raymondville, and Kenedy
County away from the coast. Light to near calm winds and the longer
nights will allow sunrise temperatures to range from the mid/upper
60s in these areas to the lower 70s in urban centers, and near 80 on
South Padre Island.

.LONG TERM (Monday Night through Saturday): Unseasonably warm and
relatively dry conditions to continue across south Texas Mon night
through Wednesday before the 500mb ridge across east TX Monday
shifts eastward Tuesday and a 500mb trough develops across the
western United States Tuesday and moves eastward across the
central U.S. Wednesday. Low to mid level moisture will pool along
and ahead of the front moving into north TX Wed night and continue
to increase Thursday before the front moves through the CWA Thurs
afternoon. This will provide a chance of showers and a slight
chance of thunderstorms across the area Thursday. A slight chance
of rain will linger Thurs night through early Friday before high
pressure brings drier and cooler air into deep south TX in the
wake of the front. Temperatures will return to normal to slightly
below normal towards the end of the week into the weekend.

.MARINE (Now through Monday):  Persistent easterly flow under the
1020+ mb high over the southeast U.S. continues to bring 7 to 8
second swell period and 2 to 4 foot swell at buoy 42020 and more
importantly buoy 42002 east of South Padre Island.  Forecast seas
should maintain the status quo which averages around 3 feet for the
entire waters, including near the coast, until Monday afternoon.
Otherwise, winds will do the usual diurnal flip flop with lighter
speeds across the Gulf by day (Laguna Madre by night) but still well
below any headlines. Deep layer dry air over all areas should keep
even the possibility of streamer showers at bay through Tuesday

Monday night through Thursday: Light to moderate southeast winds
will prevail across the coastal waters Mon night and veer to the
south Tuesday as low pressure and a weak cold front moves into the
southern plains. The pressure gradient is expected to be weak
across the western Gulf of Mexico Wednesday. Winds should back to
the southeast Wednesday and east Wed night as the cold front
moves into north Texas Wed night. The front is expected to move
through the lower TX coastal waters Thursday. Winds will shift to
the northeast Thursday and increase Thurs night in the wake of the
front. Small craft advisories will likely be needed for the
offshore waters Thurs night.

.CLIMATE...High temperature records are likely to be threatened
through Monday.  Here are the latest calendar day records and
forecast highs for the main population centers today and October 17:

October 16
Location      Current Record (year)     Forecast High
Brownsville         93 (2013)              94
Harlingen           96 (2012)              97
McAllen             98 (1984)              99

October 17
Location      Current Record (year)     Forecast High
Brownsville         94 (1917)              94
Harlingen           98 (1947)              97
McAllen             97 (2012)              99

Prior to the late week cold front, most Valley locations will rank
among the top 5 hottest Octobers through the 20th, so the "beat goes
on" since the near/record hot period began in late June.

BAYVIEW/PORT ISABEL  92  73  92  74 /   0   0   0  10
BROWNSVILLE          94  72  94  75 /   0   0   0  10
HARLINGEN            97  69  97  72 /   0   0   0  10
MCALLEN              99  70  99  75 /   0   0   0   0
RIO GRANDE CITY      95  70  97  72 /   0   0   0   0
SOUTH PADRE ISLAND   87  77  87  80 /   0   0   0  10



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