Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 211122

Area Forecast Discussion
National Weather Service Houston/Galveston TX
622 AM CDT Mon May 21 2018

A mix of VFR down to LIFR conditions are occurring across the area
this morning along with some streamer showers near the coast.
Conditions should improve to VFR later this morning, with
scattered showers and thunderstorms area-wide for most of the day
today. Another round of fog and low ceilings will be possible
tonight, particularly in areas that receive decent rain today. 11


.PREV DISCUSSION... /ISSUED 349 AM CDT Mon May 21 2018/

At 300 AM, radar was rather quiet with just a few showers near
Matagorda bay. Short term guidance is bullish with redevelopment
over much of the CWA between 09-12z. Yesterday, the Hi_Res ARW
outperformed every other model but it seems overdone today as the
air mass should be worked over. 06z surface analysis shows
several boundaries lying across SE TX and these features will
likely serve as a focus for additional shra/tsra today. Fcst
soundings show convective temperatures in the mid 80`s so would
expect development beginning later this morning and continuing
into the afternoon. NAM soundings much more unstable than the GFS
with PW values approaching 2.00 inches by 21z while the GFS is
only 1.60. 850m mb temps are cooler so trimmed a few degrees from
previous forecast Max T. Will broad brush 50 PoPs today with
lower rain chances near the coast this afternoon. Rain should end
early this evening with the loss of heating. Could get some patchy
fog by early Tuesday morning as skies slowly clear.

An upper level ridge over northern Mexico will expand into Texas
through the mid week with a gradual increase in temperatures. PW
values remain below 1.50 inches and convective temperatures are in
the upper 80`s. Subsidence from the expanding ridge should limit
convective potential but fcst soundings show weak capping that
could be overcome with heating. Can`t rule out isolated showers so
will carry 20 PoPs through the period.

The end of the week is looking more interesting. Both the Canadian
and the ECMWF try develop low pressure over the southern Gulf,
both models vary in their respective placements, with the ECMWF
farther west. The GFS keeps an open wave and moves this feature
toward the FL peninsula. The Memorial Day weekend forecast will be
tied to how this system eventually evolves. FWIW, WPC currently
has a weak low over south central Louisiana and for now will lean
in that direction. Will keep rain chances in the forecast through
the holiday weekend, especially over the eastern half of the CWA.
Confidence is low and the forecast will likely change several
times by the time next weekend rolls around. It`d be a good idea
to keep up with the forecasts for next weekend. 43

Houston Hobby did not receive measurable rain yesterday so that is
29 consecutive days without measurable rain. This is the 12th
longest streak of consecutive days without rain for this location.
Bush IAH only reached 87 yesterday and this ends the 90 day streak
at 8 days. 43

Caution flags are currently flying for Matagorda Bay and western
nearshore waters as winds remain elevated this morning. These winds
should slacken off later this morning. Light onshore flow continues
through around midweek before becoming light and variable. Periods
of showers and thunderstorms are expected on and off through the
period. 11


College Station (CLL)      89  69  91  70  92 /  50  20  20  10  10
Houston (IAH)              88  71  91  73  92 /  50  20  20  10  20
Galveston (GLS)            84  76  84  78  84 /  50  10  20  10  10


     for the following zones: Coastal waters from Freeport to
     Matagorda Ship Channel TX out 20 NM...Matagorda Bay.



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