Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 200518

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1118 PM CST Mon Feb 19 2018

A mix of MVFR/VFR ceilings and fcst soundings support MVFR
ceilings for the rest of the night. HRRR and other short term
guidance support IFR ceilings but this appears to be slightly
overdone as IFR cigs were supposed to develop between 00-02z and
that has failed to materialize. Strong winds at and just off the
surface will likely keep cigs around 1500 feet. Winds won`t fully
decouple and gusty winds will likely persist for much of the
night. The winds will likely create enough mixing to limit the fog
threat for everywhere except the immediate coast. Sea fog has been
slow to develop despite short term guidance suggesting the fog
will return. Water temps are up to 62 degrees and dew pts are in
the upper 60s so would expect some fog overnight but winds/mixing
might mitigate the threat. Fcst soundings look unstable tomorrow
aftn over the northern TAF sites with PW values approaching 1.80
inches. Will carry prevailing thunder for Tuesday afternoon at
both KCLL and KUTS based primarily on the Hi Res ARW and the GFS.
Further south, will carry a VCSH in the afternoon as PWs climb to
around 1.55 inches but soundings look a bit more stable. KIAH is
on the cusp between TSRA and SHRA but leaned toward showers at
this time.  43


.PREV DISCUSSION... /ISSUED 1004 PM CST Mon Feb 19 2018/

The KGRK VAD wind profiler shows a 35-45 knot low level jet has
developed across Central Texas this evening, feeding Gulf moisture
into the eastern half of Texas. Small disturbances translating
across Texas in the southwest flow aloft will continue to result
in the development of showers and a few thunderstorms north of an
Edna to Cleveland line overnight, consistent with where SPC
Mesoanalysis has identified the steepest mid-level lapse rates.
Evening infrared imagery is already showing some convective
enhancement for activity translating across the Rio Grande out of

The main update for this forecast was to pull rain chances
farther north for the aforementioned trends and increase overnight
low temperatures where cloud cover and elevated southerly winds
will keep overnight lows in the mid 60s to near 70.

Preliminary inspection of the 00Z guidance continues to indicate
the potential for heavy rain across the Brazos Valley and Piney
Woods areas tomorrow night. Continuing to monitor for the
potential for training showers and thunderstorms across this area
as a frontal boundary approaches the region late Tuesday night or
early Wednesday morning with fairly unidirectional wind profiles
in place. Have noticed some difference in forecast rain amounts
during this time however, likely due to the presence of some lower
level capping (NAM BUFR provides a more southwest low level flow
and has more capping/lower rain totals and the GFS BUFR has a more
southerly flow and less capping/higher rain totals). With
southwest flow aloft becoming more amplified during the day
tomorrow with the approach of an upper trough over the Great
Basin now, inclined to think low level winds will back and a more
southerly low level flow (and higher rain totals) will prevail
but will wait for the remainder of 00Z guidance to come in before
making any changes to the ongoing forecast.



College Station (CLL)      68  78  64  70  53 /  20  60  80  80  80
Houston (IAH)              68  79  67  78  62 /  10  50  60  80  70
Galveston (GLS)            66  73  66  73  64 /  10  30  50  70  60


     the following zones: Coastal waters from Freeport to the
     Matagorda Ship Channel out 20 NM...Coastal waters from High
     Island to Freeport out 20 NM...Galveston Bay...Matagorda

     Small Craft Advisory until 6 AM CST Tuesday for the following
     zones: Waters from Freeport to the Matagorda Ship Channel
     from 20 to 60 NM...Waters from High Island to Freeport from
     20 to 60 NM.



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