Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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016
FXUS64 KHGX 190848
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
348 AM CDT Tue Sep 19 2017

.DISCUSSION...
Distinct moisture plume evident on the GOES-16 Total Precipitable
Water image overhead of Southeast Texas early this morning. PWs of
2.0 inches were across all but the far northern quarter of
counties where the PWs fell to about 1.7 inches in Houston County.
The models show this moisture plume should remain overhead through
the mid afternoon period. The NAMBufr model forecast soundings
show the potential for thunderstorms with MUCAPE values 2000 to
2500 this afternoon. Could see gusty winds in the stronger storms
as an inverted V profile develops under 850 mb during the
afternoon. Also cold see isolated areas of locally heavy rainfall.
Even though the 2-inch PWs are not significant when compared to
the historical PWs for this time of the year, the K-Index values
do reach 34 this afternoon. Do not think the coverage will be as
much as yesterday. The HRRR and Texas Tech both show only isolated
coverage for the most part; although, the seabreeze and bay
breeze combined with outflows should lead to scattered coverage
inland of the coastal counties.

Wednesday and possibly Thursday may see better coverage than today.
The global models depict an upper level shortwave trough will
move across the Southern Plains into Southeast Texas. The models
then show the shortwave trough deepening over LA into Southeast
Texas on Thursday with a high pressure ridge building across the
mid MS Valley into N and Central Texas. The ridge should continue
to build on Friday as a deep layer upper level low pressure trough
deepens over the Rockies through Southern CA. There was some
discrepancy as to how far east and south the upper ridge will be
on Thursday and Friday. By the weeknight, an upper low will form
near or over the lower MS Valley area. This scenario should lead
to less shower and thunderstorm coverage over the forecast area.

The model solutions diverge next week over our area. With the
upper trough moving into the Plains, do expect rain chances will
increase on Sunday and Monday.

40

&&

.MARINE...
In general, moderate southeast winds will persist through the end of
the week across the Upper Texas Coast. Seas will remain around 3
feet as a result. Showers and thunderstorms will be possible along
the coast and inland with higher moisture over the region.

Overpeck

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      93  75  93  75  91 /  20  10  20  10  40
Houston (IAH)              90  76  90  75  89 /  30  10  40  20  30
Galveston (GLS)            87  79  87  79  86 /  20  20  30  20  30

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

Discussion...40
Aviation/Marine...39



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