Area Forecast Discussion
Issued by NWS Houston/Galveston, TX
FXUS64 KHGX 221133
Area Forecast Discussion
National Weather Service Houston/Galveston TX
633 AM CDT FRI JUL 22 2016
VFR conditions are expected. Isolated showers may affect the
immediate coastal site /KGLS/ before 15Z. The current water vapor
and the models to hint at the possibility for isolated showers
this afternoon near and east of KIAH, KCXO, and KUTS.
.PREV DISCUSSION... /ISSUED 415 AM CDT FRI JUL 22 2016/
At 3 AM, a weak area of high pressure was located over extreme SW
LA. At 850 mb, high pressure was located N MS with a patch of
deeper moisture undercutting the ridge over S LA. At 300 mb, a
strong upper level high pressure system was centered over NW TX
and this feature is sprawling much of the southern U.S. 850 mb
temperatures remain very warm and am expecting max temps today to
be similar to yesterday. Forecast soundings show PW values
approaching 2.00 inches with little capping noted after 21z.
Convective temperatures are between 93-96 degrees so not expecting
much in the way of shra/tsra until mid/late afternoon. Water
vapor imagery shows a disturbance over LA/E MS and this feature
should arrive in SE TX around 18z. Although guidance does not
suggest much precipitation coverage today, am a littler nervous
that this disturbance could bring a bit more activity to at least
the eastern half of the CWA.
Moisture levels continue to deepen on Saturday with PW values
again exceeding 2.00 inches by 21z. Convective temperatures cool
into the lower 90s but still some weak capping noted in the
750-700 mb layer. The upper level ridge plaguing the region will
begin to shift west so feel the lower heights coupled with the
lower convective temps and moisture should foster slightly higher
rain chances on Saturday.
Rain chances increase further on Sunday as PW values peak between
2.20 and 2.30 inches. Forecast soundings look very favorable with
a deeper saturated layer between 900-750 mb. Fcst soundings also
show an inverted V signature so some of the stronger storms could
produce some gusty winds. 500 mb heights lower to 591 DM and 850
mb temps continue to lower. Convective temps are around 90 so
think potential for rain on Sunday is pretty high. Storm motion on
Sunday also looks to be less than 10 knots so there could be some
pockets of locally heavy rain.
Rain chances should remain high for much of the week ahead as the
upper ridge remains to the north and west of the region. An
inverted upper trough will migrate west across the Gulf of Mexico
Tues-Thurs and this feature will keep showers and storms in the
forecast. With the added cloud cover and precipitation,
temperatures will trend to near normal or even slightly below
normal by the middle of next week.
Looks like a typical summer time pattern. Could see some increase in
showers or thunderstorms starting this weekend into the first half
of the new week, especially during the morning and early afternoon
time period each day.
The airmass should mix out during the afternoon today and Saturday.
This should allow for minimum Relative Humidity values to dip into
the 35 to 40 percent range generally west of the US-59 corridor. The
latest models are showing that an increase in the coverage of
showers and thunderstorms will be possible by Sunday and Monday.
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 99 77 98 77 97 / 10 10 20 10 30
Houston (IAH) 98 79 97 79 96 / 20 10 30 10 50
Galveston (GLS) 93 82 92 82 91 / 20 20 20 20 40