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Area Forecast Discussion (AFD)

Issued by Houston/Galveston, TX (HGX)

FXUS64 KHGX 220203

Area Forecast Discussion
National Weather Service Houston/Galveston TX
903 PM CDT Sun Jul 21 2019

.SHORT TERM [Tuesday Through Wednesday Night]...
Storms looks to have dissipated with the loss of heating and
extensive mid/high clouds across the region. More high clouds from
LA spreading into the area through 09z. Clearing trends toward
morning for some of the area except the coastal and far northwest.
Temperatures tonight should slowly lower into the mid/upper 70s.
Rain chances increasing around Galveston Bay area after 2 am.
Expect showers and thunderstorms perhaps around an hour earlier
than yesterday with the increase in low level moisture and low
convective temperatures. Greater chances should be for the I-10
corridor southward throughout the day. Much of the area should
have a large thick cirrus canopy over the region during the late
morning through afternoon hours-along with rainfall-and this may
play havoc with afternoon high temperatures and give some relief
from the elevated heat indicies.


.AVIATION [00Z TAF Issuance]...
VFR through 09z then should see some patchy MVFR ceilings develop
west of the area and spread into the CLL area and possibly
UTS/CXO/SGR. Given the behavior the last two nights may even see 
an hour of IFR at CLL near sunrise. Shower and thunderstorms
getting going around Galveston bay area early near sunrise and
spreading/developing westward mid morning. HOU/LBX/SGR/GLS the
most likely to have direct impacts and then IAH/CXO to a lesser
extent in the mid/late afternoon. 


.PREV DISCUSSION /Issued 400 PM CDT Sun Jul 21 2019/...


Scattered showers with more organized clusters developing 
thunderstorms over the eastern forecast area this afternoon. 
Outflow interaction from both inland and offshore convection 
have allowed this ongoing up and down storm activity to fester 
into the 3 PM hour. Most of these slow-moving cells will put down
a quick quarter to an inch of rainfall. Forecast calls for no 
more than 50% TS or SHRA areal coverage through shortly after the 
8 PM sunset hour. Cb convective cirrus blow off will block enough 
late afternoon sun to keep many in the lower 90s. A quiet, muggy 
overnight with a weak southwest breeze. Monday's minimum temperatures
will only fall into the upper 70s to lower 80s.

The wind shift 'slash' cool front boundary is still timed to pass
across the region on Tuesday. This will increase precipitation 
chances to likely through the day...with the highest rainfall 
occurring along and east of the I-10 corridor (near inch QPF). 
After Tuesday's rains there will be a period of late work week 
drier weather. Northerly winds will veer around to east-southeast
by Thursday and pick up weekend moisture. A silver lining will be
the bulk of unusually drier air for July...pwats are forecast to 
fall to below 0.8 inches that, with afternoon mid-level mix down,
should translate to upper 50 to lower 60 dew point air. This will
drive mid-week relative humidities to under 40% both Wednesday 
and Thursday. 31

Weak high pressure over the western Gulf of Mexico will maintain a SW-S
wind over the coastal waters tonight into Monday night with more of a 
westerly component during the late night/early morning time periods. The 
pressure gradient is not particularly tight so wind speeds not expected 
to exceed 15 knots through Monday night unless influenced by convection.
A rare July cold front is expected to cross the coastal waters Tuesday
morning and winds will become N in the wake of the front by Tuesday 
evening and veer to the NE overnight into Wednesday. A short lived SCEC
may be required for the eastern Gulf waters Tues Night/early Wednesday.
A moderate NE flow is expected Wed/Thu as high pressure builds toward the
mid Mississippi river valley. The Tuesday cold front will return north as 
a weak warm front with a weak area of low pressure developing on the front
as it heads north. East winds Thursday night will become SE as the front 
pushes north with onshore winds then persisting through next weekend. No 
rip current or tide issues are expected through Monday night. 43



College Station (CLL)  76  97  76  89  69 /  10  10  30  50  10 
Houston (IAH)          78  94  77  90  71 /  10  50  30  60  20 
Galveston (GLS)        82  91  80  90  78 /  40  60  50  70  50