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Area Forecast Discussion (AFD)

Issued by Houston/Galveston, TX (HGX)

FXUS64 KHGX 151050

Area Forecast Discussion
National Weather Service Houston/Galveston TX
550 AM CDT Sun Sep 15 2019

.SHORT TERM [Today Through Monday Afternoon]...

The thunderstorms appeared along the coast a few hours earlier than 
what models were indicating, so have been playing catch up on the 
near term PoP grids a bit (and will probably end up tweaking again 
soon). This activity is due to the northern fringe of an upper-level 
low currently located in the east-central Gulf beginning to impact 
our region as it slowly moves westward. PWATs of about 1.7 to 2 
inches is making towards SE Texas will help fuel showers and 
thunderstorms through the day today with more coverage compared to 
the last few days, but should remain south of I-10. The lower 
heights associated with the approaching disturbance should bring a 
slight reprieve from the heat that we've experienced the past few 
days, albeit only by a few degrees (so still close to record heat in 
Galveston). The slight cooling continues tomorrow with temperatures 
remaining in the low to mid 90s.

With the help of the upper-level low, isolated to scattered shower 
activity over the Gulf waters will continue overnight tonight and 
into the day tomorrow. The NMM and ARW keeps the axis of heaviest 
rainfall off the coast tonight, but then brings the rains onshore by 
the early morning hours. The GFS and EC still keeps the main area of 
showers and thunderstorms on Monday mainly south of I-10, but that 
may begin to change come midweek. 


.LONG TERM [Monday Night Through Sunday]...
Monday night should be active across the coastal waters as the
upper low crawls westward and the shear very gradually starts to
relax. NHC currently indicating 20 percent chance of this system
taking on tropical/subtropical characteristics as a TD. If this
were to occur it looks like the late Monday/Tuesday would be the
window for that to take place. Regardless of that development
occurring the main issue with this system is going to be one of
heavy rainfall. Still early to pinpoint other than to say the
southern areas the most likely recipient of the greater amounts
Monday through Wednesday. Tuesday and Wednesday probably the most
favorable time for the most efficient storms mainly driven by
daytime heating. The rain and associated cloud cover should
finally pull back the high temperatures of the recent trend. 
Thursday into Friday the upper low should be filling and centered
somewhere in the vicinity of Matagorda Bay to Austin. Rain chances
taper down Friday and Saturday with weak upper ridging taking hold
over the Gulf and into SETX. But with that transition should come
a return to hot weather. 



Moderate easterly flow is expected today ahead of an approaching 
upper level low currently situated in the east-central Gulf. Small 
craft should exceed caution today as winds will increase to 15 to 20 
knots with occasional higher gusts in the Gulf waters.
Winds become light to moderate in the overnight hours tonight,
before increasing again tomorrow afternoon. Showers and 
thunderstorms will prevail today and continue through midweek as the 
disturbance slowly moves across towards southeast Texas. Some of 
these storms may produce gusty winds, higher seas, and frequent 

Tide levels remain elevated at 1 to 1.4 feet above normal and with
the increase in winds today may be flirting with some minor Gulf
facing beach flooding and stronger rip currents.



The string of records continues for Galveston with a record high
of 96 degrees beating out the long standing record of 93 degrees
set back in 1900!



College Station (CLL)  98  74  98  74  94 /   0  10  10  10  40 
Houston (IAH)          97  76  95  76  91 /  20  20  20  20  60 
Galveston (GLS)        94  81  91  82  89 /  20  40  60  60  60