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Area Forecast Discussion (AFD)

Issued by Houston/Galveston, TX (HGX)

FXUS64 KHGX 132336

Area Forecast Discussion
National Weather Service Houston/Galveston TX
636 PM CDT Fri Sep 13 2019

Any remaining SHRA/TSRA should be west of all TAF sites but maybe 
IAH by 00Z. VFR and quiet night. Expect to see less SHRA/TSRA 
activity/coverage tomorrow (not confident enough to include in 
the 00Z TAFs so will plan on using sort fuse amendments, if needed).
Should see light winds tonight, becoming east tomorrow up to around
10 knots. 42 

.PREV DISCUSSION... /ISSUED 247 PM CDT Fri Sep 13 2019/ 

SHORT TERM...(Through Saturday)
Residual showers and thunderstorms over the area will end around
sunset with the loss of daytime heating. The air mass over SE TX
is very dry as evidenced by dew points in the mid/upper 60's so
with clears skies and dry air in place, feel overnight lows will
cool into the lower/mid 70's (immediate coast near 80) by sunrise
Saturday. An upper level low over the western Gulf will gradually
shift west through Saturday but SE TX will remain on the west and
dry side of this feature through Saturday. As the upper low 
meanders west, an upper level elongate from west to east across 
the mid- south. 500 mb heights remain relatively high on Saturday 
and 850 mb temperatures would support high temperatures in the 
middle and upper 90s. The moisture profile looks dry on Saturday 
and PW values are progged between 1.35 and 1.60 inches. Although 
an isolated shower is possible, most area will likely remain dry.

LONG TERM...(Saturday Night through next Friday)
Dry air remains in place Saturday night but moisture will begin to
advect into the coastal waters late Saturday night. PW values
increase to around 1.80 inches on MOnday. 500 heights begin to
fall and convective temperatures fall to around 92 degrees which
looks reachable. Upper levels winds are weak but broadly divergent
so feel there will be a chance of shra/tsra, mainly along the sea
breeze. Global models have been hinting at a weak area of low
pressure developing over the western Gulf on Monday and this
feature will move toward the middle Texas coast on Tuesday.
Moisture on the east/north side of this feature will rotate into
SE TX on Monday and will maintain chance PoPs. The precip and
clouds should keep temps a few degrees cooler than Sunday. 

A lot of uncertainty going into Tues-Thursday as the weak surface 
low fills but it leaves a bit of a low level convergence zone 
that looks to set up N-S along the I-45 corridor. This boundary, 
difficult to place 5 days out, will be the focus for some heavier 
showers and storms. The jet dynamics don't look terribly favorable
but the best moisture transport/deeper moisture is aimed toward SE
TX. The ECMWF and GFS seem to be targeting the same area and 
think there could be some pockets of heavier rain late Tuesday 
night into Wednesday. The GFS and ECMWF differ a bit toward 
Thu/Fri as the EC keeps things on the wet side while the GFS 
begins to dry things out. The ECMWF has performed much better in 
the long range as of late and will be leaning toward the wetter 
ECMWF solution for Thu/Fri. 43

In general, a light to moderate easterly flow will prevail for the 
next several days. Wind directions will probably be a bit more out 
of the northeast in the mornings and east-southeast in the 
afternoons. A broad upper low currently situated over the south 
central Gulf will slowly make its way westward this weekend and 
early next week. Some guidance indicates that a weak surface 
circulation may eventually develop. Regardless, the associated 
chances of showers and thunderstorms will increase across the marine 
waters as this occurs.   47


College Station (CLL)      73  98  72  97  74 /  10   0   0  10  10 
Houston (IAH)              75  96  76  96  76 /  10  10  10  20  10 
Galveston (GLS)            81  93  81  92  80 /  10  10  20  30  40