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Area Forecast Discussion (AFD)

Issued by Houston/Galveston, TX (HGX)

FXUS64 KHGX 131548

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1048 AM CDT Fri Sep 13 2019

12z soundings show PW values between 1.60 and 1.80 inches and this
is supported by satellite. 12z LCH sounding show some weak 
capping in 760 mb to 560 mb layer but the CRP sounding did not 
show much of a cap. Convective temperatures are near 90 and this 
threshold looks to be in reach but profile soundings look pretty 
dry aloft. Should start to see some isolated shra/tsra developing 
with the higher rain chances over the S-SW zones. Temperatures 
look a touch warm and made some minor tweaks to both the hourly 
and MaxT grids. Rest of the forecast looks good to go. 43


.PREV DISCUSSION... /ISSUED 613 AM CDT Fri Sep 13 2019/ 

AVIATION [12Z TAF Issuance]...

VFR conditions will prevail across all TAF sites through the period. 
There has been some patchy fog develop across the northern portion 
of the region, but it looks to be stay away from any TAF sites. 
There is the chance of some isolated showers today like the past few 
days. Have VCSH for GLS and LBX for this morning, then up toward
HOU and SGR during the afternoon. Showers may reach IAH by the
late afternoon, but opted to not include in TAF due to the 
limited coverage and low confidence. Tonight will be very similar 
to the past few nights with some areas of patchy fog.


PREV DISCUSSION /Issued 529 AM CDT Fri Sep 13 2019/...

SHORT TERM [Today Through Saturday Afternoon]...

High pressure remains in place across most of the southern US 
with some shortwaves slowly retrograding across the Gulf on the 
bottom edge of this ridge. PWs are currently around 1 to 1.2 
across much of the area, but there a slight uptick to around 1.5 
that is coming in from the east. Short range guidance does have 
some showers over the coastal waters popping up around Galveston 
Bay by around 12z-15z with this increase in PWs moving our 
direction, so PoPs have been bumped up a bit to account for that. 
Shower and thunderstorm coverage should be similar to yesterday. 
NAMnest and ARW have a bit more activity across the Matagorda and 
Jackson counties, while the NMM favors the showers to be closer 
toward Fort Bend and Harris counties. Activity decreases after 
sunset with the loss of daytime heating. Temperatures will 
continue to be about five degrees above normal today with heat 
indicies climbing into the triple digits, but remain below heat 
advisory criteria (so very similar to the yesterday). Overnight 
tonight be another tranquil night with mostly clear skies and near
to slightly above normal minimum temperatures. Saturday is 
looking very similar to the past few days with temperatures 
remaining above normal and scattered showers in the coastal waters
during the morning hours, then moving inland during the 


LONG TERM [Saturday Night Through Friday]...
Saturday night should be more typical of September with lows in
the upper 60s to lower 70s inland and rain free as upper ridge
still holding on over the region. The upper ridge will slowly be
lifting north consolidating over Arkansas on Sunday which should
lead to the upper trough over the Gulf to retrograde closer to 
SETX during the day Sunday. Slight chance along the I-69 corridor 
increasing to chance along the coast for Sunday by the afternoon. 
PW creeping up with the leading edge of the deeper 1.8-2" PW just 
barely reaching the coastal areas. Deeper moisture aligned SW-NE 
beneath the upper troughing over the coastal waters and Gulf. 
Monday and Tuesday should be warmer and more humid as the upper 
troughing fills and advances over the coast. Weak disturbance
rotating around the upper circulation should both enhance and
lessen the chances for rain during this period but timing these
this far out is unwise. For now will be increasing rain chances
Monday through Wednesday by 10-30 percent for the southern half 
of the region 5-20 percent for the northern. Slow moving storms
should be the main weather concerns. By Thursday the subtropical
high over Mexico starts to shift into the area and rain chances
should lower somewhat with a more typical diurnal seabreeze
pattern taking back hold. 



Surface high pressure building over northern Texas will bring light 
east-northeasterly flow today through Saturday. This high is 
expected to lift to the north on Sunday bringing a return to light to 
moderate onshore flow through the first half of the week. Isolated 
showers and thunderstorms may form during the early morning hours in 
the coastal waters bringing localized gusty winds. 


Potential tropical cyclone Nine advisories continue with the
system in the Bahamas moving northwest. Model trends appear to be
a little more consistent with keeping this in the Atlantic to the
east of FL/SC so no impacts expected here. A couple of other
systems in the Central and Eastern Tropical Atlantic get steered
west and northwest by the Azores high before it weakens and
troughing off the East Coast snags these taking them out as 'fish'
storms. Pressures do remain near normal or just slightly 
suppressed over the Southern Gulf/Southwestern Caribbean but as of
yet not favorable for any development not to mention TX protected
with the with upper ridging over TX. 

On a different tropical note...
Today is the anniversary of both Hurricane Ike 2008 and Humberto

Galveston set a new record high minimum temperature 84 degrees
yesterday over the long standing record of 83 which stood up 
since 1909.


College Station (CLL)      97  74  99  73  98 /  20   0   0   0  10 
Houston (IAH)              97  74  97  75  95 /  20   0  10  10  20 
Galveston (GLS)            93  81  93  80  92 /  30  10  10  40  30