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Area Forecast Discussion (AFD)

Issued by Houston/Galveston, TX (HGX)

FXUS64 KHGX 220921

Area Forecast Discussion
National Weather Service Houston/Galveston TX
421 AM CDT Mon Apr 22 2019

Partly to mostly cloudy skies across the region early this morning
with some cirrus passing through. Closer to the surface, onshore 
flow is starting to moisten under the cap. Not expecting much in 
the way of precip today...just mcldy skies with highs around 80.

Models are showing some weak disturbances embedded in a developing sw
flow aloft moving across the area tomorrow. Fcst soundings are showing
increasing saturation above 600mb, though with a fairly dry 
subcloud layer in place it's questionable whether any precip 
generated will be able to make it to the ground or not. Some of 
the guidance seems to hint at that possibility so went ahead and 
threw in some 20-30% POPs for Tues.

Shra/tstm chances increase from wnw to ese Wednesday afternoon
through Thursday morning as large scale lift increases from the
approaching upper trof. Frontal boundary sagging into cntl & north
Texas will eventually become a focus for convection during the day
and overnight Wed as it sags into and across se Tx. Surface low/wave
looks to develop along this boundary and track northeastward. At 
this time, the majority of guidance takes it's trajectory (and 
overall heavy rain threat) generally northwest of our CWA...but 
still needs to be watched closely for any progged southward 
deviations in the next few days. Assuming clouds don't hamper 
heating too much, the atmosphere becomes increasingly unstable 
thru the day especially w/sw areas. LFQ of 110-130 jet noses into 
the area aiding in upper diffluence. Appears the main wx threat 
for the HGX CWA will be the possibility of some severe wx 
Wednesday night with hail/winds being primary threat. 

Prefrontal trof should push off the coast around or shortly after
sunrise Thursday followed by the front itself. There will probably
be some lingering wrap around cloudiness and showers, but that 
will eventually move out of the area Thursday evening. As we head
into the weekend, a building ridge will bring msunny skies and 
warmer temps to the area. 47


A generally moderate (to occasionally strong) onshore flow is expect-
ed to persist these next several days. We'll continue to see periods 
of elevated winds/seas through mid week (especially for the offshore 
waters) and either SCEC or SCA flags will likely remain posted these 
next few days.  This pattern should prevail until late Weds night to 
early Thur morning when the next upper level storm system and its as-
sociated cold front moves through the area. Widely scattered showers 
and thunderstorms are possible the next few days as well, but a line 
of more organized activity will be accompanying the front when as it 
moves ito the Gulf waters. A brief period of elevated offshore winds 
is expected behind the front early Thurs, but high pressure building 
quickly into the area will allow for a more light/moderate northerly 
flow through rest of the week. As the high moves off to the east, we 
will be seeing the gradual return of onshore winds over the weekend. 


Spotty MVFR CIGS noted around SE TX this morning...but we should see 
these lifting/mixing out by mid morning. VFR conditions expected for 
this afternoon. We'll likely see a few more sites with MVFR CIGS to- 
night as moderate onshore winds persist and low-level moisture keeps 
increasing across the region. 41


College Station (CLL)      81  66  79  65  77 /   0   0  30  20  60 
Houston (IAH)              80  67  78  66  80 /   0   0  30  10  30 
Galveston (GLS)            76  70  76  69  77 /   0   0  10  10  20 


     morning for the following zones: Coastal waters from 
     Freeport to Matagorda Ship Channel TX out 20 NM...Coastal 
     waters from High Island to Freeport TX out 20 NM.

     SMALL CRAFT SHOULD EXERCISE CAUTION through late tonight for the 
     following zones: Waters from Freeport to Matagorda Ship 
     Channel TX from 20 to 60 NM...Waters from High Island to 
     Freeport TX from 20 to 60 NM.