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Area Forecast Discussion (AFD)

Issued by Houston/Galveston, TX (HGX)

FXUS64 KHGX 181120

Area Forecast Discussion
National Weather Service Houston/Galveston TX
520 AM CST Mon Feb 18 2019

Sure is nice to have the front so far south...out past buoy 42047
and beyond the KGUL/KHHV platforms (much further south than models
were progging it just 48 hrs ago.) That is probably good new for
SETX today with increasing cloudiness and cool weather. Rain
chances looks very slim and probably not until tonight across the
south is there much chance. Upglide will gradually increase
throughout the day and hence the increase in clouds along with the
persistent SW flow aloft pumping CI across TX and the CWA. The
slow moving deep upper level will drive much of the weather this
week as it comes out of the SW and then reloads this weekend. 

Tonight expect light rain to spread across the area from the south
and southwest to the north and northeast and as the front starts
back north as a warm front nearing the coast Tuesday morning. Very
strong isentropic upglide will take place on Tuesday with coastal
troughing in place. Widespread rainfall do have some concerns that
even some brief heavy rainfall could occur as 30-40kt LLJ impinges
on the coastal trough with PW of 1.5" and impressive moisture
flux. NAEFS return intervals coming in around the 10 to 30+ year
return. CIPS analogs look to focus the rainfall east of the CWA
and northeast. Soundings though show a impressive wedge of
elevated instability and could see some strings/training of
rainfall piling up with these fast 30+ knot moving showers and
thunderstorms. MUCAPE of 1000+j/kg and certainly some potential
for small hail. Upper flow buckles and diffluence increase mid 
day Tuesday with the s/w so by late afternoon/early evening expect
intensity to wane with the warming upper levels early Wednesday
morning. May have a window for sea fog over far coastal waters
Tuesday spreading into the nearshore/bays Tuesday into Tuesday
night and probably a short lived window as weak Pacific front
pushes through and offshore. Wednesday should consist of drying
out with north and northwest winds and maybe some sunshine. Then
we start it all over again Thursday with the warm front coming
back north rain chances increase and the warm front moves ashore
Friday with rain chances spiking back up. Another quick shot of
Pacific air pushes in Saturday night behind the cold front. Rinse
and repeat again next Tuesday. Hey it's El Nino what did you
expect sunshine and dry?



Hazardous marine conditions prevail across the bays and waters and 
are expected to continue through at least Tuesday morning. Tight 
pressure gradient will continue to produce strong northeast winds 
across bays and Gulf waters and as a result building seas. As of 
early this morning, bouys are reporting seas of around 5 feet over 
the nearshore waters and seas of around 9 feet over the offshore 
waters. Small Craft Advisories continue in effect for the bays 
through 9 AM CST this morning and through early Tuesday morning 
across the Gulf waters. Additionally, water levels of around 3 feet 
during high tide may be observed at Galveston Bay entrance and 
Freeport areas Monday night through Tuesday morning. Periods of sea 
fog are also possible Tuesday evening through Wednesday morning.

During the rest of the week, a wet weather pattern is expected to 
prevail as a series of coastal lows and upper level troughs move in 
and out of the region along with a moderate to fresh wind flow. 24 



College Station (CLL)      59  44  47  40  59 /   0  30  90  50  20 
Houston (IAH)              61  48  54  47  60 /   0  40  90  60  30 
Galveston (GLS)            59  54  62  53  59 /  10  50  90  60  50 


GM...Small Craft Advisory until 9 AM CST this morning for the 
     following zones: Galveston Bay...Matagorda Bay.

     through Tuesday morning for the following zones: Galveston 
     Bay...Matagorda Bay.

     Small Craft Advisory until noon CST Tuesday 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...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.