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Area Forecast Discussion (AFD)

Issued by Houston/Galveston, TX (HGX)

FXUS64 KHGX 191656

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1056 AM CST Tue Feb 19 2019

No significant changes planned for the grids for this afternoon as
conditions remain favorable for the development of widespread SHRA
(and isolated TSRA). Moderate to strong onshore winds (courtesy of
the coastal low over the Lower/Middle TX coast) will help keep the 
moisture levels elevated over the area today/tonight. While we are 
getting a bit of break from the stronger overnight activity at pre-
sent...radar is indicating increased coverage near/along the coast
with the last several scans. This activity is expected to eventual-
ly spread inland through the rest of the day. 41


.PREV DISCUSSION... /ISSUED 437 AM CST Tue Feb 19 2019/ 

Low level moisture continued to pool into the region and resulted
in overcast skies as well as passing showers mainly across the 
Gulf waters into the southern portions of the forecast area 
overnight and early this morning. Tight local pressure gradient 
resulted in a moderate to strong wind flow, particularly over the 
coastal regions and coastal waters. Winds generally from the east 
at 5 to 15 MPH inland and at 25 to 30 MPH with higher gusts across
the Gulf waters were observed overnight and early this morning. 

Surface low located over the western Gulf of Mexico will continue
to move north northeast today. Ahead of the low, an associated 
warm front will provide sufficient lifting for additional shower 
development across the region. Model consensus shows the core of 
the low entering the Gulf waters around late morning/early 
afternoon. Increase in shower and isolated thunderstorm activity 
can be expected during the late morning hours and continues 
through the night as an upper level trough approaches and moves
across the local area. As stated in the previous forecast package,
model guidance shows the right entrance region of the upper level
jet moving closer to the SE Texas region later today as well as 
an increase in the low level jet, which in combination with the
southerly moist air mass, favorable 500mb vorticity as well as 
divergence aloft, supports the development of scattered to 
numerous showers and isolated thunderstorms across the region 
today. PWAT values for today range from 1.50 to around 1.80 

The surface low should exit near the southeastern portions of the
CWA this evening/tonight and the cold front associated to the 
upper level trough should move across the local area Wednesday.
Shower activity is forecast to decrease Wednesday morning but
increases once again Wednesday night as low level moisture
increases over SE TX. With respect to the winds, velocities will 
decrease today and a southerly wind flow will set in this 
afternoon and evening. However, winds will once again increase and
become northerly overnight and early Wednesday morning. 

During the rest of the forecast period, a wet weather pattern is 
expected to continue as several surface coastal lows and upper 
level troughs move in and out of the region. Periods of showers 
and isolated thunderstorms are forecast throughout the long term
period with a few rests in between when drier air pools across 
the local areas in the wake of the cold fronts. This will also 
continue to result in fluctuating wind direction and speed during 
the next couple of days. 24


A fairly complex/changing marine forecast this week with virtually 
all kinds of hazards in play at some point. Low pressure off the 
Mexican coast will move north today and should approach Galveston 
Bay this evening. The pressure gradient will remain tight this 
morning but will begin to weaken from south to north as the low 
moves north. Will maintain the SCA for the Gulf waters through 18z 
but replace the SCA over the bays with a SCEC. The low will bring a 
warm front north and this feature will bring periods of light rain 
to the coastal waters. The surface low will move into Arkansas 
tonight and the low will drag a cold front across the coastal waters 
late tonight. A moderate to occasionally strong offshore flow will 
develop in the wake of the front as high pressure builds into the 
southern plains. Another area of low pressure will develop off Deep 
South Texas on Thursday and this feature will take a similar track 
and approach SE TX by late afternoon. Warmer and more moist air will 
flow over the cooler shelf waters and a brief period of sea fog will 
be possible Fri/Sat. Another cold front on Sunday should clear the 
fog with a moderate offshore flow. 

Strong east winds this morning will boost tide levels and water 
levels could briefly reach or exceed 3 feet early this morning. 
since the impact will be very localized and the duration so 
short, will forego a coastal flood advisory. 43


College Station (CLL)      46  41  62  43  57 /  90  40  10  30  50 
Houston (IAH)              51  48  63  49  59 /  90  50  20  40  60 
Galveston (GLS)            60  53  63  57  64 /  90  60  40  50  60 


TX...Coastal Flood Advisory from 2 PM this afternoon to 6 PM CST this 
     evening for the following zones: Chambers...Galveston 
     Island and Bolivar Peninsula.

     afternoon for the following zones: Galveston Bay...
     Matagorda Bay.

     Small Craft Advisory until 3 PM CST this afternoon 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.