Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 182031

Area Forecast Discussion
National Weather Service Houston/Galveston TX
331 PM CDT Sun Jun 18 2017

Tonight and Monday...mesoscale models suggest possibility of a
complex of showers and thunderstorms developing over OK or NE
Texas overnight then dropping southward toward northern portions
of the forecast area very late tonight or Monday morning. Airmass
more capped this far south and unclear how far it will make it
into the forecast area...but have shower chances in Houston County line with surrounding zones...then Monday for
mainly northern half of CWA. Cold front is forecast to approach
from the north but stall out before quite making it into the area.

Tuesday and beyond forecast becomes increasingly dependent on
system now over western Carribean Sea forecast by all the models
to become better organized as it moves N or NW and emerges into
the Gulf of Mexico. NHC gives this system a 70 percent chance of
becoming a tropical cyclone over the next 48 hours and a 90
percent chance over the next 5 days. The track forecast for this
system is very complicated. An upper level trough over western seen in model progs and water vapor imagery...will tend
to draw the system north perhaps toward the northern Gulf coast
and impose shear on the system. However there is some
indication...especially in latest runs...of this upper trough
becoming more cut off with steering currents then guiding the
system more toward the west on the northern flank of this cut off
low and with 500 mb ridge to the north. ECMWF...GFS...Canadian...
have all trended farther west with their tracks today perhaps due
to the handling of these features. Based on todays trends Texas
coast could see some impacts as early as late Wednesday or
Thursday. That said with complicated steering pattern and still no
well defined low center there remains much uncertainty in the
track of this system and all will need to continue to monitor. A
track to the east would mean little impact. As far as strength of
system...shear over Western Gulf and avaiable intensity guidance
would suggest most likely no stronger than a tropical storm but
will have more information on forecast intensity from the National
Hurricane Center when and if the tropical cyclone forms. 18


A weaker pressure gradient has helped to lower winds this afternoon
but seas have remained slightly elevated. However will be expecting
things to continue to quiet down tonight and will let the SCEC exp-
ire as planned. Generally light SE winds on Mon will be transition-
ing to a E/NE flow by Tue/Wed as the tropical disturbance currently
near the Yucatan finally makes its move into the central(ish) Gulf.
There is still a lot of uncertainty with the eventual track of this
system with much of the US Gulf coast in play. Mariners/marine int-
erests should stay up to date with the latest information with this
system. 41


College Station (CLL)      76  94  75  94  73 /  10  20  10  10  10
Houston (IAH)              77  95  75  95  73 /  10  20  10  20  10
Galveston (GLS)            81  90  80  90  79 /  10  10  10  20  20


     for the following zones: Coastal waters from Freeport to
     the Matagorda Ship Channel out 20 NM...Coastal waters from
     High Island to Freeport out 20 NM...Waters from Freeport to
     the Matagorda Ship Channel from 20 to 60 NM...Waters from
     High Island to Freeport from 20 to 60 NM.



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