Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 232302
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
502 PM CST Thu Jan 23 2020

.AVIATION [00Z TAF Issuance]...

Visible satellite imagery has shown that the pesky 2000 to 2500
ft deck that has been sticking around all day is finally beginning
to scatter out. Skies should become cloud free in a few hours and
the moderate northwesterly flow will also become lighter and more
variable overnight tonight. VFR conditions are expected through
the period.

&&

.PREV DISCUSSION /Issued 340 PM CST Thu Jan 23 2020/...

.SHORT TERM [Tonight Through Friday Night]...

Skies finally starting to scatter out from northwest and west to the
east as wraparound clouds slowly mixing out. Temperatures tonight
will be dropping into the mid 30s north and lower to mid 40s south
beneath clear skies. High pressure over the area Friday with light
winds and abundant sunshine.
45


.LONG TERM [Friday Night Through Thursday]...

By Friday night and into Saturday, surface high pressure centered
over the western Gulf Coast will push eastward, allowing for a
shift back to onshore flow by Saturday afternoon. With the surface
pressure gradient tightening in the wake of the departing high,
winds over the coastal waters of around 20 knots will promote
decent low level moisture advection into the area through Sunday,
by which precipitable water values should reach around 1.25 to 1.5
inches. High temperatures look to remain in the upper 60s to low
70s, slightly above seasonable norms for late January. PoPs
increase towards the end of the weekend as an upper- level trough
digging into the southwestern CONUS and an associated jet streak
push further eastward. GFS, ECMWF, and NAM are in relatively good
agreement showing the development of a weak coastal low in the
vicinity of the offshore waters by early Sunday. While
precipitation associated with this feature will impact the
entirety of the Houston CWA, the highest rainfall totals appear
likely to stay over the Gulf and coastal inland counties. Rainfall
coverage and totals will decrease in areas further north.

High pressure returns by early Monday as the coastal low advances
further into the Gulf, allowing for clearer and drier conditions.
This will be short lived, however, as the entrance of another
upper trough and associated surface low over the TX Panhandle
region will provide a return to showers on Tuesday afternoon. A
surface cold front extending from the advancing low looks to
traverse the area late Tuesday into Wednesday. GFS remains the
wetter solution compared to the ECMWF, so have kept PoPs in the
30s to account for the uncertainty still surrounding this feature.
Behind the departure of this system, look for a return to cooler and
drier conditions heading into the end of the week.

Cady


.MARINE...

Winds late this afternoon relaxing before increasing again as CAA
ramps up. SCEC flag for tonight as winds and seas respond. With high
pressure over SETX Friday winds should relax and turn to the east
Friday evening. Next upper s/w approaching Saturday and
southeasterly gradient tightens up and seas build. The onshore flow
will probably reach 15-20 knots and SCEC looks likely then relaxes
as coastal trough/low develops Sunday morning. Most of the guidance
showing the corridor from around Matagorda Bay eastward for the
track of the low. This could increase the chance for a brief sea fog
episode Sunday morning 1am to 10 am.  Offshore flow persists Sunday
after the passage of the low through Monday morning then again back
to easterly flow. Another low pressure system moves through with a
cold front arriving Tuesday night/early Wednesday.
45

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL)  38  65  41  66  54 /   0   0   0   0  40
Houston (IAH)          42  67  43  66  55 /   0   0   0  20  50
Galveston (GLS)        51  64  54  65  60 /   0   0   0  30  70

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...None.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION through late tonight 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.


&&

$$


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