Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 162013
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
313 PM CDT Sat Sep 16 2017

.DISCUSSION...

.SHORT TERM [Tonight Through Monday Night]...
GOES 16 visible satellite imagery shows southeast Texas covered
with cloud streets with little if any vertical development. After
having below normal temperatures the first week or two of
September, it is feeling like summer again with temperatures this
afternoon in the low 90s and dewpoints in the upper 60s to low
70s. Upper level analysis shows weak ridging aloft but it is
certainly enough to keep convection from forming this afternoon.

GOES 16 derived precipitable water imagery shows a plume of
higher moisture over the central Gulf. This will be the main
reason for increasing rain chances Sunday and Monday. NAM/GFS show
precipitable water values greater than 2 inches getting into the
region mainly on Monday. This should support scattered showers and
a few storms mainly on Monday but model QPF fields suggest more
isolated thunderstorm activity. The other question will be the
sinking motion in the atmosphere due to the ridge. The ridge
really does not break down much until late Monday with maybe a
weak subtle vorticity maximum that pushes across Texas Monday
evening. Any rainfall we do get will soak well into the ground
since much of the area has not really had any rainfall since
Harvey.

.LONG TERM [Tuesday Through Saturday]...
Upper level flow for next week basically changes from quasi-zonal
on Tuesday to an amplified pattern as another long wave trough
develops over the western U.S. The ridge develops through the end
of the week over much of Texas and the Mississippi River valley
through next Friday and Saturday. Deeper moisture does remain in
place through the week so forecast will keep 20 to 30 percent
chances of rain going. Models are hinting at higher rain chances
on Thursday but this largely depends upon another surge of
moisture from the Gulf. This seems to be overdone by the GFS but
ECMWF/Canadian are at least hinting at better chances as well. The
bad news about this upper level pattern is that it does not
support any cold front pushing into the area. To get that, we
would need to ridge to develop over the western U.S and the trough
to develop over the Plains through the New England states.

Overall there should be very little weather impacts this week,
just your typical summer time isolated to scattered showers and
storms that can drop a brief downpour.

Overpeck

&&

.AVIATION [18Z TAF Issuance]...

Fog/cigs have transitioned back up into VFR territory and should
remain that way well into the overnight hours. But am expecting
some additional fog/cigs to develop again considering conditions
shouldn`t be all that much different than last night. Otherwise,
guidance is suggesting some iso/sct precip developing offshore
late tonight, then along the seabreeze Sunday afternoon. 47

&&

.MARINE...
Light to moderate onshore flow and relatively low seas should
persist for the next several days. As moisture levels increase,
we`ll probably see start seeing some scattered late night and early
morning showers/tstms around.  47

&&

.TROPICAL...
Since there is an upper level ridge over the northern Gulf and a
weakness in the flow along the Atlantic coast, tropical cyclones
will be more privy to stay in the Atlantic not impacting the Gulf.
There are 3 tropical cyclones in the Atlantic with Jose, Lee and
TD 15. TD 15 will likely become Maria and impact the Caribbean
islands as it begins to turn up the Atlantic coast behind Jose.
Lee will continue as a weaker system in the Atlantic. In the
eastern Pacific, hurricane Norma should continue NNW to west of
Cabo San Lucas and slowly weaken over the next 5 days. Moisture
from it could push into Texas in the upper levels but that
moisture may only slightly influence rain chances for southeast
Texas next week.

Overpeck

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL)  70  92  72  92  74 /  10  10  10  30  10
Houston (IAH)          72  91  74  89  75 /  10  20  10  40  10
Galveston (GLS)        78  88  78  87  78 /  20  20  30  30  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...None.
GM...None.

&&

$$

SHORT TERM...Overpeck
LONG TERM...Overpeck
AVIATION...47
MARINE...47
TROPICAL...Overpeck


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