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Area forecast discussion 
National Weather Service Houston/Galveston Texas
1203 am CDT Tuesday Jul 22 2014

updated aviation.


made few changes to tafs. Air mass very humid with dewpoints
mainly in the upper 70s at the moment. With fairly light winds and
clear sky wouldnt be suprised to see some patchy fog and low
cloud development much like last conditions similar to
24 hours ago. Continue to play the tafs close to persistence. Not
out of question could see few showers along boundary to northeast
overnight as hinted at by rapid refresh. Otherwise looking at
diurnal development again mainly over coastal tafs.


Previous discussion... /issued 912 PM CDT Monday Jul 21 2014/

tweaked grids to better reflect recent into short term trends.
Did lift the most favorable region for breeze-driven convection up
from slight to low chance. The better performing arw-WRF was what
was considered when painting probability of precipitation around the Galveston Bay area
and those points a little further inland. Despite overall regional
subsidence created by the gargantuan upper ridge centered over
western Texas...similar moisture and instability profiles lean
this forecast towards persistence with relation to tomorrow's
rain showers/isolated ts probabilities. A brief late afternoon period of greater
than 103f heat indices as ambient temperatures reach the middle
90s over low-middle 70 dew points. 31

Previous discussion... /issued 655 PM CDT Monday Jul 21 2014/

updated aviation discussion.

showers and thunderstorms have pretty much dissipated past hour or
so although one shower has just developed in vicinity of ksgr along
outflow boundary. This too should dissipate over next hour or so.
Overnight...with light winds and mainly clear sky could see some
patchy fog. This low level moisture could mix up briefly to an
MVFR ceiling after sunrise as it did this morning few spots. Nmm
and arw WRF runs show few showers and storms redeveloping Tuesday
afternoon in and around Houston and Galveston Bay...much as today.

Am treating taf forecast fairly close to persistence with a period
of fog where it occurred last night...and a brief period of MVFR
ceilings likewise where this happened last night. Will go with thunderstorms in the vicinity
only for hou and iah for Tuesday afternoon...again mainly based on
persistence but also these mesoscale runs. 46

Previous discussion... /issued 336 PM CDT Monday Jul 21 2014/

a few showers have developed this afternoon in association with
the Bay/sea breeze near Galveston Bay although all activity has
been limited to the coastal counties. Dewpoints remain in the middle
to upper 70s this afternoon allowing heat index values to reach
between 100 and 105 degrees. Only a few sites have reported heat
index values of 108 or greater and these appear to be
unrepresentative given their high dewpoint temperatures. With this
in mind no heat advisory will be issued today as we should not
meet the two day 108 requirement.

The 12z GFS/NAM runs have come in a bit wetter for tomorrow and
will expand probability of precipitation slightly inland. Greatest coverage will again be
near Galveston Bay. With the strength of the ridge will limit it
to 20 probability of precipitation as any development should remain isolated as was the
case today. Rain chances are looking better for Wednesday as the
GFS now brings the upper weakness closer to our region and shunts
the upper ridge off to the west. This should allow for a brief
break in rising temperatures in addition to the chance for
rainfall. Rain chances will taper off on Thursday with hotter and
drier conditions expected this weekend. With the ridge building
back in we may be discussing triple digit temperatures for our
northwestern counties over the weekend into early next week.

Models continue to advertise an upper low deepening/digging across
the eastern United States early next week. The latest GFS run is
more aggressive with the southward progress of this system and
pushes a front and some precipitation into the region late next
Tuesday. As nice as this would be...given the time of year will
retain a fair bit of skepticism until this is supported by
additional model runs. 38/jb

Marine... light onshore flow will be the general rule this week.
Isolated showers and even a few thunderstorms as upper speed maximum
drops south along the Sabine River tomorrow. Rain chances linger
on Wednesday before upper ridging noses back in from the
northwest. 45

in the short term...VFR across the area and cap holding strong up
north for iah area northward. So will drop the thunderstorms in the vicinity for iah but will
keep it for hou southward. 45


Preliminary point temps/pops...
College Station (cll) 76 98 75 96 75 / 10 10 10 20 10
Houston (iah) 76 96 77 95 77 / 20 30 20 30 20
Galveston (gls) 81 92 81 91 81 / 20 20 20 20 20


Hgx watches/warnings/advisories...



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