Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 302107

Area Forecast Discussion
National Weather Service Houston/Galveston TX
407 PM CDT Thu Mar 30 2017

After yesterday`s storms, mostly sunny skies and light
northwesterly winds greeted the region today. Temperatures as of 3
PM CDT had risen into the mid to upper 70s. With clear skies
continuing tonight in the wake of yesterday`s system (now over
Missouri), radiational cooling will allow for overnight
temperatures to fall into the mid 50s to mid 60s.

Surface analysis shows a slowly moving cold front dropping south
across Oklahoma this afternoon, but the departure of the compact
upper low over Missouri will result in loss of mid/upper level
forcing for this feature and keep it well north of Southeast Texas
overnight. Shortwave ridging will build into the region tonight
behind this departing system, with the main axis amplifying east
of Southeast Texas on Friday as another system approaches from the
Great Basin. This amplified upper ridging will promote another
day of dry and mostly sunny conditions on Friday, as well as near
record to record high temperatures possible across much of
Southeast Texas on Friday. Record high temperatures may be
possible again along the Upper Texas Coast on Saturday.

Upper flow aloft will become increasingly south to southwest on
Saturday as a disturbance shifts from the Four Corners farther
into New Mexico. Unfortunately, there is still considerable
uncertainty regarding the Saturday and Sunday portion of the
forecast as model guidance continues to remain somewhat out of
phase regarding timing and placement of features. A surface low
looks to develop over the Panhandles with an attendant dryline
stretching into West Central Texas as a result, with speed and
moisture convergence across West Central Texas associated with the
developing surface low encouraging a few isolated showers across
the western counties on Saturday morning. Farther west (across the
Permian Basin and Low Rolling Plains), diurnal heating along the
dryline looks to result in thunderstorm development... with lift
from the approaching upper level system possibly resulting in
upscale growth into an thunderstorm complex that moves across the
state on Saturday night. This could serve as one round of rainfall
for the region should this complex develop and actually make it
to Southeast Texas.

Rain chances will increase more on Sunday, however, as the upper
disturbance digs into northern Mexico on Sunday and then sweeps
into the region on Sunday night. Precipitable water values surge
to 1.5 to possibly 1.9 by Sunday, increasing concerns for at least
a locally heavy rain as upper divergence associated with the
approaching disturbances promotes the development of numerous to
widespread showers and thunderstorms. Several features are in
place Sunday to confirm the concern for heavy rain and possibly
flooding: a surface reflection/trough and approaching cold front
associated with the upper trough that may help focus rainfall,
high atmospheric moisture content, and rainfall that has been
observed recently (generally across areas south of Interstate 10).

However, model solutions from the GFS and European during this
time show that some of the synoptic features necessary for a true
Maddox heavy rain event (in this case, how the atmospheric
moisture in the column is aligned) are out of phase... which
raises concerns on the actual severity of the heavy rain threat.
This is not to downplay the threat for heavy rain as the region
will see rain on Sunday... but the mesoscale appears to be the
bigger driver at this point for the materialization of this threat
in the region. Adding further to the uncertainty to the forecast
for Sunday is the wide spread in forecast rainfall, with SREF 3
hourly QPF plumes advertising a considerable spread anywhere from
0 to 2 inches throughout the day on Sunday. Increasing wind shear
associated with the passage of this system may also promote a
severe weather threat with stronger thunderstorms on Sunday.

Regardless, the passage of this system Sunday night will push a
cold front off the coast and end rain chances for the region at
the beginning of next week. Dry and warm conditions will become
established behind the front through mid-week, but an approaching
front may bring low rain chances back into the forecast by



North to northwest winds have been coming down this afternoon,
and so have the seas. South winds are still on schedule to come
back to the area later tonight and tomorrow and strengthen
tomorrow night and Saturday when caution flags and/or advisories
will be needed. Increasing chances of showers and thunderstorms
will accompany the moderate to strong onshore flow over the
weekend, and elevated tides might cause some minor impacts over
Gulf facing beaches. The next cold front moves off the coast
Sunday night and on into Monday with a moderate to strong offshore
flow expected to develop in its wake. Look for onshore winds to
come back Monday night and Tuesday followed by the area`s next
cold frontal passage on Wednesday. 42


Near record to record high temperatures will be possible across
parts of Southeast Texas on Friday and Saturday. Record high
temperatures and the years they occurred are listed below.

March 31 Records
LOCATION                  RECORD HIGH     YEAR
Houston Intercontinental      88          1946
Houston Hobby                 88          2016
College Station               94          1946
Galveston                     80          1941

April 1 Records
LOCATION                  RECORD HIGH     YEAR
Houston Intercontinental      89          1936
Houston Hobby                 89          1974
College Station               93          1936
Galveston                     81          1935


College Station (CLL)      56  86  64  84  67 /   0   0  10  20  60
Houston (IAH)              58  87  66  85  70 /   0   0   0  10  60
Galveston (GLS)            68  81  71  81  72 /   0   0  10  10  50




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