Area Forecast Discussion
Issued by NWS Houston/Galveston, TX
FXUS64 KHGX 250021
Area Forecast Discussion
National Weather Service Houston/Galveston TX
721 PM CDT TUE MAY 24 2016
Concerns for the 00z TAFs include low stratus development
overnight and isolated showers developing near the inland
terminals Wednesday afternoon.
Southerly to southeasterly winds around 7 to 15 knots are
expected to prevail through the period. Similar to last night,
expect MVFR stratus to develop again overnight and persist into
the late morning hours before beginning to break up/lift to VFR
with daytime heating. May see a few hours of IFR stratus at more
sheltered locations, but confidence was not high enough to include
more than a TEMPO mention in at Conroe and Huntsville.
A few showers may be able to develop again tomorrow afternoon as
convective temperatures in the mid to upper 80s are reached and
the GFS/NAM/ECMWF are fairly consistent in some activity
developing in the late afternoon to early evening hours. Included
a VCSH mention in for the inland terminals for late Wednesday
afternoon but the region looks to remain on the northern periphery
of a mid/upper level ridge and this feature may limit greater
shower coverage during this time.
.PREV DISCUSSION... /ISSUED /
Surface dew points were very warm today and heat index values
were closing in on 100 degrees. Warm and humid conditions will
prevail again Wednesday into Thursday. A few showers had developed
this afternoon beneath a weak capping inversion and near a weak
850-700 mb convergence zone. With the loss of heating and the
weakening of the convergence, feel precipitation will come to an
end around sunset. Skies should remain mostly cloudy overnight and
min temps will remain very warm. Upper level ridging will remain
over SE TX on Wednesday but PW values will approach 1.85 to 2.00
inches during the afternoon. The jet structure shows a bit of a
split over SE TX and upper level winds look divergent between
15-21z. Fcst soundings show quite a bit of dry air between 850-600
mb and a weak cap near 700 mb. Have added slight rain chances for
Wednesday due to the high moisture content and favorable jet
dynamics despite the mid level drying/cap.
Forecast soundings show a saturated column developing below 850 mb
on Wednesday night. Could get a few streamer showers beneath the
cap on Wednesday night so will maintain slight rain chances.
Thursday is looking more interesting as PW values surge to near
2.00 inches and a weak short wave moves across SE TX. Upper level
winds will once again split over SE TX and the combination of
these three ingredients should compensate for some slightly drier
air in the 850-700 layer and a weak capping inversion which should
easily erode by 18z. Will stay with chance PoPs for now but likely
PoPs may ultimately be required on Thursday, particularly over the
NW half of the region.
Rain chances should remain high on Friday as a strong and neutral
to negatively tilted upper trough moves east across the Southern
Plains. SE TX will lie in a well defined jet couplet with PW
values near 2.00 inches. CAPE values will be close to 3500 J/Kg
and LI values between -9 and -11 over the northern zones so some
of the storms could become strong to severe over the NW half.
Will maintain likely PoPs on Friday for areas away from the coast
and taper slightly lower toward the coast and over the gulf.
Some uncertainty for the weekend and early next week as global
models diverge in their respective upper air patterns. The GFS
builds a ridge over SE TX Sunday through Tuesday while the
Canadian and ECMWF maintain a weak upper trough and SW flow aloft.
Will maintain slight rain chances Sunday thru Tuesday and will
await models to build a consensus. 43
A moderate on-shore flow will continue for the next several days.
SCEC flags are up for all coastal and offshore waters through 7 AM
Wednesday morning. Winds may fall below SCEC criteria Wednesday and
Thursday as the axis of the surface ridge shifts to the east,
however the gradient tightens again later in the week, possibly
pushing winds to advisory levels on Friday. Winds and seas should
gradually subside over the Memorial Day Weekend as the gradient
loosens once again.
The current weather pattern sets up a long fetch to the Western
Carribean. Tide levels will gradually increase for the next several
days with a Coastal Flood Advisory possible for Friday as the
predicted tide levels near 3.5 feet may cause flooding of lower
lying areas on the Bolivar Peninsula and along Toddville Road in
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 74 88 73 81 72 / 20 20 20 50 30
Houston (IAH) 75 88 75 85 74 / 20 20 20 40 30
Galveston (GLS) 78 83 77 82 77 / 10 20 20 30 20
GM...SMALL CRAFT SHOULD EXERCISE CAUTION through Wednesday morning
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.