Area Forecast Discussion
Issued by NWS Houston/Galveston, TX
FXUS64 KHGX 090538
Area Forecast Discussion
National Weather Service Houston/Galveston TX
1138 PM CST Thu Dec 8 2016
VFR. Light rain or drizzle to impact more coastal hubs into early
Friday morning as light precipitation is generated per the gentle
lift of mid-level moist air over cool near surface air. Generally
a few to sct mid-level ceiling through the majority of the period
with gradually weakening northeasterlies. 31
.PREV DISCUSSION... /ISSUED 859 PM CST Thu Dec 8 2016/
Areas of mainly light rain continue generally around and to the south
of Interstate 10 this evening as a disturbance moves across the state.
Still think this activity will come to an end during the remaining
evening hours with decreasing cloud cover still possible during the
overnight hours. Unsure how much clearing we will see as some of the
latest models are keeping clouds across parts of our area overnight.
For now, feel it`s best to leave the forecast as is with the freeze
warning in effect during the late night through morning hours. Enough
cloud cover might end up keeping our overnight lows a little higher
than anticipated resulting in fewer hours at or below freezing in the
warning area. 42
PREV DISCUSSION... /ISSUED 551 PM CST Thu Dec 8 2016/
Brisk 10 to 15 mph northerlies through the daylight Friday morning
hours...coastal 20 mph northerlies gusting to near 30 mph will
persist through sunrise. VFR with generally a scattered mid-level
deck through Friday afternoon. 31
PREV DISCUSSION... /ISSUED 326 PM CST Thu Dec 8 2016/
FREEZE WARNING IN EFFECT FOR AREAS NORTH OF HOUSTON...
Surface observations at 21z show temperatures in the 40s for most
of the area which has been the case for most of the day. The lone
exception is along the coast with low 50s. Area radar are picking
up some returns with light rain coming into the area from the west
and southwest. This is in response to a short wave trough moving
across the area. Boundary layer should be quite dry with colder
airmass moving into the region so any rainfall amounts will be
light since most of the precipitation will evaporate. Any rain
chances should be ending this evening or be confined to the coast
where temperatures will be well above freezing.
There has not been any real change to the low temperature forecast
for tonight and the freeze warning. Latest update mainly depicts
what the coldest temperatures could get and what we think will
likely occur. The cold advection will continue overnight but there
may still be some insolation occurring from cloud cover and mixing
with northerly winds. Clouds should be clearing out finally during
the 10-14Z time frame (4-8AM) when temperatures should be at their
lowest. Freezing line should reach I-10 west of Houston and bend
north through northern Harris Co into Liberty Co. Harris county
will remain in freeze warning even though most of the county may
not experience freezing temperatures. There is still the potential
that northern areas of Harris county will so Harris county will
remain in the warning.
High pressure over the area tomorrow will keep cold air in place
so that max temperatures only reach the 40s. With clearing skies
and calmer winds, there is the potential for another freeze
Saturday morning primarily north and east of Houston. No freeze
warning will be needed since a freeze will have likely occurred
the night before.
Saturday high temperatures rebound into the 50s and in all
likelihood continue to increase overnight into Sunday with return
flow off the Gulf and a warm front passage. This also increases
the chances of showers for the area given isentropic lift over the
warm front surface. A fast moving short wave trough will move
across the Plains Sunday night into Monday with the GFS stronger
with the wave than the ECMWF. A front will push through Monday
ending rain chances but since the front does not push far into the
Gulf, it could push back as a warm front on Tuesday. This means
that showers may be possible again.
Forecast for the middle of the week. GFS/ECMWF/Canadian all keep
a very strong polar jet ripping across the U.S. with some what of
split flow as ridging occurs through Alaska and then the diving
jet resembling a McFarland type pattern. Right now GFS/ECMWF are
differing in next Canadian cold front where the GFS is not
stronger with this front next Wednesday and the ECMWF is weaker.
This is opposite of yesterday`s model runs. This seems to be a
good place to forecast a blend of the model solutions given the
uncertainty of the pattern evolution. 39
Winds and seas will remain elevated for the rest of today and this
evening. Winds over the Gulf will frequently gust in excess of 40
knots this evening and overnight. A Gale Warning is in effect for
nearshore waters through midnight tonight and for offshore waters
through 6AM tomorrow morning. A Small Craft Advisory is in effect
for Matagorda and Galveston Bays through midnight tonight, nearshore
waters from midnight tonight through noon tomorrow, and for offshore
waters from 6AM through noon tomorrow.
The strong offshore flow will slowly decrease throughout the day on
Friday as the surface high moves east. A moderate onshore flow is
forecast for Saturday...but winds will be increasing back to near
SCEC/SCA criteria for Sat night/Sun as the gradient tightens in
response to the next storm system moving across the Southern Plains.
The next front on Sunday night will probably stall inland and not
reach the coastal waters. Onshore winds will persist through Tuesday
night but speeds will drop off as the gradient weakens.
Although there are some timing differences between the GFS and
ECMWF, it appears that another cold front will cross the Gulf some
time around Wednesday. 11
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 30 47 33 53 50 / 20 0 10 10 40
Houston (IAH) 33 49 34 55 51 / 20 0 0 10 30
Galveston (GLS) 41 51 46 61 60 / 20 0 10 10 20
TX...Freeze Warning until 9 AM CST Friday for the following zones:
GM...Small Craft Advisory until midnight CST tonight for the
following zones: Galveston Bay...Matagorda Bay.
SMALL CRAFT SHOULD EXERCISE CAUTION through Friday morning for
the following zones: Galveston Bay...Matagorda Bay.
Small Craft Advisory until noon CST Friday 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.
Gale Warning until midnight CST tonight for the following zones:
Coastal waters from Freeport to the Matagorda Ship Channel
out 20 NM...Coastal waters from High Island to Freeport out
Small Craft Advisory from 6 AM to noon CST Friday for the
following zones: Waters from Freeport to the Matagorda Ship
Channel from 20 to 60 NM...Waters from High Island to
Freeport from 20 to 60 NM.
Gale Warning until 6 AM CST Friday for the following zones:
Waters from Freeport to the Matagorda Ship Channel from 20
to 60 NM...Waters from High Island to Freeport from 20 to