Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 132136
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
336 PM CST Tue Nov 13 2018

.DISCUSSION...

After a bit of an exciting morning with flurries and some non-
accumulating sleet across much of Southeast Texas, we will settle
into a more stable, but much colder weather pattern for several
days. Freeze warnings are in effect for all inland areas tonight.
Though a slow warmup will commence for the second half of the
week, this will only bring temperatures back to near normal this
weekend before another weak front nudges temperatures back down a
bit early next week.


.NEAR TERM [Through Tonight]...

Radar shows that today`s mix of rain, sleet, and snow has exited
the area along with the midlevel forcing that generated it, and
only some light rain showers persist in the offshore Gulf waters
off Bolivar. Meanwhile, satellite shows that the cloud edge is
just on the western edge of the area, and the far western corner
of Burleson County is starting to see clearing. This is likely
coming too late to help locations mired in the upper 30s break
fast 40 degrees. Indeed, climate sites are largely escaping record
low maximum temperatures today thanks to their temperatures at
midnight!

The clearing trend will continue from west to east across
Southeast Texas tonight, with the far eastern reaches of our area
staying mostly cloudy until near sunrise. At this time, it looks
like the cloud edge will reach I-45 at roughly 7pm, though there`s
a little wiggle room in that estimate.

Of course, how clear the sky gets will have a profound impact on
how chilly we get tonight. A freeze warning is in effect for the
inland zones, while coastal areas are left out. Strong cold
advection will help push temps down, but winds of up to 10 mph and
any lingering clouds will mitigate the crash. Winds last night
just barely kept last night`s freeze warning from verifying, so
with the winds a bit lighter and clearing beginning to take place,
it was felt most appropriate to convert the entire watch area to a
warning.


.SHORT TERM [Wednesday Through Thursday Night]...

Wednesday will be fair and cold, with highs a good 20-25 degrees
below normal, but at least pushing up towards 50 degrees. This
daytime boost might be necessary, because with clear skies and
lighter winds, temperatures should crash harder Wednesday night
than tonight. However, starting from afternoon temps about 10
degrees warmer, the ultimate result is for a low temperature
situation that is about as cold as tonight looks.

From that point begins our slow, but steady warmup into the back
half of the week. Sunny skies will help us reach the mid 50s
Thursday, and the end of strong cold advection will make for lows
that only fall into the 40s. Still 5 degrees or so cooler than
seasonal averages, but a much better situation than expansive
freeze warnings.


.LONG TERM [Friday Through Tuesday]...

The slow march upwards of temperatures under sunny skies continues
right into the weekend, when high temperatures finally reach to
around the normal values. With onshore flow resuming, likely
sometime on Friday, moisture will begin to return, increasing
humidity and providing a more solid floor to low temperatures for
the weekend.

Of course, the increased moisture also means that we may see rain
chances begin to creep upwards again late this weekend,
particularly as an approaching weak front will provide a decent
surface for warm, moist, Gulf air to get its isentropic glide on.
Look for this front to slide through slowly, reaching College
Station sometime on Sunday and reach the coast Sunday night.
Indications of this front will be subtle - the aforementioned rain
chances, a wind shift, and a small dip in temperatures early next
week. The zonal flow aloft simply won`t let a much stronger impact
occur.

And yes, I am hoping to end the discussion here without you
mentioning the middle and end of next week. Why do you ask?

Seriously, there`s broad consensus in the models for our next more
significant weathermaker in this period. But that`s about where
the consensus ends. Even with more predictable features aloft,
there is a great deal of disagreement between models about how
this situation will evolve. The NAEFS percentiles and CIPS analogs
are not providing much guidance here either. The NAEFS mean does
not deviate outside of the "Average" percentiles. CIPS extended
analogs do not suggest much signal for anything, except a decent
signal for highs above 70, and a strong confidence in highs above
60. With climo around 70 degrees...that`s not much of a surprise.


&&

.AVIATION [18Z TAF Issuance]...

Sleet, snow, and rain...what a great morning. No accumulations of
the sleet or snow with the warm ground. MVFR ceilings across the
area but dry air is mixing in across the west at 18z. Expect to go
VFR CLR from NW mid afternoon to SE late afternoon/sunset.
NW winds 10-17g15-24kt this afternoon diminishing again around
sunset.

Brief window for another hour at GLS of RA/PL/SN mix before the
band departs.

45

&&

.MARINE...

Gale warning has been dropped and will continue with SCA for the
Gulf waters.

Seas of 5-10 feet late this afternoon very slowly subsiding
tonight/Wednesday morning. Northerly winds 15 to 25 knots also
gradually subsiding mainly after midnight through Wednesday
afternoon. Low water levels in the Bays but these should recover
tonight then quickly Wednesday morning with the next full incoming
tides.

Winds relaxing into Thursday with high pressure over the area.
Eventually southeasterly flow strengthens Saturday night/Sunday with
the approach of a cold front.

45

&&

.CLIMATE...

Smashed records in Houston today, as both IAH (City of Houston)
and Hobby have recorded its earliest frozen precip on record, with
a trace of snow/graupel. This easily clears the old record at both
sites of November 23.

Galveston`s official observation only recorded rain, so its record
of earliest observed snowfall of December 4 appears safe.

As for tonight`s freeze, this does come roughly two weeks ahead of
the "average" first freeze. But a closer look at the freeze dates
shows more of a bimodal clustering, with one peak in mid-November
and a larger one in early December. So, it may be fair to say that
our freeze event will likely fall in line with an "early normal".
Perhaps unusual, but not THAT unusual.

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL)  27  48  29  57  37 /   0   0   0   0   0
Houston (IAH)          31  49  30  56  38 /   0   0   0   0   0
Galveston (GLS)        39  50  41  55  49 /   0   0   0   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...Freeze Warning from 9 PM this evening to 9 AM CST Wednesday for
     the following zones:
     Austin...Brazos...Burleson...Colorado...Grimes...Houston...Madison...Montgomery...Polk...San
     Jacinto...Trinity...Walker...Waller...Washington.

     Freeze Warning from midnight tonight to 9 AM CST Wednesday for
     the following zones: Coastal Jackson...Fort Bend...Inland
     Brazoria...Inland Harris...Inland Jackson...Inland
     Matagorda...Northern Liberty...Southern Liberty...Wharton.

GM...Low Water Advisory until 6 PM CST this evening for the following
     zones: Galveston Bay...Matagorda Bay.

     SMALL CRAFT SHOULD EXERCISE CAUTION until 10 PM CST this evening
     for the following zones: Galveston Bay...Matagorda Bay.

     Small Craft Advisory until 5 AM CST Wednesday for the following
     zones: Coastal waters from Freeport to Matagorda Ship
     Channel TX out 20 NM...Coastal waters from High Island to
     Freeport TX out 20 NM.

     Small Craft Advisory until 11 AM CST Wednesday for the following
     zones: Waters from Freeport to Matagorda Ship Channel TX
     from 20 to 60 NM...Waters from High Island to Freeport TX
     from 20 to 60 NM.


&&

$$

DISCUSSION...Luchs
NEAR TERM...Luchs
SHORT TERM...Luchs
LONG TERM...Luchs
AVIATION...45
MARINE...45
CLIMATE...Luchs


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