Tuesday, February 16, 2021

Feb. 16 21

 Area Forecast Discussion

Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 162345
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
545 PM CST Tue Feb 16 2021

.AVIATION [00Z TAF Issuance]...

Another challenging TAF cycle ahead as another winter storm makes
its way into Southeast Texas. Conditions are VFR now, but will
degrade tonight with lowering CIGs and increasing rain chances
overnight. Think the pre-storm onshore flow will keep HOU, LBX,
and GLS warm enough to avoid FZRA, though HOU will particularly be
on a razor`s edge. SGR, IAH, and CXO are currently set to start
with FZRA, but transition to SHRA/RA as warmer air filters north.
A brief transition may be possible at CLL and UTS, but would be
short and go back to FZRA/SHSN as cold air surged in as the storm
exits. To simplify a complex TAF (too late!), I don`t bother to
show a transition from FZRA at those two sites.

Multiple amendments seem likely. However, it is worth mentioning
that communications and/or power problems have plagued multiple
sites, and we are currently unable to reach SGR or LBX. We will do
our best to keep the TAF current, but because of the lack of obs,
have added AMD NOT SKED to those two.

&&

.PREV DISCUSSION /Issued 341 PM CST Tue Feb 16 2021/...

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

Weather conditions will be deteriorating tonight as low pressure
develops south of the Matagorda Bay area. As this low moves into
our coastal waters overnight and on through the waters Wednesday
morning, light precipitation will develop and spread inland while
shortwaves from the upper trof to our west scrape across the northern
parts of our area. Some icing could develop this evening where
precipitation falls near areas around freezing. The real mess looks
to begin to develop after midnight as the freezing line moves slowly
inland. Expecting increasing precipitation coverage during the
overnight through morning hours with significant icing possible
the further north you go. After looking at area soundings and model
trends, it still looks like locations north of Highway 105 will have
the greatest potential for the highest ice accumulation totals of
around 1/4 inch or higher. If this occurs, there could be devastating
impacts to structures, powerlines and agriculture. Of course, driving
should not occur - Stay home! Even areas south of Highway 105 to the
I-10 corridor will be susceptible to icing with potential totals of
around 1/10 to 1/4 inch (1/10 closer to I-10 and 1/4 closer to Highway
105). Again, the safety risk is too great to get on the roads - Stay
home! Improving conditions do not look to occur until late tomorrow
morning or early tomorrow afternoon when activity starts to come to
an end from west to east. With temperatures not expected to rise much
above freezing tomorrow afternoon (especially up north), any freezing
ice that has accumulated will be sticking around, and any melted ice
will freeze over again tomorrow night through Thursday morning with
temperatures in the 20s/30s.

Hang in there...warmer temperatures are coming! 42


.LONG TERM [Thursday Through Monday]...

Residual moisture in the wake of the departing surface low/cold
front may result in some lingering wintry precipitation heading into
Thursday morning, with light snow showers/sleet/ice pellets a
possibility. That being said, impacts from this spotty precipitation
are likely to be minor in comparison to the weather we anticipate
impacting the area in the immediate term. Behind the departing
system, northerly winds will result in another frigid day across SE
TX, with highs in the mid-30s inland to low 40s near the coast and
widespread overnight lows in the upper teens to low 20s. Actions to
protect people, pets, plants, and pipes from the persistent extreme
cold should be continued during this time.

Yet another unseasonably cold day, though a drier one, is in store
on friday as high pressure remains dominant over the South Central
CONUS. However, as this surface high pushes eastward as we reach
Saturday, a long-awaited warming trend will begin as we finally see
the re-emergence of an onshore flow pattern. As a result, highs on
Saturday break into the 50s while on Sunday temperatures reach the
mid to upper 60s at most locations.

Increasing moisture upon the redevelopment of southerly winds will
push total PWs back towards the vicinity of 1.0 in on Sunday
afternoon. Our next chance at precipitation (thankfully, it looks
like purely a rain event this time) will come on late Sunday/early
Monday as a surface cold front traverses the area and produces
scattered showers. The surge of cold air behind this departing
boundary will be comparatively weaker and far less persistent, with
lows not reaching below freezing in its wake on Monday night and
highs returning to the upper 60s/mid 70s by Tuesday afternoon.

Cady


.MARINE...

Light to moderate east to northeast winds are expected this evening
with gusts from 15 to 20 knots. Marine conditions become hazardous
late tonight ahead of a coastal low moving northward along the upper
Texas coast through Thursday. Gusty conditions and seas from 5 to 8
ft are expected along with scattered showers and a few
thunderstorms. Behind this system, a strong surface high builds in
keeping moderate to strong northwest winds. Therefore, advisory
conditions due to both winds and elevated seas will persist through
late Thursday night. Marine conditions will improve Friday into the
weekend with light south winds and seas up to 3 ft. 05

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL)  22  33  24  32  16 /  90  70  20  20   0
Houston (IAH)          27  38  29  39  25 /  80  90  20  10   0
Galveston (GLS)        38  48  35  43  30 /  90 100  20  10   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...Winter Storm Warning until 6 AM CST Thursday for the following
     zones: Austin...Brazos...Burleson...Coastal
     Harris...Coastal Jackson...Colorado...Fort
     Bend...Grimes...Houston...Inland Harris...Inland
     Jackson...Madison...Montgomery...Northern
     Liberty...Polk...San Jacinto...Southern
     Liberty...Trinity...Walker...Waller...Washington...Wharton.

GM...Small Craft Advisory from midnight tonight to noon 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...Galveston
     Bay...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.

     SMALL CRAFT SHOULD EXERCISE CAUTION until midnight CST tonight
     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...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.


&&

$$

SHORT TERM...42
LONG TERM...Cady
AVIATION...Luchs
MARINE...05

Winter Storm Warning

URGENT - WINTER WEATHER MESSAGE
National Weather Service Houston/Galveston TX
1258 PM CST Tue Feb 16 2021

...DANGEROUS ICE STORM EXPECTED TO CREATE LIFE THREATENING
CONDITIONS THROUGH TOMORROW MORNING ACROSS INLAND PORTIONS OF
SOUTHEAST TEXAS...

TXZ163-164-176>179-195>200-210>213-226-227-235-300-313-335-171200-
/O.CON.KHGX.WS.W.0003.210217T0000Z-210218T1200Z/
Austin-Brazos-Burleson-Coastal Harris-Coastal Jackson-Colorado-
Fort Bend-Grimes-Houston-Inland Harris-Inland Jackson-Madison-
Montgomery-Northern Liberty-Polk-San Jacinto-Southern Liberty-
Trinity-Walker-Waller-Washington-Wharton-
Including the cities of Baytown, Bellville, Brenham, Brookshire,
Bryan, Caldwell, Cleveland, Coldspring, College Station,
Columbus, Conroe, Corrigan, Crockett, Dayton, Devers, Eagle Lake,
Edna, El Campo, First Colony, Ganado, Groveton, Hempstead,
Houston, Huntsville, Liberty, Livingston, Madisonville,
Mission Bend, Missouri City, Navasota, Pasadena, Pecan Grove,
Prairie View, Rosenberg, Sealy, Shepherd, Somerville, Sugar Land,
The Woodlands, Trinity, Waller, Weimar, and Wharton
1258 PM CST Tue Feb 16 2021

...WINTER STORM WARNING REMAINS IN EFFECT FROM 6 PM THIS EVENING
TO 6 AM CST THURSDAY...

* WHAT...An approaching low pressure system tonight through
  tomorrow morning will bring a period of dangerous and
  potentially destructive freezing rain across the region with ice
  accumulation anticipated. Amounts are expected to range from a
  trace to a tenth of an inch along and around the Highway 59
  corridor with higher amounts expanding further northward. The
  highest totals from two tenths of an inch to in excess of one
  half inch will be to the north of a line from Bryan/College
  Station to Huntsville to Groveton. Some locations could see
  isolated higher amounts. These would be devastating amounts of
  ice with the potential to create additional power outages.


* WHERE...Inland areas of Southeast Texas.

* WHEN...Tonight through Wednesday morning.

* IMPACTS...Icy conditions will worsen quickly across the region
  tonight with the freezing rain. Very dangerous driving
  conditions from icy roads are expected. Travel should be
  avoided. Vegetation and powerlines will become coated with ice
  and as the ice accumulates will lead to breaking tree limbs and
  power lines. The power outages already present in many locations
  could well worsen. Even though some areas may thaw out briefly
  the potential for refreeze will be high Wednesday night with
  another cold front bringing subfreezing temperatures back across
  the region.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning means significant amounts of ice are
expected or occurring.

Travel is expected to become impossible across northern portions
of the area.

The latest road conditions for Texas can be found at
drivetexas.org.

&&

$$
Thoughts: Houston got 3 inches of snow!!!! The ice and snow are
still melthing from yesterday. Our power was out for a good 
32 hours where I live in Copperfield. Power finally came back 
on around 10:30 am today and had been out since around 1:30 am 
Yesterday, Monday morning. I slept under 10 blankets to keep
myself from freezing. There is another round of ice/sleet/
and snow coming to the Houston, TX area tonight and tomorrow
morning. I am excited for this to be over soon!

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