December 2017: End Of The Year Weather

[MontgomeryCoWx]

Now that’s a Christmas morning

[MontgomeryCoWx]

Per the 0z GFS, HOUSTON stays below freezing from the 23rd to the 28thand has two Ice storms

[TexasBreeze]

Moving up in time and consistency is well established. Not snow, but an ice storm profile...

[MontgomeryCoWx]

Has a “mother of God” 595 dm ridge in Alaska which would trump 1983.

[jasons2k]

I sure hope we don’t see anything like that. It would do a number on the palm trees.

[MontgomeryCoWx]

6z keeps the trend! 14 model runs in a row!

[stormlover]

I don't buy it until euro start creeping colder

[vci_guy2003]

What does the Euro say?

[snowman65]

6z keeps the trend! 14 model runs in a row!

on a roll!!....Only 12 more to go....

[harp]

What does the Euro say?

I don't believe it goes out that far yet.

[redneckweather]

The Euro shows it near the end of its run but not near as cold. I do feel very confident that Christmas will be cold. lol

[MontgomeryCoWx]

I don't buy it until euro start creeping colder

The Euro only goes out 240 hours. The operational Euro agrees with the GFS on front timing of next Friday and then the run ends. The operational Euro is 10 degrees warmer during that time, but it's operational doesn't have the same 500 mb pattern that the Euro ensembles do.

The Euro ENS and GFS ensembles are very similar to each other with a huge ridge into Alaska. Again, I'll say I'm very confident of a cold outbreak given the ensembles. For me, and everyone else, its a matter of how cold and where the precip sets up.

[MontgomeryCoWx]

Euro ENS



GFS

[srainhoutx]

While the overnight Updated GEFS Super Ensemble Day 11+ Analogs suggest December 1983 as the top Analog, I'd be a bit cautious 10+ days away and I notice the Analog date in December 1983 overnight was about 10 ahead of what actually happened in Texas and Oklahoma back on Christmas Eve 1983. While the trends continue to raise and eyebrow and is noteworthy to mention, I would like to see the magnitude of the cold air building across the Canadian Prairies in real time before biting too much on the longer range model predictions. We know that the computer models often under estimate the swallow Artic Air masses. Frankly, a December 1983 repeat is something I could live without again. Brutally cold air that froze pipes as folks left for the Christmas Holidays with tremendous property damage from pipes bursting in homes, repeated freezing rain and sleet episodes and well over 100 hours below freezing with several shots of Artic Air lasting into the New Year...let alone the long-term damage livestock and agricultural interests all the way to Brownsville into Mexico.

[tireman4]

Shall we hoist the Bear Watch?



000
FXUS64 KHGX 131014
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
414 AM CST Wed Dec 13 2017

.DISCUSSION...
Surface high pressure is centered just to our west early this morning
and is bringing light/calm winds to our entire area. After a cold
start to the morning with some high clouds streaming across the area
from the west, look for temperatures to warm into the 60s and winds
to come back around to the south and southwest this afternoon as the
surface high moves off to the east. Tonight will be not as cold as
we await for the arrival/passage of our next cold front during the
day tomorrow. There will be no rain with the front, but some rain
might develop behind the boundary late Thursday through Friday with
the lowest chances near the coast (dry well inland) and the higher
chances offshore. Cooler temperatures can be expected behind the
front as high pressure builds into the area from the northwest. Eyes
then turn toward our southwest and west over the weekend as a storm
system organizes and moves across the area. Models differ on the
timing/strength of this system with some solutions keeping the best
lift/dynamics near and off the coast Saturday through Saturday night
while other solutions bring some impressively strong lift/dynamics
across parts of our area Saturday night through Sunday morning (see
SPC`s Day 4-8 Convective Outlook). Went ahead and raised weekend
rain chances a little bit more with this morning`s forecast package,
and we`ll probably end up needing to carry much higher POPs. At
this time, it looks like the first half of next week will be mostly
on the dry side with near normal temperatures. Some models are
showing a arctic cold/wintry mix moving into the state over the
holiday weekend. Model changes are likely, and we`ll be watching
to see how everything evolves. 42

&&

.MARINE...
Pressure gradient weakens today and expect a continued decline in
winds/seas through Thurs. A cold from twill push off the coast Thurs
evening and northerly winds will gradually increase to around 25kt
after midnight into Friday morning. Small Craft Advisories will be
required. Look for areas of ran to develop behind the front as well.

Unsettled wx continues in the waters into the weekend. A quick,
strengthening onshore flow is expected early Sat. Elevated winds,
seas and increasing shower/storm coverage is expected in advance of
an approaching upper disturbance. (Can`t rule out some sea fog in
advance either). This disturbance should trek off to the east early
Sunday taking most of the precip with it and allowing a weak
training frontal boundary to make its way into the waters. 47

&&

.AVIATION...
VFR for the next 30+ hours. Just some cirrus streaming overhead. 47

&&

.FIRE WEATHER...
Dry conditions will persist once again today with RH`s bottoming out
between 25-30% this afternoon. Winds speeds will be 5-15mph, so Red
Flag Warnings are not anticipated. 47

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 65 41 63 37 58 / 0 0 10 10 0
Houston (IAH) 63 44 65 41 57 / 0 10 10 10 10
Galveston (GLS) 60 53 67 47 57 / 0 10 10 20 20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

42/47

[MontgomeryCoWx]

Wow, those analog dates are like a Top Ten Highlight list of big Winter events in Texas.

I'm familiar with 1983, 1985, 1990 and 2009.

[srainhoutx]

Wednesday morning briefing from Jeff:

Significant forecast changes required this morning for this weekend

Major arctic air intrusion possible around Christmas

Models have come into somewhat better agreement that a strong storm system will cross the area this weekend. This will require a significant raising of rain chances for the weekend. Yesterday models kept most of the moisture and lift across the Gulf of Mexico, but recent runs are now suggesting very strong dynamics will come to bear across the region Saturday evening into Sunday morning. A surface cold front will move across the area late Thursday into Friday and then stall across the NW Gulf. A strong storm system west of Baja will eject across the area this weekend. GFS is most aggressive with moisture return showing PWS rising to nearly 1.8 inches by late Saturday. Think this is overdone and will temper moisture return to around 1.5 inches of PW. Still with forecasted strong dynamics forcing a coastal surface low to form over the NW Gulf expect showers and thunderstorms to develop and move across the area Saturday afternoon into Sunday morning. Should the surface warm front back far enough NNE could see surface based storms develop near the coast and offshore with a severe weather threat. System will be fast moving and timing may change some in the coming days.

Extended:
Main focus over the coming days will be a potential arctic air intrusion into the US and TX around Christmas. Latest GFS is simply a nightmare event for much of TX the week of Christmas showing 2.22 inches of freezing rain at IAH which would be devastating. A shallow arctic air mass appears to begin to develop over NW Canada next week and plunges down the eastern slopes of the Rockies around the 21st. Extended forecast soundings show the air mass is only a few thousand feet thick with sub-freezing surface temperatures (opposite of what we had last week where the surface was above freezing and the upper levels were cold enough for snow production). GFS generates several days of isentrophic lift over the very cold surface dome with lots of moisture moving into the area from the SW on the eastern flank of an upper level trough and digs down into N MX. Setup appears to support a winter weather threat for much of the state starting late on the 23rd and lasting until the 29th.

Experience with such shallow arctic air masses is that they tend to move in faster than expected and usually a bit colder than forecast. For now will continue to watch extended model solutions…interestingly this is the 14th GFS model run in a row that has suggested a winter storm threat for TX the week of Christmas. The ECMWF on the other hand is significantly warmer than the GFS and has a somewhat different upper level pattern over the southern plains during that week and would not support a winter storm threat.

[MontgomeryCoWx]

We are officially on Bear Watch!

[jasons2k]

I just want to caution everyone that the GFS shows ‘83 and ‘89 anomalies almost every year - gets everyone excited - and they don’t quite come to fruition.

[snowman65]

And now the GFS has is snowing here again on the 23rd and dry on Christmas....