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Fairly impressive shot of Arctic air following a potent Winter Storm exiting the Southern/Central Rockies mid next week with plenty of snowfall to our North. Equally impressive very low dewpoints also noteworthy with this airmass via the 00Z GFS. Starting to see some trends and we will continue to monitor as we get closer.

Wish casting sneaking closer to Hearne and College Station...

The overnight Global Ensembles continue to suggest most of North America transitions back into a very chilly pattern that will impact the United States Coast to Coast.

Next week is shaping up to be fascinating and a great opportunity for many of us to learn more about weather in Texas, namely winter weather. We're going to have an Arctic airmass oozing southward into the state in what will probably be a shallow layer. As some have said in this forum in the last few days, the models are notoriously bad when it comes to handling these types of airmasses. A zonal flow will dominate at the higher levels of the atmosphere. Fast moving disturbances and short waves will happen from time to time. The big question will be how deep is the cold layer and will it support snow or sleet or freezing rain/drizzle ... or just a cold rain. And just how cold will it be at the surface?

I believe that both public and private sector forecasters are going to have their work cut out for them next week, especially the latter half of next week.

Take a look at the NCEP Day 7 and Day 8+ Ensemble Spaghetti charts. Notice the big dip in the Northern branch Jet Stream as well as the Southern branch Jet Stream flowing almost zonal over Texas. While it is way too soon to accurately predict what the sensible weather may bring, it does raise an eyebrow when we see the potential for disturbances moving over a shallow cold layer of air at the surface. Typically when we see such pattern over Texas, we start to pay a little closer attention. We will continue to monitor the trends as the New Year begins.

The 12z GFS is now matching the last 2 runs of the Para GFS, with showing a band of mix precipitation moving from Southcentral Texas to Southeast Texas late next week, it even shows snow accumulation fwiw... lol

Now this is what I call a nice Snow Map! LOL.

post a picture

Can you imagine how this shot of air will feel. We're now in the 80's and we're talking high's probably in the 40's, maybe lower, in the latter half of next week. It will shock you to the very core, and as srain would say, sensible weather will become anything but sensible. More like insane. That's Texas in a nutshell.

Heat Miser wrote:Can you imagine how this shot of air will feel. We're now in the 80's and we're talking high's probably in the 40's, maybe lower, in the latter half of next week. It will shock you to the very core, and as srain would say, sensible weather will become anything but sensible. More like insane. That's Texas in a nutshell.

And past history here in Central/SE Texas tells us this is typically what happens when we have wild weather swings from one extreme to the other.

Interestingly the 12Z GEFS individual ensemble members have numerous members with a potential Coastal low/trough developing as a couple of upper air disturbances pass overhead after the cold air at the surface is in place. It's far too soon to know with any certainty exactly what our sensible weather will bring other than a very high probability that we will see multiple days of much below normal temperatures, possibly lasting 4 to 6 days.

The afternoon ECMWF suggests very cold Arctic air arrives with embedded disturbances moving across the Region after the cold air at the surface is in place. The trends continue to advertise a cold and unsettled pattern potential as we end the first week of January.

The afternoon updated Climate Prediction Center Day 6 to 10 Temperature and Precipitation Outlook suggests below normal temperatures and below normal precipitation. The change in the temperature Outlook is considerably colder than yesterday. Also the Day 8 to 14 Outlook suggests colder than normal temperatures continue.

The GFS meteogram suggests 2 opportunities for wintry mischief. The first chance is next Friday/Saturday with a second chance over the second week of January.

00z GFS much warmer for Houston....However points out a bigger winter storm for dallas.

Oh GFS... You're not typically the one to support winter wishcasts. That's the Euro's job.

The overnight ensemble guidance continues to advertise a notable blocking signature in the Medium to Long Range suggesting the possibility of a widespread Arctic intrusion arrives for much of North America the middle of next week. There is way too much uncertainty regarding the various deterministic solutions with run to run volatility to be certain on the finer points regarding our sensible weather, which is expected beyond 3 to 5 days. That said gone will be the daily record heat we've been experiencing since Christmas.

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
157 AM EST THU DEC 29 2016

VALID 12Z SUN JAN 01 2017 - 12Z THU JAN 05 2017

...ARCTIC AIR TO INCREASINGLY SWEEP THE NATION NEXT WEEK IN STORMY
WINTER FLOW...

...GUIDANCE/PREDICTABILITY ASSESSMENT AND WEATHER
HIGHLIGHTS/THREATS...

THE MODELS AND ENSEMBLES OVERALL REASONALLY AGREE IN SHOWING THAT
A STRONG NERN PAC MEAN RIDGE WILL ENCOURAGE AMPLIFYING/REINFORCING
WRN US TROUGHING ALOFT NEXT WEEK AS A POTENT SERIES OF SYSTEMS DIG
SHARPLY SOUTHWARD. THESE NEARLY DAILY SYSTEMS WILL PRODUCE LOCALLY
INTENSE WINTERY PCPN SWATHS ENHANCED SIGNIFICANTLY BY
TERRAIN...BUT WILL ALSO WORK DOWN TO LOWER ELEVATIONS ACROSS MUCH
OF THE WEST. SUBSEQUENT NEWD EJECTION OUT ACROSS THE CENTRAL AND
E-CENTRAL US WILL FURTHER SPIN UP DEEPENED LOWS AND ASSOCIATED
FRONTAL SYSTEMS TO FOCUS ORGANIZED PCPN INCLUDING AN EMERGING
SRN/E-CENTRAL TO ERN US HEAVY RAINFALL THREAT. MEANWHILE EXPECT
OVERTOP QUITE A SURGE OF ARCTIC AIR WITH WIDESPREAD RECORD COLD
TEMP POTENTIAL TO INCREASINGLY SPILL DOWN ACROSS MUCH OF THE
NATION NEXT WEEK IN THE WAKE OF SYSTEM PASSAGES. THIS SCENARIO
SETS THE STAGE FOR A PROLONGED PATTERN WITH ACTIVE WINTER WEATHER
THREATS. THIS MAY BE ESPECIALLY PREVALENT BUT NOT LIMITED TO THE
N-CENTRAL US AND WITHIN A LEAD OVERRUNNING THEATA-E ADVECTION
PATTERN. SMALLER SCALE EMBEDDED SYSTEM TIMINGS AND FLOW
INTERACTIONS ARE LESS RUN TO RUN CONSISTENT OVER TIME...LENDING AN
ENSEMBLE MEAN FORECAST APPROACH. ACCORDINGLY...THE 12 UTC ECMWF
ENSEMBLE MEAN WAS USED AS A MAIN STARTING POINT FOR PRODUCTION OF
THE WPC MEDIUM RANGE PRODUCT SUITE AS IT SEEMS TO BEST PROVIDE A
GOOD COMPROMISE SOLUTION OF DETAILED BUT MORE RUN-RUN VARIED
GFS/ECMWF DETERMINISTIC RUNS.

PLEASE REFER TO WPC MEDIUM RANGE SURFACE FRONTS/PRESSURES AND 500
MB PROG GRAPHICS ALONG WITH ASSOCIATED 2.5 KM SENSIBLE WEATHER
GRIDS AND UPCOMING QPF AND WINTER WEATHER OUTLOOK PROBABILITY
GUIDANCE FOR MORE COMPREHENSIVE DEPICTION THROUGH MEDIUM RANGE
TIME SCALES.

SCHICHTEL

The cold air is coming and the question now is HOW cold ... and for us in south central and southeast Texas, more questions on precip and precip types. At the least, plants/pipes/pets/people protection in about a week's time appears to be on the menu.

Impressive Teleconnection Indices, particularly a very -EPO (East Pacific Oscillation) as well as a tanking AO (Arctic Oscillation) that has been usually positive due to the very deep Polar Vortex anchored over the Arctic Circle for months. There are signs that the strength of the Stratospheric Polar Vortex may weaken which tends to favor a lobe of very cold air at the surface developing across Central Canada or near Hudson Bay. Such a signature seen via the 500mb charts would suggest very cold air will be funneled South into the Great Basin and the lee side of the Rockies into the Plains.
Also the overnight Day 11+ GEFS Super Ensemble Analogs are sprinkles with analog dates that favor an upper air pattern that may be capable of delivering precipitation above the very shallow Arctic Airmass at the surface. The Top Analog date centered on January 9th is 1968. January 7, 1968 brought freezing rain to Houston that glazed our Freeways at that time. 1971 also is an analog date that sticks out. January 7th-8th, 1971 also brought freezing rain to Houston and again glazed our Freeway system. That said it is far too soon to know with in certainty what the sensible weather will bring and no two patterns are exactly alike, but it is worth noting the possibilities associated with such an Upper Air Pattern projected later next week.

srainhoutx you think we have a shot at any wintry weather in our neck of the woods.

cperk wrote:srainhoutx you think we have a shot at any wintry weather in our neck of the woods.

If anyone could actually forecast with that kind of specifics across our geographical area 9 to 10 days out, they are far better than I am...or making a lucky guess. Just too many variables at this range to accurately predict. Odds are always against us down here as we all know.

LOL...the 12Z ECMWF suggests sub -20's at 850mb over SE Texas.