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It looks like December will begin rather chilly as a strong shot of colder Canadian air arrives late this week. I am not seeing any significant rainfall chances in our sensible weather forecast into the coming weekend.

Changes are brewing during the first full week of December via the Ensemble Guidance suggesting significant pressure falls across the West Coast and Inter Mountain West as a deep trough and a winter like low pressure system exists the Southern/Central Rockies into the Plains and pulls some very cold and snow packed Canadian air well S into the Eastern 2/3rds of the United States near December 7th, +/- a day our two. There are strong signals via our Hemispheric Reconnection Indices suggesting a blocking regime may be possible. A - EPO/-AO/-NAO pattern with a hint of a + PNA suggests that a very deep and cold trough may become established by December 8th or so ushering in the coldest air of the season. We'll need to monitor for any unforeseen upper air disturbances rotating around that deep Central US trough or possibly a disturbance riding along the sub tropical jet stream atop that cold air at the surface next week. We will see.

To further go with what Srain has alluded to...this is from NWS Hastings, NE..but...

Any idea how cold it will be here next week with the front?

Gee we need some rain. It's either feast or famine for us. No in-between any more. Won't debate the causes, but I think our climate is permanently whacked.

The afternoon Updated Extended Analogs/Upper Air Pattern continues to advertise a change is brewing around the 8th of December, +/- a day or 2.

Interesting.... ^^^^^

NOAA and the GEFS Ensemble holding strong for blue norther.



GFS - not so much.

Canadian is bringing the heavy (firewood) lumber:

The dreaded AccuWeather, but still...in agreement.

Looking at the overnight GEFS/ECMWF EPS Ensembles for hour 192, I see a very similar Upper Air Pattern suggested by those computer schemes. Both suggest strong Ridging along the West Coast extending N into Alaska and portions of the Artic with a deep trough developing across Central and Eastern Canada into the United States along and East of the Rocky Mountain Chain. With a N to NW flow aloft, dense snow refrigerated cold air locked up in Canada should spill South with ease all the way down into Texas.

I don't see any significant changes in the Medium Range sensible weather forecast for next week other than an increase in our rain chances which will need to be monitored. Still looking like the first in a series of strong cold fronts arrive mid next week with rain chance slowly increasing Tuesday into Wednesday as the front nears our Region. There is a chance of some over running nasty cold rain Wednesday night into next Thursday with temperatures in the low to mid 40's.

The extended Ensemble Guidance advertises that each additional cold front will bring colder air each shot suggesting we step down and see potentially colder air with each of the Canadian Cold Fronts into mid December. Not going to attempt to make a forecast for the extended range as we know the models can't be completely trusted beyond 3 to 5 days, but let just say that if the current Upper Air Pattern projected via the ensembles hold, somewhere across the Northern Plains could see temperatures nearing the -40F range as we near the Mid December timeframe. It is looking like Winter is arriving in Texas.

That is good to hear about our upcoming pattern change. Looking forward to it feeling like the holiday season!!!

djjordan wrote:That is good to hear about our upcoming pattern change. Looking forward to it feeling like the holiday season!!!

Yes! Looking forward to it here in SE Louisiana as well!

A nice December morning across SE TX.

The overnight Teleconnection Indices (-EPO /+PNA /-AO Regime) as well as the Long Range Ensembles suggest no significant changes regarding the Pattern Change ahead. The first shot of Canadian Air push in after a Cold Front arrives Tuesday with the Canadian front following Wednesday. The is a chance of showers and possibly some thunderstorms beginning Monday and continuing into Tuesday as the cold front arrives. The fly in the ointment is some over running moisture looks possible as the Canadian Front arrives Wednesday with a chilly rain chance continuing into Thursday.

The Medium and Long Range ensemble guidance continue to advertise a series of Canadian Air dropping South every few days as a piece of the Polar Vortex becomes established near Hudson Bay at the Upper Levels with its Anticyclonic spin tapping into pieces of Upper Level Disturbances dropping South on the East side of a potent Upper Level Ridge building across the NE Pacific into Alaska creating a 'bridge' which will tap into some very cold Siberian Air that appears to plunge across the Artic into Canada and at least the Eastern 2/3rds of the United States. Expect each additional Cold front following next week to progressively bring colder shots of Polar/Canadian Air into the Lower 48 through at least the 15th to 17th of December. I will not take a shot at talking about precipitation beyond next week, but needless to say the Analogs of past similar patterns suggest someone across Texas and possibly Louisiana may see precipitation of the wintry type in such an Upper Air Pattern. Stay Tuned!

As all of us who live along the Gulf Coast know, the timing is EVERYTHING with these arctic systems. Usually, the moisture is gone once the cold air arrives. But, every once in a while, either a ULL or gulf surface low develops that throws moisture up over the cold air giving us some winter fun. Will it happen this time? We likely won't know until 24 hours out.

Take this with a grain of salt, but it looks cool...

000
FXUS64 KHGX 011728
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1128 AM CST Fri Dec 1 2017

.AVIATION...
Light northeasterly winds will continue to turn easterly, eventually
switching to an onshore flow by Saturday morning. VFR conditions
expected to prevail throughout the TAF period. Light southeasterly
flow in the early morning hours will help to advect in some
moisture, impacting our more rural coastal sites and therefore
lowered visibilities at SGR and LBX to MVFR conditions. Also
dropped visibilities to 5 SM at CLL to account for this potential
chance for radiational fog, to account for clear skies, added
moisture, and light winds. Otherwise, expecting the best chance
for fog to be contained to the western more rural TAF sites mainly
between 09-15Z overnight. VFR conditions will once again emerge
Saturday morning, with clear skies and light southeasterly winds.

Hathaway

&&

.PREV DISCUSSION... /ISSUED 1003 AM CST Fri Dec 1 2017/

DISCUSSION...
12z soundings at both CRP and LCH support high temperatures in the
mid/upper 70`s. The air mass is dry and a large diurnal range in
temperatures are expected. Have bumped temps up a few degrees to
come into closer agreement with the 12z soundings. Rest of the
forecast looks on track and no other changes planned. 43

PREV DISCUSSION... /ISSUED 329 AM CST Fri Dec 1 2017/

MARINE...
Northeasterly winds will veer easterly as high pressure moves off to
the east. Looks for these winds to continue into the weekend, before
becoming more directly onshore Sunday as a warm front lifts through
the area. The warmer, more moist airmass will bring potential for
some fog, and possibly showers. Onshore flow will become more
moderate early next week, and the offshore waters will at least
flirt with SCEC thresholds at times from late Sunday night to very
early on Tuesday. Though confidence is low on specifics at this
time, will have to keep an eye out for sea fog potential as
dewpoints over the waters increase Sunday into the early week.
Finally, still looking for a strong cold front Tuesday, with
strengthening, gusty northeast winds developing Tuesday night behind
the front, also building seas, particularly in the offshore waters.
Small craft conditions appear likely at this time, but with
specifics to be worked out, continue to monitor forecasts.

Luchs

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 75 53 76 57 74 / 0 0 10 10 40
Houston (IAH) 76 52 76 57 74 / 0 0 10 20 40
Galveston (GLS) 73 61 73 64 73 / 0 0 10 20 40

&&

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

$$

Discussion...43
Aviation/Marine...08

From JB:

Euro has it snowing all the way to the gulf coast late next week.
Interesting

srainhoutx wrote:NWS Fort Worth‏Verified account @NWSFortWorth · 3h3 hours ago
Below-normal temperatures are on the way next week, which is depicted here by @CIPSAnalogs. In fact, much of the country will see below normal temperatures with the upcoming pattern change. #dfwwx #ctxwx

Impressive cold on the 850mB Euro: