Upcoming cold for the South (Models, Maps, Discussions)

[Tyler]

Edit: [AFD ERASED] Whoops sorry Don. You already posted the AFD.

Anyway, nice disscussion from Houston this morning, finally realizing just how cold this airmass really is.

[wxman22]

Looks like the 6z of the GFS is still hinting at some possible wintry precip Saturday night....

[Tyler]

The only problem with the 6z is its WAY too warm, 850 temp wise. IMO, the 6z and 18z model runs should not be used beyond 84 hours as they always have wacky solutions in the extended. It is to my understanding that they use old data, and that is the reason for such a bad forecast in the extended.

I'm still looking over the 0z until the 12z comes out.

[Tyler]

We are now getting into the view of the NAM with the upcoming arctic intrusion.

Here is the 84:

http://www.nco.ncep.noaa.gov/pmb/nwprod ... _084.shtml

Check that out! 1052MB High!

[southerngale]

Ummm....I think my locals are getting on board. Yesterday they had the high for Saturday at like 56° or so and I just checked and they're now showing a high of 44° for Saturday. I'm sure it will change some before then...which direction I don't know but a 10+ degree drop in a day is a lot IMO.

http://www.kfdm.com/weather.shtml

[Kelarie]

From Austin/San Antonio NWS...

BOTH THE ECMWF AND GFS SOLUTIONS SHOW A MAJOR PATTERN CHANGE UNDERWAY...WITH A MODIFIED ARCTIC AIRMASS PUSHING THROUGH SOUTH TEXAS LATE FRIDAY. THE ECMWF CONTINUES TO SHOW RUN-TO-RUN CONSISTENCY DEPICTING THIS AIRMASS MOVING THROUGH DURING THE DAY FRIDAY...WITH THE GFS BEHIND IT BY 6-12H. THE MAIN QUESTION FOR FRIDAY/SATURDAY IS WHETHER OR NOT WE`LL GET PRECIP...THE FRONT IS A GIVEN AT THIS POINT. AN UPPER LOW...CURRENTLY SEVERAL HUNDRED MILES WEST OF CALIFORNIA...IS FORECAST TO MOVE OVER NW MEXICO AND THEN OPEN-UP AND MOVE EAST OVER SOUTH TEXAS FRIDAY NIGHT INTO SATURDAY. MOST OF THIS ENERGY WILL MOVE SOUTH OF OUR AREA. WILL GO WITH ONLY SLIGHT CHANCE POPS FOR NOW...ALTHOUGH THE GFS MOS SHOWS POPS RANGING FROM 30-50 PERCENT...PER COORDINATION WITH SURROUNDING OFFICES AND TENDENCY TOWARD DRIER ECMWF SOLUTION. NEXT WEEKEND LOOKS COLD...WITH TEMPERATURES 10-15 DEGREES BELOW NORMAL.

[Extremeweatherguy]

NWS in Houston has lowered the forecast again...here is the latest (still to warm...but getting closer):

Friday Night: A 30 percent chance of showers. Mostly cloudy, with a low near 42.

Saturday: A 30 percent chance of showers. Mostly cloudy, with a high near 52.

Saturday Night: Partly cloudy, with a low around 30.

Sunday: Mostly sunny, with a high around 54.

[jeff]

Significant upper air pattern change underway with much colder conditions expected by this weekend.

First off is Red Flag Warning conditions today for areas west of I-45. Once again dry fuels and strong surface winds will create very high fire danger. 700am Palestine Profiler has 30kts at 500 meters and this will mix down to the surface this afternoon. Winds should peak during the early afternoon with gust upwards of 35-40mph.

Large scale ridging is building into Alaska with deep downstream troughing being carved out over the central and eastern US. Cold arctic air mass which has been building over NW Canada and Alaska for the past several weeks will be on the move southward. Upper air pattern set up will release this air mass into the US at the end of this week and into TX this weekend.

Timing of arctic boundary into the state is still uncertain with sometime Friday being the most likely. This air mass is shallow and may slide southward faster than model projections suggest. Upper air pattern supports the coldest air going just east of TX, but we will receive a good blow. ECMWF 850mb temps plunge to 0 to -4 C by 600pm Saturday (down from 6.0C at 00Z Sat) evening with strong surface cold air advection starting Friday night. Given impressive cold air advection and cold mid level temps. along with cloud cover, highs Saturday will likely remain in the 40’s.

Wild card and forecasting nightmare will be S CA upper level low which ejects across TX Friday night and Saturday. GFS shows a saturated air mass and rain looks like a good bet Friday night into Saturday. Based on forecast soundings of critical thickness values, the precip. should end before the air is cold enough for anything besides liquid. 06Z Sat profile has a large above freezing layer from 3387m to the surface, however if the air mass is colder than forecast (which is possible) I could see a small sub-freezing layer near the surface resulting in freezing rain, although this is not likely at this time.

Clearing skies Saturday night and again Sunday spell trouble for overnight lows with a hard freeze possible for all inland locations Sunday and Monday mornings. Should the arctic air mass take a more southern trajectory into the plains, highs and lows for this weekend are too warm and will have to be undercut by several more degrees.

[Portastorm]

Thanks for the post Jeff and good to see you back!

I'm glad you mentioned that disturbance that may impact parts of south and central Texas this weekend. My experience in watching those is that they are very tricky for forecasters in both strength and movement. If our temps end up closer to freezing, it could make for a very difficult forecast Saturday evening.

Meanwhile, the march to colder has begun. Front blew through Austin here before sunrise. We're struggling to maintain lower 50s right now.

[Tyler]

Jeff, thank you so much for your analysis on the upcoming situation. It is much appreciated. This weekend certainly looks interesting.

Winter took a vacation, but now its back, with a bite.

[LAwxrgal]

I took a peek at my extended forecast...
From the NWS New Orleans:

SATURDAY
MOSTLY CLOUDY WITH A 40 PERCENT CHANCE OF RAIN
SHOWERS. HIGHS IN THE MID 50S.

SATURDAY NIGHT
DECREASING CLOUDS. COLDER. LOWS IN THE LOWER
30S.

SUNDAY
MOSTLY SUNNY. HIGHS IN THE MID 50S.


But on the Weather Channel website, it's only forecasting a high of 54 on Saturday (with a 60% chance of showers) and 46 on Sunday....

Any cold snap we get has to come from Texas, and so does the return flow after the cold snap is over.

[cctxhurricanewatcher]

How long does this cold snap last for us? I know we will not have brutal cold for the whole month. But does this have a chance to knock us down to below normal for the rest of the month into March? JB seems to think it will.

After two 90+ degree days last week, I'm ready for below normal for about 4 weeks or so. After that, the 90+ days won't be too far off.

[Portastorm]

Looks like yesterday's NWS forecasted highs for today in Austin may bust by as much as 5 degrees. Progged highs were mid 60s. It's 58 now in downtown Austin at high noon. My guess is maybe we gain 3-4 degrees during max heating and that's it.

Will the trend of busted high temsp continue later this week? Could be!

[Tyler]

Most likely. Models continue to under-estimate how cold these canadian airmasses really are.

Better enjoy these "warm" temperatures right now, highs will be stuck in the 40's this weekend!

[Tyler]

12z Euro day 5, quicker and colder with the arctic front (as it has been all along. the ECMWF has been VERY consistent, so I would tend to follow it during this time period):

COLD: (since the Euro only goes day by day, I would expect between day 5 and 6 for 850MB temps to be around -6C):



Euro day 7: There is more where that came from my friends, and this air, IS EVEN COLDER!:

[Brent]

Local weather forecast:

Thursday - 02/09
Breezy and colder with a few morning flurries possible.
Low: 30 High: 37

Wind: NW 8-16 mph Sun Percentage: 35% Hours Of Rain: 1/2
Rain Potential: 0.01" Severe Weather Threat: None

Friday - 02/10
A good supply of sunshine.
Low: 29 High: 48

Wind: NE 5-10 mph Sun Percentage: 75% Hours Of Rain: 0
Rain Potential: 0.00" Severe Weather Threat: None

Saturday - 02/11
Mostly cloudy and colder. A chance of flurries Saturday night.
Low: 30 High: 40

Wind: N 8-16 mph Sun Percentage: 30% Hours Of Rain: 1/4
Rain Potential: 0.01" Severe Weather Threat: None

Sunday - 02/12
Cold with a mix of sun and clouds. Some early morning flurries.
Low: 25 High: 35

Wind: N 7-14 mph Sun Percentage: 45% Hours Of Rain: 1/4
Rain Potential: 0.01" Severe Weather Threat: None

[aggiecutter]

That brutally cold air in Canada on the day 7 EURO will be making its way down the latter part of next week. That's when it'll get very cold in the southern plains.

http://wwwt.emc.ncep.noaa.gov/gmb/ens/t ... 20612.html

[AL Chili Pepper]

Sheesh, talking about a warm winter day....it must be 75 degrees out there right now. Started off cool before the SW wind kicked in, and now it's fit for the beach and barbeques. Check out this temp gradient. Almost 30 degrees within just a few miles.

[PTrackerLA]

This cold will definately come as quite a shock for most people as we probably won't get out of the 40's Saturday and Sunday. Low's will likely be in mid/upper 20's here as well, possibly the first hard freeze of the season...

[Extremeweatherguy]

One thing to consider for Houston is that even if we do not get wintry precipitation; any left over water from the rain on Saturday would likely freeze Saturday night...having the same effect as if we were to see light freezing rain...icy bridges and overpasses may become a problem no matter what. Just something to consider...