January Weather Discussion: Slight Chance Severe Storms

[srainhoutx]

Norman, OK:

AT THIS POINT... LARGE CANADIAN/ARCTIC AIRMASS BEGINS TO SLIDE SOUTH
OUT OF CANADA AND MOVES QUICKLY SOUTH ALONG THE LEE OF THE ROCKIES.
EXPECT TO SEE A TRANSITION FROM CHANCE OF RAIN TO SNOW SUNDAY NIGHT
INTO MONDAY AS AIRMASS SPILLS SOUTH THROUGH OKLAHOMA AND NORTH
TEXAS. DO NOT ANTICIPATE MUCH IN THE WAY OF ACCUMULATING SNOW...
JUST THAT MUCH COLDER AIR WILL SQUEEZE MOISTURE OUT AS IT DEEPENS
WITH THE AID OF A DISTURBANCE IN THE MID LEVELS. REAL STORY WILL BE
THE MUCH COLDER TEMPERATURES AND WIND CHILLS THAT WILL ACCOMPANY
THIS FRONT. MANY LOCATIONS MAY SEE TEMPERATURES REMAIN BELOW
FREEZING FOR SEVERAL DAYS... ALONG WITH WIND CHILLS IN THE SINGLE
DIGITS OR EVEN BELOW ZERO. THIS AIRMASS THEN LOOKS TO REMAIN IN
PLACE ACROSS THE CENTRAL PART OF THE COUNTRY THROUGH NEXT WEEK.

[srainhoutx]

Dodge City, KS:

DAYS 3-7...

THE EXTENDED FORECAST POSES SOME CHALLENGES AS THE MODELS HAVE STILL
NOT COME TOGETHER ON THE PATTERN OR SOLUTION IN THE SAT-TUE TIME
FRAME.

THE LATEST MODELS OF THE ECMWF AND CANADIAN ARE BOTH SHOWING THE
SOUTHERN WAVE THEY DEPICTED PREVIOUSLY WILL STAY SOUTH OF US AND THE
LATER NORTHERN STORM WILL BEAR DOWN ON US. HAVE LOWERED ALL TEMPS
STARTING ABOUT SUNDAY, AND WENT INTO NEGATIVE DIGITS IN OUR
NORTHWEST FOR LOWS BOTH TUESDAY MORNING AND FURTHER INTO WEDNESDAY
MORNING. THE ECMWF IS VERY AGGRESSIVE WITH PLUNGING THE LOWER LEVEL
COLD AIR SOUTH THROUGH THE LEE SIDE OF THE ROCKIES LATE SUNDAY INTO
SUNDAY NIGHT. THE COLD AIR THEN DAMS UP AGAINST THE ROCKIES AND IS
DELAYED JUST A BIT BEFORE BUILDING UP AND WORKING THE COLD AIR EAST
INTO OUR NORTHWEST CWA MONDAY MORNING. PER ALL MODELS, THE SNOW
SHOULD COME IN FROM THE NORTH OR NORTHWEST AS EARLY AS SATURDAY
NIGHT AND PLUNGE SOUTHEAST WITH THE COLD AIR. INCREASED SNOW POPS
FOR SUNDAY AFTERNOON AND KEPT THE 40-45 PERCENT POPS IN OUR
NORTHEAST AND EAST SECTIONS THROUGH 12 MONDAY. THE LATEST ECMWF
MODEL RUN STARTS TO MOVE THE SNOW FIELD TO THE EAST DURING THE DAY
MONDAY, SO POPS WILL TAPER OFF FROM WEST TO EAST MONDAY. THE OTHER
FEATURE WORTH NOTING IS ALL MODELS, THE ECMWF, THE GFS AND THE
CANADIAN ARE FORECASTING FROM 2 TO 6 INCHES OF SNOW ACROSS PARTS OF
CWA. AS THIS STORM APPROACHES, POPS AND SNOWFALL AMOUNTS WILL
LIKELY NEED TO BE ALTERED, AND AN ADVISORY OR MORE MAY NEED TO BE
ISSUED. THE OTHER NOTEWORTHY WEATHER ELEMENT IS THE WIND FORECAST
FOR MONDAY, NORTH AT 15 TO 30 MPH. IF THE GRADIENT TURNS OUT TO BE
ANY STRONGER, THAT MAY BE MORE REASON TO CONSIDER AN ADVISORY.

[wxman57]

HGX AFD ? Houston hello? Lol

It'll be "interesting" to see if on tomorrow morning's zone forecast the NWS goes with a low in Houston of below freezing next Tuesday with a high in the 40s. I'll bet they don't. Let's see, I'll bet they go with a low in the upper 30s and a high in the 50s. Maybe even 40-42 for next Tuesday's low. They don't like to go for extreme temps beyond a few days out.

Here's a meteogram from 12Z GFS data. Now REMEMBER - the GFS was forecasting a snow event for all along the TX Coast for THIS weekend 7 days ago. Now look at what it's forecasting for Saturday...

[srainhoutx]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
331 PM CST TUE JAN 4 2011

.DISCUSSION...
APPROACHING UPPER LEVEL IMPULSES IN COMBINATION WITH WARM FRONTAL
BOUNDARY MOVING NORTH ACROSS CWFA PRODUCING SCATTERED SHOWERS OVER
SW ZONES AND SPREADING EASTWARD. WE KEPT HIGHER CHANCES RAIN
SOUTHERN PORTIONS LOWERING IT TO 30 PERCENT NORTH. COLD FRONT PUSHING
ACROSS NORTHERN ZONES EARLY MORNING AND SHOULD BE OFFSHORE BY MID
DAY WEDNESDAY. DEWPOINTS RISING AS WARM FRONTAL BOUNDARY PUSHES
NORTH WITH READINGS THIS MID AFTERNOON IN THE MID 60S SW ZONES TO
NEAR 60 NEAR GLS. WITH COOL SHELF WATERS NEAR THE COAST IT WOULD
NOT BE LONG UNTIL WE SEE AREAS OF SEA FOG DEVELOPING. INLAND AREAS
SHOULD EXPECT PATCHES OF FOG LATER TONIGHT (MAINLY LIGHT). FOG MAY
LINGER NEAR THE COAST AND NEARSHORE WATERS DURING THE EARLY TO MID
MORNING HOURS WEDNESDAY UNTIL THE FRONT PUSHES THROUGH. DRYING
EXPECTED AS WEAK HIGH PRESSURE RIDGE ACROSS THE AREA LATER
WEDNESDAY. HIGH WILL SETTLE OVER REGION THURSDAY AND FRIDAY GIVING
US COOL NIGHTS AND MILD DAYS. A VIGOROUS UPPER LEVEL DISTURBANCE
WILL APPROACH OUR REGION SATURDAY AFTERNOON AND EVENING AND THEN
MOVE EAST FROM THE AREA SUNDAY. WITH STRONG ENERGY FROM THIS SYSTEM
ALONG WITH LOW LEVEL JET IN PLACE WE CAN EXPECT A GOOD CHANCE OF
SHOWERS AND THUNDERSTORMS FROM SATURDAY AFTERNOON TO SATURDAY NIGHT.
SUNDAY SHOULD SEE DIMINISHING RAIN CHANCES WEST TO EAST. EARLY
NEXT WEEK A LARGE UPPER TROUGH/LOW WILL MOVE OVER THE GREAT BASIN
AND PULL ALONG THE MODIFIED AR ARCTIC AIR MASS SITTING OVER WESTERN
CANADA. WE SHOULD START TO SEE SIGNIFICANTLY COLDER AIR MASS
FILTERING INTO OUR REGION MONDAY NIGHT WITH STRONG COLD AIR
ADVECTION CONTINUING FOR SEVERAL DAYS. MORE ON THIS LATER. 37

[srainhoutx]

New Orleans:

.LONG TERM...
THE MAIN FOCUS STILL IS TOWARDS A STRONG UPPER LEVEL DISTURBANCE
ASSOCIATED WITH CURRENT AFOREMENTIONED CUT-OFF LOW MOVING ALONG
THE SOUTHERN BRANCH AND IMPACTING THE CENTRAL GULF STATES LATE
THIS WEEKEND. MODELS STILL DIFFER ON ACTUAL TRACK AND TIMING WITH
THE GFS NOW SHOWING LESS NEGATIVE TILT ORIENTATION AND LIFTING
INTO THE MIDDLE OF THE COUNTRY...BUT STILL PLACING LARGE SCALE
LIFT OVER THE FORECAST AREA FOR A POTENTIAL HEAVY RAINFALL EVENT
SUNDAY INTO MONDAY. THE ECMWF SHOWS MORE NEGATIVE TILT AND
DYNAMICS MUCH CLOSER TO FORECAST AREA IN THE LATE SATURDAY/EARLY
SUNDAY TIME FRAME. A COMPROMISE ON BOTH TIMING AND LOCATION WOULD
STILL SPELL A LIKELIHOOD OF STRONG TO SEVERE SURFACE BASED
THUNDERSTORMS SUNDAY FOR THE AREA. SOME COLD WEATHER THEN SETTLES
INTO THE REGION AND POTENTIALLY SETS THE STAGE FOR WHAT COULD BE A
STRETCH OF MUCH BELOW NORMAL TEMPERATURES BEYOND THE 7 DAY
FORECAST PERIOD...MORE ON THIS LATER AS MODELS CONTINUE TO RESOLVE
ISSUES WITH THE SPLIT FLOW AND COLD AIR POOLING OVER POLAR CANADA.

[srainhoutx]

Austin/San Antonio:

BIG CHANGES TOWARD THE END OF THIS FORECAST FOR NEXT WEEK. A
STRONG COLD FRONT WILL DROP DOWN FROM THE NORTHERN PLAINS BRINGING
VERY COLD AIR. LOWS WILL BE 20S MOST PLACES AND HIGHS WILL
STRUGGLE INTO THE 40S.

[C2G]

In one of Joe Bastardi's videos he used snow cover maps, and although he believed they may be a little extreme in their depictions, it showed snow cover pretty much to the Gulf Coast and very close to us here in Houston.
On one hand I'm excited, on the other hand I've grown to despise cold weather.
But I guess if it's going to be cold we might as well have a little moisture around to make it exciting.
Although, I'm not real excited about the prospect of driving 60 miles round trip to and from work.

[srainhoutx]

Last, but not least, Dallas/Ft Worth: Very lengthy discussion

.EXTENDED/COLD WX NEXT WEEK...
CONFIDENCE REMAINS HIGH THAT MUCH OF THE CONTINENTAL US WILL SEE
TEMPERATURES WELL BELOW NORMAL FOR MUCH OF NEXT WEEK AND THERE
HAS BEEN MUCH DISCUSSION AS TO WHETHER OR NOT IT WILL GET AS COLD AS
SOME OF THE MORE SEVERE ARCTIC INTRUSIONS OF YEARS PAST. LATEST
GLOBAL MODEL GUIDANCE CONTINUES TO SHOW EXPECTED OSCILLATIONS WITHIN
THE OVERALL UPPER AIR PATTERN BUT THE GENERAL CONSENSUS IS THAT
RIDGING OVER ALASKA WILL BUILD SUFFICIENTLY STRONG AND BECOME
PARTIALLY BLOCKED AS TO ALLOW A MASSIVE CHUNK OF COLD AIR TO HEAD
SOUTH INTO THE CONTINENTAL US. THE FIRST SHOT OF THIS COLD AIR WILL
MOVE RAPIDLY INTO NORTH TEXAS EARLY MONDAY WITH STRONG NORTHERLY
WINDS AND SHARPLY COLDER TEMPERATURES. AS WE HEAD THROUGH NEXT WEEK
HOWEVER...THERE ARE SOME CONCERNS AS TO WHETHER THE OVERALL PATTERN
WILL REMAIN FAVORABLE FOR CONTINUED SURGES OF COLD AIR.

EXTENSIVE ANALYSIS OF ARCHIVED UPPER AIR DATA FROM PREVIOUS RECORD
BREAKING COLD EVENTS INCLUDING THE SEVERE COLD SNAPS OF 1983 AND
1989 YIELD A COUPLE OF INTERESTING DETAILS. THE MOST SIGNIFICANT
ARE THE TEMPERATURES AT THE SOURCE OF BITTERLY COLD AIR.
GENERALLY... ARCTIC INTRUSIONS INTO NORTH TEXAS BEGIN WITH EXTREMELY
COLD AIR PARCELS WITHIN THE 800 TO 500MB LAYER LOCATED OVER
NORTHWEST/ NORTH-CENTRAL CANADA. THESE PARCELS WILL GRADUALLY
SUBSIDE AND WARM AS THEY HEAD SOUTH BUT ARE USUALLY STILL VERY COLD
BY THE TIME THEY REACH THE SURFACE. IN AT LEAST A HALF-DOZEN MAJOR
COLD SNAPS INCLUDING 1983/1989/1996...THE 500MB TEMPS ACROSS
NORTHWEST CANADA WERE TYPICALLY IN THE -45 TO -50C RANGE...AND 700MB
TEMPS WERE TYPICALLY IN THE -30 TO -35C RANGE. THE RECORD COLD OF
1983 HAD A SAMPLED 500MB TEMP OF -50C IN NORTHERN MONTANA. AS OF
NOW...NEITHER THE GFS NOR THE ECMWF HAS TEMPERATURES THAT COLD
ACROSS CANADA. PROGGED 850MB TEMPS ACROSS NORTH TEXAS ARE IN THE
-10 TO -15C RANGE WHICH DEFINITELY SUPPORTS COLD TEMPERATURES AT THE
SURFACE...HOWEVER IN THE EXTREME EVENTS...H85 TEMPS WERE IN THE -17
TO -20C RANGE WITH A FRIGID -24C AT OKC IN 1983. GIVEN THE FORECAST
TEMPERATURES THROUGH NEXT WEEK...CONFIDENCE IS INCREASING THAT THIS
WILL NOT BE HISTORICALLY COLD ACROSS NORTH TEXAS. OF COURSE THIS
ASSUMES A PERFECT PROG OF THE MODEL TEMPERATURES. THE OTHER CONCERN
IS THE POSITION OF THE UPPER RIDGE OVER ALASKA. THE LATEST RUNS
CONTINUE TO BUILD AN ANOMALOUSLY STRONG RIDGE OVER AK THEN HAVE HAD
SOME TROUBLE AS TO WHETHER IS WILL MOVE NORTH OR WEST INTO SIBERIA.
THIS RIDGE POSITION HAS IMPLICATIONS ON THE UPPER PATTERN OVER THE
WESTERN US. TYPICALLY WE LIKE TO SEE A STRONG TROF POSITIONED OVER
THE WEST/SW US WHICH DOES NOT MOVE TO KEEP THE COLD AIR FLOWING
SOUTHWARD. THESE MODEL DISCREPANCIES ARE EXPECTED IN THE 10-15 DAY
PERIOD AND WILL CONTINUE TO BE MONITORED.

AS OF NOW WE WILL CONTINUE TO SHOW THE STRONG FRONT ON MONDAY/END OF
THE CURRENT FORECAST PERIOD/ AND WILL INTRODUCE HIGH TEMPERATURES IN
THE UPPER 20S/LOWER 30S FOR TUESDAY THROUGH THE END OF NEXT WEEK.
OVERNIGHT LOWS WILL GENERALLY BE IN THE LOWER TEENS AND LOWER 20S.
IT SHOULD BE STRESSED THAT CONSIDERABLE DISCREPANCIES WITHIN THE
FINER DETAILS EXIST THIS FAR OUT AMONG NOT ONLY THE OPERATIONAL
GUIDANCE BUT AMONG THE INDIVIDUAL ENSEMBLE MEMBERS. SEVERAL
ENSEMBLE MEMBERS TO INDICATE A FAVORABLE RIDGE/TROF POSITION THROUGH
NEXT WEEK AND KEEP THE COLD AIR COMING SO IT WILL BE NECESSARY TO
FINE TUNE TEMPERATURE FORECASTS THROUGH NEXT WEEK. WHAT MAKES THIS
SYSTEM SIGNIFICANT IS THE POTENTIAL FOR THERE TO BE AN EXTENDED
PERIOD OF VERY COLD TEMPERATURES ACROSS THE REGION. IT IS THE
DURATION OF SUB-FREEZING AIR THAT CAN HAVE SERIOUS IMPACTS TO THE
REGION VERSUS JUST THE TEMPERATURES THEMSELVES.

CONCERNING PRECIPITATION POTENTIAL...LATEST 12Z ECMWF DOES SHOW AN
AREA OF QPF ALONG THE FRONT ON MONDAY LIKELY IN AN AREA OF STRONG
FRONTOGENETIC FORCING SQUEEZING OUT ANY AVAILABLE MOISTURE. TEMPS
ARE SUFFICIENTLY COLD FOR SNOW...BUT IT IS THE ONLY MODEL DOING SO
WITH SUCH VIGOR ATTM. BEING 7 DAYS OUT...WILL LEAVE THE 10 POPS IN
AND SEE IF THIS TREND CONTINUES. INTO NEXT WEEK...WITH TEMPS SO
COLD ANY MOISTURE COULD CREATE WINTRY PRECIPITATION BUT AS OF NOW IT
APPEARS THAT THINGS WILL BE VERY DRY. THESE DETAILS WILL BE WORKED
OUT OVER THE NEXT SEVERAL DAYS.

DUNN

[srainhoutx]

Folks, as we have been discussing, the cold air is coming. As wxman57 stated, we just will not know how cold until we see the air mass in Alaska/Western Canada. With that said, it does look like some interesting days are ahead and we encourage folks to start getting a plan of action to protect your property in order. I'll leave you with this Special Weather Statement from Norman. I expect to see more of these as the week progresses and much closer to home.


SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NORMAN OK
302 PM CST TUE JAN 4 2011

OKZ004>048-050>052-TXZ083>090-051100-
HARPER-WOODS-ALFALFA-GRANT-KAY-ELLIS-WOODWARD-MAJOR-GARFIELD-
NOBLE-ROGER MILLS-DEWEY-CUSTER-BLAINE-KINGFISHER-LOGAN-PAYNE-
BECKHAM-WASHITA-CADDO-CANADIAN-OKLAHOMA-LINCOLN-GRADY-MCCLAIN-
CLEVELAND-POTTAWATOMIE-SEMINOLE-HUGHES-HARMON-GREER-KIOWA-JACKSON-
TILLMAN-COMANCHE-STEPHENS-GARVIN-MURRAY-PONTOTOC-COAL-COTTON-
JEFFERSON-CARTER-JOHNSTON-ATOKA-LOVE-MARSHALL-BRYAN-HARDEMAN-
FOARD-WILBARGER-WICHITA-KNOX-BAYLOR-ARCHER-CLAY-
302 PM CST TUE JAN 4 2011

...TURNING MUCH COLDER EARLY NEXT WEEK...

A LARGE ARCTIC AIRMASS BUILDING ACROSS NORTHERN CANADA IS EXPECTED
TO MOVE SOUTH OVER THE WEEKEND. THIS ARCTIC AIR WILL THEN SPREAD
SOUTH ACROSS OKLAHOMA AND NORTH TEXAS EARLY NEXT WEEK BRINGING AN
END TO THE CURRENT STRETCH OF MILD WEATHER.

IN ADVANCE OF THE COLD AIR ARRIVING... A STORM SYSTEM OFF THE
CALIFORNIA COAST WILL MOVE EAST ACROSS TEXAS AND OKLAHOMA OVER THE
WEEKEND. THIS STORM WILL BRING A CHANCE OF RAIN TO THE AREA SATURDAY
AND PERHAPS A RAIN SNOW MIX TO PARTS OF THE AREA SATURDAY NIGHT AND
SUNDAY. AS THE COLD AIR ARRIVES EARLY NEXT WEEK THE PRECIPITATION
MAY TRANSITION TO SOME LIGHT SNOW BEFORE ENDING.

THIS ARCTIC AIR WILL BE THE COLDEST OF THE SEASON AND ALONG WITH
BRISK NORTH WINDS WILL LIKELY PRODUCE VERY LOW WIND CHILLS. SOME
LOCATIONS COULD SEE MULTIPLE DAYS WITH TEMPERATURES REMAINING BELOW
FREEZING AND WINDS CHILLS BELOW ZERO. THESE COLD CONDITIONS COULD
LINGER THROUGH MUCH OF NEXT WEEK.

RESIDENTS OF OKLAHOMA AND NORTH TEXAS ARE ENCOURAGED TO BEGIN
PREPARING NOW FOR THE POSSIBILITY OF AN EXTENDED PERIOD OF VERY COLD
CONDITIONS. PROVIDE WATER AND SHELTER TO OUTSIDE PETS... AND PROTECT
PIPES AS THE EXTENDED COLD COULD RESULT IN SOME BECOMING FROZEN.
ALSO IF TRAVELING... TAKE ALONG BLANKETS AND COLD WEATHER GEAR IN CA
SE YOU BECOME STRANDED.

[harpman]

GFS should be running right now. Some one please report. Thanks.

[Mr. T]

Hgx going for a high of 40 degrees next Tuesday! That is pretty good for 7 days out

[Ptarmigan]

If this winter had an analog, it would be 1988-1989. We had a hard freeze in February 1989. I would not be surprised if there is a freeze next week.

[Ptarmigan]

And to think we're a few model runs away from it all being hog wash to it being the strongest outbreak in history. LOL. I sure was surprised to find out that the highest pressure observed in the USA was "ONLY" 1064. Makes you wonder what kind of mojo the 1899 freeze had. Man, if a 1070 comes down into Montana, Houston may see low single digits....did I just say that?

I could imagine the high pressure in the 1899 Freeze was very high. It could of been in the 1100 millibar range. It also went over Montana. The highest pressure in America was 1078.4 mb and in Northway, Alaska on January 31, 1989. That occurred before Houston got that huge freeze in February 1989.
http://findanswers.noaa.gov/noaa.answer ... 4&start=16

That time Alaska was in a deep freeze.

[C2G]

Hgx going for a high of 40 degrees next Tuesday! That is pretty good for 7 days out

Yup, I was looking at that a few minutes ago. For them to jump on the wagon this early has me worried. I was expecting to see them predicting high's in the 50's and 60's.

[Andrew]

18z isn't much different. It looks very similar to the 12z run.

[srainhoutx]

18z isn't much different. It looks very similar to the 12z run.

[tireman4]

It is still way too far out, but the consistency is a telling thing right now.

[Andrew]

18z pushes the cold off to the east at hour 240

[helloitsb]

seems like the 18z just doesn't want to agree, cold is there just not as long.

[Ptarmigan]

This could be like the February 1989 freeze.

I looked at the February 1989 freeze and the pressure was 1048 mb and it was a surface high, since there is no high pressure in the upper part. There was a strong upper level low over the Pacific Northwest.

http://docs.lib.noaa.gov/rescue/dwm/198 ... 90205.djvu

You need to download a free DJVU viewer to see the map.
http://www.celartem.com/en/download/djvu.asp#win