Dallas/Forth Worth...arctic intrusion on the way!

[Johnny]

NATIONAL WEATHER SERVICE FORT WORTH TX
417 PM CST TUE JAN 27 2004

...SIGNIFICANT CHANGES TO THE FORECAST...

WE ARE EXTREMELY CONCERNED ABOUT THE ARCTIC AIRMASS OVER NORTHERN
CONUS/SOUTHERN CANADA. AT 18Z...TEMPERATURES IN SOUTHERN
SASKATCHEWAN WERE IN THE -30C TO -40C RANGE. THE ARCTIC FRONT
EXTENDED FROM SOUTHEASTERN SOUTH DAKOTA THROUGH SOUTHWESTERN NORTH
DAKOTA AND HAD ALREADY MOVED THROUGH RAPID CITY. COMPARISON OF
ANALYSIS TO ETA FORECASTS PLACES THE FRONT ABOUT ONE STATE AHEAD OF
SCHEDULE. THE PRESSURE RISE/FALL COUPLET HAS BEEN CALCULATED TO BE
MOVING SOUTHEAST AT 30 KT. THIS IS CONSISTENT WITH THE WINDS
PERPENDICULAR TO THE FRONT...AND THUS A CLOSE ESTIMATE OF THE FRONTS
SPEED. AFTER COORDINATION WITH NORMAN...AMARILLO...AND SAN
ANGELO... WE FEEL THE FRONT WILL MOVE ACROSS THE RED RIVER LATE IN
THE DAY ON WEDNESDAY. THIS IS ABOUT 18 HOURS AHEAD OF ANY GUIDANCE
THAT WE HAVE AVAILABLE. FURTHERMORE...POST FRONTAL TEMPERATURES WILL
BE DRASTICALLY COLDER THAN WE CURRENTLY HAVE FORECAST. WE SEE
NOTHING THAT WILL STOP THE MOVEMENT OF THIS AIRMASS AT THIS TIME.
SURFACE PRESSURE RISES ASSOCIATED WITH THIS FEATURE ARE ON THE ORDER
OF 6 TO 9 MB IN 3 HOURS...WITH SURFACE PRESSURES IN EXCESS OF 1040
MB CENTERED IN WESTERN ALBERTA. TEMPERATURES ARE AS COLD AS -40
NEAR THE CENTER OF THIS HIGH. VISIBLE SATELLITE IMAGERY SHOWS SNOW
COVER ALL THE WAY TO NORTHERN OKLAHOMA...SO VERY LITTLE MODIFICATION
IS ANTICIPATED.

THIS IS THE SCENARIO AS WE SEE IT NOW. AND THIS IS SUBJECT TO
CHANGE... FRONT WILL CROSS RED RIVER LATE WEDNESDAY AFTER MOST OF
THE CWA HAVE HIGHS ABOUT 2 CATEGORIES WARMER THAN TODAY. FRONT WILL
MOVE THROUGH DFW BEFORE MIDNIGHT...THEN SOUTHERN ZONES BY 0900Z
THURSDAY. WINDS WILL TURN NORTHERLY AND INCREASE TO 20 TO 25 MPH
THURSDAY NIGHT BEHIND THE FRONT AS TEMPERATURES FALL RAPIDLY INTO
THE 20S AND EVENTUALLY THE UPPER TEENS ACROSS THE NORTH.
TEMPERATURES THURSDAY WILL STAY IN THE 30S AREAWIDE WITH NORTHERLY
WINDS.

THE FLY IN THE OINTMENT IS THE VIGOROUS DISTURBANCE MOVING ONTO THE
NORTHERN CALIFORNIA COAST THIS AFTERNOON. CURRENT GUIDANCE DIGS THIS
FEATURE WELL INTO NORTHERN MEXICO... AND INTO THE NORTHERN GULF BY
FRIDAY. EVEN THIS TRACK WOULD KEEP MOST...IF NOT ALL ....OF THE
PCPN SOUTH OF OUR CWA. WE FEEL THAT THE INTRUSION OF ARCTIC AIR MAY
PUSH THE SYSTEM EVEN FURTHER SOUTH. ON THE OTHER HAND...IF THE
ARCTIC AIRMASS IS TOO SHALLOW TO ALTER THE UPPER-LEVEL FLOW (VIA
THERMAL WIND ARGUMENTS) THEN THE STORM SYSTEM COULD HAVE INTERESTING
IMPLICATIONS TO NORTH TEXAS WEATHER BY WEEKS END. FOR NOW...WE ARE
GOING TO TAKE THIS ONE STEP AT A TIME AND INTRODUCE THE SIGNIFICANT
TEMPERATURE CHANGES. THEN...WE WILL TRY TO GET A BETTER HANDLE ON
WHAT THE UPPER-LEVEL DISTURBANCE WILL DO.

[SacrydDreamz]

Blue Norther? What exactly is the criteria for using that term?

[PTrackerLA]

The GFS looks like it might have been right a few days ago after all. It's going to be exciting to see how all this unfolds but I have a strong feeling there will be winter precip coming to the deep south.

[Suzi Q]

HONK HONK HONK

[PTrackerLA]

HONK HONK HONK

You got that right lol!

[Stormsfury]

Blue Norther? What exactly is the criteria for using that term?

A blue norther is an arctic front which plunges deep into the southern Plains (generally in TX) and can drop temperatures suddenly as the front blasts through the area ... it's NOT uncommon to see temperatures to drop as much as 50º!!! ...

This is what happened in OKC on November 11th, 1911 1(11/11/11) when OKC set daily record highs and low on the SAME DAY! ...

SF

[CaptinCrunch]

.DISCUSSION...
357 AM CST

CHALLENGING FORECAST FOR THE NEXT FEW DAYS AS ARCTIC/POLAR AIR MOVES
SOUTHWARD THROUGH THE PLAINS. THE LEADING EDGE OF THE FRONT IS
CURRENTLY MOVING THROUGH CENTRAL KANSAS AND EASTERN COLORADO WITH
TEMPS DIRECTLY BEHIND IT IN THE SINGLE DIGITS AND SOME VERY COLD
TEMPS (NEGATIVE TEENS AND 20S) ACROSS THE NORTHERN PLAINS. THIS COLD
AIR IS EXTREMELY SHALLOW AS NOTED BY THE PROFILER DATA AND THE
TEMPERATURE TRENDS OF THE EASTERN COLORADO STATIONS IN THE LAST FEW
HOURS.

THE FIRST ORDER OF CONCERN IS WHEN WILL THIS AIR REACH
NORTH TEXAS AND HOW MODIFIED WILL IT BE. ALL THE MODELS...WITH THE
EXCEPTION OF THE CANADIAN...HAVE UNDERESTIMATED THE STRENGTH OF THE
SURFACE HIGH IN SOUTHERN SASKATCHEWAN THIS MORNING. HOWEVER...00Z
ANALYSIS DOES REVEAL A DEVELOPING LEE TROUGH WHICH WILL CAUSE SOME
DOWN SLOPE WINDS AND MIXING ON THE WESTERN EDGE OF THE VERY SHALLOW
COLD AIR (THIS HAS BEEN HAPPENING ALL MORNING IN EASTERN COLORADO).
OUR CURRENT THINKING IS THAT THE MIXING TODAY WILL ERODE AND MODIFY
THE LEADING EDGE OF THIS AIR MASS. THEREFORE...WE WILL DELAY
FRONTAL PASSAGE UNTIL THURSDAY. FOR NOW WILL STILL GO WELL BELOW
GUIDANCE DUE TO A MUCH FASTER FROPA TIME.

LOOKS LIKE A REINFORCEMENT OF MUCH DEEPER COLD AIR WILL ARRIVE
THURSDAY NIGHT...AS STRONG COLD AIR ADVECTION (NOTED ON 00Z 850
ANALYSIS) MOVES INTO THE REGION BEHIND EXITING SHORT WAVE. WILL
KEEP TEMPS ON FRIDAY IN THE MID 30S TO THE MID 40S. TEMPS SHOULD
BEGIN TO REBOUND SATURDAY...AS A STRONG TROUGH DEVELOPS LEE OF THE
ROCKIES AND WINDS TURN TO THE SOUTH.

ANOTHER COLD FRONT WILL MOVE INTO NORTH TEXAS ON SUNDAY AND COOL
TEMPS INTO THE 40S TO LOWER 50S...EXCEPT FOR MID TO UPPER 50S IN THE
EXTREME SOUTH PRIOR TO FROPA.

DRY AND COOL NORTHWEST FLOW WILL PREVAIL MONDAY AND THURSDAY AND KEEP
TEMPS IN THE 40S TO LOWER 50S.

FOR NOW...WILL KEEP FORECAST DRY THROUGH DAY 7 AS UPPER LEVEL
SUPPORT SHOULD REMAIN WELL NORTH OR JUST SOUTH OF THE REGION. ONLY
OUTSIDE CHANCE OF PRECIP WOULD BE IN THE SOUTHERN ZONES THURSDAY
NIGHT/FRIDAY...AS A SHORT WAVE SWINGS ACROSS SOUTH TEXAS. IT APPEARS
THE TRACK OF THIS SYSTEM WILL BE TOO FAR SOUTH...SO WILL LEAVE 0

[boomerdawg]

Blue Norther? What exactly is the criteria for using that term?

A blue norther is an arctic front which plunges deep into the southern Plains (generally in TX) and can drop temperatures suddenly as the front blasts through the area ... it's NOT uncommon to see temperatures to drop as much as 50º!!! ...

This is what happened in OKC on November 11th, 1911 1(11/11/11) when OKC set daily record highs and low on the SAME DAY! ...

SF

They did it again around the same day in 1995 or 1996. I was living in Norman. Went to class at 81 degrees early in the afternoon. By 8 PM it was snowing and lows before midnight were in the low to mid 20's throughout the metro. I'll never forget it.