Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 162353
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
553 PM CST TUE DEC 16 2014

.UPDATE...FOR 00Z AVIATION DISCUSSION BELOW

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 300 PM CST TUE DEC 16 2014

AN UPPER LEVEL LOW...THAT WAS LOCATED ACROSS NORTHERN MN THIS
AFTN...WILL SLOWLY ROTATE E-SE ACROSS CENTRAL MN AND INTO CENTRAL
WISCONSIN BY EARLY WEDNESDAY MORNING...AND INTO THE EASTERN GREAT
LAKES BY WEDNESDAY NIGHT AS THE SYSTEM BEGINS TO SHEAR OUT. THERE
REMAINS ENOUGH MOISTURE IN THE DENDRITIC GROWTH ZONE TO CONTINUE
CHC/S OF FLURRIES ACROSS THE NE 2/3 OF MPX CWA TONIGHT...WITH A SLOW
DECREASE TO THE NE ACROSS WC WI AND NORTHERN WI BY WEDNESDAY AFTN.

THE MAIN FORECAST CONCERN WILL BE CLOUD COVER WHICH MAY HOLD THRU
THE SHORT TERM PERIOD ACROSS CENTRAL/EC MN AND WC WI. FURTHER TO THE
SW ACROSS SC/SW/WC MN...THE MOISTURE DEPTH IS MUCH SHALLOWER AND
ANY MIXING IN THE BOUNDARY LAYER WILL ALLOW FOR BREAKS IN THE
OVERCAST. IT MAY EVEN BECOME PARTLY CLOUDY IF THERE IS ENOUGH
DRIER AIR ADVECTED INTO SW/SC MN DURING THE OVERNIGHT HRS. AM
LEANING TOWARD A MOSTLY CLOUDY SKY IN THOSE AREAS DUE TO SLIGHT
CAA AND CONTINUED HIGH MOISTURE VALUES BLW 2K. EVEN IF WE GET MORE
SUNSHINE...BOUNDARY LAYER THERMAL PROFILES INDICATE HIGHS IN THE
TEENS AND LOWER 20S FOR THIS TIME OF YEAR.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 300 PM CST TUE DEC 16 2014

NOT MANY CHANGES IN THE EXTENDED...WITH QUIET WEATHER EXPECTED
THROUGH THE WEEKEND...WITH THE NEXT CHANCE FOR PRECIP NOT COMING
UNTIL THE BEGINNING OF NEXT WEEK.

FOR THE REST OF THE WORK WEEK...THE TOUGHEST PART OF THE FORECAST
WAS DETERMINING THE DEGREE OF CLOUD COVER WE WILL SEE. THERE WAS
CERTAINLY HOPE THAT WE WOULD SEE SOME SUN THIS WEEK...BUT RH TIME
HEIGHTS OFF THE 16.12 NAM IN PARTICULAR SHOW LOW STRATUS REMAINING
IN PLACE THROUGH FRIDAY. THE BIG QUESTION FOR CLOUDS IS HOW MUCH CAN
WE SCOUR THEM OUT ON WEDNESDAY. THE PROBLEM IS THAT ONCE WE HIT
WEDNESDAY NIGHT...WINDS WILL BECOME LIGHT AS THE SFC RIDGE SLOWLY
MOVES ACROSS THE UPPER MS VALLEY...CUTTING OFF THE MECHANICAL MIXING
PROCESS. AS THAT IS HAPPENING WE WILL BE SEEING MID LEVEL HEIGHT
RISES...WHICH WILL RESULT IN SUBSIDENCE...INCREASING TEMPERATURES
AND A STRENGTHENING INVERSION. THIS MEANS THAT WHATEVER IS LEFT OF
THE CLOUDS WEDNESDAY NIGHT WILL BE WITH US THURSDAY AND FRIDAY AS
WELL. BY THE WEEKEND...WE GET BACK INTO A MORE ZONAL FLOW
ALOFT...WITH A RATHER WAVY PATTERN SETTING UP...WHICH WILL BRING MID
AND UPPER LEVEL CLOUD COVER BACK...WITH CLOUD COVER INCREASING AGAIN
BY THE BEGINNING OF THE NEXT WEEK AS THE NEXT STORM SYSTEM MOVES IN.
THE BEST SHOT AT SEEING SOME SUN IN THE COMING WEEK LOOKS TO BE ON
FRIDAY...THOUGH MID/UPPER CLOUDS MAY SPOIL THE PARTY EVEN IF WE LOSE
THE STRATUS. IT IS CERTAINLY PLAUSIBLE THAT WE MAY HAVE PARTS OF THE
AREA THAT DO NOT SEE MUCH IN THE WAY OF BREAKS IN THE CLOUDS UNTIL
THE CHRISTMAS HOLIDAY.

WITH CLOUDS EXPECTED TO BE MORE WIDESPREAD THAN INITIALLY
THOUGHT...MAIN CHANGES MADE TO THE FORECAST FOR THE REST OF THE WORK
WEEK WAS TO INCREASE CLOUD COVER. WITH THE INCREASED CLOUD CAME A
SLIGHT INCREASE IN OVERNIGHT LOWS AND DECREASE IN AFTERNOON HIGHS AS
WELL. BESIDE THAT...MODELS CONTINUE TO KEEP A MID-WEEK SYSTEM WELL
TO OUR SOUTH...SO HAVE MAINTAINED A DRY FORECAST AS WELL.

GOING INTO THE WEEKEND...WE WILL FINALLY START GETTING INTO THE BACK
SIDE OF THE HIGH THAT IS CURRENTLY EXTENDING FROM THE CENTRAL
DAKOTAS THROUGH CENTRAL OK /IT IS A SLOW MOVER/. THE SOUTHERLY WINDS
WILL USHER IN AN INCREASE IN BOTH SFC DEWPOINTS AND TEMPERATURES...
WITH HIGHS ABOVE FREEZING LIKELY RETURNING BY SUNDAY. HAVE ALSO
CONTINUED WITH A DRY FORECAST FOR THE WEEKEND AS THE UPPER WAVES
LOOK RATHER DIFFUSE AND DISORGANIZED...NOT LOOKING TO DO MUCH MORE
THAN LEAD TO A RETURN TO MOSTLY CLOUDY OR JUST PLAIN CLOUDY SKIES.

PRECIPITATION CHANCES ARE BEGINNING TO LOOK BETTER FOR THE MON/TUE
TIMEFRAME. OVER THE WEEKEND...WE WILL SEE UPPER RIDGING ONCE AGAIN
BUILD INTO THE ERN PACIFIC...WITH TROUGHING INCREASING DOWNSTREAM
ACROSS NOAM. AS THIS IS HAPPENING...A SHORT WAVE WILL WORK ACROSS
THE NORTH SIDE OF THE RIDGE ON SUNDAY AND WORK ACROSS THE
INTERNATIONAL BORDER MONDAY/TUESDAY...TAKING ON A NEGATIVE TILT AND
STRENGTHENING AS IT DOES SO. AS THE WAVE STRENGTHENS...BOTH THE
GFS/ECMWF SHOW A SFC LOW DEVELOPING NEAR THE SASK/MONTANA BORDER ON
SUNDAY THAT WORKS ACROSS MN MONDAY AS IT DEEPENS AND SLOWS DOWN IN
RESPONSE TO THE UPPER WAVE TAKING ON A NEGATIVE TILT. MAIN CHANGE
SEEN WITH THE 12Z GFS/ECMWF TODAY IS BOTH MODELS SHIFTED THIS LOW
SOUTH SOME. HOWEVER...THEY DID NOT SHIFT FAR ENOUGH SOUTH TO REMOVE
THE THREAT FOR MIXED PRECIP...WITH BOTH MODELS STILL SHOWING
TEMPERATURES WARM ENOUGH ON MONDAY FOR MUCH OF THE AREA TO SEE RAIN
BEFORE COLD AIR RETURNS MONDAY NIGHT...SWITCHING EVERYTHING OVER TO
SNOW MONDAY NIGHT INTO TUESDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 555 PM CST TUE DEC 16 2014

DESPITE A FEW BREAKS IN THE LOW CLOUD DECK...OVERALL MVFR CIGS
WILL PREVAIL THROUGH WEDNESDAY MORNING. ANOTHER SPOKE OF SHORTWAVE
ENERGY WILL FUEL CONTINUED SCATTERED SNOW SHOWER ACTIVITY
TONIGHT...PARTICULARLY AT KMSP-KRNH-KEAU. VISIBILITIES WILL
GENERALLY RANGE FROM 3SM-5SM WITH THE SNOW SHOWERS. WESTERN SITES
/KAXN-KRWF/ SHOULD BEGIN TO SCATTER OUT BY LATE WEDNESDAY
MORNING...ALTHOUGH IT WILL LIKELY BE MID TO LATE AFTERNOON BEFORE
THE REMAINDER OF THE SITES ACHIEVE VFR CIGS. NORTHWEST WINDS
DECREASE BELOW 10KTS FOR THE OVERNIGHT HOURS...THEN SETTLE IN
AROUND 5 KTS FROM THE NORTH FOR WEDNESDAY.

KMSP...
PREVALENT CIGS AROUND 2KFT ARE EXPECTED THROUGH THE OVERNIGHT
HOURS. VSBYS IN SNOW SHOWERS DOWN TO 3SM ARE POSSIBLE MAINLY PRIOR
TO 03Z...THEN VSBYS SHOULD STAY AOA 5SM WITH SCATTERED SNOW
SHOWERS OVERNIGHT. EXPECT BREAKS IN THE OVC MVFR DECK AFTER 15Z
WEDNESDAY...THEN SCATTERING AFTER 22Z.

/OUTLOOK FOR KMSP/

THU...VFR. WINDS LIGHT NORTH WIND UNDER 5 KTS.
FRI...VFR. WINDS SSE 5 KTS.
SAT...VFR. WINDS SSE 5 KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&

$$


SHORT TERM...JLT
LONG TERM...MPG
AVIATION...LS






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