Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 212154
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
354 PM CST WED JAN 21 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 308 PM CST WED JAN 21 2015

WATER VAPOR IMAGERY OVERLAID WITH A RAP H5 ANALYSIS THIS AFTERNOON
SHOWS A RATHER ACTIVE PATTERN. THE RIDGE ON THE WEST COAST IS
AMPLIFYING...WITH A BROAD TROUGH ACROSS MOST OF NOAM EAST OF THE
ROCKIES. WITHIN THIS THROUGH...THE MOST PROMINENT FEATURE IS THE
WAVE MOVING THROUGH THE 4 CORNERS REGION...BUT THIS WILL REMAIN WELL
SOUTH OF US. CLOSER TO HOME THE SHORTWAVE THAT BROUGHT THE SNOW IN
YESTERDAY IS NOW OFF OVER SRN MICHIGAN. THE PV WITH THIS WAVE
EXTENDS BACK TO THE WEST INTO A TROUGH WITH ITS BASE IN WYOMING.
WITHIN THIS...YOU WILL FIND YET ANOTHER EMBEDDED SHORTWAVE SLOWLY
MOVING SOUTH THROUGH SODAK. AS WE GO THROUGH TONIGHT THIS BAGGY
THROUGH WILL SAG SOUTH OF US...WITH SHORTWAVE RIDGING TAKING ITS
PLACE FOR THURSDAY. UNTIL THIS GENERAL TROUGHINESS CLEARS THE
AREA...WE WILL MAINTAIN THE CLOUDS WITH OCCASIONAL LIGHT
SNOW/FLURRIES...THOUGH NO ADDITIONAL ACCUMULATIONS ARE EXPECTED.

THE BIG QUESTION FOR THE SHORT TERM IS WHEN EXACTLY WILL THESE
CLOUDS CLEAR OUT. ON THE HEELS OF THE UPPER WAVE MOVING OUT WILL A
SFC RIDGE MOVING IN. THE SUBSIDENCE AND DRYING WITH THIS WILL HELP
CLEAR OUT THE CLOUDS. BELIEVE THE NAM BUFR SOUNDINGS ARE TOO MOIST
IN THE LOW LEVELS...SO FOLLOWED MORE OF A GFS IDEA WITH SKIES
CLEARING FROM N TO S TONIGHT....THOUGH WENT A BIT SLOWER THAN THE
NAM GIVEN THE HRRRS DEPICTION OF HOW THE STRATUS SHIELD WILL CLEAR
OUT THIS EVENING.  WE WILL SOME CLEAR SKIES ON THURSDAY BEFORE
MID/HIGH CLOUDS INCREASE AGAIN ACROSS CENTRAL MN DURING THE
AFTERNOON IN RESPONSE TO A SHORTWAVE MOVING ACROSS SRN CANADA.

TEMPERATURES WILL BE THE TRICKIEST PART OF THE FORECAST AS THEY WILL
BE HIGHLY DEPENDENT ON CLOUD COVER. FOR PLACES THAT KEEP THE
CLOUDS...LOWS WILL STAY IN THE 20S. YOU LOSE YOUR CLOUDS...WELL WITH
LIGHT WINDS TEMP DROPS WILL BE OFF TO THE RACES...LIKELY SETTLING IN
THE SINGLE DIGITS IF ENOUGH TIME WITH CLEAR SKIES CAN HAPPEN. THIS
WOULD BE MOST LIKELY FOR CENTRAL MN. FOR THURSDAY...SW WINDS WILL BE
INCREASING THROUGH THE DAY. THIS WILL QUICKLY PUT AN END TO THE WEAK
CAA WE ARE SEEING THIS AFTERNOON...WITH HIGHS BACK IN THE 30S LIKELY
OUT IN THE MN RIVER VALLEY...WITH WARMER TEMPS STILL TO COME.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 308 PM CST WED JAN 21 2015

A CLIPPER SYSTEM WILL BE SLIDING EAST THROUGH THE SOUTHERN
CANADIAN PROVINCES BY THURSDAY NIGHT...BUT ESSENTIALLY ALL PRECIP
WILL STAY NORTH OF THE INTERNATIONAL BORDER. THE MAIN CONCERN FOR
OUR AREA IS WHETHER OR NOT ANY PRECIP WILL BE PRODUCED ALONG THE
COLD FRONTAL BOUNDARY ASSOCIATED WITH THIS SYSTEM THAT IS SET TO
DROP SOUTH THROUGH OUR AREA ON FRIDAY. MODELS GENERALLY AGREE ON
SQUEEZING OUT LIGHT PRECIP ALONG THIS FRONTAL BOUNDARY. THERMAL
PROFILES REMAIN WARM...SO ANY LIGHT PRECIP THAT DOES FALL WILL BE
A MIX OF SNOW...SLEET...AND RAIN.

THE OVERALL PATTERN IN THE LONG RANGE WILL CONSIST OF AN UPPER
RIDGE ACROSS WESTERN NORTH AMERICA AND A TROUGH ACROSS EASTERN
NORTH AMERICA. YET ANOTHER CLIPPER WILL DIVE SOUTHEAST THROUGH
CANADA THIS WEEKEND...BUT THIS SYSTEM LOOKS STRONGER AND THE
SHORTWAVE WILL AMPLIFY AS IT APPROACHES THE NORTHERN STATES. THE
LATEST GFS RUN INDICATES A SLIGHT SHIFT TO THE EAST WHICH WOULD
PUT WESTERN WI AND EXTREME EASTERN MN UNDER THE HEAVIEST
POTENTIAL...WHICH REMAINS AT ABOUT 0.20-0.30" OF LIQUID QPF. IN
THIS AREA...THERMAL PROFILES ARE INDICATIVE OF ALL SNOW HERE SO A
COUPLE OF INCHES OF ACCUMULATION REMAINS A POSSIBILITY.
HOWEVER...THIS SYSTEM IS STILL 3.5-4 DAYS AWAY SO MUCH CAN
CHANGE. ESPECIALLY BECAUSE THERE IS DECENT POTENTIAL FOR A STRONG
NOR`EASTER TO MOVE UP THE EAST COAST. THIS FEATURE WILL PLAY A
KEY PART IN THE EVOLUTION OF UPSTREAM FEATURES SO SHIFTS IN OUR
CLIPPER ARE CERTAINLY POSSIBLE.

AS WE HEAD INTO NEXT WEEK...THE WESTERN RIDGE WILL BASICALLY HOLD
FIRM AND THE ECMWF INDICATES ANOTHER LIGHT SNOWFALL EVENT POSSIBLE
FOR OUR AREA. THERE IS NOT MUCH AGREEMENT WITH THIS SYSTEM
HOWEVER...AS THE GFS IS MUCH STRONGER AND NORTHEAST OF OUR AREA
WITH THE MAIN PRECIP.

TEMPERATURES LOOK TO REMAIN ABOVE NORMAL THROUGH EARLY NEXT WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1144 AM CST WED JAN 21 2015

MAIN ISSUE THIS TAF PERIOD WAS WHEN TO BRING THROUGH CLEARING
TONIGHT/THU MORNING. BELIEVE THE NAM IS WAY TO OVERDONE ON LOW
LEVEL MOISTURE AND BELIEVE AS THE SFC RIDGE WORKS THROUGH...IT
WILL BRING CLEARING SKIES WITH IT. FOR TIMING...THE HRRR SUGGESTS
THAT THE GFSLAMP IS A BIT TOO AGGRESSIVE WITH ITS CLEARING...SO
WENT SLOWER WITH CIG IMPROVEMENTS THAN WHAT THE LAMP HAS. BASED
ON OBS UPSTREAM...CONDS WILL LIKELY DETERIORATE AS SITES GET INTO
THE BACK EDGE OF THE STRATUS...SO TRENDED TAFS BACK TO IFR/LOW END
MVFR BEFORE CLEARING THEM OUT. ALTHOUGH NO ACCUMULATIONS ARE
EXPECTED...EAU WILL SEE -SN CONTINUE FOR NO MORE THAN A COUPLE OF
HOURS...WHILE ANOTHER AREA OF SNOW IN WC MN MAY BRUSH RWF THIS
AFTERNOON.

KMSP...WE WILL BE MAINTAINING THE STRATUS...LIKELY THROUGH THE
WHOLE NIGHT. STILL SEE NO REASON WHY CIGS WILL NOT IMPROVE TO
ABOVE 017 THIS AFTERNOON...BUT THE LARGE BANK OF IFR CONDS ACROSS
NRN MN PUSHED ME TO BRINGING CIGS BACK UNDER 017 TONIGHT. WILL
HAVE TO WATCH TRENDS...BUT COULD SEE MSP DEALING WITH IFR CIGS
AGAIN THU MORNING. EXPECT STRATUS TO CLEAR OUT BY 15Z AT THE
LATEST...AND ONCE IT DOES ITS MAINLY CLEAR SKIES WITH SW WINDS
FOR THE REST OF THE TAF PERIOD.

/OUTLOOK FOR KMSP/
FRI...MVFR CIGS IN AFTN. WIND SW AT 10 KTS.
SAT...VFR. CHC IFR/MVFR -SN LATE. WINDS NW 5-10 KTS.
SUN...IFR/MVFR. CHC MORNING -SN. WINDS NE 5-10 KTS.


&&

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

$$

SHORT TERM...MPG
LONG TERM...SPD
AVIATION...MPG


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