Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 281004
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
404 AM CST SAT FEB 28 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 404 AM CST SAT FEB 28 2015

THE SHORT TERM CONCERN IS TIMING OF CLOUDS AND THREAT OF LIGHT
SNOW/FLURRIES INTO TONIGHT.

RETREATING HIGH PRESSURE TO THE SOUTHEAST THIS MORNING.  THIS HAS
ALLOWED A SOUTHERLY WIND TO BE ESTABLISHED OVER MOST OF THE CWA.
PRESSURE GRADIENT AND PRESSURE FALLS DEVELOPING TO THE WEST...AHEAD
OF THE NEXT WEAK SURFACE FRONT MOVING INTO THE WESTERN DAKOTAS.
THIS FEATURE MOVES EAST TODAY.  ISENTROPIC LIFT...ALBEIT
WEAK...MOVES NORTH AND EAST ACROSS MOST OF MN PORTION OF THE CWA
DURING THE DAY.  THIS SHOULD INCREASE THE CLOUD COVER AND THERE IS A
THREAT OF SOME LIGHT SNOW OR FLURRIES TONIGHT AHEAD OF THE
FRONT/UPPER WAVE.  THIS FEATURE REMAINS WEAK...AND BUFKIT PROFILES
ARE INDICATING RATHER SHALLOW MOIST LAYER.  IT DOES APPEAR DEEP
ENOUGH OVER THE NORTHERN PORTION TO MENTION SLIGHT CHANCE POPS AT
THIS TIME.

CLOUDS DROP SOUTH AND EAST WITH THE FEATURE AND SHOULD GRADUALLY
MOVE EAST THROUGH 12Z SUNDAY. THE AIR BEHIND THE SYSTEM ISNT MUCH
COLDER THIS TIME AROUND...WITH THE BETTER COOLING LOCKED FARTHER
NORTH. HIGHS IN THE 20S SHOULD ONCE AGAIN BE FOUND OVER THE CWA.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 404 AM CST SAT FEB 28 2015

ONLY REAL CONCERN IN THE LONG TERM IS THE SYSTEM FOR EARLY NEXT
WEEK. ALL AVAILABLE GUIDANCE HAS SHOWN A NORTHWARD SHIFT
OVERNIGHT. IN FACT...A DPROG/DT ON THE GFS SHOWS EACH OF THE LAST
FOUR RUNS /EXCEPT THE INCOMING 06Z RUN/ HAD SOME SLIGHT DEEPENING
AND A MORE NORTHERLY TRACK. MAIN REASON FOR THE SHIFT IS A WEAKER
NORTHERN WAVE ACROSS CANADA AND A LATER ARRIVAL OF THE ARCTIC
FRONT. GFS ENSEMBLES ARE BECOMING MORE TIGHTLY CLUSTERED AND ITS
AVERAGE LOW TRACK FROM ERN CO/NWRN KS TO SERN IA TO NEAR MILWAUKEE
BY TUESDAY EVENING IS IN CLOSE AGREEMENT WITH THE DETERMINISTIC
GFS/ECMWF. THUS... CONFIDENCE IS BEGINNING TO INCREASE THAT THE
SOUTHEASTERN HALF OF MINNESOTA AND ALL OF WISCONSIN WILL SEE SOME
ACCUMULATING SNOW WITH THE QUESTION BEING HOW MUCH.

RIDGING OVER THE GULF OF MEXICO WILL ALLOW FOR RICH MOISTURE TO
STREAM NORTHWARD INTO THE PLAINS MONDAY. BY MONDAY NIGHT...INCREASING
MOISTURE ADVECTION AND ISENTROPIC LIFT ACROSS THE UPPER MIDWEST
WILL ALLOW SNOW TO BLOSSOM IN ADVANCE OF THE SYSTEM AND NORTH OF
THE WARM FRONT. THE SNOW WILL BECOME STEADIER AND MORE INTENSE AS
THE UPPER WAVE ARRIVES TUESDAY MORNING. BY TUESDAY AFTERNOON
ISENTROPIC DOWNGLIDE AND RAPID DRYING WILL ERODE THE SNOW SHIELD
WITH MOST AREAS DRY BY 00Z.

THE POSITIVELY TILTED NATURE OF THE SYSTEM AND A SHEARING OF THE
UPPER WAVE WITH TIME WILL LIMIT THE DURATION OF MOST INTENSE SNOW.
THEREFORE NOT ANTICIPATING A MONSTER SNOWFALL...BUT SEVERAL INCHES
ARE CERTAINLY POSSIBLE.

THE SECOND ASPECT OF THIS STORM TO WATCH IS THE PASSAGE OF THE
ARCTIC FRONT TUESDAY AFTERNOON. 925 MB WINDS INCREASE TO AS MUCH
AS 40 KT IMMEDIATELY BEHIND THE FRONT WITH THE MAX ISOTACHS
SLIDING SE ACROSS THE MN RIVER VALLEY BETWEEN 18Z TUE AND 03Z
WED. NEEDLESS TO SAY...FOLLOWING A FRESH SNOWFALL THIS WOULD LEAD
TO QUITE A BIT OF BLOWING SNOW FOR A TIME.

COLD TEMPERATURES RETURN WEDNESDAY BUT THE TROUGH WILL LIFT OUT
LATE WEEK WITH A MILDER AND QUIET PATTERN TO FOLLOW FOR NEXT
WEEKEND.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1104 PM CST FRI FEB 27 2015

HIGH CONFIDENCE OF VFR THROUGH THE MORNING AND THROUGH THE DAY.
WINDS WILL BE LIGHT TONIGHT...BUT INCREASE DURING THE AFTERNOON
WITH SOME GUSTS UP NEAR 20KTS. THE CHANCE FOR MVFR CEILINGS
INCREASES NEAR THE END OF THE TAF PERIOD.

KMSP...

HIGH CONFIDENCE IN VFR THROUGH THE DAY TODAY. WINDS WILL SLOWLY
VEER TO THE SOUTH WITH TIME. LOW CLOUDS WILL BE ON THE INCREASE
LATE THIS EVENING/NIGHT. DRY FORECAST THROUGH THE TAF PERIOD.

/OUTLOOK FOR KMSP/

SUN...MVFR POSSIBLE EARLY. WINDS W AT 10 KTS.
MON...VFR WITH MVFR/IFR -SN LIKELY LATE. WINDS SE AT 10KTS.
TUE...MVFR/IFR AND SN LIKELY. WINDS SW 10KTS TURNING NW.

&&

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

$$

SHORT TERM...DWE
LONG TERM...BORGHOFF
AVIATION...CLF



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