Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 072029
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
229 PM CST SUN FEB 7 2016

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 225 PM CST SUN FEB 7 2016

SEVERAL CONCERNS OVER THE NEXT 24 HRS AS A BLIZZARD & WINTER
STORM WARNING TAKES EFFECT IN THE NEXT FEW HRS.

FIRST...

UPDATED EARLIER ON THE DELAY OF THE BLIZZARD WARNING IN PARTS OF SW
MN DUE TO VERY MILD TEMPS DURING THE DAY AND SNOWFALL HADN/T
MATERIALIZE. PLUS WIND SPEEDS HAVE NOT YET BECOME STRONG ENOUGH TO
CREATE THE BLOWING SNOW WHERE A CRUST ON THE SNOWPACK HAD OCCURRED.
OTHER AREAS THAT HAVE A WINTER STORM WARNING AND/OR ADVISORIES IN
EFFECT TONIGHT REMAIN FINE DUE TO SIGNIFICANT BLOWING SNOW STILL
EXPECTED...BUT LIKELY NOT UNTIL LATER THIS EVENING.

CURRENT REGIONAL RADAR AND WATER VAPOR IMAGERY INDICATED A POTENT
SHORT WAVE MOVING SOUTHWARD ACROSS NORTHERN MN THIS AFTN. THIS SHORT
WAVE WILL BE THE MAIN FACTOR OF GENERATING SNOWFALL THIS EVENING.
PLUS...THE DENDRITIC ZONE DEEPENS QUITE RAPIDLY BEHIND THE ARCTIC
FRONT THAT WAS CO-LOCATED WITH THE SHORT WAVE. ALTHOUGH THE WIND
SPEEDS HAVE NOT DEVELOPED AS STRONG AS PREVIOUSLY INDICATED AS OF 2
PM...THESE WINDS WILL LIKELY DEVELOP THIS EVENING ONCE THIS SHORT
WAVE MOVES THROUGH. AGAIN...IT IS MORE OF A DELAY OF THE BLIZZARD
CONDITIONS IN SW/SC MN TONIGHT. AS PREVIOUSLY STATED...THE DENDRITIC
GROWTH ZONE DEEPENS ENOUGH THAT WITH ANY MOISTURE RIDING SOUTHWARD ON
THE UPPER LEVEL STORM SYSTEM...PERIODS OF LIGHT SNOW WILL OCCUR.
ALTHOUGH QPF AMTS WILL BE LIGHT AND UNDER A TENTH OF AN INCH. A GOOD
AREA OF 1-2 INCHES OF SNOW IS LIKELY BY MONDAY MORNING FOR MOST OF
CENTRAL AND EASTERN MN/WESTERN WI...WITH AMOUNTS LESS THAN 1 INCH IN
SW/WC/SC MN.

AS PER WIND SPEEDS... AREA MODEL SOUNDINGS DEVELOP A DRY ADIABATIC
LAPSE RATE BETWEEN THE SFC...UP TO 90/85H. WITH THIS TYPE OF
SOUNDING...MOMENTUM TRANSFER WILL BE MAXIMIZED FROM WINDS ON TOP OF
THE THIS STEEP LAPSE RATE. THEREFORE...AS THE SHORT WAVE MOVES
THRU AND STRONGER WINDS ALOFT BEGIN TO MIX DOWN...MUCH STRONGER WINDS
WILL DEVELOP...LEADING TO BLIZZARD CONDS.

EXPECT THE STRONG WINDS TO CONTINUE THRU NOON ON MONDAY. THE PRESSURE
GRADIENT SHOULD BEGIN TO LESSEN BY MONDAY AFTN...DECREASING THE WIND
SPEEDS. ALTHOUGH BLOWING SNOW WILL CONTINUE AS WIND GUSTS OF 30 TO 40
MPH WILL LIKELY HOLD THROUGH THE AFTN.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 225 PM CST SUN FEB 7 2016

THE LONGER TERM CONCERN IS TIMIMG OF ANY SNOW MOVING ALONG THE
BAROCLINIC ZONE OFF TO THE WEST OF THE AREA...AS THE UPPER AIR
PATTERN BECOMES AMPLIFIED WITH THE EASTERN CONUS TROUGH AND RIDGE
TO THE WEST.

ANY SNOW SHOWERS/FLURRIES AND PATCHY BLOMING SNOW WILL COME TO AN
END MONDAY NIGHT OVER THE CWA. SOME CLEARING IS LIKELY IN THE WAKE
OF THE SYSTEM. WHERE IT DOES CLEAR...TEMPERATURES SHOULD BE ABLE
TO COOL THROUGH THE SINGLE DIGITS TO AROUND ZERO IN CENTRAL MN.

THE SURFACE RIDGE BUILDS ACROSS THE AREA TUESDAY AND LINGERS OVER
THE AREA THROUGH THE WORK WEEK. H85 TEMEPRATURES REMAIN GENERALLY
MINUS 15 TO MINUS 20 OVER THE EASTERN HALF OF THE CWA. THIS SHOULD
PROVIDE THE COOLER THAN NORMAL TEMPERATURES THE CFS HAS BEEN
SHWOOING THE LAST SEVERAL RUNS. THE DETERMINISTIC RUNS CONTINUE TO
HAVE SOME RUN TO RUN DISCONTINUITY PROBLEMS WITH ANY POSSIBLE
LIGHT SNOW BAND THAT IS GENERATED WITH ANY WEAK IMPULSE THAT WORKS
OVER THE WESTERN RIDGE. HAVE OPTED TO CONTINUE THE DRY FORECAST
FOR THE WEEK AS THE SURFACE RIDGE DOMINATES. AS THE EASTERN TROUGH
TRANSLATES FARTHER EAST INTO THE WEEKEND...WE SHOULD SEE A SLOW
WARMING TRNED ALONG WITH A CHANCE OF SNOW RETURNING TO THE AREA
ABOUT SUNDAY OR SO.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1130 AM CST SUN FEB 7 2016

HIGH CONFIDENCE THAT CONDS WILL DETERIORATE RAPIDLY THIS AFTN FROM
NW TO SE ACROSS CENTRAL AND SOUTHERN MN. TIMING MAYBE OFF AN HR OR
TWO...BUT WINDS PLUS -SN/-SHSN WILL SPREAD SE ACROSS WESTERN MN
AND INTO EASTERN MN BY 00Z. MVFR VSBYS WILL DROP TO OCCASIONAL
IFR/LIFR OR EVEN VLIFR BY THE LATE AFTN THRU THE OVERNIGHT HRS AS
WINDS INCREASE TO 25-35 KTS...AND GUSTS APPROACHING OR EXCEEDING
35-45 KTS IN WESTERN MN. WIND GUSTS OF 25-30 KTS WILL OCCUR IN
EASTERN MN...WITH 20-25 KTS IN WC WI. LOW VSBYS IN -SN/BLSN WILL
LIKELY CONTINUE OVERNIGHT...THRU MONDAY MORNING...BEFORE CONDS
SLOWLY IMPROVE AFTER THIS TAF PERIOD.

KMSP...

HIGH CONFIDENCE THAT CONDS WILL DETERIORATE RAPIDLY BY LATE AFTN
WITH VSBYS LOWERING TO IFR BY 00Z. SCATTERED -SN/-SHSN/BLSN WILL
DEVELOP AFT 21Z...WITH -SN LIKELY BY 00Z. KEPT ONLY A SHORT TEMPO
PERIOD THIS EVENING DUE TO HIGH TRAFFIC CONCERNS...BUT IFR VSBYS
WILL LIKELY CONTINUE OVERNIGHT/MONDAY MORNING IN -SN/BLSN. WINDS
WILL INCREASE BY LATE AFTN/EVENING WITH SUSTAINED WINDS OF 22-25
KTS...WITH GUSTS OF 30-35 KTS. WOULD NOT EXPECT IMPROVING CONDS
UNTIL AFT 18Z MONDAY.

/OUTLOOK FOR KMSP/

TUE...VFR. WIND NW 10-15 KTS.
WED...VFR. WIND NW 10 KTS.
THU...VFR. WIND N 5 KTS...BECOMING W.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...BLIZZARD WARNING FROM 7 PM THIS EVENING TO NOON CST MONDAY FOR
     MNZ065>067-073>076-082>085-091>093.

     WINTER STORM WARNING UNTIL NOON CST MONDAY FOR MNZ041-047-048-
     055.

     WINTER WEATHER ADVISORY UNTIL NOON CST MONDAY FOR MNZ042>045-049-
     050.

     WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO NOON CST
     MONDAY FOR MNZ051>053-059>063-068>070-077-078.

     WINTER STORM WARNING UNTIL NOON CST MONDAY FOR MNZ054-056>058-
     064.

&&

$$

SHORT TERM...JLT
LONG TERM...DWE
AVIATION...JLT



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