Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 211253
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
753 AM CDT TUE APR 21 2015

.UPDATE...
ISSUED AT 747 AM CDT TUE APR 21 2015

UPDATED TO INCLUDE 12Z AVIATION DISCUSSION BELOW.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CDT TUE APR 21 2015

TODAY AND TONIGHT...SFC ANALYSIS SHOWS A LARGE SFC LOW WITH A
988MB CENTER OVER ERN ONTARIO PROVINCE THIS MRNG WITH A SFC TROF
SNAKING AROUND ITS PERIPHERY FROM ERN MI INTO NRN IL AND THRU SRN
IA/NE. WV IMAGERY SHOWS A DEEP H5 ROTATING UPR LOW SHIFTED
SLIGHTLY WWD OF THE SFC FEATURE...ALLOWING THE LONGWAVE TROF TO
EXPAND AND REMAIN ANCHORED OVER ERN NOAM THRU TNGT. THESE FEATURES
WILL PROMOTE ISOLD/SCTD -RA/-SN SHOWERS TO DRIFT SEWD THRU THE WFO
MPX CWFA FOR MUCH OF THE DAY INTO TNGT...MAINLY ALONG AND N OF THE
I-94 CORRIDOR. NOT MUCH IN THE WAY OF QPF BUT EVEN TEMPERATURES
INTO THE MID-UPR 30S MAY BE SUBJECT TO SNOWFLAKES DUE TO THE DEEP
COLD LAYER AND PROMINENT CAA WITH NW FLOW ALOFT. HIGHS WILL RANGE
THRU THE 40S. THERE WILL AGAIN BE THE CONCERN FOR STRONG WINDS
OVER SWRN PORTIONS OF THE CWFA WHERE CLOUD COVER WILL BE LESS AND
CAN BETTER ABLY TAP INTO STRONG WINDS AT THE TOP OF THE MIXING
LAYER. HAVE GONE WITH A WIND ADVY FOR WRN AND SRN PORTION OF THE
CWFA AFTER COLLAB WITH SURROUNDING OFFICES. WINDS WILL SETTLE DOWN
TO 10 MPH OR LESS TNGT INTO TMRW MRNG. THIS SCENARIO COMBINED WITH
DECRG CLOUDS AND CONTINUED CAA WILL ALLOW FOR TEMPERATURES SO DROP
BELOW THE FREEZING MARK EARLY WED MRNG. LOWS TNGT WILL BOTTOM OUT
IN THE MID 20S TO AROUND 30.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 400 AM CDT TUE APR 21 2015

THE PRIMARY WEATHER DRIVER IN THE LONG TERM CONTINUES TO BE THE
DEEPLY AMPLIFIED TROUGH /WHICH IS ESSENTIALLY OVERHEAD RIGHT NOW/
AS IT SETS UP OVER THE NORTHERN GREAT LAKES FROM WEDNESDAY THROUGH
THURSDAY. DURING THIS TIME...WE WILL BE UNDER A PERSISTENT
NORTHWEST FLOW ALOFT...AND CANADIAN HIGH PRESSURE WILL SINK INTO
THE UPPER MIDWEST AT THE SURFACE. SO...DIURNALLY DRIVEN NORTHWEST
WINDS WILL PERSIST BOTH DAYS...GENERALLY 10 TO 20 MPH AT LEAST
WITH SOME GUSTS OVER 20...ESPECIALLY ON WEDNESDAY. THE MAJORITY OF
THE CLOUD COVER ASSOCIATED WITH THE TROUGH WILL HAVE PUSHED TO THE
EAST OF OUR AREA...LEAVING US WITH ABUNDANT SUNSHINE WITH THE
EXCEPTION OF PARTS OF WEST CENTRAL WI WHICH MAY SEE WRAP AROUND
STRATUS SWING THROUGH ON WEDNESDAY.

ONCE FRIDAY COMES...ATTENTION TURNS TO A SHORTWAVE EJECTING OUT OF
THE COLORADO FRONT RANGE. THERE IS ACTUALLY DECENT AGREEMENT
BETWEEN THE GFS/ECMWF/GEM IN HANDLING THIS ENERGY...BUT THE
DETAILS IN HOW FAR NORTH THE PRECIPITATION MAKES IT IS WHERE THE
DIFFERENCE OCCUR. IT LOOKS LIKE AS WE GO THROUGH FRIDAY NIGHT AND
SATURDAY...A SURFACE LOW WILL DEEPEN NEAR KANSAS AND MOVE NEARLY
DUE EAST. THE EC/GEM AGREE WELL WITH THIS ASPECT...WHEREAS THE GFS
TAKES THE LOW SOUTH THROUGH OKLAHOMA TOWARD ARKANSAS. BOTH THE
EC/GEM SPREAD MOISTURE AND WAA LIFT INTO SOUTHERN MN...SO AT LEAST
SLIGHT CHANCE POPS ARE WARRANTED AT THIS TIME. HOWEVER...IF THE
GFS SOLUTION IS ON THE RIGHT TRACK...FRIDAY WOULD REMAIN DRY.

HIGH PRESSURE LOOKS TO BUILD IN AGAIN ON SUNDAY...BEFORE ANOTHER
SHORTWAVE APPROACHES THE REGION SUNDAY NIGHT/MONDAY...AND LIGHT
RAIN WILL BE A POSSIBILITY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 747 AM CDT TUE APR 21 2015

LARGE DEEP LOW PRES CENTER OVER THE CENTRAL GRT LKS INTO ERN
ONTARIO PROVINCE WILL KEEP LOW VFR/UPR MVFR CLOUDS IN PLACE FOR
MUCH OF THE DAY. WEAK SHORTWAVES ROUNDING THE PERIPHERY OF THE
DEEP LOW WILL SPREAD ISOLD/SCTD -RA/-SN SHWRS INTO MAINLY THE WI
TAF SITES BUT POSSIBLY KSTC/KMSP AS WELL. CONDS WILL IMPROVE AS
THE DAY PROGRESSES AND THE LOW SHIFTS OFF TO THE E...ALLOWING MORE
SOLID VFR CEILINGS BY LATE THIS AFTN FOLLOWED BY SCATTERING OUT OF
CLOUDS OVERNIGHT INTO TUE. STRONG/GUSTY NW WINDS WILL CONTINUE
THRU THE DAY TDA THEN DIMINISH TO ARND 10 KT OVERNIGHT INTO TUE.

KMSP...VFR CEILINGS LOOK TO PREVAIL ALTHOUGH THE OCNL UPPER-END
MVFR CEILING CANNOT BE RULED OUT THRU THIS MRNG...ESP IF A SMALL
BATCH OF PRECIP MAKES IT INTO KMSP. OTHERWISE...CONDS WILL
GRADUALLY IMPROVE THIS EVENING THROUGH OVERNIGHT...WITH CLOUDS
SCATTERING OUT OVERNIGHT. STRONG GUSTY NW WINDS WILL GENERALLY
REMAIN FROM 290-320 DURG THIS TAF PERIOD. NO VSBY RESTRICTIONS
EXPECTED AS ANY HEAVIER BATCHES OF PRECIP LOOK TO REMAIN E OF
KMSP.

/OUTLOOK FOR KMSP/
WED...VFR. WINDS NW 15G25KTS.
THU...VFR. WINDS NW 10-15KT.
FRI...VFR. WINDS NE 5-10 KT.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WIND ADVISORY FROM NOON TODAY TO 6 PM CDT THIS EVENING FOR
     MNZ047-048-054>057-064-065-067-073>076-082>085-091>093.

WI...NONE.
&&

$$

UPDATE...JPC
SHORT TERM...JPC
LONG TERM...SPD
AVIATION...JPC



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