Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 292104
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
404 PM CDT SUN MAR 29 2015

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 355 PM CDT SUN MAR 29 2015

POTENT COLD FRONT CONTINUES TO MAKE GRADUAL PROGRESS FROM MN INTO
WI THIS AFTN. STRONG WINDS HAVE DEVELOPED IN THE WAKE OF THE
FRONT...SOME TO THE TUNE OF 40-50 MPH /INCLUDING MSP AIRPORT/...
ALONG WITH CLEARING SKIES WITHIN STRONG SUBSIDENCE MIXING DOWN LLJ
ALOFT. ANY LINGERING PRECIP HAS SHIFTED E OF THE CWFA INTO ERN WI
AND REMAINING CLOUD COVER WILL BE SOON TO FOLLOW AS THE FRONT
SCOURS OUT THE LOWER LEVELS. WINDS WILL GRADUALLY DIMINISH
OVERNIGHT AS HIGH PRES SETTLES OVER THE AREA...AND WILL KEEP THE
CLEAR SKIES IN PLACE THRU TMRW MRNG. THE HIGH PRES RESPITE WILL BE
BRIEF AS A WEAK LOW PRES SYSTEM WILL APPROACH WITHIN NW FLOW
ALOFT. VERY LITTLE UPPER LEVEL SUPPORT AND MOISTURE COMES WITH
THIS SYSTEM...AND EVEN THAT WILL BE MORE FOCUSED INTO NRN MN THAN
IN THE MPX CWFA...SO THE ONLY POPS THAT REMAIN WILL BE SLGT CHC
POPS FOR THE NRN AND ERN FRINGES OF THE CWFA...FOR LIGHT RAIN.
OTHERWISE...DESPITE THE NW FLOW ALOFT...TEMPS WILL CONTINUE ON A
MODERATING TREND TNGT INTO MON DUE A WARM AIR RIDGE OVER THE SWRN
STATES BEGINNING TO SHIFT INTO THE CENTRAL CONUS. THOUGH THE CLEAR
SKIES AND LIGHTER WINDS TNGT WILL ALLOW LOWS TO DROP TO THE LOW-
MID 30S OVERNIGHT...HIGHS TMRW WILL SURGE INTO THE 60S IN THE MN
PORTION OF THE CWFA AND INTO THE 50S FOR THE WI PORTION OF THE
CWFA.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 355 PM CDT SUN MAR 29 2015

ONLY CONCERN IN THE EXTENDED PERIOD IS THE POTENTIAL OF TSRA
WEDNESDAY AFTN/EVENING AS A SHARP COLD FRONT MOVES ACROSS THE
UPPER MIDWEST.

EC/GFS/GEM ALL HAVE TRENDED SLOWER WITH THE SHRTWV MOVING ACROSS
THE NORTHERN ROCKIES AND INTO THE NORTHERN PLAINS WEDNESDAY
NIGHT. THE EC HAS BEEN THE MOST CONSISTENT AND HAD THE BEST
FORECAST FOR TODAYS SYSTEM WITH THE SLOWER MOVEMENT AND MORE
MOISTURE A FEW DAYS AGO. THE SLOWER SOLUTION WILL HAVE A MAJOR
IMPACT ON THE DEVELOPMENT OF SHRA/TSRA WEDNESDAY AFTN/EVENING.
PREVIOUS RUNS HAD THE MAIN AREA DEVELOPING SE OF MPX WHICH SEEM
LIKELY DUE TO THE INITIAL STRONG CAP AND LOWER DEW PTS.
HOWEVER...WITH THIS SLOWER MOVEMENT 85H WINDS HAVE INCREASED
SIGNIFICANTLY AHEAD OF THIS COLD FRONT.

DUE TO THE SLOWER SOLUTION AND MOISTURE ADVECTION EXPECTED AHEAD
OF THE FRONT WEDNESDAY AFTERNOON...DEW PTS WILL LIKELY RISE AS
WELL. THE CURRENT RUN OF THE EC HAVE DEW PTS NEARLY 55 DEGREES IN
FAR SW MN WED AFTN. THE GFS IS EVEN HIGHER WITH 55-60 DEGREE DEW
PTS AS FAR NORTH AS KMKT. IF THESE HIGHER MOISTURE VALUES IN THE
BOUNDARY LAYER SURGE NORTHWARD ACROSS THE UPPER MIDWEST AS
FORECAST...THE CAP WILL WEAKEN CONSIDERABLY DURING THE AFTN AS
TEMPS RISE INTO THE 70S.

ALTHOUGH SHEAR VALUES ARE AMPLE ENOUGH FOR ORGANIZED CONVECTION...
MLCAPE WILL BE DEPENDENT ON THE AMOUNT OF BOUNDARY LAYER
MOISTURE ADVECTING NORTHWARD AHEAD OF THE COLD FRONT. CURRENT
FORECAST SOUNDINGS OF SFC CAPE HAVE NEARLY 1000-1500 J/KG ON THE
LATEST GFS RUN...WITH THE EC A CLOSE SECOND WITH NEARLY 1000 J/KG
DURING THE MID/LATE AFTN HRS. SVR WX IS POSSIBLE...ESPECIALLY
CONSIDERING MID LEVEL LAPSE RATES OF /8.0 C/KM FROM 70-50H/...WIND
SHEAR VALUES AND LOWER FREEZING LEVEL. AGAIN...THIS IS HIGHLY
DEPENDENT ON THE AMOUNT OF INSTABILITY.

PAST WEDNESDAY NIGHT...COOLER WX WILL DEVELOP AS THE MEAN FLOW
BECOMES MORE WNW AND THICKNESS VALUES DECREASE BY THE END OF THE
WEEK. HOWEVER...IT SHOULD BE SHORT LIVED WITH A MORE W/SW FLOW
DEVELOPING NEXT WEEK. IN ADDITION...NORMAL HIGHS FOR EARLY APRIL
ARE IN THE 50S. SO EVEN BLW NORMAL TEMPS STILL MEAN HIGHS ABV
FREEZING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 110 PM CDT SUN MAR 29 2015

CDFNT CONTINUES TO MAKE EFFICIENT PROGRESS FROM W TO E ACRS THE
WFO MPX COVERAGE AREA TDA...WITH A PRONOUNCED WIND SHIFT AND INCRS
IN WIND SPEEDS ALONG WITH CLEARING SKIES BEHIND IT. FOR THE TAF
SITES NOT YET OUT OF THE CLOUD COVER AND PRECIP...WHICH ATTM IS
SOLELY THE WI TAF SITES...CONDS WILL DETERIORATE TO POSSIBLY IFR
VSBY FOR A BRIEF PERIOD BEFORE MVFR CIGS PREVAIL THROUGH MID-TO-
LATE AFTN. FOR THE MN TAF SITES...THE CLEARING HAS ALREADY
OCCURRED FOR KAXN-KRWF...AND WILL THEN OCCUR SHORTLY THEREAFTER
EARLY THIS AFTN FOR KSTC-KMSP. SKIES WILL THEN REMAIN CLR
OVERNIGHT INTO TMRW MRNG BEFORE HIGH CLOUDS MOVE IN MID-TO-LATE
DAY. WINDS WILL DIMINISH THIS EVE AND OVERNIGHT...EVENTUALLY
DROPPING BELOW 5 KTS OVERNIGHT INTO TMRW MRNG.

KMSP...35-40KT WINDS OCCURRED WITH THE PASSAGE OF THE PRECIP BUT
HAVE NOW DROPPED TO 15-25KT IN THE WAKE OF THE PRECIP. AS SKIES
CLEAR OUT AND BETTER MIXING DEVELOPS TO TAP WINDS ALOFT...WILL
LOOK FOR NW WINDS TO INCRS TO THE 25-35KT RANGE FOR MUCH OF THE
AFTN INTO THE EVE BEFORE DECOUPLING ALLOWS SFC WINDS TO SETTLE
DOWN TO ARND 10 KT. SKIES WILL CLEAR OUT BY ARND 22Z AND REMAIN
CLR OVERNIGHT THRU TMRW AHEAD OF THE NEXT WEAK SYSTEM THAT WILL
REMAIN N OF MSP.

/OUTLOOK FOR KMSP/
TUE...VFR. WINDS NW 5-10 KTS.
WED...VFR. MVFR/-SHRA POSSIBLE IN THE AFTN/EVE. WINDS S 15-25 KTS.
THU...VFR. WINDS W 10-20 KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WIND ADVISORY UNTIL 6 PM CDT THIS EVENING FOR MNZ041>043-047>051-
     054>070-073>078-082>085-091>093.

     FIRE WEATHER WATCH UNTIL 7 PM CDT THIS EVENING FOR MNZ064-073-
     074-082-091.

WI...NONE.
&&

$$

SHORT TERM...JPC
LONG TERM...JLT
AVIATION...JPC



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