Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 012057
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
357 PM CDT FRI MAY 1 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 256 PM CDT FRI MAY 1 2015

CDFNT CONTINUES TO SLOWLY SHIFT EWD ACRS WRN-CENTRAL MN THIS AFTN
BUT ITS PROGRESS LOOKS TO BE SLOWED BY UPR LVL RIDGING AND NVA...
EFFECTIVELY WASHING OUT WHAT IS LEFT OF THE FNT. IN ADDITION...THE
PRECIP ASSOCIATED WITH THE CDFNT IS OUTRACING THE FRONT...SO THE
PRECIP IS GRADUALLY DIMINISHING OVER WRN WI WHILE WRN-CENTRAL MN
SLOWLY CLEARS OUT. WITH THE CDFNT STALLING OVER ERN MN...CLOUDS
WILL REMAIN THERE THE LONGEST. IN ADDITION...WINDS OVER WRN MN
WILL CONTINUE FROM THE NW GOING INTO THE EVE WITH CENTRAL MN
LGT/VRBL AND ERN-SRN MN FROM A MAINLY SLY COMPONENT. AS THE CDFNT
WASHES OUT OVERNIGHT...AND A SMALL BUBBLE UPR LVL RIDGE MOVES
ACRS...SKIES WILL CLEAR OUT AND THEN ALLOW SLY WINDS TO PREVAIL
OVERNIGHT INTO SAT MRNG. MAINLY CLEAR SKIES WILL THEN CONTINUE FOR
MUCH OF THE DAY ON SATURDAY UNDER ZONAL FLOW ALOFT AND S-SW FLOW
AT THE SFC. THIS WILL PROMOTE STRONG WARMING FOR THE WEEKEND...
INCLUDING BRINGING HIGHS INTO THE LWR 80S FOR MUCH OF THE WFO MPX
CWFA ON SATURDAY. LOWS TNGT WILL AGAIN DROP INTO THE 40S.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 256 PM CDT FRI MAY 1 2015

THE LONG-WAVE PATTERNS IN THE EXTENDED FAVORS A FEW PERIODS OF
ACTIVE WEATHER WITH THE FIRST ARRIVING WITH WELL-ADVERTISED RAIN
SUNDAY /MAINLY IN THE AFTERNOON AND EVENING/. A HEALTH POLAR JET
WILL ASSIST THE EAST-SOUTHEAST PROGRESSION OF A TROUGH ACROSS
SOUTHERN CANADA LATE THIS WEEKEND. AS A RESULT...A THETA-E RIDGE
BUILD IN ACROSS THE UPPER MISSISSIPPI RIVER VALLEY BY SUNDAY. THE
ADDED WARMTH WILL LIKELY BRING BOTH 1000-2000 J/KG OF MLCAPE TO
SOUTHERN AND EASTERN MN...BUT ALSO A LITTLE BIT OF A CAPPING
INVERSION DUE TO THE MID LEVEL ADVECTION OF WARMER TEMPS. WE
FOLLOWED THE TREND OF THE PREVIOUS FORECAST BY TRYING TO CONFINE
THE BULK OF THE THUNDERSTORM ACTIVITY TO THE AFTERNOON AND EVENING
HOURS. SOME MID-LEVEL SHOWERS SHOWERS ARE POSSIBLE EARLIER IN THE
DAY ALONG THE NORTHERN AND WESTERN FRINGES OF THE CWA. THE
FORECAST AREA WILL GET CLOSE TO THE RIGHT ENTRANCE REGION OF THE
JET...BUT NOT UNTIL LATER IN THE DAY ON SUNDAY. HIGH CLOUD COVER
MAY LIMIT THE TEMPS SOMEWHAT...BUT THE THERMAL RIDGE IS QUITE WARM
AND MORE AKIN TO JUNE/JULY. THE WIND FIELD ON SUNDAY IS NOT VERY
IMPRESSIVE FROM A DEEP LAYER SHEAR PERSPECTIVE. SO...WHILE A FEW
STRONG STORMS ARE POSSIBLE...WE DON`T THINK THIS WILL BE A BIG
SEVERE WEATHER PROBLEM. PERHAPS WITH A COUPLE MARGINALLY SEVERE
WIND/HAIL REPORTS. NONETHELESS...WE DO EXPECT REALLY GOOD
THUNDERSTORM COVERAGE ALONG THE FRONT AS IT PASSES THROUGH
/ESPECIALLY IN EASTERN MN AND WI/. HIGH PRESSURE BUILDS IN BEHIND
THE FRONT SUNDAY NIGHT AND WILL SET THE STAGE FOR A COUPLE DRY
DAYS ON MONDAY AND TUESDAY. THE FLOW IS EASTERLY DURING THIS
PERIOD...WHICH USUALLY DOES THE TRICK IN BRINGING THE FORECAST
AREA DRY WEATHER.

A LARGE TROUGH WILL TAKE ITS TIME MOVING EAST FROM THE WEST COAST
DURING THE WEDNESDAY-FRIDAY TIMEFRAME. THE FLOW WILL BE
SOUTHERLY...SO WE SHOULD HAVE A MOISTURE SOURCE AND NOW THERE IS
AT LEAST SOME VEGETATION GROWING SOUTH OF HERE...SO THE
EVAPOTRANSPIRATION TERM IS NO LONGER ZERO. OVERALL...THE
COMBINATION OF MOISTURE AND NORTHEASTWARD PROPAGATING SHORTWAVES
SHOULD BRING MN/WI AT LEAST A COUPLE ROUNDS OF THUNDER DURING THIS
TIME /WED- FRI/. WE`LL NEED TO IRON OUT THE DETAILS EARLY NEXT
WEEK AS WE GET A BETTER IDEA ON TIMING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 256 PM CDT FRI MAY 1 2015

BATCH OF RAIN OVER ERN MN INTO WRN WI AT THE START OF THE 02/18Z
TAFS WILL CONTINUE TO SHIFT OFF TO THE E THRU THE REST OF THE AFTN
HRS. SOME SHORT-TERM MODEL GUIDANCE HINTS AT SOME RE-DEVELOPMENT
OF CONVECTION OVER SRN AND ERN MN...BUT CLOUD COVER IN ADVANCE OF
THE CDFNT MAY WELL HINDER SUCH DEVELOPMENT PLUS THERE IS OVERALL
DISAGREEMENT IN A CONVECTIVE SCENARIO SO WILL OMIT ANY FURTHER
PRECIP BEYOND CURRENT ACTIVITY. CLOUDS WILL DIMINISH OVERNIGHT
THRU TMRW...RESULTING IN SKC CONDS FOR MUCH OF THE DAY TMRW. WINDS
OVER WRN MN WILL SNAP FROM NW TO S LATER THIS EVE WHILE THE REST
OF THE COVERAGE AREA REMAINS S TO SE WHILE DROPPING TO ARND 5 KT.
WINDS THEN INCRS FROM THE S TMRW...INCLUDING TO THE 15G25KT AREA
BY MIDDAY TMRW.

KMSP...PRECIP HAS SHIFTED E OF KMSP AT INITIALIZATION WITH NO
FURTHER PRECIP EXPECTED AT KMSP. CANNOT RULE IT OUT ALTOGETHER AS
ISOLD CONVECTION MAY WELL DEVELOP MID-TO-LATE AFTN...BUT CHCS ARE
TOO LOW ATTM FOR INCLUSION. CLOUDS THEN DIMINISH THIS EVE THRU
OVERNIGHT...REMAINING SKC THRU TMRW.

/OUTLOOK FOR KMSP/
SUN...VFR. -TSRA/MVFR LIKELY AFTERNOON/EVENING. WINDS SW 5-10
KTS...BECOMING NW 10-15 KT IN THE AFTERNOON.
MON...MAINLY VFR. CHANCE MVFR CIGS. WINDS N 5-10 KTS.
TUE...MAINLY VFR. CHANCE -TSRA/MVFR IN THE EVENING. WINDS SE 10-15
KTS.

&&

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

$$

SHORT TERM...JPC
LONG TERM...CLF
AVIATION...JPC



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