Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 011821
AFDMPX

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

.UPDATE...
ISSUED AT 100 PM CDT FRI MAY 1 2015

UPDATED TO INCLUDE 18Z AVIATION DISCUSSION BELOW.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 408 AM CDT FRI MAY 1 2015

THE SHORT TERM CONCERNS ARE THE EXTENT OF SHOWERS DURING THE DAY
AND CLOUD COVER AFFECTING HIGH TEMPERATURES.

RADAR IS CURRENTLY SHOWING ABOUT A 40 MILE WIDE BAND OF SHOWERS
MOVING ACROSS WESTERN MINNESOTA.  THIS BAND IS FORECAST TO MOVE EAST
INTO CENTRAL MN THROUGH 12Z AND GRADUALLY WEAKEN AS IT MOVES TOWARD
WEST CENTRAL WISCONSIN.  RATHER DRY AIRMASS REMAINS TO THE EAST...SO
A WEAKENING TREND IS STILL EXPECTED.  TRIED TO TRAIL OFF POPS AS IT
MOVES EAST DURING THE MORNING.  HIRES MODELS CONTINUE TO SHOW THE
FRONT STALLING INTO CENTRAL MN WITH THE POSSIBILITY OF REDEVELOPMENT
LONG THE BOUNDARY LATE AFTERNOON WITH WEAK CAPE AND CONVERGENCE
ALONG THE FRONT.  HELD ONTO A SMALL POP FOR THIS POSSIBILITY. CLOUDS
ARE EXPECTED TO REMAIN INTO THE EASTERN PORTION OF THE CWA THROUGH
MUCH OF THE AFTERNOON.  THIS SHOULD HOLD DOWN TEMPERATURES INTO THE
60S OVER THIS REGION. LOWER/MID 70S ARE EXPECTED TO THE WEST...WITH
MORE SUNSHINE DEVELOPING INTO THE AFTERNOON.

CLEARING CONDITIONS INTO THE NIGHT.  LOW TEMPERATURES SHOULD BOTTOM
OUT IN THE 40S TO AROUND 50.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 408 AM CDT FRI MAY 1 2015

THICKNESSES AND MID LEVEL TEMPERATURES WILL BE INCREASING BY
SATURDAY AS A TROUGH BEGINS TO SINK INTO THE PACIFIC NORTHWEST.
GUIDANCE STILL APPEARS SEVERAL DEGREES TOO COOL WITH HIGHS
SATURDAY BUT BIAS CORRECTED VERSIONS OFFER A MUCH MORE REALISTIC
SOLUTION. TEMPS WILL TOUCH 80 JUST ABOUT EVERYWHERE WITH LOCATIONS
IN THE MINNESOTA VALLEY OUT WEST REACHING THE MID TO POSSIBLY
UPPER 80S. AS IS OFTEN THE CASE THIS TIME OF YEAR...MOISTURE
RETURN WILL LAG THE ARRIVAL OF WARMER TEMPS SO ANOTHER DAY WITH
HUMIDITIES DROPPING INTO THE TEENS TO 20S APPEARS LIKELY.

MOISTURE WILL BEGIN TO ARRIVE LATE SATURDAY NIGHT AND ESPECIALLY
SUNDAY AS A FRONT SINKS SOUTHEAST INTO THE NORTHERN PLAINS AND
UPPER MISSISSIPPI VALLEY. A FEW SHOWERS OR STORMS MAY DEVELOP
ALONG THE FRONT LATE SATURDAY NIGHT ACROSS THE DAKOTAS AND
NORTHERN MINNESOTA...WHICH COULD PUSH INTO CENTRAL MINNESOTA
SUNDAY MORNING. THERMAL RIDGING IN PLACE ACROSS SRN MN AND WRN WI
SHOULD ALLOW TEMPS TO JUMP RATHER QUICKLY THROUGH EARLY AFTERNOON
PROVIDED THERE IS A PERIOD OF SOME SUN IN THE MORNING. THIS
THERMAL RIDGE WILL ALSO BRING A BETTER POTENTIAL FOR CAPPING
THROUGH MIDDAY IN THESE AREAS SO MAINTAINED A DRIER FORECAST
SIMILAR TO THE NAM. OVERALL...MODELS SEEM TO HAVE THE TEMPORAL
SIDE OF THINGS WELL HANDLED WITH THE ECMWF BEING A QUICK OUTLIER.

AS SUNDAY AFTERNOON PROGRESSES...AN ELEVATED MIXED LAYER WILL
ARRIVE FROM THE WEST WITH LAPSE RATES EXCEEDING 7.5 TO 8 C/KM. IF
DEW POINTS DO CLIMB INTO THE UPPER 50S AS FORECASTED...MUCAPE OF
1500 TO 2000 J/KG SHOULD BE REALIZED AS CAPPING ERODES. THIS
WILL ALLOW THUNDERSTORMS TO GROW MORE NUMEROUS ALONG THE FRONT AS
IT REACHES SRN MN AND WRN WI. RAISED POPS INTO THE HIGH LIKELY
CATEGORY WITH EVEN SOME CATEGORICALS IN WISCONSIN. MID/UPPER LEVEL
WINDS ARE PRETTY WEAK BUT ARE A BIT STRONGER FROM PREVIOUS
FORECASTS SO CANNOT RULE OUT SOME HAIL OR STRONG WINDS WITH THESE
STORMS PARTICULARLY GIVEN THE GOOD LAPSE RATES. WINDS LESS THAN
40 KT THROUGH THE COLUMN WILL LIMIT THE OVERALL SEVERE POTENTIAL.

THE FRONT WILL SAG SOUTH QUICKLY SUNDAY EVENING WITH ALL OF THE
ACTIVITY TO THE SOUTH BY MIDNIGHT. HIGH PRESSURE WILL BUILD OVER
MINNESOTA MONDAY AND PUSH INTO THE GREAT LAKES TUESDAY. DRY
EAST/NORTHEAST FLOW WILL KEEP ANY POTENTIAL FOR PRECIP WELL TO THE
SOUTH SO REMOVED ANY MENTION DURING THESE PERIODS.

A LARGE SLOW MOVING SYSTEM WILL TAKE SHAPE MID TO LATE WEEK OVER
THE PLAINS. THE GULF WILL BE OPEN AND MOISTURE SHOULD FLOW NORTH
UNRESTRICTED INTO THE NORTHERN PLAINS AND UPPER MIDWEST. PIECES OF
ENERGY ROTATING AROUND THE SYSTEM WILL GENERATE CLUSTERS OF
SHOWERS AND THUNDERSTORMS. CONFIDENCE IS QUITE LOW ON WHICH
PERIODS WILL HAVE THE BEST POTENTIAL FOR RAIN AS THERE COULD BE
MANY DRY HOURS FOLLOWING THESE BANDS/CLUSTERS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 100 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.
&&

$$

UPDATE...JPC
SHORT TERM...DWE
LONG TERM...BORGHOFF
AVIATION...JPC



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