Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 271753 AAB
AFDMPX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1253 PM CDT WED MAY 27 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CDT WED MAY 27 2015

TODAY AND TONIGHT...EARLY MORNING SATELLITE IMAGERY INDICATED A
COMPACT CIRCULATION ADVANCING NORTHEAST THROUGH NORTHWESTERN WI. THE
BACK EDGE OF THE CLOUD DECK ASSOCIATED WITH THIS FEATURE WAS PUSHING
INTO EXTREME WESTERN MN...A TREND OF CLEARING SKIES EXPECTED TO
PROGRESS EASTWARD THROUGH THE DAY.  THE CONCERN THEN BECOMES IF ANY
CU AND POSSIBLY ELEVATED POPCORN SHOWERS/THUNDERSTORMS DEVELOP THIS
AFTERNOON.  MODEL SOUNDINGS INDICATE DEEP MIXING TO NEAR 750MB AND
THE MAX T FORECAST WAS BASED OFF A MIX DOWN FROM THIS LEVEL...AND IS
SLIGHTLY COOLER THAN THE PREVIOUS FORECAST...IN PART DUE TO THE
WIDESPREAD RAIN YESTERDAY MOISTENING THE SURFACE.

NORTHWESTERN WI STILL LOOKS TO HAVE THE BEST SHOT AT THUNDER
TODAY...STILL IN THE CYCLONIC CIRCULATION DEPARTING OVER THE
NORTHERN GREAT LAKES. HOWEVER...EVALUATION OF SEVERAL HI-RES
CONVECTIVE ALLOWING MODELS INDICATE DECENT AGREEMENT IN BRINGING
ISOLATED THUNDER THROUGH THE ENTIRE FA TODAY.  THE HRRR IS THE MOST
CONCERNING AS EVERY NEW HOURLY RUN THAT HAS COME IN OVERNIGHT
CONTINUES TO CONSISTENTLY SHOW SCATTERED SHOWERS AND THUNDER
DEVELOPING DURING THE AFTERNOON.  THIS MAKES SENSE GIVEN MODEL
SOUNDINGS INDICATE THAT THE CONVECTIVE TEMPERATURE IN THE LOW 80S
WILL BE REACHED AND SHOW INSTABILITY IN THE 700-300MB LAYER. I
DON/T FEEL CONFIDENT IN THUNDER ACTUALLY DEVELOPING GIVEN THE
RIDGE PUSHING IN...BUT GIVEN THAT THE
HRRR/ARW/NMM/MPXWRF/HOPWRF/NSSL WRF ALL ARE TRYING TO GENERATE
POPCORN SHOWERS AND THUNDERSTORMS...DECIDED IT WAS BEST TO INCLUDE
ISOLATED THUNDER ACROSS THE REMAINDER OF THE AREA FOR JUST A FEW
HOURS DURING THE AFTERNOON FOR DIURNALLY DRIVEN CONVECTION.

WE`LL QUICKLY GET BACK IN SOUTHWESTERLY FLOW ALOFT TONIGHT ON THE
BACK SIDE OF THE UPPER LEVEL RIDGE...WHICH IS A PRECURSOR OF THINGS
TO COME ON THURSDAY AND FRIDAY. A SHORTWAVE WILL ADVANCE INTO THE
DAKOTAS TOMORROW NIGHT AND WILL SPREAD CLOUD COVER INTO THE WESTERN
HALF OF THE FA BY THURSDAY MORNING. GUIDANCE GENERALLY AGREES THE
PRECIP WILL BE JUST ABOUT TO ARRIVE EARLY THURSDAY MORNING...SO KEPT
SLIGHT CHANCE POPS IN FOR FAR WESTERN MN EARLY THURSDAY MORNING
AHEAD OF THIS NEXT SYSTEM...WHICH WILL BE DISCUSSED IN MORE DETAIL
IN THE LONG TERM PORTION OF THIS DISCUSSION.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 400 AM CDT WED MAY 27 2015

MORE SHOWERS AND THUNDERSTORMS ARE IN STORE FOR THE REGION DURING
THE EARLY PORTIONS OF THE LONG TERM. DETERMINISTIC SOLUTIONS ARE
IN GOOD AGREEMENT ON DEEPENING A NORTHERN STREAM SHORT WAVE AS IT
HEADS FROM THE NORTHERN PLAINS THROUGH THE UPPER MISSISSIPPI
VALLEY FROM THURSDAY THROUGH FRIDAY. THE NAM IS THE MOST
AGGRESSIVE WITH A CLOSED H7 LOW FORMING OVER EASTERN NE AND IA ON
FRIDAY. ALL OF THE SOLUTIONS POINT TO A STRENGTHENING UPPER JET
OVER SOUTHERN ONTARIO WITH THE RIGHT ENTRANCE REGION LYING ACROSS
NORTHERN MN. IN ADDITION...RATHER STRONG MID LEVEL FRONTOGENESIS
WILL PASS ACROSS THE FA ON FRIDAY. THE MAIN CONCERN DURING THIS
PERIOD IS THE POTENTIAL FOR HEAVY RAIN WITH PRECIPITABLE WATER
VALUES PROGGED TO REACH AROUND 1.6 INCHES ON BOTH THE NAM AND
GFS. THIS IS IN RECORD TERRITORY FOR MPX SOUNDING CLIMATOLOGY FOR
THE END OF MAY. IN FACT...THE MAX MOVING AVERAGE IS 1.54 INCHES.
HENCE...LIKELY POPS BEGIN ACROSS WESTERN MN THURSDAY AFTERNOON AND
TRANSITION EAST DURING THE NIGHT. LIKELY TO CATEGORICAL POPS ARE
IN PLACE FOR FRIDAY...ESPECIALLY FROM THE TWIN CITIES ON EAST AND
SOUTH...WHEN THE BEST FORCING MOVES THROUGH. WIDESPREAD RAIN
AMOUNTS OF 1.25 TO 1.5 INCHES ARE EXPECTED FROM THE TWIN CITIES ON
EAST AND SOUTH WITH AMOUNTS FROM 0.75 TO 1.25 INCHES TO THE WEST
AND NORTH. A FEW STRONG TO SEVERE STORMS ARE POSSIBLE LATE
THURSDAY FROM WEST CENTRAL INTO CENTRAL MN AHEAD OF THE
APPROACHING COLD FRONT. THE SEVERE THREAT ON FRIDAY LOOKS TO BE
SOUTH OF HERE DUE TO THE EXTENSIVE CLOUDS/RAIN ACROSS THE FA.

SATURDAY WILL BE A SUNNY BUT COOL DAY AS HIGH PRESSURE DIPS DOWN
ACROSS THE AREA FROM THE NORTH. THE HIGH WILL MOVE OFF TO THE EAST
RATHER QUICKLY ON SUNDAY WITH SOUTHERLY FLOW INCREASING AHEAD OF
THE NEXT LOW PRESSURE SYSTEM MOVING INTO THE NORTHERN PLAINS. THIS
FEATURE MAY BRING SOME SHOWERS AND THUNDERSTORMS TO THE FA FOR
MONDAY AND TUESDAY. THIS WOULD BE THE IDEA FROM THE GFS WHILE THE
ECMWF WOULD SPREAD THE ACTIVITY NORTHEASTWARD FROM THE DAKOTAS
INTO NORTHERN MN...KEEPING THE FA DRY. AT THIS POINT...ONLY LOW
CHANCE POPS ARE IN PLACE.

THE WARMEST DAY IN THE LONG TERM IS THURSDAY WITH HIGHS AROUND 80.
HIGH TEMPERATURES DROP ABOUT 10 DEGREES FOR FRIDAY (70) AND
ANOTHER 10 DEGREES FOR SATURDAY (60). TEMPERATURES BEGIN A SLOW
CLIMB WITH MIDDLE TO UPPER 60S ON SUNDAY...UPPER 60S TO LOWER 70S
FOR MONDAY...WITH MIDDLE TO UPPER 70S FOR TUESDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1253 PM CDT WED MAY 27 2015

STILL SKC AROSS MOST OF MN AND WESTERN WI...BUT SHOULD BEGIN TO
SEE HIGH BASED CU DEVELOP WITHIN THE NEXT COUPLE HOURS. THERE ARE
CONFLICTING SIGNALS FOR THE DEVELOPMENT OF ISOLATED SHOWERS AND
THUNDERSTORMS THIS AFTERNOON. SATELITE TRENDS AND THE TOTAL LACK
OF CU DEVELOPMENT TO THIS POINT WOULD ARGUE AGAINST CONVECTIVE
DEVELOPMENT...BUT THERE ARE SEVERAL HOURS OF HEATING LEFT. GIVEN
THE UNCERTAINTY IN DEVELOPMENT...AND IF ANY WERE TO OCCUR THEY WOULD
BE ISOLATED...LEFT SHRA OR TSRA OUT OF ALL THE TAFS FOR NOW.

KMSP...VFR CONDITIONS FOR THE NEXT 30 HOURS. SHOULD BEGIN TO SEE
SOME CU DEVELOP AROUND 8KFT BY 20-21Z. INCREASING MID/HIGH CLOUDS
TONIGHT...BUT THE NEXT CHANCE OF RAIN WILL HOLD OFF UNTIL CLOSER
TO THURSDAY NIGHT.

/OUTLOOK FOR KMSP/
FRI...MVFR/IFR CIGS/VSBYS IN SHRA/TSRA. WINDS SW 5-10 KTS BCMG
NNW AT 10-20 KTS.
SAT...VFR. WINDS NE 10 KTS.
SUN...VFR. WINDS SE 10 KT.

&&

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

$$

SHORT TERM...SPD
LONG TERM...RAH
AVIATION...BORGHOFF


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