Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 201815
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
115 PM CDT WED MAY 20 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM CDT WED MAY 20 2015

SOUTHERN MN/WESTERN WI IS CAUGHT BETWEEN AN ADVANCING UPPER LOW
ACROSS NORTH CENTRAL NEBRASKA AND ANOTHER SHRTWV RIDING SE
ACROSS NORTH DAKOTA. MOISTURE IS LIMITED BLW 10K ACROSS SOUTHERN
MN WHERE THIS UPPER LOW WILL MOVE ACROSS THE AREA LATER THIS
MORNING. -SHRA AND ASSOCIATED MOISTURE FIELD MAY BE ENOUGH TO
FORCE SOME SPRINKLES OR -SHRA AS FAR NORTH AS THE I-90 CORRIDOR.
HOWEVER...EVEN OBS ACROSS NW IOWA ARE NOT REPORTING ANY MEASURABLE
PRECIPITATION WITH THE RADAR RETURNS IN THE AREA THIS MORNING.
THEREFORE...WILL CONTINUE SLIGHT CHC NEAR THE IA BORDER THRU 18Z.
OTHERWISE...SKIES WILL BE CLOUDY IN THE FAR SOUTH...WITH PARTLY TO
MOSTLY SUNNY IN THE NORTHERN CWA. AFTN TEMPS REFLECT THIS WITH
HIGHER TEMPS IN CENTRAL MN WHERE SUNSHINE WILL BE MORE COMMON...TO
THE 50S ALONG THE IOWA BORDER. NO CHANGES TONIGHT AS TEMPS WILL
ONCE AGAIN FALL INTO THE 40S...WITH A FEW 30S IN WESTERN WI.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 340 AM CDT WED MAY 20 2015

THU-FRI...THE FIRST COUPLE DAYS OF THE EXTENDED FORECAST WILL BE
DOMINATED BY SFC HIGH PRES AND NW FLOW ALOFT DUE TO A PERSISTENT
SERN CANADA UPR LVL LOW. HOWEVER...DESPITE THE NW FLOW ALOFT...THE
UPR LOW WILL BE SHIFTING OFF TO THE E WHICH WILL ACTUALLY ALLOW H5
HEIGHTS TO RISE SLIGHTLY. WITH SFC HIGH PRES ALLOWING PLENTY OF
SUNSHINE DURG THIS TIME...THIS COMBINATION WILL ALLOW TEMPS TO
RISE SLIGHTLY DURG THE PERIOD...KEEPING THE WARMING TREND GOING
FOR THE LATTER PORTION OF THE WORKWEEK. HIGHS ON THU WILL RANGE
FROM THE UPR 60S TO THE LWR 70S...THEN INCRS FURTHER ON FRI TO THE
LOW-MID 70S.

SAT-TUE...A PATTERN CHANGE IS IN STORE FOR THE HOLIDAY WEEKEND
INTO EARLY NEXT WEEK AS THE SFC HIGH PRES CENTER SHIFTS TO THE MID
ATLC COAST AND THE UPR LVL LOW OVER ERN CANADA MOVES INTO THE
ATLC. IN THE MEANTIME...A LARGE DOME OF UPR LVL HIGH PRES WILL
DEVELOP OVER THE SERN CONUS WHILE A DEEP UPR LVL LOW PRES CENTER
DEVELOPS OVER THE 4-CORNERS REGION. THIS WILL ALLOW A LARGE SURGE
OF MODIFIED TROPICAL AIR FROM THE GOMEX TO SLIDE NWD INTO THE
N-CENTRAL CONUS OVER THE WEEKEND. IN ADDITION...AS UPR LVL FLOW
BECOMES MORE MERIDIONAL THAN ZONAL...SEVERAL SHORTWAVES WILL RIDE
NNE WITHIN THE MEAN UPR LVL FLOW WITHIN A VERY DEEPLY MOIST
ENVIRONMENT. WEAK CAPPING PLUS THE DEVELOPMENT OF A SFC LOW PRES
CENTER OVER THE PLAINS SHIFTING NE OVER THE WEEKEND WILL ALLOW FOR
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS FOR MAINLY THE
SATURDAY NIGHT THROUGH MONDAY TIMEFRAMES. DIFFICULT TO PIN DOWN
BETTER TIMING THAN THE 12-HOURLY BLOCKS AT THIS POINT BUT
CONFIDENCE IS HIGH ENOUGH TO RUN WITH LIKELY POPS SAT NIGHT INTO
SUN NIGHT. THE PROLONGED PERIOD OF RAIN DOES LOOK TO BRING DECENT
QPF TO THE REGION...WITH AROUND A HALF INCH FOR MUCH OF THE WFO
MPX CWFA...AND POSSIBLY ISOLD HIGHER AMOUNTS UNDER STRONGER
STORMS. SEVERE POTENTIAL LOOKS LOW AT THIS POINT DUE TO WEAK LAPSE
RATES AND FAIRLY MEAGER INSTABILITY WITH LACK OF SUNSHINE FOR MUCH
OF THE PERIOD. PRECIP CHANCES WANE MON INTO TUE AS THE UPR LVL
TROF OVER THE ROCKIES LIFTS OFF TO THE NE...LEAVING LITTLE SFC
FORCING IN PLACE AND A MUCH MORE ZONAL FLOW ALOFT. AS FOR
TEMPERATURES...LITTLE DAY-TO-DAY CHANGE IS EXPECTED WITH THE MOIST
AIRMASS IN PLACE AND NO EVIDENT SIGNIFICANT TEMP ADVECTION PROGGED
IN ANY OF THE LONG-TERM MODELS. HIGHS WILL CONTINUE TO RUN
GENERALLY IN THE UPR 60S TO MID 70S THROUGH THE PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1249 PM CDT WED MAY 20 2015

PLENTY OF HIGH CLOUDS TODAY WITH A GRADUAL CLEARING TREND THIS
EVENING...BUT THERE IS HIGH CONFIDENCE IN VFR AND MINIMAL AVIATION
WEATHER CONCERNS. THE TOUGH PART OF THE FORECAST WILL BE PINNING
DOWN A WIND DIRECTION...WHICH IN GENERAL WILL BE LIGHT W-NW
THROUGH THE TAF PERIOD.

KMSP...
NOT MUCH TO ADD TO THE DISCUSSION ABOVE. HIGH CONFIDENCE IN VFR
WITH LIGHT W-NW WINDS THROUGH THE EVENING RUSH.

/OUTLOOK FOR KMSP/
FRI...VFR. WINDS LGT AND VARIABLE BECOMING S/SE AT 5 KTS.
SAT...VFR. CHC -SHRA. WINDS S/SE 5 TO 10 KTS.
SUN...VFR. CHC -SHRA. WINDS S/SE 10 TO 15 KTS.

&&

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

$$

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


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