Area Forecast Discussion
Issued by NWS Twin Cities, MN

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119
FXUS63 KMPX 170905
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
405 AM CDT SUN MAY 17 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 AM CDT SUN MAY 17 2015

AN ACTIVE WEATHER DAY IS AHEAD...AS A NEARLY STACKED LOW PRESSURE
SYSTEM PIVOTS ACROSS WESTERN/NORTHERN MINNES0TA.

THE COMPLEX OF SHOWERS AND THUNDERSTORMS THAT BLOSSOMED OVER MO/IA
WILL LIFT NORTH ACROSS SOUTHERN/CENTRAL MN THIS MORNING. BY
18Z...THE BULK OF THE FORECAST AREA SHOULD BE EXPERIENCING A LULL
IN THE ACTIVITY AS SAID CONVECTION LIFTS INTO NORTHERN MN. THE
ASSOCIATED CONVECTIVE DEBRIS /CLOUD COVER/ MAY INITIALLY HINDER
THUNDERSTORM REDEVELOPMENT...BUT AN IMPRESSIVE PUNCH OF PV
ADVECTION WILL LIFT INTO CENTRAL/EASTERN MN BY MID AFTERNOON. MID
LEVEL DRYING IS FORECAST TO WORK INTO SOUTHEAST/EAST CENTRAL MN
THIS AFTERNOON AS WELL...WHICH SHOULD YIELD ADEQUATE SCATTERING
OF THE LOW CLOUDS TO TRIGGER SUFFICIENT ATMOSPHERIC
DESTABILIZATION IN THE WARM SECTOR OVER OUR AREA. SUPERCELL
THUNDERSTORM MODE LOOKS LIKELY...GIVEN THE EXTENT OF DEEP LAYER
SHEAR...AND SFC-3KM PARAMETER VALUES ILLUSTRATE A THREAT FOR
TORNADOES...EVEN THOUGH THE WARM FRONT IS NORTH OF THE AREA. THE
PRIMARY WINDOW FOR SEVERE STORMS LOOKS TO OCCUR BETWEEN 18Z AND
23Z...WITH THE HIGHEST THREAT AREA BEING LOCATIONS ALONG/EAST OF
THE INTERSTATE 35 CORRIDOR. HEAVY RAINFALL WILL BE POSSIBLE AGAIN
TODAY IN THE STRONGER STORMS...ALTHOUGH IT WILL OCCUR PRIMARILY
EAST OF WHERE THE HIGHER TOTALS OCCURRED ON SATURDAY...SO DO NOT
HAVE STRONG FLOODING CONCERNS ABOVE AND BEYOND GENERAL PONDING
ISSUES.

HIGH TEMPS TODAY WILL LIKELY BE THE HIGHEST WE WILL SEE THROUGH
THE NEXT WEEK...WITH HIGHS TOPPING OUT IN THE 70S. LOWS TONIGHT
WILL SNEAK INTO THE UPPER 30S ACROSS WEST CENTRAL MN....WITH 40S
ELSEWHERE.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 405 AM CDT SUN MAY 17 2015

THE EXTENDED PERIOD CAN BE CHARACTERIZED AS MAINLY DRY AND
UNSEASONABLY COOL FOR AT LEAST THE FIRST TWO DAYS /MONDAY AND
TUESDAY/...WITH POSSIBLY MORE PRECIPITATION BY NEXT WEEKEND.

MONDAY MORNING THE INTENSE SFC LOW WILL BEGIN TO FILL AND MOVE OFF
TO THE NORTHEAST ACROSS THE NORTHERN GREAT LAKES. WRAP AROUND
MOISTURE WILL BE CONFINED TO CENTRAL/NORTHERN MN WHERE THE HIGHEST
POPS WILL BE LOCATED. HOWEVER...SOME SPRINKLES COULD MOVE INTO
SOUTHERN MN/WC WI DUE TO COLD AIR ALOFT AND RESIDUAL MOISTURE NEAR
THE AREA.

STANDARD 85H/92H TEMPERATURE ANOMALIES ARE 2-4 BLW NORMAL BY
MONDAY/MONDAY NIGHT WHICH TRANSLATES TO SFC TEMPS NEARLY 20-30
DEGREES BELOW NORMAL. EVEN THE GEFS/NAEFS MEAN 85H TEMPS RETURN
INTERVAL BASED ON CLIMATOLOGY /1985 - 2012/ ARE ONCE EVERY 10 YEARS
FOR THESE TYPE OF TEMPS FOR MID MAY. EVEN SOME AREAS IN THE
NORTHERN PLAINS ARE OUTSIDE CLIMATOLOGY NORMS WHICH MEANS SOME
RECORD LOWS ARE POSSIBLE EARLY NEXT WEEK BASED ON THE AMOUNT OF
CLOUD COVER AND SFC WINDS.

THE MEAN UPPER FLOW WILL BE WEST/NW ACROSS THE UPPER MIDWEST
AS AN UPPER RIDGE HOLDS ACROSS WESTERN CANADA...AND AN UPPER LOW
BUILDS SOUTHWARD ACROSS HUDSON BAY BY MIDWEEK. THE MEAN UPPER FLOW
ACROSS THE WESTERN AND SOUTHERN PART OF THE CONUS WILL BE MORE
PROGRESSIVE WITH SEVERAL STORM SYSTEMS AFFECTING THAT REGION. NOT
UNTIL LATE IN THE EXTENDED PERIOD...POSSIBLY AS LATE AS
SATURDAY/SUNDAY WILL WE GET INTO A MORE PROGRESSIVE FLOW FROM
THE SW AS THE UPPER RIDGE BREAKS DOWN IN WESTERN CANADA AND AN UPPER
LOW MOVES INLAND INTO THE SW CONUS. TEMPS WILL SLOWLY MODERATE BY
THE END OF THE WEEK WITH 60S/70S MOVING BACK INTO THE REGION.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1126 PM CDT SAT MAY 16 2015

VERY TRICKY CONVECTIVE FORECAST OVER THE NEXT 24 HOURS SO THERE IS
POTENTIAL FOR FREQUENT UPDATES TO ROUTINE TAFS ALONG WITH
AMENDMENTS. A SFC LOW MOVG FROM SD IN WRN MN OVERNIGHT INTO TMRW
MRNG WILL SHOVE A WMFNT NWD FROM SWRN MN INTO N-CENTRAL MN.
CURRENT CONVECTION CONTINUES TO SHOW SIGNS OF WANING BUT STILL MAY
IMPACT MAINLY ERN MN INTO WRN WI...PARTICULARLY DEVELOPMENT FROM
THE S RATHER THAN FROM THE W OVERNIGHT. SHORT-TERM MODELS
INDICATE CONVECTION WILL SPREAD OVER MUCH OF THE AREA OVERNIGHT.
WITH ADDITIONAL HEATING AND INSTABILITY TMRW ALONG WITH AN APCHG
UPPER LEVEL LOW...THE TABLE IS BEING SET FOR A MORE ORGANIZED
STRONG/SEVERE TSTM THREAT MID- TO-LATE AFTN...ALTHOUGH A NARROW
BAND OF CONVECTION IS POSSIBLE MID-TO-LATE MRNG. SO OVERALL...
QUITE THE COMPLICATED PICTURE. CEILINGS ARE EXPECTED TO DROP TO NO
LOWER THAN MID-MVFR RANGE WHILE VSBY MAY HAVE A WIDE VARIANCE
DEPENDING ON POCKETS OF HVY RAIN.

KMSP...ONGOING SHWRS/TSTMS W OF MSP AIRPORT LOOKS TO STAY
IMMEDIATELY W OF THE 5SM RADIUS SO AM THINKING THERE WILL BE
MINIMAL IMPACTS TO THE TERMINAL FROM THIS ACTIVITY. LITTLE TO NO
PRECIP IS THEN EXPECTED THRU THE OVERNIGHT HRS...THEN
STRONG/SEVERE ACTIVITY LOOKS TO DEVELOP MAINLY MID-TO-LATE AFTN.
WILL CONTINUE TO KEEP CEILINGS ABV 2500FT BUT VSBY MAY TAKE
SIGNIFICANT HITS SHOULD HVY RAIN MOVE ACRS THE TERMINAL. WILL
MONITOR AND AMEND AS NEEDED ALONG WITH KEEP IN TOUCH WITH MSP OPS.

/OUTLOOK FOR KMSP/
MON...MVFR CIGS. SCT -SHRA. WINDS NW AT 15-25 KTS.
TUE...MVFR CIGS EARLY. WINDS N AT 10 KTS.
WED...VFR. WINDS NNE 5 KTS.


&&

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

$$

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



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