Area Forecast Discussion
Issued by NWS Twin Cities, MN

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
339
FXUS63 KMPX 171825
AFDMPX

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

.UPDATE...

SKIES ARE CLEARING OUT ACROSS THE AREA LATE THIS MORNING AS A
PRONOUNCED MID-LEVEL DRY SLOT TODAY. BIGGEST CHANGE SEEN WITH THE
SEVERE THREAT TODAY IS IT IS NOT LOOKING AS GREAT. THE BIGGEST
REASON IS INSTABILITY LOOKS MARGINAL TODAY...WITH MLCAPES
LARGELY STAYING UNDER 1000 J/KG. THE BIGGEST ISSUE IS WE HAVE
BROAD FORCING WITH THE UPPER WAVE MOVING ACROSS THE REGION WITH AN
UNCAPPED ENVIRONMENT. THE LIMITED CAPPING MEANS AS SOON AS A
LITTLE BIT OF INSTABILITY IS ACHIEVED...CONVECTION WILL BE
INITIATED...WHICH WILL QUICKLY START TO CONSUME ANY CAPE PRESENT.
GIVEN THE LOW LEVEL WIND FIELDS...STRONG WINDS WILL LIKELY BE THE
MAIN THREAT...WITH THE TORNADO THREAT INCREASING SOME THIS
AFTERNOON AS O-1KM INCREASES AHEAD OF THE EWRD ADVANCING COLD
FRONT.

.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 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 125 PM CDT SUN MAY 17 2015

LIKE THE IDEA OF THE HRRR...WITH WIDESPREAD SHOWERS AND
THUNDERSTORMS DEVELOPING THIS AFTERNOON AS THE STACKED LOW MOVES
THROUGH MN WITH MARGINAL INSTABILITY BUT VIRTUALLY NO CIN. DECIDED
TO CONTINUE TREND OF HANDLING THIS SCENARIO WITH VC GROUPS AND
EXTENDED TEMPO GROUPS FOR THUNDER. HAVE HIGH CONFIDENCE IN STORMS
OCCURRING...JUST LOW CONFIDENCE ON TIMING/TRACKS OF THE NUMEROUS
STORMS THAT ARE EXPECTED. AS WE GET BEHIND THE COLD FRONT...LOW
STRATUS BACK OVER THE DAKOTAS WILL SWING THROUGH...WITH TIMING ON
ITS ARRIVAL NOT TOO DIFFERENT BETWEEN THE HRRR/SREF/NAM/LAMP...SO
MAIN ISSUE WITH THAT IS MORE HOW LOW WILL IT BE AS OPPOSED TO WHEN
WILL THOSE CLOUDS GET TO EACH AIRPORT. MAIN CHANGE MADE TO THE
PREVIOUS TAF WAS TO GO WITH MORE WINDS GIVEN STRENGTH OF MIXED
LAYER WINDS ON NAM SOUNDINGS...WOULD NOT BE SURPRISED TO SEE SOME
WIND GUSTS IN WRN MN TONIGHT THROUGH MON MORNING GET INTO THE 40S
KTS.

KMSP...ALREADY SEEING SHOWERS BUBBLE UP AT 18Z...AND THINKING
THIS THEME OF SCT SHOWERS/STORMS WILL BE WITH US THROUGH ABOUT 1Z.
TEMPO GROUP FOR THUNDER IS BASED ON WHEN THE HRRR BRINGS THE
GREATEST COVERAGE OF STORMS THROUGH. ALSO HAVE HIGH CONFIDENCE IN
MVFR CIGS RETURNING TONIGHT. THOUGH HAVE KEPT CIGS ABOVE 017...MAY
CIGS GET DOWN BETWEEN 010-015 DURING THE MORNING ON MONDAY. WINDS
COULD ALSO BE PROBLEMATIC MONDAY MORNING...WITH STRONG CROSS
WINDS EXPECTED IN THE EARLY MORNING BEFORE WINDS CONTINUE TO VEER
MORE TOWARD A 300 DIRECTION IN THE AFTERNOON.

/OUTLOOK FOR KMSP/
TUE...MVFR CIGS EARLY. WINDS N AT 10 KTS.
WED...VFR. WINDS NNE 5 KTS.
THU...VFR. WINDS NNW 5 KTS.

&&

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

$$

SHORT TERM...LS
LONG TERM...JLT
AVIATION...MPG



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.