Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 021720
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1220 PM CDT SAT MAY 2 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 402 AM CDT SAT MAY 2 2015

THE SHORT TERM CONCERNS ARE HIGH TEMPERATURES TODAY AND TIMING OF
ANY CONVECTIVE THREAT LATER TONIGHT.

SUNSHINE EXPECTED TODAY...WITH TEMPERATURES MIXING TO AROUND
775MB...EXPECTING AFTERNOON HIGHS TO MAX OUT IN THE UPPER 70S AND
LOWER 80S MOST AREAS.  HIGHER DEWPOINT AIR OFF JUST TO THE SOUTH OF
THE AREA...MAY BE ENOUGH TO GENERATE ISOLATED TSRA INTO THE FAR
SOUTH THIS AFTERNOON AND EVENING.  MIXING SHOULD OCCUR TO THE
WEST...WITH SOUTHERLY WINDS INCREASING THIS AFTERNOON.  AT THE
MOMENT IT APPEARS THEY WILL REMAIN BELOW 20 MPH FOR THE MOST PART.
HUMIDITY VALUES WILL DROP INTO THE LOWER 20S OVER WEST CENTRAL MN
HOWEVER.  WILL CONTINUE TO MENTION THE ELEVATED FIRE DANGER WEST
CENTRAL IN THE AFTERNOON.

THE COLD FRONT OVER THE CENTRAL DAKOTAS WILL MOVE INTO NORTHWEST MN
TONIGHT WILL BE THE FOCUS OF SHOWERS AND A FEW THUNDERSTORMS OVER
THE WESTERN CWA LATER TONIGHT.  LOW LEVEL JET WILL BE ON THE
INCREASE SOMEWHAT AND WITH LOW LEVEL WAA PATTERN...MAY ALSO GENERATE
SOME ELEVATED THUNDER ALONG WITH THE DECAYING DIURNAL ACTIVITY
ASSOCIATED WITH THE COLD FRONT. STILL MAINTAINING CHANCE POPS WITH
THIS ACTIVITY.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 402 AM CDT SAT MAY 2 2015

THE COLD FRONT WILL BE SITUATED ROUGHLY FROM WEST CENTRAL TO NORTH
CENTRAL MN EARLY SUNDAY MORNING. THERE MAY BE SOME ACTIVITY
ONGOING ALONG IT...MOST OF IT CONFINED TO NORTHERN MINNESOTA. 06Z
NAM SHOWS A PRETTY ROBUST CLUSTER OF SHOWERS AND STORMS OVER WEST
CENTRAL MN ON THE NOSE OF A LLJ...WHICH COULD SPREAD CLOUDS AND
DECAYING RAINFALL EAST - KEEPING INSTABILITY FROM FULLY
MATERIALIZING FOR THE REST OF THE DAY. FOR NOW...GOING TO ASSUME
THIS IS NOT A LIKELY SCENARIO PER CAM OUTPUT AND THE REST OF THE
GLOBAL MODELS WHICH SHOW LESS DEVELOPED SHOWERS AND STORMS.

THE FRONT WILL PROPAGATE SOUTHEAST THROUGH THE DAY AND SHOULD BE
JUST ABOUT OUT OF THE CWA BY 00Z MONDAY. SHOWERS AND THUNDERSTORMS
BECOME NUMEROUS ALONG IT EARLY TO MID AFTERNOON FROM SOUTHWEST MN
TO NORTHWEST WI. DEW POINTS ARE EXPECTED TO CLIMB INTO THE
MID/UPPER 50S AS STEEP LAPSE RATES OVERSPREAD THE AREA MIDDAY.
MODERATE INSTABILITY WITH 1500-2000 J/KG CAPE IS LIKELY TO DEVELOP
BUT THERE ARE SOME QUESTIONS REMAINING WHETHER THE CAP WILL FULLY
ERODE...OR THE DIFFERENCE BETWEEN A BROKEN LINE AND A SOLID LINE.
WRFARW AND WRFNMM DO SHOW A PRETTY SOLID LINE OF STORMS DEVELOPING
BETWEEN 20-21Z...IMPLYING IT WILL FULLY ERODE ALONG THE FRONT.
INCREASED POPS INTO THE 80-95 PERCENT RANGE IN THE SOUTHEAST CWA
WHERE THE LINE WILL LIKELY BE FULLY DEVELOPED BY LATE AFTERNOON...
AND MAINTAINED LIKELIES A BIT FURTHER WEST WHERE THIS LINE SHOULD
ORIGINATE. COULD SEE A FEW REPORTS OF SEVERE WEATHER...EITHER
DAMAGING WIND FROM BOWING LINE SEGMENTS OR MARGINALLY SEVERE HAIL
FROM THE MORE INTENSE UPDRAFTS. OVERALL...THE LIMITING FACTOR FOR
A BETTER RISK IS LACK OF STRONG MID LEVEL WINDS.

HIGH PRESSURE WILL PASS ACROSS NORTHERN MINNESOTA AND WISCONSIN
MONDAY AND MONDAY NIGHT RESPECTIVELY. ANY PRECIP DURING THESE
PERIODS WILL BE OVER IOWA INTO SRN WI/NRN IL NEAR THE STALLED
BOUNDARY. TEMPS HERE WILL REMAIN SLIGHTLY ABOVE AVERAGE WITH
MOSTLY CLEAR SKIES.

MODELS DIFFER ON HOW QUICKLY THE FRONT LIFTS BACK NORTH NEXT WEEK.
NAM AND ECMWF ARE QUICKER OWING TO A LLJ THAT DOES NOT VEER EAST
LATE MONDAY NIGHT/TUESDAY LIKE THAT OF THE GFS AND CANADIAN. DID
INCREASE POPS TUESDAY...BUT KEPT THEM IN THE CHANCE CATEGORY...
HIGHEST SOUTH. THE FRONT WILL LIFT NORTH BY TUESDAY NIGHT AND
BRING THE INITIAL BAND OF SHOWERS AND THUNDERSTORMS THROUGH BY
WEDNESDAY MORNING.

MOST OF WEDNESDAY AND WEDNESDAY NIGHT COULD BE DRY...WITH THE
PARENT SYSTEM WELL TO THE WEST...FRONT TO THE NORTH...AND LITTLE
FORCING IN THE WARM SECTOR. IN FACT...IT COULD BE RATHER WARM AND
HUMID. HIGHS IN THE 80S...LOWS IN THE 60S...AND DEW POINTS IN THE
60S ARE NOT OUT OF THE QUESTION GIVEN THE DEGREE OF MOISTURE
STREAMING NORTH FROM THE GULF. AS THE SYSTEM PUSHES EAST LATE
WEEK...THURSDAY COULD BRING THE NEXT BEST CHANCE OF STORMS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1215 PM CDT SAT MAY 2 2015

A COMPLEX OF SHRA/TSRA IN SE IOWA AND ASSOCIATED SHRTWV MOVING
EASTWARD THIS AFTN...MAY ALLOW FOR AN ISOLD SHRA/TSRA IN FAR SC/SE
MN AND INTO WC WI AFT 20Z-01Z. THERE IS ENOUGH AGREEMENT IN THE
SHORT TERM MODELS TO SUPPORT VCSH FOR KEAU BETWEEN 23-01Z.
ELSEWHERE...VFR CONDS WILL REMAIN THRU THE NEXT 6-9 HRS. THINGS
GET MORE COMPLICATED AFT 6Z AS A FRONT MOVES INTO FAR NW MN ALONG
WITH -SHRA. AT THIS TIME...CONFIDENCE IS LOW ENOUGH TO ONLY
WARRANT VCSH WITH A PROB30. WE SHOULD HAVE A BETTER HANDLE ON
CONVECTION OVERNIGHT ONCE SHRA/TSRA DEVELOP IN THE DAKOTAS. WINDS
WILL BE GENERALLY FROM THE S/SW THIS AFTN/TONIGHT...THEN SHIFT TO
THE NW FROM NW TO SE DURING DAY SUNDAY.

KMSP...

CONFIDENCE REMAINS LOW ON WHERE THE INITIATION OF CONVECTION
DEVELOPS LATE TONIGHT/SUNDAY. SO WILL CONTINUE WITH ONLY VCSH AFT
18Z WHERE THE PROXIMATE OF THE FRONT WILL BE LOCATED NEAR THE
AIRPORT. TIMING AND HOW WIDESPREAD THE SHRA/TSRA BECOME REMAIN
UNCERTAIN...SO WILL HOLD OFF ON VCTS OR TSRA/SHRA. WINDS WILL
REMAIN FROM THE S/SSW THIS AFTN/TONIGHT...THEN BECOME SW-W BY
18Z...AND SHIFT TO THE NW BETWEEN 18-21Z.

/OUTLOOK FOR KMSP/

MON...MAINLY VFR. CHC OF MVFR CIGS. WINDS N-NE 5-10 KTS.
TUE...VFR EARLY. SHRA/TSRA AFTN AND EVENING WITH MVFR/IFR CIGS/VSBYS.
WINDS SE 10-20 KTS.
WED...VFR...WITH CHC OF MVFR/IFR CIGS/VSBYS IN SHRA/TSRA.
WINDS SE 10-20 KTS.

&&

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

$$

SHORT TERM...DWE
LONG TERM...BORGHOFF
AVIATION...JLT



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