Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 030018
AFDMPX

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

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 321 PM CDT SAT MAY 2 2015

THROUGH MIDNIGHT...INCREASING THETA-E ADVECTION ASSOCIATED WITH A
DECAYING SHRA/TSRA COMPLEX ACROSS IOWA...WILL LIKELY PRODUCE A FEW
SHRA/ISOLD TSRA ALONG THE MN/IA BORDER THRU SUNSET...WITH SOME
ACTIVITY MOVING AS FAR NE INTO WC WI BEFORE DISSIPATING. WILL
MONITOR RADAR TRENDS IF ACTIVITY BECOMES MORE WIDESPREAD THAN
PREVIOUSLY INDICATED AND RAISE POPS. OTHERWISE...THERE REMAINS NO
FOCUS FOR SHRA/TSRA ACTIVITY OVERNIGHT AS THE LLJ WILL DEVELOP
ACROSS SD/ND...AND JUST BRUSH WC MN AFTN MIDNIGHT. UPPER JET
SUPPORT IS ALSO LACKING...WITH THE ORIENTATION OF THE UPPER JET
NOT CONDUCIVE FOR LARGE SCALE ASCENT UNTIL LATER SUNDAY. IN
ADDITION...ANY SHRA/TSRA THAT DEVELOP IN WC MN/CENTRAL MN WILL BE
ISOLD/SCT BASED ON THE LACK OF DEEP MOISTURE. SOME OF THE MODELS
HAVE THIS AREA OF SHRA/TSRA SPREADING EASTWARD INTO CENTRAL/EC MN
BY SUNRISE...BUT AGAIN...THE FOCUS WILL LIKELY BE NORTH OF OUR CWA
AS THE NOSE OF THE LLJ REMAINS IN NORTHERN MN AND LIMITED UPPER
LEVEL SUPPORT. THE BEST SCENARIO IS CONTINUE WITH ISOLD/SCT
SHRA/TSRA THRU THE MORNING BEFORE THE FRONT MOVES INTO
EASTERN/SOUTHERN MN AND BECOMES THE MAIN FOCUS OF SHRA/TSRA DURING
THE AFTN.

ALTHOUGH STRONG MOISTURE ADVECTION IS EVIDENT DURING THE LATE
MORNING/AFTN OF SUNDAY ACROSS SC/SE MN AND INTO WC WI...ELEVATED
CAP WILL LIKELY HOLD ANY INITIATION OF CONVECTION UNTIL 19-21Z
WHERE SOME OF THE SHORT TERM WRF MODELS INDICATED TSRA DEVELOPING
ALONG THE FRONT.

BASED ON THE LACK OF DEEP MOISTURE INITIALLY...PRECIPITATION AMTS
WILL BE LOW /GENERALLY ONE TENTH OF AN INCH OR LESS/ IN WC/CENTRAL
MN. A BETTER CONCENTRATION OF TSRA WILL OCCUR IN SC/SE MN AND INTO
WC WI. THESE AREAS WILL LIKELY SEE ONE QUARTER TO ONE HALF INCH...
LOCALLY HIGHER AMTS IF TSRA START TO TRAIN. BASED ON THE SPEED OF
THE FRONT MOVING SE OF OUR CWA...MOST OF THE SHRA/TSRA ACTIVITY
WILL BE LIMITED TO THE FIRST 1-3 HRS SUNDAY EVENING IN SC MN AND
WC WI.

SVR WX POTENTIAL IS HIGHLY DEPENDENT ON THE AMT OF CLOUD COVER...
WHICH IS RELATED TO SFC TEMPS. ALSO BOUNDARY LAYER MOISTURE WHICH
IS INITIALLY SHALLOW. IN ADDITION...STRONGER WIND SHEAR VALUES OF
30 KTS OR GREATER ARE ACROSS CENTRAL/NORTHERN MN DURING THE PRIME
PERIOD OF TSRA INITIATION. SC/SE MN AND WC WI WILL HAVE AMPLE
MLCAPE OF 1500 J/KG DURING THIS TIME...BUT WEAKER WIND SHEAR WILL
LIMIT THE ORGANIZATION OF THE TSRA/S AND SVR WX. HOWEVER...THERE
IS ENOUGH INSTABILITY TO PRODUCE SOME LARGE HAIL STONES AND GUSTY
WINDS. PLEASE SEE THE LATEST SPC DAY 2 AND DAY 1 LATER TONIGHT ON
THE POTENTIAL OF SVR WX.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 321 PM CDT SAT MAY 2 2015

MONDAY WILL FEATURE A RESPITE FROM PRECIPITATION...AND LIKELY THE
ONLY DAY NEXT WEEK THAT LOOKS TO BE FREE FROM PRECIPITATION...AS
THE STRONG COLD FRONT OF SUNDAY SETTLES WELL S OF THE AREA OVER
THE OHIO AND MID-MISS RIVER VALLEY REGIONS. HIGH PRESSURE WILL
SHIFT EWD ACRS THE DAKOTAS/MN/WI MON IN MON NIGHT. WHILE THIS
OCCURS...ANOTHER AREA OF LOW PRESSURE WILL DEVELOP OVER THE LEE OF
THE ROCKIES...PICKING UP THE STALLED CDFNT. THE FRONT WILL THEN
SLOWLY LIFT BACK N OF AS A WMFNT LATE TUE THRU WED ACRS THE
REGION. THIS WILL BE THE START OF A PROLONGED PERIOD OF HAVING
OCCASIONAL ROUNDS OF SHWRS/TSTMS THRU THE REST OF THE WEEK. WITH
THE WMFNT LIFTING N...THERE LOOKS TO BE PLENTY OF RAINFALL AS A
LLJ INTERACTS WITH THE SFC FEATURES...ALONG WITH A SURGE OF
MOISTURE FROM THE GOMEX...ALLOWING FOR DECENT QPF AMOUNTS.
FOLLOWING THIS WILL BE A PRONOUNCED WARM SECTOR THU INTO FRI...
MAKING FOR MORE HUMID CONDITIONS AND MORE AIRMASS TSTM
DEVELOPMENT. THE CDFNT THEN LOOKS TO SWING THRU EARLY FRI BRINGING
ADDITIONAL ORGANIZED SHWRS/TSTMS BUT THE PROGRESSION OF THIS FNT
LOOKS TO BE FAIRLY SLOW...KEEPING THE CHCS FOR SHWRS/TSTMS IN
PLACE INTO SATURDAY.

NO WORRIES ABOUT FROST AS LOWS WILL RANGE FROM 40-60 ALL WEEK
WHILE HIGH TEMPS RANGE FROM THE MID 60S TO NEAR 80 DEGREES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 718 PM CDT SAT MAY 2 2015

ISOLATED TSRA AROUND KMKT WILL MOVE SLOWLY ENE THROUGH SUNSET AND
THEN DISSIPATE. OUTFLOW FROM THESE STORMS MAY REACH INTO KMSP AND
THE SATELLITE AIRPORTS AND SWITCH WINDS TO THE SW FOR AN HOUR OR
SW IN THE 01Z-03Z PERIOD. OTHER STORMS OVER SE ND ARE SHOWING
SIGNS OF WEAKENING WHILE MOVING TO THE EAST. SHORT TERM MODEL
SOLUTIONS SUGGEST SOME SHOWERS PASSING THROUGH KAXN IN THE 02Z-05Z
PERIOD...KSTC AND KRWF FROM 07Z-10Z AND AFTER 10Z FOR KMSP...KRNH
AND KEAU. EVEN WITH THE SHOWERS OVERNIGHT...CEILINGS ARE EXPECTED
TO STAY VFR WITH MINOR EXCURSIONS INTO MVFR OR LOWER VSBYS. MODEL
SOLUTIONS REMAIN ON TRACK ON MOVING A COLD FRONT THROUGH THE TAF
SITES ON SUNDAY...PASSING KAXN IN THE LATE MORNING AND REACHING
KEAU IN THE EVENING. A BROKEN LINE OF STRONG TO SEVERE STORMS IS
EXPECTED TO BLOSSOM FROM NW WI THROUGH THE TWIN CITIES TO KFSD IN
THE 22Z-23Z PERIOD AND THEN PUSH OFF TO THE SE...LIKELY BEING SE
OF KEAU BY 02Z. DUE TO THE NATURE OF THE THUNDERSTORMS...USED
PROB30 GROUPS AT THIS POINT. WOULD HAVE USED A TEMPO AT KEAU BUT
IT IS BEYOND THE TAF PERIOD WHEN THE BEST CHANCE FOR TSRA MOVES
THROUGH. WILL USE A TEMPO ON THE 06Z ISSUANCE.

KMSP...RADAR SHOWS A WELL DEFINED OUTFLOW BOUNDARY HEADING
NORTHEAST TOWARDS THE TWIN CITIES FROM CONVECTION NEAR KMKT. THIS
MAY RESULT IN SW WINDS AT 15-20 KNOT WINDS REACHING THE AIRFIELD
EARLY THIS EVENING. OTHERWISE...VFR THROUGH MUCH OF THE PERIOD.
SOME SHOWERS ARE EXPECTED IN THE VICINITY FROM BEFORE DAYBREAK
THROUGH LATE MORNING. BEST CHANCES FOR THUNDERSTORMS ALONG A COLD
FRONT SUNDAY AFTERNOON ARE IN THE 21Z-24Z PERIOD.

/OUTLOOK FOR KMSP/
MON...VFR. WINDS N-NE 5-10 KTS.
TUE...VFR EARLY. SHRA/TSRA AFTN/EVE WITH MVFR/IFR CIGS/VSBYS.
      WINDS SE 10-20 KTS.
WED...VFR. CHC MVFR/IFR CIGS/VSBYS IN SHRA/TSRA.
      WINDS SE 15-20 KTS.

&&

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

$$

SHORT TERM...JLT
LONG TERM...JPC
AVIATION...RAH


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