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000
FXUS63 KMPX 172027
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
327 PM CDT FRI MAY 17 2013

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 327 PM CDT FRI MAY 17 2013

TSRA/S HAVE BEGUN ACROSS SW/WC MN EARLY THIS AFTN. THE TSRA WERE
ASSOCIATED WITH TIGHT INSTABILITY GRADIENT ACROSS FAR SW MN WHERE
DEW PTS HAVE RISEN INTO THE LOW TO MID 60S. THERE REMAINS AN
ELEVATED BOUNDARY ACROSS THIS AREA WHICH SHOULD FOCUS CONVECTION
THRU THE AFTN BEFORE THE MAIN FOCUS ACTIVITY DEVELOPS ACROSS
SD/NEBRASKA OVERNIGHT. RESIDUAL SHRA/ISOLD TSRA WILL REMAIN ACROSS
EC MN/WC WI DURING THE LATE AFTN/EARLY EVENING HRS. THERE STILL
REMAINS SOME SUBTLE SHRTWV ACROSS SW MN WHICH MAY ENHANCE THE SHRA
ACROSS EC MN/SE MN DURING THE EVENING. AFT MIDNIGHT THE MAIN FOCUS
FOR SHRA/TSRA ACTIVITY SHOULD REMAIN ACROSS WC/CENTRAL MN WHERE A
STRONGER SHRTWV MOVING ACROSS THE HIGH PLAINS OF NEBRASKA/SD
INTERACT WITH THE AMPLE MOISTURE ACROSS THIS REGION. ALTHOUGH SVR WX
IS POSSIBLE IN FAR WC MN AFT MIDNIGHT...THE BULK OF THE SVR WX
SHOULD REMAIN ACROSS SD/NEBRASKA WHERE HIGHER SHEAR VALUES AND
INSTABILITY EXISTS.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 327 PM CDT FRI MAY 17 2013

THE PERIOD BEGINS WITH A DEEP UPPER TROUGH JUST EAST OF THE
ROCKIES. MODEL CONSENSUS TODAY IS FOR TWO UPPER LOWS TO FORM OVER
THE WEEKEND. THE FIRST TO FORM WILL BE OVER THE DAKOTAS...WHICH
IS PROJECTED TO MOVE INTO NW MN ON SUNDAY. THIS FIRST LOW IS THE
FOCUS FOR HEAVY RAIN AND SOME SEVERE WEATHER ACROSS THE EASTERN
DAKOTAS...WEST CENTRAL AND NW MN. THE DETAILS ARE STILL NOT CLEAR
WITH WRF SOLUTIONS VARYING ON THE TIMING AND LOCATION OF THE
CONVECTION. THE 15Z SREF INDICATES PROBABILITIES AROUND 30 PERCENT
FOR AN INCH OF RAIN SATURDAY NIGHT ACROSS EASTERN SD AND WEST
CENTRAL MN. PROBABILITIES FOR TWO INCHES OF RAIN ARE AROUND 10
PERCENT JUST WEST OF THE MN BORDER. MODEST CAPE AND SHEAR VALUES
ARE PROJECTED SATURDAY EVENING ACROSS OUR FAR WEST. THERE IS NOT
MUCH OF A LOW LEVEL JET AND THE SURFACE TROUGH IS ACROSS CENTRAL
SD AND SE ND/NRN MN. AT THIS POINT...A FEW SEVERE STORMS CAN NOT
BE RULED OUT FOR OUR WEST CENTRAL MN COUNTIES.

A SECOND UPPER LOW IS EXPECTED TO FORM BY SUNDAY MORNING OVER
WESTERN NE/KS AND DEEPEN WHILE MOVING TO KFSD BY MONDAY MORNING.
DEEPENING SURFACE LOW PRESSURE WILL ADVANCE NORTHEAST THROUGH THE
CENTRAL PLAINS...LIKELY ENDING UP BETWEEN OMAHA AND NORFOLK
NEBRASKA BY SUNDAY EVENING. DP/DT TODAY SHOWED JUST A SLIGHT SW
DRIFT WITH TIME (SLOWING). A WARM FRONT WILL STRETCH ESE FROM THE
LOW ACROSS IA AND INTO SOUTHERN IL AND WILL MARK THE BOUNDARY OF
ADVANCING MT AIR. A COLD FRONT WILL TRAIL SOUTH FROM THE LOW INTO
THE SOUTHERN PLAINS. SHEAR AND CAPE VALUES INCREASE MARKEDLY ON
SUNDAY OFF TO OUR SOUTH WITH 50 KNOT 500 MB WINDS ADVANCING NE
FROM KS INTO IA BY EVENING. THE AREA EAST OF THE COLD FRONT...AS
WELL AS ALONG AND SOUTH OF THE WARM FRONT...IS A PRIME AREA FOR
SEVERE WEATHER SUNDAY AFTERNOON/EVENING. DEPENDING ON HOW THINGS
WORK OUT...SEVERE STORMS MAY PUSH INTO SOUTHERN/SE MN SUNDAY
EVENING AS THE WARM FRONT ADVANCES NORTHWARD.

WITH THE SLOWER MOVEMENT TO THE UPPER/SURFACE LOWS...THIS OPENS THE
DOOR FOR THE THREAT OF SEVERE WEATHER OVER FAR EASTERN MN AND
WEST CENTRAL WI ON MONDAY. ITS POSSIBLE FOR STORMS TO DEVELOP
ALONG THE MN/WI BORDER AROUND MIDDAY ON MONDAY AND ADVANCE
EASTWARD ACROSS WEST CENTRAL WI IN THE AFTERNOON. THIS IS SOMETHING
LATER SHIFTS WILL NEED TO KEEP AN EYE ON. THE TUESDAY THROUGH
THURSDAY PERIOD WILL FEATURE THE UPPER LOW SLOWLY PASSING ACROSS
THE FA WITH SCATTERED SHOWERS...PLENTY OF CLOUDS AND HIGH
TEMPERATURES RUNNING SOME 10 DEGREES BELOW NORMAL. DRY WEATHER IS
FORECAST TO RETURN ON FRIDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1159 AM CDT FRI MAY 17 2013

MAY AVIATION CONCERN THIS AFTN IS ASSOCIATED WITH
CONVECTION...ESPECIALLY ACROSS SW/SC/WC MN WHERE INSTABILITY HAS
INCREASED SIGNIFICANTLY SINCE THIS MORNING. ELSEWHERE...RESIDUAL
BOUNDARY LAYER MOISTURE WILL HOLD ONTO HIGH END MVFR CIGS ACROSS
EC MN...AND PORTIONS OF WC WI. HOWEVER..THIS SHOULD BE TEMPORARY
ONCE ENOUGH MIXING IN THE BOUNDARY LAYER DEVELOPS THIS AFTN.
CONVECTION ACROSS SC MN NEAR KAEL WILL BE THE FOCUS ACROSS SE MN
IN THE SHORT TERM...OR UNTIL 21Z. OTHER -SHRA DEVELOPMENT... WAS
ASSOCIATED WITH AN ELEVATED INSTABILITY LAYER IN S MN. THESE SHRA
WILL CONTINUE FOR AREAS OF EC MN AS THE MEAN FLOW REMAINED FROM
THE E/ENE. WILL CONTINUE VCTS FOR KRWF WHERE BEST INSTABILITY
REMAINS THIS AFTN. BUT NOT CONFIDENT ENOUGH TO WARRANT IFR/MVFR
CIGS/VSBYS IN TSRA. AFT 00-3Z/18...THE MAIN ACTIVITY SHOULD FOCUS
ACROSS SD...AND INTO WC MN DURING THE OVERNIGHT HRS. MVFR/IFR CIGS
MAY REDEVELOP IN THE WAKE OF THE BOUNDARY LAYER MOISTURE HOLDING
ACROSS THE REST OF MN AND WC WI. WINDS WILL REMAIN FROM THE E/ESE
THIS AFTN AND GUSTY EARLY...BECOMING MORE SE/SSE BY SATURDAY
MORNING.

KMSP...

MVFR CIGS WILL LIKELY CONTINUE THRU 21Z WITH A PERIOD OF
SHRA...LIMITING VSBYS ARND 5-6SM. CIGS SHOULD LIFT TO LOW END VFR
BY THE AFTN...AND CONTINUE THRU THE EVENING...BEFORE LOWERING BACK
TO MVFR OVERNIGHT. SFC WINDS WILL REMAIN FROM THE ESE AND GUSTY
THIS AFTN ARND 20 KTS...THEN BECOME MORE SE/SSE SATURDAY MORNING.

/OUTLOOK FOR KMSP/

SAT NGT...VFR/MVFR CIGS. CHC IFR IN HEAVIER TSRA. SE-S WINDS 5-10 KTS.
SUN...VFR/MVFR CIGS. CHC IFR IN HEAVIER TSRA. S-SE WINDS 8-12 KTS.
MON...VFR/MVFR CIGS. CHC SHRA CHC IFR IN TSRA. S WIND 10-15 KTS.

&&

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

$$

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