Area Forecast Discussion
Issued by NWS Twin Cities, MN

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469
FXUS63 KMPX 161804
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
104 PM CDT SAT MAY 16 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM CDT SAT MAY 16 2015

VERY LOW CONFIDENCE IN AREAL COVERAGE OF TSRA/SHRA TODAY...AT LEAST
THRU 18Z AS CAMS AND LOCAL WRF MODELS HAVE NO INDICATION OF CURRENT
CONVECTION EARLY THIS MORNING AND THE EVOLUTION OF THE CONVECTION
THRU NOON. ALTHOUGH SHRA/TSRA HAVE DEVELOPED AFT 7Z ALONG THE
ADVANCING WARM FRONT THAT WAS IN NORTHERN IOWA....THE MORE
CONCENTRATED AREA OF SHRA/TSRA WAS ALONG A STRONGER SHRTWV ACROSS
NE/SD WHICH SHOULD BE THE MAIN ACTION IN SW/WC MN DURING THE
MORNING. THE LATEST HRRR AS OF THE 6Z MODEL RUN DOES HAVE SOME
SUPPORT OF SHRA/TSRA MOVING INTO FAR SW/WC MN BETWEEN 12-15Z WITH
THE ACTIVITY IN NE/SD. IT THEN HAS THIS ACTIVITY DISSIPATING AS IT
MOVES TO THE NE ACROSS SOUTHERN/CENTRAL MN BY NOON. HAVE USED THIS
SCENARIO WITH MORNING POPS/WX GRIDS. THIS AFTN/EVENING IS MORE
RELATED TO AFTN HEATING AND THE DESTABILIZATION OF THE ATMOSPHERE
AND ANY LEFTOVER BOUNDARIES FROM EARLIER CONVECTION...WHICH WILL
LEAD TO WIDELY SCATTERED TSRA THIS AFTN. THE MAIN SHOW SHOULD HOLD
OFF UNTIL LATE AFTN/EVENING AS THE NEXT STRONG SHRTWV MOVES NE
ACROSS THE PLAINS AND INTO THE UPPER MIDWEST.

SEVERE WX PARAMETERS DO SUPPORT ISOLD SVR STORMS BY LATE
AFTN/EVENING AS SHEAR VALUES AND INSTABILITY MAXIMIZE. DEPENDING
UPON THE AMOUNT OF INSTABILITY BASED ON CLOUD COVER AND SFC
HEATING...WILL DETERMINE THE AREAL EXTENT OF THE SVR STORMS. BY THE
MID/LATE EVENING...ANY SVR STORMS WILL BE ELEVATED WHICH LEADS TO
MORE MARGINAL SVR HAIL THEN ANY OTHER SVR THREAT. WILL NEED TO
MONITOR THE EVOLUTION OF STORMS ACROSS THE PLAINS LATE TONIGHT AND
SEE IF ANY EVOLVE INTO A BOW ECHO AND MOVE NE ACROSS THE UPPER
MIDWEST. SEE THE LATEST SPC DAY1/DAY2 FOR MORE INFORMATION.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 406 AM CDT SAT MAY 16 2015

THE LONG TERM PERIOD WILL START OFF ON AN ACTIVE NOTE...WITH A
SUB-995MB LOW PROGGED TO BE NEARING THE SOUTHWEST CORNER OF
MINNESOTA AT DAYBREAK SUNDAY. STRONG LLVL MOISTURE
TRANSPORT/CONVERGENCE AHEAD OF THE TROUGH WILL EXPAND INTO THE
FORECAST AREA BY DAYBREAK SUNDAY...AND GENERATE WIDESPREAD SHOWER
AND THUNDERSTORM ACTIVITY THROUGH THE MID MORNING HOURS. SAID
ACTIVITY WILL LIFT NORTH AND EAST OF THE AREA BY EARLY AFTERNOON.
THE BREAK FROM CONVECTION SHOULD BE BRIEF...AS THE MID/UPPER LOW
PASSES OVERHEAD AT PEAK DAYTIME HEATING. WHILE CONVECTIVE DEBRIS
MAY LIMIT THE POTENTIAL FOR DESTABILIZATION DURING THE
AFTERNOON...STEEP MID LEVEL LAPSE RATES PROVIDED BY THE MID/UPPER
LOW WILL RESULT...AND THEREFORE YIELD A THREAT FOR HAIL. WHILE
COVERAGE/INTENSITY OF STORMS MAY BE MINIMIZED GIVEN THE SYSTEM
WILL BE IN ITS OCCLUSION/WEAKENING PHASE...EFFECTIVE SHEAR VALUES
APPEAR ADEQUATE FOR AT LEAST A FEW STRONG TO SEVERE STORMS ON
SUNDAY AFTERNOON.

THE LOW TAKES ITS TIME GETTING OUT OF THE AREA...EVENTUALLY
REACHING THE UP OF MICHIGAN ON MONDAY MORNING. EXPECTED TO SEE
LIGHT WRAP-AROUND /SCATTERED/ SHOWERS LINGERING ACROSS CENTRAL
MN/WI THROUGH MONDAY.

BEHIND THE TROUGH...BROAD HIGH PRESSURE BUILDS INTO THE DAKOTAS
AND MN ON TUESDAY...AND THEN SPRAWLS OUT ACROSS THE NORTH CENTRAL
CONUS THROUGH THE WEEK. THIS WILL MAKE FOR A DRY STRETCH...WITH NO
ADDITIONAL MEASURABLE PRECIPITATION EXPECTED FROM TUESDAY THROUGH
FRIDAY. IT WILL ALSO YIELD COOL TEMPERATURES...WITH HIGHS IN THE
60S AND LOWS IN THE 30S AND 40S. FROST MAY BE A CONCERN ON MONDAY
NIGHT AND TUESDAY NIGHT...AS LOWS DIP INTO THE LOW/MID 30S ACROSS
PARTS OF CENTRAL MN/WI.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1246 PM CDT SAT MAY 16 2015

CURRENT SCENARIO MAKES FOR A MESSY AVIATION FORECAST FOR THE AREA.
A SURFACE LOW IS PUSHING INTO WESTERN SOUTH DAKOTA FROM THE
WEST...WITH A WARM FRONT EXTENDING EAST AND DEW POINTS IN THE MID
60S SURGING NORTHWARD INTO SOUTHERN MN. DEW POINT DEPRESSIONS WILL
REMAIN JUST A COUPLE DEGREES...AND LOW LEVEL LCL`S SHOUDL REMAIN
IN PLACE. SO...EXPECTING WIDESPREAD MVFR TO HOLD FOR THE MOST PART
WITH A FEW PERIODS OF SCATTERING OCCURRING THIS AFTERNOON. LATE
THIS AFTERNOON...A LINE OF THUNDERSTORMS IS EXPECTED TO DEVELOP
AND PUSH EAST INTO WESTERN MN AND CONTINUE NORTHEAST THROUGH THE
EVENING. RWF/STC/AXN MAY ALL BE DRIECTLY IMPACTED BY THIS
LINE...BUT MSP MAY BE ONTHE SOUTHERN PERIPHERY OF THESE
STORMS...WILL BE SOMETHING TO MONITOR. AS THE LOW DEEPENS IN SOUTH
DAKOTA TONIGHT AND TOMORROW MORNING...WE`LL REMAIN IN UNSTABLE AIR
AND MORE THUNDERSTORM DEVELOPMENT IS EXPECTED TOMORROW MORNING.

KMSP...BEST CHANCE FOR THUNDER TONIGHT WILL BE FROM 03Z TO
06Z...HOWEVER THE HRRR INDICATES THE POSSIBLITY THAT THE
THUNDERSTORM CLUSTER MOVING THROUGH WESTERN MN THIS AFTERNOON MAY
SLIDE JUST NORTH OF MSP...BUT IF IT DOES STILL EXPECT OTHER SPOTTY
THUNDERSTORM DEVELOPMENT LATE TONIGHT. FOR TOMORROW
AFTERNOON...STRONG THUNDERSTORMS LOOK TO DEVELOP AND MOVE THROUGH
FROM ROUGHLY 20-23Z.

/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...JLT
LONG TERM...LS
AVIATION...SPD



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