000
FXUS63 KMPX 201801
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
101 PM CDT MON MAY 20 2013

.UPDATED FOR 18Z AVIATION DISCUSSION...
ISSUED AT 1250 PM CDT MON MAY 20 2013

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CDT MON MAY 20 2013

TODAY-TONIGHT...BROAD UPPER LEVEL CENTRAL CONUS TROUGH WILL SLOWLY
MEANDER TWD THE E...WITH ITS CUTOFF LOW WOBBLING OVER WRN MN AND THE
ERN DAKOTAS. SEVERAL SHORTWAVE SPOKES WILL ROTATE ARND THIS UPPER
LOW...SWINGING THRU THE MPX CWFA TDA INTO TNGT. THE MAIN ISSUES ARE
AROUND TIMING OF PRECIP AND POTENTIAL FOR SEVERE WX IN FAR ERN MN
INTO WRN WI. SCATTERED SHWRS THIS MRNG WILL CONTINUE TO DEVELOP AND
DISSIPATE AS MODELS INDICATE DRY SLOTTING TO SHIFT NE INTO THE
REGION THIS MRNG...LASTING THRU AT LEAST MID AFTN. THIS WOULD HALT
ANY WIDESPREAD PRECIP BUT ISOLD TO SCATTERED SHWRS/TSTMS CERTAINLY
CANNOT BE RULED OUT. ONCE THIS DRY SLOTTING SHIFTS WELL INTO NRN MN
AND NW WI BY THIS EVE...ANOTHER SWATH OF MOISTURE WILL BR DRAGGED
INTO THE REGION WHICH WILL BE ABLY TAPPED TO PRODUCE ADDITIONAL
BANDS OF PRECIP...IF NOT A LARGE PRECIP SHIELD. ONE DETERMINING
FACTOR WILL BE THE PLACEMENT OF THE SFC LOW UNDER THE UPPER LOW. THE
SFC LOW LOOKS TO REMAIN PRIMARILY NEAR THE ND/SD/MN TRIPLE POINT...
AND THIS POSITION WOULD KEEP THE BULK OF THE PRECIP ALONG AND N OF
ITS LATITUDE. AS FOR SEVERE WX POTENTIAL...THE EWD SHIFT OF THE
UPPER TROUGH PUTS THE BEST JETTING AND EXIT REGION OVER FAR ERN MN
AND WRN WI. IN ADDITION...THE BREAK IN THE PRECIP MAY ALLOW FOR A
FEW BREAKS IN THE OVERCAST...ALLOWING FOR ADDITIONAL
INSTABILITY...ESP IN WRN WI WHERE PRECIP HAS NOW VIRTUALLY SHUT DOWN
EVERYWHERE. THIS WILL ALLOW A RELOADING OF THE ATMOS TO GENERATE
MLCAPE IN THE 2000-2500 J/KG RANGE WITH LITTLE CAPPING...WHILE
CENTRAL-WRN MN WILL BE DEALING WITH LESS IMPRESSIVE LAPSE RATES AND
INSTABILITY PARAMETERS. STILL HAVE A SLGT RISK IN PLACE PER SPC IN
THEIR SWODY1 FOR ALL OF FAR ERN MN THRU WI WHICH IS VERY REASONABLE.
AS FOR TEMPERATURES AND DEWPOINTS...WITH THE WMFNT CONTINUING TO
LUMBER NWD THRU THE CWFA AND ITS TRAILING CDFNT STILL IN THE
DAKOTAS...ANOTHER WARM/HUMID DAY CAN BE EXPECTED. WILL LOOK FOR
HIGHS FROM ARND 70 IN WRN MN TO THE LOWER 80S IN WRN WI... WITH LOWS
TNGT AGAIN MILD IN THE MID 50S TO LWR 60S. DEWPOINTS WILL AGAIN
REACH THE LWR 60S...KEEPING AN UNSEASONABLY HUMID AIRMASS IN PLACE.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 400 AM CDT MON MAY 20 2013

IT ISN`T UNTIL TUESDAY NIGHT/WEDNESDAY MORNING THAT WE FINALLY
SEE SOME SLOW EASTWARD PROGRESS WITH THE TROUGH OVER THE CENTRAL
CONUS. DURING THIS TIME THE SURFACE LOW SLOWLY FILLS AND MOVES
FROM MN TO WI. HOWEVER...BEFORE THEN...DURING THE DAY ON
TUESDAY...WE EXPECT SCATTERED SHOWERS ACROSS PRIMARILY CENTRAL MN
AND NORTHERN WI. JUST LIKE THIS MORNING...WHERE WE SEE GOOD DRYING
SHOWING UP IN THE WATER VAPOR IMAGERY ACROSS EASTERN NE AND
WESTERN IA...TUESDAY SHOULD SEE A DRY SLOT ACROSS THE SOUTHERN
HALF OF THE FORECAST AREA. BETTER Q-VECTOR CONVERGENCE AND
SLIGHTLY BETTER FGEN IS LOCATED ACROSS THE NORTHERN FORECAST AREA
JUST NORTH OF THE DRY WEDGE SHIFTING NORTHEAST DURING THE DAY. AS
A RESULT...KEPT HIGH CHANCE POPS OR LIKELY POPS IN THE FORECAST
FOR THE NORTHERN CWA...BUT LOWERED POPS OR WENT NO WEATHER IN THE
SOUTHERN CWA TUE/TUE NIGHT. LINGERING INSTABILITY IN EASTERN MN
AND WESTERN WI WARRANTS THUNDERSTORMS FOR THE WEATHER TYPE ON
TUESDAY...BUT EVEN BEFORE TUESDAY NIGHT THE MUCAPE SLIDES FARTHER
EASY AND DIMINISHES. THEREFORE...KEPT THE THUNDER OUT OF THE
FORECAST IN MOST LOCATIONS TUESDAY NIGHT AND WEDNESDAY. WE ALSO
COOLED TEMPERATURES A BIT ON WEDNESDAY...ESPECIALLY ACROSS CENTRAL
MN...WHERE LIGHT SHOWERS MAY BE MORE WIDESPREAD AND HANG AROUND
LONGER. ALSO...WITH EAST-SOUTHEAST SHIFT TO THE SYSTEM ON
WEDNESDAY...THE BETTER LARGE-SCALE FORCING SHOULD GET PULLED
ACROSS THE AREA. SO WEDNESDAY`S POPS ARE ACTUALLY HIGHER THAN
TUESDAY`S AND ARE COMPARABLE TO THE PROBABILITIES FORECASTED
TODAY. HOWEVER...THE QPF IS LOW.

LOOKS LIKE WE`LL GET A BRIEF REPRIEVE FROM THE WET WEATHER THURSDAY
AND FRIDAY WITH A SURFACE HIGH BUILDING IN TROUGH...RIDGE...TROUGH
PATTERN SETTING UP ACROSS THE CONUS. THE WEATHER PREDICTION CENTER
PREFERS A GFS/GEFS/EC/EC-MEAN BLEND IN THE EXTENDED AND TO THAT
SEEMS REASONABLE GIVEN THE RELATIVELY SMALL SPREAD IN THE LONG
WAVE PATTERN...EVEN WITH AN ANOMALOUSLY DEEP TROUGH ALONG THE WEST
COAST. BY THE WEEKEND...A WARM FRONT IS FORECAST TO MOVE EAST
ACROSS SD/NE AND APPROACH WESTERN MN. MOST OF THE FORECAST AREA
TAKES SOME TIME TO MOISTEN IN LIGHT OF THE DRIER E-SE FLOW UNDER
THE RIDGE. NONETHELESS...WITH AT LEAST SOME MOISTURE PLACE...THE WARM
ADVECTION COULD KICK OFF SOME SHOWERS BY SATURDAY...ESPECIALLY IN
WESTERN MN.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1250 PM CDT MON MAY 20 2013

SHOWERS WILL CONTINUE TO INCREASE IN COVERAGE THIS
AFTERNOON...WITH A FEW ISOLATED THUNDERSTORMS POSSIBLE AS WELL.
COULD SEE VISBYS BRIEFLY DROP BENEATH THE HEAVIER SHOWERS...BUT
MAINLY EXPECTING VFR/MVFR. TONIGHT FORECAST GUIDANCE SHOWS CIGS
DROPPING AGAIN...WITH IFR/LIFR CONDITIONS ACROSS THE NORTH AT KAXN
AND KSTC.

KMSP...
SHOWERS WILL CONTINUE TO MOVE ACROSS THE METRO AREA TODAY...WITH
AN OUTSIDE CHANCE OF THUNDER AS WELL. HOWEVER THE COVERAGE FOR
THUNDER WILL BE SCARE SO REMOVED IT FROM THE AFTERNOON TIMING AND
HAVE JUST A SHORT VCTS THIS EVENING AS INDICATED BY THE SHORT TERM
HRRR AND HOPWRF MODELS. SHOWERS WILL DECREASE IN COVERAGE LATER
TONIGHT.

/OUTLOOK FOR KMSP/
WED...VFR/MVFR CIGS WITH -SHRA LIKELY. WINDS NE AT 05G10KTS.
THU...VFR. WINDS NE AT 10KTS.
FRI...VFR. WINDS SE AT 10G15KTS.

&&

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

$$

SHORT TERM...JPC
LONG TERM...CLF
AVIATION...JRB