698
FXUS63 KMPX 252056
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
356 PM CDT SAT MAY 25 2013
SHORT TERM
(THIS EVENING THROUGH SUNDAY)
ISSUED AT 315 PM CDT SAT MAY 25 2013
LARGE AREA OF SURFACE LOW PRESSURE OVER EASTERN PORTION OF
NORTHERN ROCKIES CONTINUES TO SLOWLY BECOME BETTER ORGANIZED
INTO TONIGHT. WARM FRONTAL BOUNDARY ASSOCIATED WITH SAME
WILL AGAIN BE THE CATALYST FOR ANY ORGANIZED SHOWER AND
THUNDERSTORM ACTIVITY TONIGHT INTO SUNDAY. AREA OF CONVECTION
ALREADY FIRING UP ALONG NORTHERN EDGE OF THIS BOUNDARY AS SEEN
ON IR SATELLITE IMAGERY. CONDITIONS SHOULD REMAIN DRY OVER
MUCH OF THE FA THIS EVENING...WITH POSSIBLE DEVELOPMENT OF
SHOWERS AND ISOLATED THUNDER AFTER MIDNIGHT MAINLY SOUTHWEST
OF A LINE FROM MORRIS TO OLIVIA TO OWATONNA. SURFACE FORCING
FOR THIS ACTIVITY IS MINIMAL...PER WEAK THETA-E ADVECTION.
SIMILARLY...UPPER AIR SUPPORT PER GFS40 250MB DIVERGENCE
IS ALSO QUITE LACKING...SAVE STRONG DIVERGENCE COUPLET ABOVE
FAR SOUTHWEST MN NEAR 26/12Z. SO AT THIS JUNCTURE LOOKS LIKE
MAIN THREAT FOR ANY ORGANIZED OVERNIGHT INTO MID MORNING
CONVECTIVE ACTIVITY WILL EMANATE FROM MCS GENERATED TONIGHT
OVER CENTRAL SODAK...AND PROGRESSION OF SAME SE INTO
SW MN...AND PORTIONS OF SOUTH CENTRAL MN AND MUCH OF NORTHERN
HALF OF IA. MUCH OF THE REST OF THE DAYLIGHT HOURS SHOULD BE
DRY...MINUS FAR WEST CENTRAL MN...WHERE LATE SUNDAY AFTERNOON
CONVECTION COULD EASILY FIRE NEAR THE WARM FRONTAL BOUNDARY...AND
WHERE BEST MOISTURE TRANSPORT VECTORS ARE OBSEVERED. GRADIENT WILL
TIGHTEN A TAD FURTHER BY LATE SUNDAY MORNING OVER THE
REGION...GUARANTEEING ANOTHER DAY OF MODERATE SE FLOW. HIGH
TEMPERATURES ON SUNDAY WILL BE SIMILAR TO TODAY'S...AS THICK
STRATO-CU CONTINUES TO BLANKET MUCH OF THE FA.
LONG TERM
(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 315 PM CDT SAT MAY 25 2013
A WET LONG TERM FORECAST PERIOD IS SHAPING UP FOR NEXT WEEK...AS THE
FORECAST AREA REMAINS DOWNSTREAM OF A DEEPENING WESTERN CONUS
MID/UPPER TROUGH. WHILE THERE WILL BE DRY WINDOWS OF TIME HERE AND
THERE...THE MAJORITY OF MODEL SOLUTIONS INDICATE THE POTENTIAL FOR
WIDESPREAD TOTAL RAINFALL AMOUNTS OF TWO TO FOUR INCHES BETWEEN
SUNDAY NIGHT AND NEXT SATURDAY.
THE SUNDAY NIGHT INTO MONDAY MORNING TIME FRAME IS LOOKING LIKE IT
SHOULD BE ONE OF THOSE WINDOWS WHERE MOST OF THE FORECAST AREA SHOULD
REMAIN DRY...IN BETWEEN DETECTABLE SHORTWAVES AND IN THE ABSENCE OF
A NOTABLE FORCING MECHANISM. THAT ALL CHANGES ON MONDAY HOWEVER...AS
SHOWN BY THE GFS AND ECMWF...WHICH CONTINUE TO BRING A DECENT MID
LEVEL SHORTWAVE ACROSS THE AREA FOR THE MEMORIAL DAY HOLIDAY. THE
NAM FEATURES IT AS WELL...BUT IS A TAD SLOWER...AND IS SHIFTED
SLIGHTLY TO LATER MONDAY INTO TUESDAY. MODELS CONTINUE TO PORTRAY AN
IMPRESSIVELY DIFFLUENT UPPER LEVEL THICKNESS PATTERN DURING THIS
TIME FRAME. WITH PLENTY OF MOISTURE FUNNELING NORTH FROM THE GULF
/AS SHOWN BY FORECAST PRECIPITABLE WATER VALUES 200 PERCENT OF
NORMAL ON MONDAY NIGHT/ THE POTENTIAL FOR A GOOD SOAKING RAINFALL ON
MONDAY AND MONDAY NIGHT WITH WIDESPREAD 1 TO 2 INCH AMOUNTS IS
CERTAINLY QUITE POSSIBLE.
THE NEXT TIME FRAME FOR NOTABLE PRECIP IS EXPECTED TO ARRIVE ON
LATE TUESDAY INTO WEDNESDAY...AS A WARM FRONT LIFTS NORTH INTO THE
FORECAST AREA...AND IS AGAIN SUPPORTED BY A BROAD UPPER LEVEL
DIFFLUENT PATTERN. IN ADDITION TO THE POTENTIAL FOR HEAVY
RAINFALL...A THREAT FOR ORGANIZED SEVERE WEATHER WILL ENTER THE
PICTURE...ESPECIALL ON THURSDAY AND FRIDAY AS THE SURFACE LOW NEARS
THE AREA AND DEEP LAYER SHEAR INCREASES. IN FACT...THE CIPS ANALOGS
FOR SEVERE WEATHER INDICATE THERE ARE SEVERAL MATCHES TO HISTORICAL
OUTBREAK EVENTS...INCLUDING JUNE 17TH OF 2010...
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 100 PM CDT SAT MAY 25 2013
REMNANTS OF MCS WHICH PRODUCED MODERATE TO HEAVY AMOUNTS OF
PRECIPITATION OVER MUCH OF NORTHERN IOWA...AND LIGHTER AMOUNTS
ABOVE FAR SOUTHERN MN CONTINUES TO DECREASE IN COVERAGE AND
INTENSITY AS IT TREKS INTO NORTHERN IL. CLOSER TO HOME...LARGE
SWATH OF STRATO-CU CONTINUES TO BLANKET ALL OF THE TAF REGION.
WESTERN HALF OF THIS REGION DEALING WITH MVFR...TO LOW END
MVFR CIGS...WITH VFR CONDITIONS ELSEWHERE. ALTHOUGH IR SATELLITE
CONFIRMING SOME REDEVELOPMENT OF LOWER CIGS OVER EASTERN SODAK
...LOSS OF HEATING BY EARLY THIS EVENING SHOULD GIVE GREEN
LIGHT TO SHORT TERM LOSS OF CIGS OVER KAXN...KSTC...AND KRWF
...WITH REDEVELOPMENT POSSIBLE LATER THIS EVENING AHEAD OF
AREA OF CONVECTION FORMING OVER CENTRAL DAKOTAS AFTER 03Z.
NOTHING VERY SUBSTANTIAL CONCERNING FORCING IN RESPECT TO
CONVECTION DURING THE NEXT 24 HOURS OR SO...SAVE TONIGHT
OVER WEST CENTRAL THROUGH SOUTH CENTRAL MN. WITH THAT SAID
TEMPO GROUPS WILL BE THE RULE AT MOST WESTERN TAF LOCATIONS
WITH INSTABILITY PARAMETERS INDICATING POSSIBLE SHORT TERM
THUNDER AT KRWF. LIGHT TO MDT SE FLOW WILL CONTINUE FOR MUCH OF
THE FORECAST PERIOD. VFR VSBYS WILL BE SEEN INTO SUNDAY AFTN
...MINUS SHORT PERIODS OF MVFR ASSOCIATED WITH POSSIBLE CONVECTION.
VFR CIGS EXPECTED AT ALL AIRPORT LOCATIONS AFTER 15Z.
KMSP...
CONFIDENCE IS NOT HIGH FOR SHOWER ACTIVITY LATER THIS EVENING.
MODERATE THETA E ADVECTION AND VERY POTENT 250MB DIVERGENCE
COUPLETS AFTER 06Z...COULD GENERATE A PASSING SHOWER AT KMSP.
MUCH BETTER BET CONCERNS FAIRLY DRASTIC LOWERING OF VFR TO
MVFR CIGS BY 23Z TIME PERIOD. ACTUALLY HAVE A FAIRLY LARGE
AREA OF LOW MVFR CIGS OVER WEST CENTRAL WI ATTM ADVECTING
IN THIS DIRECTION. HEATING SHOULD ELEVATE CIGS AS THEY PROCEED
EAST. ALTHOUGH CURRENT FORECAST DEPICTS CONTUINUATION OF MVFR CIGS
THROUGH 15Z...THERE IS A POSSIBILITY OF A SHORT TERM BREAK IN
THE CLOUD COVER MENTIONED ABOVE BETWEEN 03Z AND 05Z. AFTER 15Z
MDT SE FLOW AND VFR CIGS AND VSBYS SHOULD BE ANTICIPATED TIL
END OF PERIOD. BETTER CHANCES FOR CONVECTIVE ACTIVITY WILL
BE ENCOUNTERED BY LATE SUNDAY NIGHT.
MPX WATCHES/WARNINGS/ADVISORIES
MN...NONE.
WI...NONE.
SHORT TERM...AJZ
LONG TERM...LS
AVIATION...AJZ
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