Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 060328
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1028 PM CDT TUE MAY 5 2015

.UPDATE...FOR 06Z AVIATION DISCUSSION BELOW

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 303 PM CDT TUE MAY 5 2015

SFC ANALYSIS SHOWS A WEAVING WMFNT EXTENDING EWD FROM THE KS/CO
AREA ACRS THE MID-MISS RIVER VALLEY REGION INTO THE NRN OHIO
VALLEY REGION. ALOFT...A NW-SE ORIENTED RIDGE AXIS EXTENDS SEWD
FROM MANITOBA PROVINCE THRU THE DAKOTAS AND INTO THE SERN CONUS.
ALONG AND JUST AHEAD OF THIS FRONT IS LOW CLOUDS WITH ISOLD RAIN
SHOWERS. GOING INTO THE EVE AND OVERNIGHT HRS...BOTH SFC AND ALOFT
FEATURES WILL STEADILY SHIFT NWD...BRINGING TOGETHER A DEEPER SLY
FLOW IN THE WAKE OF EACH FEATURE. HOWEVER...THE LACK OF
CONVERGENCE AT THE SFC AND BAGGY FLOW ALOFT WILL SPELL ONLY ISOLD-
SCTD -SHRA COVERAGE FOR SRN AND WRN MN OVERNIGHT THRU TMRW MRNG.
IN ADDITION...THERE STILL IS PLENTY OF BLYR DRIER AIR THAT WILL
NEED TO BE OVERCOME TO HAVE MEASURABLE PRECIP SO QPF AMOUNTS WILL
BE RATHER UNIMPRESSIVE...WHICH HAS BEEN THE TREND IN SHORT-TERM
MODEL RUNS THRU THE DAY. ONCE THESE FEATURES LIFT INTO CENTRAL AND
NRN MN BY TMRW MRNG...A MORE POIGNANT UPR LVL TROF AXIS FROM THE
NRN PLAINS THRU THE MID-MISS RIVER VALLEY WILL LIFT NWD...AND THIS
PVA WILL AID IN CREATING NOT ONLY INCREASED COVERAGE OF SHWRS BUT
ALSO BETTER POTENTIAL FOR A FEW TSTMS FROM TIME TO TIME DURG THE
DAY. THUS...HAVE SHOWN POPS IN THE 30-50 PERCENT RANGE FOR TNGT
FOLLOWED BY POPS IN THE 50-70 PERCENT RANGE FOR TMRW. SEVERE WX
POTENTIAL ALSO LOOKS RATHER LIMITED DUE TO THE LACK OF
INSOLATION/INSTABILITY AND MEAGER LAPSE RATES. SPEAKING OF THE
LACK OF INSOLATION...THE NWD MOVING CLOUDS THIS AFTN HAVE TOYED
WITH MAX TEMPS IN FAR SRN MN. TEMPS HELD IN THE MID-UPR 50S AROUND
THE I-90 CORRIDOR WHILE WRN AND CENTRAL MN HAD TEMPS HITTING THE
LOW-MID 70S. THE BLANKET OF CLOUDS WILL KEEP TEMPS IN THE 50-60
DEGREE RANGE FOLLOWED BY HIGHS IN THE LOW-MID 70S AREA-WIDE TMRW.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 303 PM CDT TUE MAY 5 2015

WEDNESDAY NIGHT THROUGH FRIDAY MORNING: A LARGE UPPER LEVEL RIDGE
WILL PERSIST ACROSS CENTRAL US INTO SOUTHERN CANADA FROM WEDNESDAY
NIGHT INTO THURSDAY.  HOWEVER...A POTENT MID-LEVEL SHORTWAVE WILL
MOVE FROM THE NORTHERN PLAINS STATES AND INTO MINNESOTA DURING THIS
PERIOD.  AHEAD OF THIS FEATURE...DEEP SOUTHERLY FLOW WILL BRING WARM
AND MOIST AIR INTO OUR AREA FROM WEDNESDAY NIGHT INTO THURSDAY.
COMBINED WITH AN ELONGATED SURFACE LOW MOVING THROUGH THE EASTERN
DAKOTAS AND NORTHERN MN...THIS SETUP WILL LEAD TO MULTIPLE CHANCES
OF PRECIPITATION DURING THIS PERIOD.

FROM WEDNESDAY EVENING THROUGH THURSDAY MORNING...A WARM FRONT WILL
MOVE NORTHWARD THROUGH OUR CWA...PROVIDING ENHANCED FORCING ALONG
WITH POSITIVE VORTICITY ADVECTION AHEAD OF THE APPROACHING MID-LEVEL
SHORTWAVE.  THE BEST PRECIPITATION CHANCES WILL BE IN WESTERN
MN...WHERE THE STRONGEST FORCING WILL RESIDE.  WENT WITH LIKELY POPS
IN THIS REGION...AND CHANCE POPS ELSEWHERE.

BY THURSDAY AFTERNOON...THE SHORTWAVE AND SURFACE LOW WILL MOVE INTO
WESTERN MN...WITH SOUTHERN MN AND WESTERN WI IN THE WARM SECTOR.
NOT SURE HOW UNSTABLE THE ATMOSPHERE WILL GET WITH WIDESPREAD CLOUD
COVER AND ONGOING SHOWERS AND STORMS POSSIBLE IN THE MORNING AND
EARLY AFTERNOON...BUT THERE IS THE POTENTIAL FOR STRONG STORMS
DURING THE LATE AFTERNOON AND EVENING AHEAD OF THE COLD FRONT MOVING
INTO MN.  THE 12Z NAM BRINGS CAPE UP TO 2500 J/KG INTO THE TWIN
CITIES AREA BY 00Z ON THURSDAY EVENING...WHILE THE GFS LIMITS CAPE
VALUES TO 1000-1500 J/KG AT THIS TIME.  COMBINED WITH 0-6 KM BULK
SHEAR VALUES FROM 20-30 KTS...FORCING FROM THE SHORTWAVE AND COLD
FRONT...AND SURFACE DEWPOINTS IN THE LOWER 60S....THUNDERSTORMS WILL
BE LIKELY FROM THURSDAY AFTERNOON THROUGH THE EVENING HOURS...AND
SEVERE WEATHER CANNOT BE RULED OUT IN EASTERN MN AND WESTERN
WI...ESPECIALLY IF THE CAPE VALUES SHOWN IN THE NAM OCCUR OVER THESE
AREAS.

CHANCES FOR STRONG TO SEVERE STORMS WILL DIMINISH THURSDAY NIGHT AS
INSTABILITY DECREASES. HOWEVER...THE COLD FRONT WILL BE SLOW TO MOVE
THROUGH OUR AREA...AND ENOUGH MOISTURE AND FORCING WILL PERSIST TO
MAINTAIN CHANCES OF SHOWERS AND THUNDERSTORMS ACROSS THE REGION
THROUGH EARLY FRIDAY MORNING.

FRIDAY THROUGH MONDAY...AFOREMENTIONED WAVE WILL BE DEPARTING TO
THE NORTHEAST...WHILE AN UPPER LOW STRENGTHENS OVER THE FOUR
CORNERS REGION THROUGH SATURDAY. HIGH PRESSURE TO OUR NORTH WILL
KEEP US DRY FOR SATURDAY...WITH MAINLY NORTHEAST WINDS OF AROUND
10 MPH BY THE AFTERNOON. THIS NEXT LOW WILL LIFT NORTHEAST THROUGH
MONDAY...AND LOOKS TO SPREAD WIDESPREAD RAIN INTO SOUTHERN MN BY
SUNDAY EVENING IN A WAA REGIME. WITH THE SURFACE LOW EXPECTED TO
TRACK TO OUR SOUTH...WE`LL GENERALLY BE ON THE COOL/DEFORMATION
SIDE OF THIS SYSTEM. SO...TEMPERATURES LOOK TO FALL BELOW NORMAL
SUNDAY AND CONTINUE THROUGH AT LEAST MONDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1030 PM CDT TUE MAY 5 2015

CIGS AND VSBYS WILL CONTINUE TO DEGRADE TONIGHT AS A WARM FRONT
LIFTS NORTH ACROSS THE AREA. SCATTERED RAIN SHOWERS ACROSS
CENTRAL MN/WI WILL BE POSSIBLE INTO THE EARLY MORNING HOURS...BUT
MORE WIDESPREAD SHOWERS AND THUNDERSTORMS ARE EXPECTED TO SPREAD
INTO THE WESTERN AREA ON WEDNESDAY AFTERNOON...AND EXPAND EAST-
NORTHEAST ACROSS THE AREA DURING THE EVE. IFR CIGS WILL BECOME
PREVALENT BETWEEN 06Z AND 09Z. VSBYS SHOULD BE PRIMARILY 3SM OR
GREATER...WITH PATCHY FOG POSSIBLE OVERNIGHT. SHOULD SEE
TEMPORARY IMPROVEMENT ON WEDNESDAY MORNING AS THE FIRST WAVE OF
SHOWERS LIFTS NORTH OF THE AREA...AND THEN THE NEXT BATCH MOVES IN
FROM THE WEST DURING THE AFTERNOON...THIS TIME WITH THUNDER
POSSIBLE. SOUTHEAST WINDS THROUGH THE PERIOD...WITH GUSTS
DIMINISHING TONIGHT THEN REDEVELOPING ON WEDNESDAY MORNING.

KMSP...
EXPECT IFR CIGS /BELOW 1000 FT/ THROUGH THE OVERNIGHT...WITH
PATCHY BR AND SHOWERS REMAINING ISOLATED AT BEST. MORE WIDESPREAD
ACTIVITY EXPECTED BY 00Z THU...WITH ISOLD THUNDER POSSIBLE.

/OUTLOOK FOR KMSP/
THU...MVFR CONDS LIKELY WITH IFR CONDS POSSIBLE IN SHRA/TSRA.
WINDS S 17-25 KTS.
FRI...VFR. WINDS NW 7-10 KTS.
SAT...VFR. WINDS NE 10-15 KTS.

&&

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

$$

SHORT TERM...JPC
LONG TERM...ADL/SPD
AVIATION...LS


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