Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 010506
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1206 AM CDT FRI AUG 1 2014

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 358 PM CDT THU JUL 31 2014

SURFACE ANALYSIS SHOWS EXTENSIVE HIGH PRESSURE OVER MUCH OF THE
NORTH-CENTRAL STATES...THAT WILL PUSH SOUTHEAST INTO THE OHIO
VALLEY THIS PERIOD. THERE IS A WEAK AREA OF LOW PRESSURE OVER
SOUTHEASTERN ONTARIO WITH A COLD FRONT EXTENDING WESTWARD NEAR
THE INTERNATIONAL BORDER. WATER VAPOR IMAGERY CONTINUES TO NICELY
SHOW THE PERSISTENT UPPER LEVEL LOW OVER EASTERN CANADA WITH
SEVERAL SHORTWAVES ROTATING AROUND THE WESTERN AND SOUTHERN
SIDES...ALONG WITH SOLID NORTHWEST FLOW OVER THE NORTH-CENTRAL
STATES. KMPX RADAR INDICATES ANOTHER AFTERNOON OF ISOLATED
SHOWERS/THUNDERSTORMS OVER WESTERN WISCONSIN...WITH THE CELLS
AGAIN DRIVING TO THE SOUTHEAST UNDER THE MEAN NORTHWEST FLOW
ALOFT. THE LACK OF A STRONG SHORTWAVE ON THE WESTERN SIDE OF THE
UPPER TROUGH MEANS EVEN LESSER STORM COVERAGE AND INTENSITY
COMPARED TO YESTERDAY...BUT ENOUGH SUCH THAT 20-30 POPS ARE
REQUIRED FOR THE REST OF THIS AFTERNOON INTO THIS EVENING. ANOTHER
TRANQUIL OVERNIGHT PERIOD TONIGHT IS EXPECTED FOLLOWED BY ANOTHER
AFTERNOON OF SCATTERED SHOWERS AND THUNDERSTORMS FOR WESTERN
WISCONSIN INTO EASTERN MINNESOTA FOR FRIDAY. THE COVERAGE LOOKS TO
BE BETTER FRIDAY DUE TO A MORE PRONOUNCED SHORTWAVE TROUGH AXIS ON
THE WEST SIDE OF THE LARGE TROUGH DROPPING SOUTH THROUGH MN/WI.
ADDING IN MODEST INSTABILITY AND THERE ARE MORE INGREDIENTS
AVAILABLE FOR GREATER COVERAGE AND INTENSITY OF STORMS FOR FRIDAY
AFTERNOON. NOT LOOKING FOR ANY ORGANIZED SEVERE WEATHER BUT AN
ISOLATED STRONG TO SEVERE STORM CONTAINING LARGE HAIL AND/OR
STRONG WIND GUSTS CANNOT BE RULED OUT. AS FOR TEMPERATURES...MORE
OF THE SAME. HIGHS ON FRIDAY LOOK TO BE NEARLY IDENTICAL TO TODAY
FOR THE ENTIRE COVERAGE AREA...WITH HIGHS HITTING THE UPPER 70S TO
LOWER 80S. LOW TEMPERATURES TONIGHT LOOK TO BE SLIGHTLY
HIGHER...OWING TO A MORE SOUTHERLY COMPONENT IN THE LOW LEVEL
WINDS...ALBEIT QUITE LIGHT. MINIMUM TEMPERATURES LOOK TO RANGE
FROM THE MIDDLE 50S TO LOWER 60S.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 358 PM CDT THU JUL 31 2014

FOR THE EXTENDED...WE ARE STILL LOOKING FOR A WETTER SYSTEM TO
IMPACT THE AREA IN THE TUESDAY/WEDNESDAY TIME FRAME AS WE
DEAMPLIFY THE PATTERN THAT HAS BEEN WITH US ALL OF THIS WORK.
ALTHOUGH MORE WIDESPREAD PRECIPITATION WILL BE A CHANGE FROM THIS
WEEK...THE ONE THING THAT WILL NOT BE CHANGING MUCH WILL BE OUR
TEMPERATURES...WHICH WILL CONTINUE TO RUN SLIGHTLY BELOW TO NEAR
NORMAL.

THE LONG TERM PERIOD WILL START WITH WHAT WILL BE THE FINAL
SHORTWAVE TO ROTATE AROUND THE WRN PERIPHERY OF THE ERN NOAM
TROUGH...MOVING SE OF THE MPX AREA FRIDAY EVENING. SUBSIDENCE AND
BUILDING HEIGHTS IN THE WAKE OF THIS WAVE WILL LEAD TO YET ANOTHER
CLEAR NIGHT FRIDAY NIGHT...FOLLOWED BY A DRY DAY SATURDAY THAT WILL
ALSO BE A FEW DEGREES WARMER THAN WHAT WE HAVE SEEN THIS WEEK.

ALTHOUGH WE WILL BE DRY ON SATURDAY...A WEAK COLD FRONT WILL BE
DIPPING INTO NRN MN...THAT WILL BE INTO CENTRAL MN BY SATURDAY
MORNING. FROM SATURDAY MORNING THROUGH TUESDAY...THIS FRONT WILL
MORE OR LESS STALL OUT BETWEEN CENTRAL MN AND NRN IA...WHICH MEANS
FROM SUNDAY THROUGH TUESDAY...THERE ARE BASICALLY CHANCE POPS EVERY
DAY AS THIS FRONT LOITERS IN THE REGION. FORCING EACH DAY DOES NOT
LOOK ALL THAT IMPRESSIVE...MAINLY CONSISTING OF WEAK WAVES ROTATING
AROUND THE NE PERIPHERY OF THE ROCKIES RIDGE. EACH WAVE WILL LEAD TO
A SLIGHT INCREASE IN SRLY LOW LEVELS WINDS AND ASSOCIATED ISENTROPIC
LIFT OVER THE FRONT...INCREASING CHANCES FOR PRECIP. HOWEVER...THERE
IS QUITE A BIT OF SPREAD IN THE MODELS WITH TIMING OF THESE SUBTLE
FEATURES...HENCE THE FAIRLY WIDESPREAD SMEARING OF LOW CHANCE POPS
ACROSS THE AREA FROM SUNDAY THROUGH MONDAY NIGHT.

THE SIGNAL FOR MORE WIDESPREAD PRECIP BEGINS TO INCREASE TUESDAY AND
LOOKS BEST TUESDAY NIGHT INTO WEDNESDAY MORNING....WHERE POPS WERE
INCREASED INTO THE LIKELY CATEGORY. DURING THE DAY ON TUESDAY...AN
UPPER LOW THAT WILL ORIGINATE IN THE SW MONSOON THIS WEEKEND WILL
BEGIN EMERGING OUT OF THE NRN ROCKIES. AS THIS HAPPENS...A LEE SIDE
TROUGH WILL BEGIN TO DEVELOP FROM WRN SODAK DOWN THROUGH EASTERN
COLORADO AND WILL MOVE ALONG THE FRONT STALLED OUT ACROSS THE PLAINS
TUESDAY AND WEDNESDAY. A STRENGTHENING LLJ AHEAD OF THIS TROUGH WILL
RESULT IN INCREASED ISENTROPIC LIFT ACROSS THE NEARBY
BOUNDARY...WITH AFTERNOON STORM COVERAGE EXPECTED TO INCREASE AS A
RESULT. BOTH THE GFS/ECMWF ARE NOW SHOWING A GOOD SLOW MOVING MCS
SIGNAL ACROSS SRN MN TUESDAY NIGHT AS DIFFERENTIAL DIVERGENCE
BECOMES MAXIMIZED WITHIN THE RIGHT ENTRANCE REGION OF AN UPPER JET
STREAK THAT WILL COINCIDE WITH A 30-40 KT LLJ NOSING UP INTO SRN MN.
THIS HAS BEEN A VERY CONSISTENT SIGNAL IN THE ECMWF THE LAST SEVERAL
RUNS...HENCE INCREASING POPS UP INTO THE LIKELY CATEGORY TUESDAY
NIGHT. BOTH THE GFS AND ECMWF SHOW A NICE 2-4 INCH QPF SWATH WORKING
ACROSS THE HEART OF THE MPX CWA AND WORKING ACROSS CENTRAL WI. WE
SHOULD MORE OR LESS GET ON THE BACK SIDE OF THIS SYSTEM WEDNESDAY
NIGHT...WITH THE END OF NEXT WORK WEEK LOOKING TO BE DRY.

THOUGH NO WIDESPREAD SEVERE WEATHER IS EXPECTED...BEING ON THE
PERIPHERY OF THE UPPER RIDGE...WE WILL BE MAINTAINING H5 WINDS
AROUND 30KTS...WHICH WILL KEEP BULK SHEAR UP AROUND 30 KTS AS
WELL...SO SOME ISOLATED SEVERE STORMS CAN NOT BE RULED OUT ANY DAY
FROM SUNDAY THROUGH WEDNESDAY. THE BEST POTENTIAL FOR SEVERE
WEATHER WOULD BE TUESDAY NIGHT GIVEN THE POTENTIAL FOR AN
MCS...THOUGH THE HEAVY RAIN SIGNAL LOOKS BETTER THAN THE SEVERE
RISK. FORTUNATELY...WE HAVE BEEN DRY THE LAST 3 OR 4 WEEKS...SO THE
FLASH FLOOD RISK WILL BE NO WHERE NEAR AS HIGH AS WHAT WE WERE
DEALING WITH IN JUNE.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1156 PM CDT THU JUL 31 2014

ISOLATED STORMS CONTINUE OVER A SMALL AREA OF WEST CENTRAL
WISCONSIN AFFECTING THE KEAU AREA. THIS IS ASSOCIATED WITH WEAK
SHORT WAVE DRIFTING ACROSS THE AREA...WITH STEEP MID LEVEL LAPSE
RATES.  WILL CONTINUE TO MENTION VCSH FOR ABOUT AN HOUR INTO THE
TAF. THEN CLEARING EXPECTED. LIGHT WINDS AND SMALL TEMP/DEWPT
SPREADS COULD GENERATE SOME PATCHY MVFR VSBYS/FOG INTO WEST
CENTRAL WI/CENTRAL MN. WILL MENTION THAT POSSIBILITY AT KEAU/KRNH
AND KSTC FOR NOW...IN THE 10Z-13Z PERIOD. THEN THE NEXT SHORT WAVE
TO AFFECT MAINLY EASTERN AREAS IN THE 18Z-02Z PERIOD. WILL MENTION
A PROB30 THUNDER THREAT OVER THE EASTERN SITES FOR NOW. MAY HAVE
TO EXPAND FURTHER NORTHWEST IF WAVE SLOWS A BIT. WINDS WILL BE
LIGHT INTO FRIDAY AS WELL...PERHAPS MORE OF A NW-N WIND DIRECTION
AND LESS THAN 10KTS.

KMSP...VFR INTO FRIDAY WITH VCSH MENTIONED BEGINNING AT 19Z AND
PROB390 THUNDER MENTIONED FROM 19Z-23Z AS ANOTHER WEAK WAVE DROPS
OVER THE AREA. SHOULD END BY 02Z WITH CLEARING THEREAFTER. LIGHT
WINDS INTO THE MORNING...BECOMING MORE NW-N DURING THE LATER
MORNING/AFTERNOON. THEY WILL SLACKEN INTO FRIDAY EVENING AS WELL.

/OUTLOOK FOR KMSP/
SAT...VFR. WINDS VARIABLE 5 KTS.
SUN...VFR. SLIGHT CHANCE TSRA. WINDS SW 5-10 KTS.
MON...VFR. CHANCE TSRA. WINDS SW 5-10 KTS.

&&

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

$$

SHORT TERM...JPC
LONG TERM...MPG
AVIATION...DWE






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