Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 292359 AAA
AFDMPX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
659 PM CDT WED JUL 29 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 221 PM CDT WED JUL 29 2015

EARLY AFTERNOON SATELLITE IMAGERY SHOWED AN IMPRESSIVE CYCLONE IN
EASTERN ONTARIO...WITH 90 DEGREE TEMPS IN THE WARM SECTOR REACHING
AS FAR NORTH AS THE SHORES OF JAMES BAY. COLD AIR CONTINUED TO WRAP
AROUND THE SOUTHERN SIDE OF THIS CYCLONE...AND THIS CANADIAN
AIRMASS WAS RESPONSIBLE FOR THE SEASONABLY DRY DEWPOINTS OVER THE
UPPER MIDWEST.

LATER THIS EVENING THE WESTERLY WIND GUSTS WILL SUBSIDE...AND
OVERNIGHT LOWS WILL FALL TO NEAR 60 ACROSS THE REGION WHICH IS RIGHT
AROUND CLIMATOLOGY FOR LATE JULY. ON THURSDAY THE WIND GUST WILL
PICK UP AGAIN...BUT HAVE A SLIGHT NORTHERLY COMPONENT. NO CHANCE OF
RAIN IS EXPECTED WITHIN THE NEXT 36 HOURS.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 221 PM CDT WED JUL 29 2015

THE LONGER TERM STILL LOOKS RELATIVELY QUIET... WITH THE MOST
INTERESTING PERIOD IN TERMS OF PCPN LOOKING TO BE OVER THE
WEEKEND. IN THE BIG PICTURE... NORTHWEST UPPER FLOW STILL LOOKS TO
PREDOMINATE THROUGH THE PERIOD... WITH THE EXTENDED GUIDANCE ALL
IN BASIC AGREEMENT ON THAT. SO... CHANCES FOR PCPN WILL BE MAINLY
TIED TO SHORTWAVES DROPPING SOUTHEAST THROUGH THE AREA AND THEIR
ATTENDANT WEATHER SURFACES LOWS/WAVES. NONE OF THESE APPEAR TO
HAVE SUFFICIENT MOISTURE/INSTABILITY TO DO ANYTHING UNTIL THE
SATURDAY/SUNDAY TIME FRAME. THE GFS AND ECMWF BOTH SHOW ONE SUCH
FEATURE MOVING THROUGH THE REGION LATE SATURDAY
AFTERNOON/EVENING... WITH THE SOUTHWEST PORTION OF THE AREA LIKELY
HAVING THE BEST SHOT OF SEEING PCPN DEVELOP AND/OR AN UPSTREAM MCS
MOVE THROUGH THE AREA. HOWEVER... CHANCE POPS DO INCLUDE ALL OF
THE AREA GIVEN UNCERTAINTY IN WHERE THE SHORTWAVE WILL TRACK AND
HOW FAR NORTH ELEVATED INSTABILITY WILL EXTEND. CURRENTLY...
SUNDAY IS POP-FREE... WITH CHANCE POPS ADVERTISED ONCE AGAIN FOR
SUNDAY NIGHT. THIS IS WITH ANOTHER NORTHWEST FLOW WAVE DROPPING
THROUGH THE AREA. THE GFS HAS A MORE SUBSTANTIAL SURFACE FEATURE
THAN THE ECMWF SUNDAY AFTERNOON/EVENING... BUT BOTH MANAGE TO
DEVELOP SOME PCPN OVER THE REGION BY SUNDAY NIGHT. TIMING CHANGES
COULD CERTAINLY LEAD TO POPS BEING INCLUDED A BIT EARLIER ON
SUNDAY IN SUBSEQUENT FORECASTS... SO IT WILL BEAR WATCHING. IN
ADDITION... THE GFS MANAGES TO BRING MLCAPE VALUES AOA 2000 J/KG
INTO MOST OF THE AREA AHEAD OF THIS FEATURE... AND WITH DECENT
MID-UPPER LEVEL NORTHWEST FLOW THE DEEP LAYER SHEAR IS AOA 40KT.
SO... AT THE CURRENT TIME IF WE/RE GOING TO HAVE ANY TIME PERIOD
FOR MORE ROBUST CONVECTION ACROSS THE AREA IT MAY BE WITH THE
SYSTEM MOVING THROUGH LATER ON SUNDAY. CWASP VALUES FROM THE GFS
SUNDAY EVENING ARE IN THE 50-70 RANGE... SO ALTHOUGH NOT
OVERWHELMING DO AT LEAST SUGGEST SOME POTENTIAL FOR STRONGER
STORMS SHOULD THINGS DEVELOP. AFTER THAT.... WE LOOK TO SEE SOME
RIDGING AND DRY WEATHER ON MONDAY BEFORE CHANCES FOR PCPN RETURN
LATER TUESDAY INTO WEDNESDAY AS THE UPPER RIDGE STARTS TO FLATTEN
AND SHIFT A BIT EASTWARD AND WE SEE BETTER LOW LEVEL MOISTURE WORK
INTO THE REGION.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 659 PM CDT WED JUL 29 2015

WEST WINDS WILL EASE EARLY THIS EVENING AND FALL TO LESS THAN 10
KT TONIGHT BEFORE INCREASING AGAIN THURSDAY. VFR CONDITIONS
EXPECTED.

KMSP...NO ADDITIONAL CONCERNS.

/OUTLOOK FOR KMSP/
FRI...VFR. WIND NW 10 KT.
SAT...VFR WITH MVFR/TSRA POSSIBLE LATE. WIND SW AT 5-10 KT.
SUN...VFR. WIND S AT 5 KT.

&&

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

$$

SHORT TERM...JRB
LONG TERM...
AVIATION...BORGHOFF



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