Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 291152
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
652 AM CDT MON JUN 29 2015

.UPDATE...
ISSUED AT 635 AM CDT MON JUN 29 2015

UPDATED TO INCLUDE 12Z AVIATION DISCUSSION BELOW.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 412 AM CDT MON JUN 29 2015

TODAY AND TONIGHT...SFC ANALYSIS SHOWS A LOW PRES CENTER IN CENTRAL
IL...RESPONSIBLE FOR THE SHWRS/TSTMS OF YDA....ALONG WITH A CDFNT
DRAPED OVER QUEBEC/ONTARIO/MANITOBA PROVINCES. IT IS THIS CDFNT...
AS IT SINKS SWD ACRS THE AREA TDA...THAT WILL BE THE FOCUS FOR AFTN
STRONG-TO-SEVERE CONVECTION.

THE FIRST CONCERN FOR TDA WILL BE AREAS OF FOG OVER WRN WI
TDA...RESULTING FROM A HIGHLY MOIST BLYR UNDER THE NIGHTLY INVERSION
WITH CALM WINDS. A NUMBER OF SITES ARE REPORTING 1/4SM WITH CALM
WINDS. THESE CONDS ARE NOT EXPECTED TO IMPROVE THRU DAYBREAK SO HAVE
OPTED TO ISSUE A DENSE FOG ADVY FOR ALL THE W-CENTRAL WI COUNTIES
THRU 9AM CDT THIS MRNG.

GOING INTO THE AFTN HOURS...A FAIRLY EVIDENT H7 SHTWV TROF
DISTURBANCE ON WV IMAGERY EARLY THIS MRNG RIDING SEWD FROM MANITOBA
WITHIN PRONOUNCED NW FLOW ALOFT WILL AID IN CONVECTIVE DEVELOPMENT
OVER MAINLY THE ERN HALF OF THE WFO MPX CWFA LATER TDA. THE
AFOREMENTIONED PLENTIFUL LLVL MOISTURE WILL CONTRIBUTE TO DEWPOINTS
IN THE LWR 60S FOR MUCH OF THE CWFA TDA. IN ADVANCE OF THE
CDFNT...THIS MOISTURE POOLING WILL ALLOW MLCAPES TO INCRS TO ARND
1500 J/KG. MIDLVL LAPSE RATES OF 6-7 DEG C ALONG WITH MODEST SHEAR
AND WEAK CAPPING WILL PROMOTE STRONG-TO-SEVERE TSTM DEVELOPMENT THIS
AFTN INTO THIS EVENING. THE MAIN HAZARD LOOKS TO BE STRONG/DMGG
WINDS IN ASSOCIATION WITH DOWNBURSTS AND OUTFLOW COLLISIONS...WITH
SOME OF THE DEEPER CORES CAPABLE OF PRODUCING LARGE HAIL. THE BEST
TIMING FOR A WINDOW FOR SEVERE WX LOOKS TO BE IN THE 3PM-9PM
TIMEFRAME...MAINLY DUE TO PEAK HEATING OF THE DAY. THE BROAD SWATH
OF THE SFC CDFNT COMBINED WITH THE PATH OF THE SHTWV ALOFT PUTS
VIRTUALLY THE ENTIRE CWFA AT RISK...WHICH IS ALIGNED WELL WITH THE
SWODY1 DEPICTION. THE LOSS OF HEATING SHOULD ALLOW FOR A DIMINISHING
OF THE CONVECTIVE COVERAGE THIS EVENING...SLOWLY MOVING AWAY TO THE
SOUTH AND EAST OVERNIGHT. THERE IS POTENTIAL FOR FOG REDEVELOPMENT
OVERNIGHT INTO EARLY TUE MRNG...ESP SHOULD WINDS DROP OFF ONCE
AGAIN.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 412 AM CDT MON JUN 29 2015

BY TOMORROW MORNING...THE NORTH TO SOUTH ORIENTED JET STREAK WILL BE
OVERHEAD...WITH THE CENTER OF THE UPPER LEVEL TROUGH POSITIONED OVER
THE GREAT LAKES.  ALL THE FORCING WILL HAVE SHIFTED EAST OF OUR
AREA. MEANWHILE...THE NEXT SHORTWAVE WILL BE TOPPING THE WESTERN
RIDGE AND DIVE SOUTHEAST TOWARD THE DAKOTAS.  THE JET STREAK WILL
SHIFT TO OUR EAST...AND THE INCOMING SHORTWAVE AND PV ADVECTION WILL
BE AIDED IN BRINGING LIFT INTO THE CENTRAL DAKOTAS BY THE UPPER
LEVEL DIVERGENCE ASSOCIATED WITH THE RIGHT ENTRANCE REGION OF THE
JET. AS WE HEAD INTO WEDNESDAY...THE LATEST GUIDANCE INDICATES THE
FORCING WILL CONTINUE SOUTHEAST THROUGH THE DAKOTAS TOWARD
IOWA...JUST SKIMMING WESTERN MN AND LEAVING EASTERN MN AND WESTERN
WI DRY.  SO...I ENDED UP TRIMMING THE EASTERN EXTENT OF THE POPS ON
WEDNESDAY...AND LIKELY STILL HAVE BLED TOO FAR EAST BASED ON A BLEND
OF THE NAM/GFS/SREF.  THE ECMWF IS MORE BULLISH IN QPF AMOUNTS
ACROSS THE EASTERN DAKOTAS AND SPREADS AMOUNTS OF 0.1-0.2" INTO
WESTERN MN...WHICH IS WHY I BLED THE POPS EAST OF THE NAM/GFS/SREF.
HOPEFULLY WE`LL SEE SOME CONVERGENCE IN THE GUIDANCE IN THE NEXT
RUNS OF THE MODELS.  I REDUCED QPF QUITE A BIT ACROSS WESTERN MN
BASED ON THE NAM/GFS INDICATING THE FORCING WEAKENING/SKIMMING
WESTERN MN...AND KEPT THE TWIN CITIES AREA DRY.

THE THURSDAY SYSTEM HAS SLOWED DOWN A BIT WITH THE EC BEING A FEW
HOURS FASTER THAN THE GFS IN BRINING DOWN THE NEXT SHORTWAVE IN THE
NORTHWEST FLOW REGIME. THE EC STILL INDICATED LIGHT PRECIP SPREADING
ACROSS THE AREA BY THURSDAY AFTERNOON...SO LEFT THE CHANCE POPS IN
THE SUPERBLEND BE...BUT I WOULDN`T BE SURPRISED TO SEE THE
PROGRESSION SLOWED DOWN IN THE COMING FORECASTS BASED ON THE TREND.
IN FACT...THE GFS SOLUTION WANTS TO INDICATE THAT LOW LEVEL DRY AIR
AND THE SURFACE HIGH OVER THE GREAT LAKES WILL KEEP THE PRECIP AT
BAY ACROSS EASTERN MN AND WESTERN WI...SO WOULD NOT BE AT ALL
SURPRISED IF THURSDAY ENDS UP TO BE A DRY DAY...WITH BETTER CHANCES
FOR PRECIP THURSDAY NIGHT.

LOOKING AHEAD TO INDEPENDENCE DAY WEEKEND...THE UPPER FLOW WILL
BECOME MORE ANTICYCLONIC LATE FRIDAY AND FOR THE 4TH OF JULY...AHEAD
OF A DEEP UPPER LOW PUSHING INTO ALBERTA.  FOR OUR
AREA...INDEPENDENCE DAY LOOKS DRY...WITH PARTLY CLOUDY SKIES AND
HIGH TEMPERATURES NEAR 80. THAT UPPER LOW WILL CONTINUE EAST
THROUGH SUNDAY AND REMAIN NORTH OF THE BORDER...BUT THE TRAILING
COLD FRONT WITH THE SURFACE LOW COULD SPARK WIDESPREAD SHOWERS AND
THUNDERSTORMS SUNDAY AFTERNOON AND NIGHT.


&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 635 AM CDT MON JUN 29 2015

WI TAF SITES WILL DEAL WITH IFR/LIFR FOG THRU APPROXIMATELY 14Z
THEN SHOULD QUICKLY RETURN VFR FOR THE REST OF THE MRNG INTO THE
AFTN. SCATTERED SHWRS/TSTMS WILL THEN DEVELOP BY MID-AFTN OVER
MUCH OF THE COVERAGE AREA...EXCEPT FOR POSSIBLY FAR SWRN MN /WHICH
MAKES RWF THE LEAST LIKELY OF ALL TAF SITES TO EXPERIENCE FLIGHT
COND DETERIORATION/. MOST PERSISTENT SHWRS/TSTMS LOOK TO OCCUR
OVER WI SO HAVE SHOWN THE STRONGEST REDUCTION IN FLIGHT CONDS
THERE...BUT THE NATURE OF THE PRECIP WILL BE HIT-AND-MISS
CONVECTIVE CELLS SO THERE MAY EASILY BE SOME BOUNCING OF CONDS
FROM VFR DIRECTLY TO IFR AND VICE VERSA. SLIGHTLY LESSER CHANCES
OF CONVECTION GOING WEST SO HAVE GONE A LITTLE MORE CONSERVATIVE
FOR KMSP-KSTC-KAXN. THE TIMING AND FLIGHT COND FORECAST MAY WELL
NEED TO BE ADJUSTED BASED ON RADAR TRENDS. CONDS IMPROVE
ALTOGETHER LATE THIS EVENING INTO THE EARLY MRNG AS A COLD FRONT
PUSHES THRU THE REGION. THAT SAID...THERE STILL MAY BE SOME MVFR
GROUND FOG APPROACHING DAYBREAK TUE MRNG.

KMSP...VFR CONDS TO START THE 29/12Z TAF...ALTHOUGH IFR FOG IS NOT
ALL THAT FAR OFF TO THE E PER REMARKS IN MSP METAR. GROUND FOG IS
EXPECTED TO BURN OFF BY AROUND 14Z AND WITH WLY WINDS ON THE WRN
FRINGES OF THE METRO...THE DENSER FOG IS NOT EXPECTED TO REACH
KMSP. HAVE HIGHLIGHTED LATE AFTN INTO THE EARLY EVE FOR BEST SHOT
AT CONVECTION INTO KMSP...BUT IT MAY WELL LAST LONGER THAN THE 4
HOUR TEMPO CURRENTLY ADVERTISED. WILL MONITOR RADAR TRENDS AND
ADJUST AS NEEDED. CONDS IMPROVE LATE THIS EVE THRU OVERNIGHT TO
VFR WITH CONDS EXPECTED TO REMAIN AS SUCH THRU LATE MRNG TUE.

/OUTLOOK FOR KMSP/
TUE...VFR. WINDS NE AT 5-10 KTS.
WED...VFR WITH MVFR -TSRA POSSIBLE. WINDS ENE AT 5-10 KTS.
THU...VFR WITH MVFR -TSRA POSSIBLE. WINDS SE AT 5-10 KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR WIZ014>016-
     023>028.

&&

$$

UPDATE...JPC
SHORT TERM...JPC
LONG TERM...SPD
AVIATION...JPC


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