Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 042321
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
621 PM CDT SAT JUL 4 2015

.UPDATED FOR 00Z AVIATION DISCUSSION...
ISSUED AT 608 PM CDT SAT JUL 4 2015

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 346 PM CDT SAT JUL 4 2015

THE SHORT TERM CONCERNS CONTINUE TO BE THE SMOKE PLUME TRAVERSING
THE AREA AND THE TIMING OF ANY CONVECTION INTO WESTERN MN SUNDAY
AFTERNOON.

SMOKE IS SLOWLY EXITING TO THE EAST. LATEST MODEL GUIDANCE SUGGESTS
THE BACK EDGE OF THE THICKER SMOKE SHOULD EXIT INTO WESTERN
WISCONSIN AFTER 8 PM.  AFTER THAT...IMPROVING CONDITIONS OVERALL AS
WINDS REMAINS SOUTHERLY THROUGH THE NIGHT.  COULD HAVE SOME VSBY
ISSUES INTO WISCONSIN YET OVERNIGHT WITH LIGHTER WINDS AND THE SMOKE
INVOLVED...BUT THAT TOO SHOULD BE EXITING THAT REGION EARLY SUNDAY
MORNING.

LITTLE CONVECTIVE THREAT THROUGH SUNDAY AFTERNOON...AS THE FRONT
SHOULD REMAIN TO THE NORTHWEST OF THE CWA UNTIL LATE SUNDAY
AFTERNOON. THE LATEST HIRES SOLUTIONS ARE INDICATING THE FRONT
REMAINING NORTHWEST OF THE AREA UNTIL AFTER 00Z MON.   WE DID
INCREASE POPS OVER THE FAR WEST MAINLY IN THE 21Z-00Z PERIOD. THERE
DOES REMAIN A SEVERE WEATHER THREAT...BUT IT SHOULD OCCUR AFTER 00Z
MON.

TEMPERATURES SHOULD BE ABLE TO WARM THROUGH THE 80S MOST AREAS
SUNDAY AFTERNOON...WITH A 90 POSSIBLE INTO THE SOUTHWEST IF CLOUDS
REMAIN THIN THROUGH THE AFTERNOON.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 346 PM CDT SAT JUL 4 2015

MAIN FOCUS DURING THIS PERIOD IS THE SEVERE WEATHER AND HEAVY
RAINFALL/FLOODING THREAT SUNDAY NIGHT AND MONDAY. THE PATTERN FOR
THIS EVENT IS BEGINNING TO LOOK LIKE A MADDOX HEAVY RAIN SYNOPTIC
SETUP WITH VERY DEEP MOISTURE AND STRONG MID LEVEL WINDS AND
DYNAMICS. TYPICALLY THIS CLASSIFICATION OCCURS IN THE COOL SEASON
DUE TO THE KINEMATICS REQUIRED...BUT WE MAY BE TALKING ABOUT IT IN
JULY WHICH IS ALSO PRIVY TO MODERATE INSTABILITY AND SOME OF THE
RICHEST MOISTURE OF THE YEAR. IN FACT...BASED ON THE PRECIPITABLE
WATER FORECASTS ON THE GFS...NAM...AND SREF...VALUES WILL SURPASS
3 STANDARD DEVIATIONS ABOVE NORMAL AND COULD APPROACH ALL TIME
RECORDS OF JUST UNDER 2.5 INCHES. THUS...IT IS LOOKING
INCREASINGLYLIKELY THIS COULD BE A HIGH IMPACT EVENT IN SOME
AREAS AND ONE THAT SHOULD BE WATCHED VERY CLOSELY AS IT ENTERS THE
TEMPORAL DOMAIN OF HI-RES MODELS. THE POTENTIAL FOR HEAVIEST
RAINFALL WILL SHIFT SOMEWHAT IN LATER FORECASTS...SO IT IS NOT
IMPORTANT TO FOCUS ON SPECIFIC DETAILS AT ANY GIVEN POINT YET.

A TROUGH AND ASSOCIATED COLD FRONT WILL BE APPROACHING FROM THE
NORTHWEST SUNDAY AFTERNOON AND WILL REACH WRN MN BY EVENING.
THERE ARE MINOR TIMING DIFFERENCES AMONGST THE MODELS...BUT NONE
ALL THAT SIGNIFICANT. BROAD SOUTH FLOW AHEAD OF THE FRONT WILL
CONTINUE BRINGING MOISTURE NORTHWARD...WITH THE MAXIMUM MOISTURE
TRANSPORT NOT SURPRISINGLY BEING ASSOCIATED OVERNIGHT WITH THE
45-55 KT SOUTHWEST LLJ.

THUNDERSTORMS WILL RAPIDLY DEVELOP ALONG THE FRONT LATE SUNDAY
AFTERNOON ACROSS ERN SODAK IN A VERY FAVORABLE ENVIRONMENT. THE
ARRIVAL OF THE ELEVATED MIXED LATER FROM THE PLAINS ATOP STRONG
HEATING/A MOISTENING BOUNDARY LAYER...AND THE APPROACH OF THE
TROUGH/STRENGTHENING LIFT SHOULD OVERCOME ANY CAPPING. THESE
THUNDERSTORMS WILL BUILD EASTWARD INTO WRN MN THROUGH THE
EVENING...POSSIBLY BECOMING A FORWARD PROPAGATING MCS ACROSS SRN
MN OVERNIGHT IF A COLD POOL CAN ORGANIZE A LA THE HRW-NMM. IT IS
UNCLEAR HOW THIS WOULD IMPACT THE THREAT FOR HEAVY RAINFALL. IT IS
CONCEIVABLE THE DEVELOPMENT OF ANY MCS COULD SHUNT ANY MOISTURE
TRANSPORT TO THE SOUTH AND EAST. HOWEVER...IF THE MCS IS
RELATIVELY WEAK AS IT MAY BE DUE TO LESS THAN OPTIMAL SHEAR...THEN
ADDITIONAL DEVELOPMENT COULD TAKE PLACE OVERNIGHT ALONG ITS SOUTHERN
EDGE AND ON THE NOSE OF THE VEERED LLJ.

ANOTHER SOLUTION MAY BE THAT AN ORGANIZED MCS DOES NOT FORM. IN
THAT CASE THE THREAT FOR EXCESSIVE RAINFALL IS VERY REAL ACROSS
WESTERN AND CENTRAL MN SUNDAY NIGHT INTO MONDAY NEAR A SLOW MOVING
FRONT...WHICH IS ALSO PARALLEL TO THE MEAN FLOW. SLOW MOVING/BACK
BUILDING CELLS WOULD BE POSSIBLE. IN ADDITION...WITH PW VALUES
GREATER THAN 2 INCHES...IT WON/T TAKE TOO MUCH TIME TO ACCUMULATE
SEVERAL INCHES OF RAIN IN SPOTS. A LOW PRESSURE WILL TRAVEL NORTH
ALONG THE FRONT OVERNIGHT AND COULD HELP FURTHER FOCUS AN AREA OF
HEAVY RAIN IN THIS AREA BY PROVIDING MORE LIFT AND SLOWING THE
EASTWARD PROGRESSION OF THE FRONT TO ITS NORTH.

THE LOW WILL LIFT OUT MONDAY MORNING WITH RAIN BEING CONFINED TO
THE TRAILING COLD FRONT OVER ERN MN/WRN WI BY AFTERNOON. WITH
MOISTURE TRANSPORT WEAKENING AND THE FRONT MORE PROGRESSIVE...
EXCESSIVE RAINFALL POTENTIAL DOES EASE BY MONDAY.

LOOKS COOL MID WEEK WITH HIGH PRESSURE BUILDING SOUTHEAST INTO THE
UPPER MIDWEST. BY LATE WEEK AND NEXT WEEKEND...UPPER RIDGING
APPEARS TO BUILD EAST INTO THE CENTRAL PLAINS AND MISSISSIPPI
VALLEY WHICH COULD BRING A MORE ACTIVE PATTERN ON ITS NORTHERN
PERIPHERY. TEMPERATURES WILL ALSO BE WARMING ABOVE AVERAGE DURING
THIS TIME AS WELL.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 608 PM CDT SAT JUL 4 2015

CONDITIONS WILL CONTINUE TO FLUCTUATE BETWEEN VFR/MVFR DO TO THE
RESIDUAL SMOKE/HAZE FROM THE CANADIAN FOREST FIRES. SOUTHERLY
WINDS WILL INCREASE SUNDAY MORNING...WHICH SHOULD HELP TO INCREASE
VISIBILITY. AFTERNOON GUSTS NEAR 20KTS ARE EXPECTED ACROSS THE
REGION. A LINE OF THUNDERSTORMS WILL MOVE IN FROM THE NORTHWEST
SUNDAY EVENING/NIGHT...BUT THIS IS BEYOND THE TIMEFRAME OF THE
TAFS.

KMSP...
SMOKE/HAZE WILL LINGER THIS EVENING CAUSING MVFR CONDITIONS AT
TIMES. CONDITIONS SHOULD IMPROVE AS SOUTHERLY WINDS INCREASE ON
SUNDAY MORNING. AFTERNOON GUSTS NEAR 20 KTS ARE EXPECTED. LOOKING
AHEAD...THUNDERSTORMS SHOULD MOVE INTO THE METRO AFTER 06Z MONDAY.
HAVE VCSH AT 05Z TO HINT AT THEIR ARRIVAL.

/OUTLOOK FOR KMSP/
MON...MVFR/IFR WITH TSRA EARLY...THEN VFR. WINDS NW AT 10-15 KT
TUE...VFR. WIND NNW AT 5-10 KT
WED...VFR. WIND SW AT 5-10 KT

&&

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

$$

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


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