Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 051140
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
640 AM CDT SUN JUL 5 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 346 AM CDT SUN JUL 5 2015

CONCERNS IN THE SHORT TERM ARE CENTERED AROUND CONVECTIVE
TRENDS TODAY AND TONIGHT ALONG WITH THE THREAT OF SEVERE WEATHER
LATE TODAY AND EARLY TONIGHT. OVERALL CONFIDENCE IN THE FORECAST
REMAINS PRETTY HIGH BUT THERE HAVE BEEN SOME CHANGES TO THE
FORECAST WITH REGARDS TO THUNDERSTORM CHANCES FOR TODAY.

EARLY THIS MORNING...SCATTERED THUNDERSTORMS WERE ACROSS EASTERN SD.
THEY ARE LOCATED IN THE AXIS OF LOW LEVEL MOISTURE TRANSPORT ALONG
WITH ELEVATED INSTABILITY. THEY ARE SLOW TO MOVE EAST WITH THE 850-
300MB THICKNESS PATTERN ALMOST N-S ALONG THE SD/MN BORDER.
HOWEVER...AS THE MORNING PROGRESSES THE LOW LEVEL MOISTURE
TRANSPORT WILL WORK INTO WESTERN MN AND EVENTUALLY INTO EASTERN
AREAS THIS AFTERNOON. ALTHOUGH THERE WILL BE A WEAKENING IN THE
LOW LEVEL JET THIS MORNING AS MIXING ENSUES...VARIOUS CAMS SUGGEST
SOME SCATTERED TO WIDELY SCATTERED ACTIVITY WILL PROGRESS INTO OUR
FAR WESTERN CWA. THIS ACTIVITY SHOULD DIMINISH OR END BY LATE
MORNING...TIED TO THE WEAKENING OF THE LOW LEVEL JET.
THEREFORE...SOME CHANCES POPS ARE NOW IN PLACE ACROSS THE WEST
THIS MORNING.

THE CONVECTIVE TRENDS FOR THIS AFTERNOON HAVE LOWER CONFIDENCE AS
SEVERAL THINGS COME INTO PLAY. FIRST...THE AFOREMENTIONED MORNING
ACTIVITY MAY END UP FESTERING ACROSS CENTRAL MN AND THEN REINTENSIFY
THIS AFTERNOON FROM THE TWIN CITIES ON NORTHWARD. THIS IS THE
SCENARIO DEPICTED IN THE ARW AND NMM AS WELL AS THE EXPERIMENTAL
HRRR. THE LATTER SOLUTION GOES AS FAR AS DEVELOPING THINGS ALL THE
WAY BACK TO REDWOOD FALLS. THIS IS PLAUSIBLE AS THE LOW LEVEL
MOISTURE TRANSPORT WILL LIE ACROSS CENTRAL AND SOUTHERN MN THIS
AFTERNOON ALONG WITH BUILDING CAPE. POSSIBLY OFFSETTING THIS WILL BE
A BUILDING CAP. IN ADDITION...THE WESTERLY FLOW IN THE H7-H5 LAYER
CONTAINS SEVERAL PERTURBATION THAT WILL BE MOVING ACROSS THE AREA
DURING THE DAY AIDING IN THE FORCING. SO...A CHANGE MADE OVERNIGHT
WAS TO ADD CHANCE TO LIKELY POPS FROM THE METRO ON NORTH IN THE LATE
AFTERNOON HOURS TODAY WITH CHANCE POPS BACK TO THE SOUTHWEST.

COMPLICATING MATTERS TODAY...WHICH COULD DERAIL ALL OF THE
ABOVE...ARE THUNDERSTORMS OVER EASTERN MT. EARLIER RUNS IN THE NIGHT
OF THE HRRR SHOWED A STRONG BOWING COMPLEX OF STORMS MOVING INTO
WEST CENTRAL MN DURING THE EARLY AFTERNOON HOURS. THE LATEST RUN HAS
WEAKENED THIS TREND...BUT THIS WILL NEED TO BE WATCHED.
OTHERWISE...BY LATE THIS AFTERNOON A COLD FRONT SHOULD MEANDER FROM
NORTH CENTRAL MINNESOTA THROUGH EASTERN SOUTH DAKOTA AND WESTERN
NEBRASKA. STORMS SHOULD INTENSIFY ALONG THE NORTHERN PORTIONS OF THE
FRONT...FROM ABERDEEN SD THROUGH INTERNATIONAL FALLS. CAMS ARE
SUGGESTIVE THAT A BOWING COMPLEX OF STORMS MAY WORK SOUTHWARD ACROSS
OUR FAR WESTERN CWA EARLY IN THE EVENING WITH DAMAGING WINDS. A
SECOND AREA OF STRONG TO SEVERE STORMS WILL LIKELY DEVELOP A LITTLE
LATER SOUTHWEST OF ABERDEEN. THESE STORMS MAY RACE EASTWARD DURING
THE LATE EVENING HOURS AHEAD OF A DEEPENING LOW PRESSURE SYSTEM AND
CAUSE ANOTHER BOUT OF SEVERE WEATHER ACROSS SOUTHERN MN. DAMAGING
WINDS WERE MENTIONED IN THE FORECAST ACROSS THE WEST AND SOUTH WITH
CONFIDENCE BEING PRETTY HIGH.

IN ADDITION TO THE SEVERE WEATHER THREAT...THERE REMAINS A CONCERN
FOR HEAVY RAINFALL TONIGHT. PRECIPITABLE WATER VALUES TONIGHT ARE
FORECAST TO BE AROUND 2.25 INCHES FROM WEST CENTRAL INTO NORTHEAST
MINNESOTA. SREF PROBABILITIES FOR GREATER THAN 2 INCHES OF RAIN IS
IN THIS SAME AREA AND HAS REMAINED QUITE CONSISTENT FOR SEVERAL DAYS
NOW. OUR QPF GRIDS FOR TONIGHT INDICATE A LARGE AREA OF OVER 2
INCHES OF RAIN ACROSS WEST CENTRAL MN WITH 1.25 TO 1.75 ACROSS
CENTRAL MN. AMOUNTS DWINDLE TO BETWEEN A QUARTER AND A HALF INCH
OVERNIGHT FROM ALBERT LEA TO EAU CLAIRE. HOWEVER...THESE AREAS WILL
SEE A GOOD AMOUNT OF RAIN ON MONDAY AS THE FRONT MOVES THROUGH.

FINALLY...BECAUSE OF THE VARYING CONVECTIVE TRENDS TODAY...THE HIGH
TEMPERATURE FORECAST OF MIDDLE TO UPPER 80S MAY BE ON THE LOW SIDE
BASED ON 850MB TEMPERATURES AND THE FACT THAT THE FIRE SMOKE HAS
REALLY DIMINISHED ALOFT. WEST CENTRAL MN IS THE MOST LIKELY AREA FOR
HIGHER HIGHS WITH LOWER TO MIDDLE 90S POSSIBLE IF MORE SUNSHINE
OCCURS ASSOCIATED WITH LESS THUNDERSTORM APPROACHING/DEVELOPING.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 346 AM CDT SUN JUL 5 2015

MAIN CONCERNS IN THE LONG TERM DEAL WITH TIMING THE DEPARTURE OF
PRECIP CHANCES ON MONDAY...THE STRENGTH/PLACEMENT OF A SHORTWAVE THU
NIGHT/FRIDAY...FOLLOWED BY HOW QUICKLY THE SUBTROPICAL RIDGE BUILDS
IN OVER THE SW CONUS OVER THE WEEKEND.

12Z MONDAY WE WILL HAVE A COLD FRONT BISECTING MN FROM ABOUT SIOUX
FALLS TO DULUTH...WITH MOST GUIDANCE INDICATING AROUND A 1002 MB LOW
OVER CENTRAL MN ALONG THIS BOUNDARY. WE WILL BE STARTING OUT WITH
THE THUNDERSTORMS FROM TONIGHT MOVING INTO WRN WI...LIKELY IN A
DECAYING PHASE. DEPENDING ON HOW WELL DEFINED THE SFC LOW IS...WE
COULD HAVE A GOOD DEAL OF STRATIFORM PRECIP TRAILING THE FRONT IN
WRN MN IN THE DEFORMATION REGION WEST OF THE LOW. FOR THE REST OF
THE DAY...WE ARE SEEING SOME TIMING DIFFERENCES WITH HOW QUICKLY
PRECIP MOVES OUT...WITH THE ECMWF HANGING PRECIP BACK A BIT SLOWER
THAN THE NAM/GFS. FAVORED POPS ON MONDAY TOWARD THE FASTER
SOLUTIONS. CURRENT THINKING IS THAT WE WILL SEE RATHER EXTENSIVE
SHOWERS/THUNDERSTORMS PUSH ACROSS THE REGION THROUGH THE
MORNING...WHICH WILL IN TURN PUSH AFTERNOON ACTIVITY MAINLY EAST OF
AN ALBERT LEA TO LADYSMITH LINE. NOT EXPECTING MUCH POST FRONTAL
PRECIP EITHER AS THE SFC LOW WILL BE PUSHING ACROSS LAKE SUPERIOR
DURING THE AFTERNOON...SO THAT WRAP AROUND SHOWER ACTIVITY WILL BE
NORTHEAST OF THE AREA AS WELL BY THE AFTERNOON.

IN THE WAKE OF THIS FRONT...MODELS CONTINUE TO SHOW A 1020MB HIGH
WORKING DOWN OUT OF CANADA...WITH DEWPOINTS BACK DOWN IN THE 40S
ACROSS THE AREA BY TUESDAY MORNING. IN FACT...CURRENT FORECAST FOR
LOWS TUESDAY MORNING IS A BIT HIGHER THAN WHAT THE RAW MODEL BLEND
HAS...WHICH IS UPPER 40S ACROSS CENTRAL MN.
OTHERWISE...TUESDAY WILL BE A GREAT DAY TO SKIP WORK AND DO
SOMETHING OUTSIDE AS WINDS WILL BE LIGHT...SKIES SUNNY WITH HIGHS IN
THE LOWER 70S...WHICH IS ABOUT 10 TO 15 DEGREES BELOW NORMAL. ABOUT
THE ONLY POTENTIAL BLEMISH FOR TUESDAY IS THE THREAT FOR SMOKE TO
ACCOMPANY THE CANADIAN HIGH ONCE AGAIN.

FOR THE REST OF THE WEEK...WE WILL SEE TEMPERATURES GRADUALLY WARM
BACK CLOSER TO NORMAL BY FRIDAY. THERE A FEW CHANCES FOR PRECIP
MENTIONED WED NIGHT AND AGAIN THU NIGHT/FRI...THOUGH SUPPORT FOR
SAID POPS CONTINUES TO LOOK WEAK...ESPECIALLY FOR ANYTHING MIDWEEK.
THE THU NIGHT/FRI PRECIP CHANCES ARE DRIVEN BY THE  GFS/CANADIAN...
WHICH SHOW POTENT LITTLE SHORTWAVE COMING OUT OF THE ROCKIES AND
WORKING TOWARD WI. THE ECMWF HAS THIS WAVE AS WELL...BUT DRIVES IT
SOUTH ACROSS MID MISSISSIPPI VALLEY.

THE WEEKEND STILL LOOKS TO BRING WARMER...MORE HUMID...AND
POTENTIALLY MORE ACTIVE WEATHER AS A SUB TROPICAL RIDGE STARTS
BUILDING TO OUR SW. AS IT DOES SO...ENERGY FROM THE CLOSED UPPER LOW
CURRENTLY WEST OF CALIFORNIA WILL BE WORKING ACROSS THE REGION THIS
WEEKEND. LOTS OF DIFFERENCES IN THE DETAILS...BUT BOTH THE GFS/ECMWF
WOULD SUPPORT HIGHS WORKING BACK UP INTO THE MID/UPPER 80S WITH
DEWPS AROUND 70 FOR NEXT WEEKEND. QUESTION FOR PRECIP WILL BECOME
TIMING/PLACEMENT OF WAVES RUNNING AROUND THE RIDGE...BUT THERE WILL
CERTAINLY BE INCREASING POTENTIAL FOR SOME HEALTHY BOUTS OF
PRIMARILY NOCTURNAL CONVECTION.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 640 AM CDT SUN JUL 5 2015

SCATTERED SHRA AND ISOLATED TSRA WILL WORK ACROSS WESTERN MN
THROUGH MID MORNING BEFORE DISSIPATING. VCSH USED AT KRWF AND
KAXN. REDEVELOPMENT IS EXPECTED TO THE WEST AND NORTH OF THE TWIN
CITIES DURING THE LATE AFTERNOON. SOME OF THIS CONVECTION MAY MOVE
ACROSS THE TWIN CITIES AND INTO WESTERN WI BEFORE WEAKENING IN THE
EARLY EVENING. GUSTY SOUTH WINDS UP TO 25 KNOTS AT THE TAF SITES
THIS AFTERNOON. THE MAIN SHOW STILL APPEARS TO BE STRONG TO
SEVERE CONVECTION DEVELOPING LATE TODAY ALONG A COLD FRONT FROM
NORTH CENTRAL MN THROUGH CENTRAL SD. THIS ACTIVITY SHOULD IMPACT
KAXN...KSTC AND KRWF IN THE EARLY EVENING. STRONG WINDS ARE
EXPECTED WITH THE CONVECTION WITH GUSTS OF 40-45 KTS INSERTED INTO
THE TEMPO GROUPS AS THE STORMS BOW SOUTHWARD ACROSS WESTERN MN.
EVENTUALLY THIS ACTIVITY WILL REACH INTO EASTERN MN AND WESTERN WI
DURING THE OVERNIGHT HOURS. BY THIS TIME...MORE OF A HEAVY RAIN
EVENT IS EXPECTED TO BE UNDERWAY. DUE TO THE VERY MOIST CONDITIONS
DEVELOPING TONIGHT...THE AFOREMENTIONED TAF SITES WILL LIKELY HAVE
LOW MVFR OR EVEN IFR CEILINGS HEADING INTO MONDAY MORNING.

KMSP...SCATTERED SHRA/ISOLATED TSRA IS POSSIBLE DURING THE LATE
AFTERNOON AND EVENING...ESPECIALLY TO THE NORTH AND EAST OF THE
METRO. WIDESPREAD SHRA/TSRA DURING THE OVERNIGHT HOURS AND EARLY
MONDAY MORNING. CEILINGS/VSBYS DURING THESE PERIODS WILL BE MVFR
OR LOWER. GUSTY SOUTH WINDS UP TO 25 KNOTS THIS AFTERNOON.

/OUTLOOK FOR KMSP/

MON AFTN...VFR WITH SHRA ENDING. WINDS NW 15-20 KTS.
TUE...VFR. WINDS NNW 5-10 KTS.
WED...VFR. WINDS S 5-10 KTS.

&&

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

$$

SHORT TERM...RAH
LONG TERM...MPG
AVIATION...RAH


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