Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 190910
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
410 AM CDT SAT JUL 19 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 410 AM CDT SAT JUL 19 2014

THE BROKEN LINE OF STORMS THAT FORMED OVER THE DAKOTAS HAS ADVANCED
INTO THE NORTHWEST HALF OF MINNESOTA OVERNIGHT...BUT IS NOW IN A
WEAKENING PHASE AS FORCING ALONG THE FRONT DIMINISHES AND
INSTABILITY WANES. UP UNTIL THE LAST SET OF RUNS...THE CAMS
INCLUDING HRRR AND HOPWRF HAVE INDICATED THIS ACTIVITY WILL RE-FIRE
LATER THIS MORNING. FORECAST SOUNDINGS ARE VERY MEAGER WITH
INSTABILITY DUE TO POOR LAPSE RATES...AND THE FRONT ESSENTIALLY
WASHES OUT. THUS...KEPT ONLY A SLIGHT CHC OF THUNDERSTORMS ACROSS
WESTERN AND CENTRAL MN THIS MORNING DUE TO ONGOING ACTIVITY BUT
REMOVED CHANCES FOR THE REST OF THE PERIOD...INCLUDING TONIGHT.
HIGHS TODAY WILL BE QUITE SIMILAR TO YESTERDAY IN THE UPPER 70S TO
MID 80S.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 410 AM CDT SAT JUL 19 2014

AN UPPER LEVEL RIDGE WILL BUILD ACROSS THE UPPER MISSISSIPPI
VALLEY FROM SUNDAY THROUGH MONDAY NIGHT WITH HEAT AND HUMIDITY
INCREASING DRAMATICALLY. HIGHS IN THE LOWER 90S ARE LIKELY ACROSS
WEST CENTRAL MN SUNDAY AFTERNOON WITH 90 TO 95 ACROSS CENTRAL AND
SOUTHERN MN ON MONDAY. DEW POINTS WILL RISE INTO THE MIDDLE 70S
ACROSS WEST CENTRAL MN ON SUNDAY WITH MIDDLE 70S COMMON ACROSS
ALL OF THE FA ON MONDAY. SURFACE DEW POINT FORECASTS FROM BOTH THE
ECMWF AND GFS SHOW POCKETS OF 80 DEG DP/S. APPARENT TEMPERATURE
FORECASTS FOR MONDAY ARE FROM 100 TO 105 FROM THE TWIN CITIES ON
WEST TO THE SD BORDER AS WELL AS INTO CENTRAL MN. SOME AREAS OF
105 TO 110 ARE NOTED IN WEST CENTRAL MN. CONTEMPLATED ON ISSUING
AN EXCESSIVE HEAT WATCH FOR A LARGE PART OF THE MN CWA FOR MONDAY
AFTERNOON AND EVENING DUE TO THE EXCESSIVE INDICES IN WEST CENTRAL
MN BUT COLLABORATION ISSUES AND THE DURATION OF THE EXCESSIVE
HEAT (ONLY ONE DAY) PUT A DAMPER ON THAT. HOWEVER...AN EXCESSIVE
HEAT WATCH WAS ISSUED FOR THE TWIN CITIES METRO FOR THE
AFOREMENTIONED PERIOD WHERE RULES ARE A LITTLE DIFFERENT. AS IT
STANDS...THE METRO AREA MEETS EXCESSIVE HEAT WARNING CRITERIA FOR
MONDAY AFTERNOON AND EARLY EVENING WITH INDICES FROM 100 TO 105
DEGREES. IN ADDITION...A FRONTAL BOUNDARY SLIPPING SOUTHWARD
INTO THE AREA MONDAY NIGHT AND TUESDAY IS SHOWING SIGNS OF
SLOWING. BOTH THE ECMWF AND GFS INDICATE A COMPLEX OF STORMS
PASSING ACROSS CENTRAL MN AND ADJOINING AREAS OF WEST CENTRAL WI
EARLY TUESDAY MORNING. IF THIS SCENARIO LOOKS LIKE IT WILL
HOLD...THEN THE EXCESSIVE HEAT WATCH WOULD NEED TO BE EXTENDED
THROUGH THE NIGHT ACROSS THE TWIN CITIES AS OVERNIGHT LOWS WOULD
LIKELY BE NEAR 80 DEGREES WITH THE DEW POINT NEAR 75. IN FACT...A
YEAR AGO AND A DAY...7/18/13...MSP HAD A HIGH OF 94 WITH A LOW OF
80 WITH HEAT RELATED PRODUCTS IN EFFECT. THIS ALSO RAISES A RED
FLAG ABOUT HEAT RELATED PRODUCTS THAT MAY BE NEEDED ACROSS
SOUTHERN MN ON TUESDAY AS THE HEAT AND HUMIDITY PEAK AHEAD OF THE
BOUNDARY. AGAIN...BOTH MONDAY NIGHT AND TUESDAY ARE DEPENDENT ON
WHERE THE STORMS OCCUR. IN SUMMARY...CONFIDENCE IS HIGH THAT WE
WILL NEED AN EXCESSIVE HEAT WARNING FOR THE TWIN CITIES ON MONDAY
WITH AT LEAST AN ADVISORY FOR THE REMAINDER OF CENTRAL AND
SOUTHERN MN.

NOW ABOUT THE STORM POTENTIAL MONDAY NIGHT AND TUESDAY WITH THE
FRONTAL BOUNDARY. THIS IS SETTING UP TO BE AN EXCESSIVE RAINFALL
EVENT. PRECIPITABLE WATER VALUES ARE PROGGED BY THE GFS TO REACH
2.5 INCHES AT 12Z ON TUESDAY JUST NORTH OF THE METRO. THIS WOULD
BE A MAX PW RECORD IF IT OCCURS. THE ECMWF HAS BEEN CONSISTENT ON
SHOWING A BAND OF 2 TO 4 INCH RAINFALL ACROSS CENTRAL MN LATE
MONDAY NIGHT/EARLY TUESDAY. THE GFS IS CATCHING ON AND HAS BEEN
MOVING ITS MAX RAINFALL AREA NORTHWARD OVER THE PAST FEW RUNS. IT
NOW HAS A 3 TO 5 INCH AREA EARLY TUESDAY CENTERED JUST SOUTH OF
HIGHWAY 8 IN WEST CENTRAL WI. THIS IS PLAUSIBLE WITH THE HIGH PW
FORECAST. THE AREAS DEPICTED ARE AT THE NOSE OF STRONG 925-850MB
MOISTURE TRANSPORT. AT 500 MB...THERE IS A CORE OF 50 KNOT WINDS
PASSING JUST TO OUR NORTH. THUNDERSTORM EVENTS IN THE PAST
FOLLOWING EXCESSIVE HEAT HAVE LEAD TO DAMAGING WIND EVENTS WHICH
IS CERTAINLY EVIDENT IN THE CIPS ANALOGS.

WE WILL FINALLY BE IN THE WAKE OF THE FRONTAL BOUNDARY BY
WEDNESDAY WITH COOLER AND LESS HUMID CONDITIONS INTO FRIDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1233 AM CDT SAT JUL 19 2014

MAIN CONCERN FOR THE OVERNIGHT WILL BE THE BROKEN LINE OF STORMS
ACROSS FAR WEST CENTRAL MN THROUGH NORTH CENTRAL MN AND ITS
EVOLUTION. MODELS ARE INSISTING THIS ACTIVITY WILL DIMINISH DURING
THE NEXT FEW HOURS BEFORE REGENERATING TOWARD DAWN ACROSS CENTRAL
MN. NOT ENTIRELY BUYING INTO THIS SCENARIO YET AND LEFT ALL TAF
SITES DRY FOR NOW THROUGH SATURDAY. THERE MAY BE A POP UP STORM OR
TWO SATURDAY AFTERNOON...BUT INSTABILITY APPEARS VERY MEAGER AND
FORCING IS WEAK. THEREFORE...VFR CONDITIONS ARE HIGHLY LIKELY
THROUGH THE PERIOD UNLESS A ROGUE STORM HAPPENS TO POP UP
OVERHEAD.

KMSP...NO ADDITIONAL SIGNIFICANT CONCERNS.

/OUTLOOK FOR KMSP/
SUN...VFR. SOUTH WIND 10-15 KTS WITH GUSTS TO 20 KTS.
MON...VFR. SOUTH WIND 10 KTS.
TUE...MVFR POSSIBLE WITH A CHANCE OF SHRA/TSRA. SOUTH WIND 5 TO 15
KT BECOMING WEST TUESDAY AFTERNOON.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...EXCESSIVE HEAT WATCH FROM MONDAY AFTERNOON THROUGH MONDAY
     EVENING FOR MNZ060>063-068>070.

WI...NONE.
&&

$$

SHORT TERM...BORGHOFF
LONG TERM...RAH
AVIATION...BORGHOFF





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