Area Forecast Discussion
Issued by NWS Twin Cities, MN

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KMPX 191755
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1255 PM CDT SAT JUL 19 2014

.UPDATE...
ISSUED AT 1240 PM CDT SAT JUL 19 2014

UPDATED TO INCLUDE 18Z AVIATION DISCUSSION BELOW.

&&

.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 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1240 PM CDT SAT JUL 19 2014

VFR CONDS XPCTD AT ALL SITES THRU THE NEXT 24 HRS. A WEAK CDFNT
LINGERING IN NW MN WILL KEEP CLOUD COVER OVER MUCH OF S-CENTRAL MN
INTO WRN WI THRU TMRW AFTN...MAINLY HIGH CLOUDS...WITH SOME MIDLVL
CU MIXED IN FROM TIME TO TIME. PRECIP ECHOES ARE FEW AND FAR
BETWEEN...AND THAT WILL CONTINUE TO BE THE CASE THRU TMRW WITH
FORCING LACKING TO PRODUCE PRECIP. SW WINDS THRU THIS EVE WILL
BECOME SLY TNGT THRU TMRW...AND BECOME BREEZY/GUSTY AFTER
DAYBREAK TMRW.

KMSP...VFR THROUGHOUT WITH NO SIGNIFICANT CONCERNS.

/OUTLOOK FOR KMSP/
MON...VFR. S WIND 10 KTS.
TUE...MVFR PSBL WITH CHC SHRA/TSRA. S WIND 5-15 KT BCMG W.
WED...VFR. N WIND 10 KTS.

&&

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

WI...NONE.
&&

$$

UPDATE...JPC
SHORT TERM...BORGHOFF
LONG TERM...RAH
AVIATION...JPC





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.