111
FXUS63 KMPX 131945
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
245 PM CDT MON JUL 13 2020
SHORT TERM
(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 244 PM CDT MON JUL 13 2020
THE MAIN STORY FOR THE SHORT TERM IS THE SEVERE WEATHER RISK
ACROSS MUCH OF THE AREA. A SURFACE LOW AND AN ASSOCIATED COLD
FRONT IS SITUATED IN CENTRAL NORTH DAKOTA AND WILL CONTINUE TO
MOVE OFF TO THE NORTHEAST THROUGH TOMORROW. CLEAR SKIES THROUGH
MUCH OF THE MORNING AND INCREASING SOUTHERLY WINDS HAVE ALLOWED
TEMPERATURES TO WARM INTO THE 80S WITH DEW POINTS IN THE MID TO
UPPER 60S. WINDS ARE ESPECIALLY STRONG ACROSS WESTERN MINNESOTA
WITH GUSTS OF 25-30+ KTS. A CU FIELD STARTED POPPING UP AROUND 18Z
ACROSS SOUTHERN MINNESOTA AND WESTERN WISCONSIN WHILE CLOUD COVER
AHEAD OF AN ONGOING AREA OF CONVECTION ASSOCIATED WITH THE
AFOREMENTIONED SURFACE LOW MAKES ITS WAY INTO WESTERN MINNESOTA.
EXPECT CLOUD COVER TO CONTINUE TO INCREASE THROUGH THE REMAINDER
OF THE AFTERNOON.
WHILE THE 12Z SOUNDING FROM MPX SHOWS A STRONG CAPPING INVERSION,
EXPECT THAT TO ERODE BY LATE THIS AFTERNOON AND EVENING. OUR 12Z
SOUNDING ALSO DID NOT HAVE PARTICULARLY IMPRESSIVE LAPSE RATES,
BUT FURTHER TO THE WEST, THE 12Z ABR SOUNDING SHOWED MUCH BETTER
INSTABILITY WITH A 700MB-500MB LAPSE RATE OF 7.9C/KM. MODELS SHOW
THIS BETTER INSTABILITY MOVING WESTWARD INTO OUR AREA BY THIS
EVENING. WHILE THERE WILL BE PLENTY OF CAPE ACROSS CENTRAL AND
SOUTHERN MINNESOTA, THE BETTER SHEAR LOOKS TO BE IN NORTHERN
MINNESOTA AND BACK INTO NORTH DAKOTA. CAMS SUGGEST THAT A FEW
DISCRETE CELLS MAY FORM LATE THIS EVENING, WITH ALL SEVERE HAZARDS
POSSIBLE, BEFORE THINGS TRANSITION TO MORE OF A LINEAR MODE WITH
DAMAGING WINDS BECOMING THE MAIN THREAT. THIS LINE OF STORMS WILL
MOVE SOUTHEAST ACROSS THE STATE AND WILL WEAKEN SOME AS IT
APPROACHES THE TWIN CITIES METRO BY AROUND MIDNIGHT. EXPECTING
THIS LINE TO DISSIPATE FURTHER AS IS GETS OUT OF THE MORE
FAVORABLE ENVIRONMENT ACROSS SOUTHEASTERN MINNESOTA/WESTERN
WISCONSIN.
HOWEVER, WE'RE NOT DONE YET... THE COLD FRONT WILL MOVE THROUGH
THE REGION ON THE HEELS OF THIS ACTIVITY TUESDAY BRINGING
ANOTHER ROUND OF HEAVY RAIN. THERE WILL BE PLENTY OF MOISTURE WITH
PWATS NEARING 2". THIS, COMBINED WITH ANY PREVIOUS RAINFALL FROM
MONDAY'S ROUND OF ACTIVE WEATHER, WILL LEAD TO TWO DAY RAINFALL
TOTALS OF WELL OVER AN INCH IN MANY PLACES. RAIN AND CLOUD COVER
THROUGH THE MAJORITY OF THE DAY WILL PREVENT TEMPERATURES FROM
REACHING EVEN 80 DEGREES IN MOST LOCALES, WHICH WILL BE SOME OF
THE COOLEST DAYTIME HIGHS WE'VE SEEN IN ABOUT THREE WEEKS. BY
TUESDAY EVENING, THE FRONT MOVES ON AND TAKES THE RAIN AND CLOUD
COVER WITH IT, BRINGING CLEARING SKIES FROM WEST TO EAST
OVERNIGHT.
LONG TERM
(WEDNESDAY THROUGH MONDAY)
ISSUED AT 244 PM CDT MON JUL 13 2020
HIGH PRESSURE WILL MOVE INTO THE UPPER MIDWEST FOLLOWING THE COLD
FRONTAL PASSAGE TUESDAY NIGHT. TEMPERATURES AND DEWPOINTS WILL
ALSO DECREASE AND WEDNESDAY'S WEATHER WILL BE VERY COMFORTABLE
WITH MOSTLY SUNNY SKIES, LIGHT WINDS, AND HIGHS IN THE LOW 80S.
THURSDAY WILL BE SLIGHTLY WARMER, AS THE CANADIAN CONTINENTAL
AIRMASS ONLY STAYS FOR A QUICK VISIT BEFORE IT IS KICKED OUT BY
SOUTHWESTERLY FLOW FROM THE HIGH PLAINS. A SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS ACROSS CENTRAL MN EXISTS, AS THE TAIL-
END IMPULSE OF THE TROUGH MOVING INTO THE NORTHERN PLAINS TODAY
PASSES THROUGH. HOWEVER, MEAGER LIFT SHOULD LIMIT PRECIPITATION
COVERAGE. THE STRONGER LOW-LEVEL SOUTHWESTERLY WAA BEGINS TOWARDS
THURSDAY NIGHT AS RIDGING SHIFTS INTO SOUTH-CENTRAL CANADA IN
ADVANCE OF A SHORTWAVE TROUGH IN THE PACIFIC NORTHWEST. FORECAST
MODELS DO TRY TO DEVELOP SOME OVERNIGHT CONVECTION ACROSS EASTERN
SD AND SOUTHERN MN FROM THE WAA THURSDAY NIGHT. HOWEVER, WITH 850
MB TEMPERATURES NEARING 20 DEGREES C CAPPING MAY VERY WELL LIMIT
CONVECTIVE DEVELOPMENT.
THE GFS CONTINUES TO BE THE OUTLIER WITH REGARD TO TEMPERATURES ON
FRIDAY. IT PRODUCES A RATHER LARGE AREA OF QPF OVER MN FRIDAY
MORNING AND AFTERNOON, WHICH LIMITS THE NORTHWARD ADVANCEMENT OF
THE SURFACE WARM FRONT. ON THE OTHER HAND, THE ECMWF LIMITS THE
REGIONAL EXTENT OF CONVECTION TO IA AND SOUTHERN MN AS WELL AS THE
DURATION. BECAUSE OF THIS, FORECAST HIGHS FOR FRIDAY FOR THE
ECMWF ARE IN THE UPPER 80S (ABOUT 7 DEGREES WARMER THAN THE GFS).
QUITE UNCOMFORTABLE WEATHER BEGINS FRIDAY NIGHT AS FORECAST LOWS
ARE PROJECTED TO BE IN THE LOW 70S FOR SOUTHERN MN TO NEAR 70
ELSEWHERE. DEWPOINTS WILL INCREASE INTO THE LOW 70S ON SATURDAY
AND HIGH TEMPERATURES INTO THE LOW-90S. AS ONE MAY EXPECT WITH THE
LARGE AMOUNTS OF HEAT AND MOISTURE, THERE SHOULD BE NO SHORTAGE
OF INSTABILITY FOR CONVECTION. MODELS PRODUCE QPF OVER MOST OF THE
NORTHERN PLAINS THROUGHOUT SATURDAY AS THE AFOREMENTIONED PACIFIC
NORTHWEST TROUGH IMPINGES ON OUR REGION. THUNDERSTORMS ARE LIKELY
WITH ANY OF THE PRECIPITATION THAT DEVELOPS AND SEVERE WEATHER IS
ALSO A POSSIBILITY. HOWEVER, SATURDAY IS CURRENTLY TOO FAR AWAY
FOR FORECAST CONFIDENCE TO BE HIGH.
NEXT WEEK LOOKS TO BE SLIGHTLY COOLER WITH MORE ACTIVE WEATHER AS
A SERIES OF SHORTWAVE TROUGHS WILL SLIDE THROUGH THE NORTHERN
PLAINS. SO FOR THOSE NEEDING WATER FOR YOUR LAWN OR GARDENS, MORE
HELP SHOULD BE ON THE WAY.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 115 PM CDT MON JUL 13 2020
MULTIPLE PERIODS OF CONVECTION WILL BE THE MAIN CONCERN FOR THIS
TAF PERIOD. VFR CONDITIONS WILL REMAIN THROUGH THE REST OF THIS
AFTERNOON THEN CONDITIONS ARE EXPECTED TO DETERIORATE THROUGH THE
EVENING HOURS AS CLUSTERS OF THUNDERSTORMS DEVELOP OVER EASTERN ND
INTO NORTHWESTERN MN THEN CONGEAL AS THEY SHIFT SE THROUGH
CENTRAL-SOUTHERN MN INTO WESTERN WI. CONVECTION LOOKS TO FIRST HIT
OUR WESTERN MN TAFS BETWEEN ROUGHLY 00Z-04Z THEN CONTINUE PUSHING
EASTWARD. IFR CONDITIONS ARE LIKELY, MAINLY DUE TO VISIBILITY IN
MOD-HVY RAIN, WITH MVFR CEILINGS. SOME OF THE STORMS MAY ALSO BE
STRONG-SEVERE DURING THE EVENING HOURS. THE BULK OF THIS FIRST
ROUND WILL END PRIOR TO DAYBREAK BUT THEN A MORE HEAVY/PERSISTENT
RAIN THREAT DEVELOPS AFTER DAYBREAK AND CONTINUES FOR THE FIRST
HALF OF THE DAY TUESDAY. MVFR CONDITIONS ARE MOST LIKELY BUT IFR
CONDITIONS CANNOT BE RULED OUT. AS THIS ACTIVITY WILL BE OCCURRING
WITH A FRONTAL PASSAGE, WINDS WILL ALSO SHIFT DIRECTIONS.
GUSTY/BREEZY SE WINDS THROUGH THIS AFTERNOON WILL DIMINISH GOING
INTO THE EVENING THEN CAN BE EXPECTED TO SWING TO NW OVERNIGHT
INTO TOMORROW MORNING.
KMSP...MOST SHORT-TERM MODELS GENERALLY AGREE THAT THE BEST
CHANCES FOR CONVECTION AROUND KMSP WILL BE 03Z-07Z AND AGAIN
14Z-18Z, BUT THOSE TIMES COULD VARY BY ABOUT AN HOUR OR SO ON
EITHER SIDE. THERE WILL ALSO BE INTERMITTENT SHOWERS BEFORE/AFTER
THE EVENING CONVECTION BUT THE RAINFALL TOMORROW LOOKS TO BE MORE
SUSTAINED. THERE ARE ALSO THE STRONG-SEVERE HAZARDS WITH THE
STORMS ALONG WITH POTENTIAL FOR FREQUENT LIGHTNING.
/OUTLOOK FOR KMSP/
WED...VFR. WIND SW 5 KTS.
THU...VFR. WIND SW 5-10 KTS.
FRI...MAINLY VFR. CHC SHRA/TSRA/MVFR. WIND S 5-10 KTS.
MPX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
SHORT TERM...DYE
LONG TERM...CTG
AVIATION...JPC
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