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 281208
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
708 AM CDT SUN SEP 28 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 401 AM CDT SUN SEP 28 2014

IT WILL BE ANOTHER VERY WARM DAY ACROSS THE REGION WITH A BIG CHANGE
IN THE TEMPERATURE PATTERN BEGINNING ON MONDAY. THE LOW LEVEL
THERMAL PATTERN TODAY IS MUCH LIKE THAT ON SATURDAY WITH A LITTLE
MORE SOUTHWEST COMPONENT TO THE WIND...ESPECIALLY FROM WEST CENTRAL
THROUGH NORTHEAST MINNESOTA AHEAD OF AN APPROACHING COLD FRONT.
MIX-DOWN FROM 825 MB YIELDED HIGHS FROM AROUND 80 TO THE LOWER 80S
WHICH HAS BEEN A FEW DEGREES TOO COOL THE PAST TWO DAYS. THEREFORE...
A 75 PERCENT PREVIOUS HIGH AND 25 PERCENT MIX-DOWN WAS USED TO
ACCOUNT FOR A LITTLE MORE CLOUDINESS DURING THE AFTERNOON. WEST
CENTRAL MINNESOTA IS THE WARMEST WITH HIGHS IN THE MIDDLE 80S.

AS FOR PRECIPITATION TODAY...INTRODUCED SOME SMALL POPS ACROSS WEST
CENTRAL MINNESOTA DURING THE AFTERNOON. MOST OF THE CAMS ARE
INDICATING A FEW SHOWERS AND ISOLATED THUNDERSTORMS DEVELOPING. BUFR
SOUNDINGS ARE SHOWING A FEW HUNDRED J/KG OF CAPE DEVELOPING ACROSS
THE WEST THIS AFTERNOON. THIS IS ALSO ACCOMPANIED BY WEAK ASCENT
FROM AN H7 SHORT WAVE ROTATING IN FROM THE CENTRAL PLAINS. SATELLITE
IMAGERY OVERNIGHT HAS SHOWN QUITE A FIELD OF ACCAS SPREADING NORTH
THROUGH KS/NE AND INTO SE SD.

FOR TONIGHT...A COLD FRONT CURRENTLY FROM NORTHWEST MINNESOTA
THROUGH WESTERN NEBRASKA WILL SLIP SLOWLY SOUTHEAST...REACHING THE
TWIN CITIES BY DAYBREAK MONDAY. SOME SHOWERS WILL OCCUR ALONG AND
BEHIND THE FRONT TONIGHT...ESPECIALLY ACROSS CENTRAL MINNESOTA. A
SECOND AREA OF SHOWERS IS POSSIBLE TONIGHT ACROSS WEST CENTRAL AND
SOUTHWEST MINNESOTA ALTHOUGH MAINLY AFTER MIDNIGHT...AS ANOTHER
RIPPLE IN THE MID LEVEL FLOW MOVES THROUGH ALONG WITH INCREASING LOW
LEVEL MOISTURE TRANSPORT.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 401 AM CDT SUN SEP 28 2014

MAIN CHALLENGE THIS PERIOD CONTINUES TO BE TIMING OF PRECIP CHANCES
THROUGHOUT THE WORK WEEK AS SEVERAL PIECES OF SHORTWAVE ENERGY WORK
THROUGH A MEAN TROUGH THAT WILL BE WORKING ACROSS THE CENTER OF NOAM
THROUGH THE WEEK. OTHER CHALLENGE WAS WHAT TO DO WITH HIGHS ON
MONDAY...WHICH ARE LOOKING TO BE AS MUCH AS 20-30 DEGS COLDER NORTH
OF I-94 THAN WHAT WE ARE EXPECTING FOR TODAY.

THE LONG TERM PERIOD WILL START OFF WITH TODAY/TONIGHTS COLD FRONT
DOWN ALONG THE IOWA BORDER. TUESDAY INTO WEDNESDAY...A COMPACT SFC
LOW WILL LIFT NORTH ACROSS THE DAKOTAS. COLD FRONT ASSOCIATED WITH
IT WILL MOVE ACROSS MN TUESDAY EVENING...BUT WILL STALL
WEDNESDAY/WEDNESDAY NIGHT ACROSS ERN MN/NW WI...BEFORE GETTING
PUSHED EAST OF THE AREA BY A STRONGER SECONDARY COLD FRONT THURSDAY
NIGHT. THIS FORECAST PERIOD WILL END WITH US BEING ON THE NORTH SIDE
OF A SFC HIGH THAT WILL BE HEADING FOR THE LOWER MS RIVER VALLEY.

FOR MONDAY...EXPECT EXTENSIVE STRATUS ACROSS THE AREA IN THE WAKE OF
THE COLD FRONT...MUCH LIKE WE ARE SEEING RIGHT NOW BEHIND THE FRONT
ACROSS THE NW HALF OF NODAK INTO NW ONTARIO. BOOSTED CLOUD COVER
SIGNIFICANTLY ON MONDAY...AND ALSO CUT A GOOD 5 TO 10 DEGREES OFF OF
HIGHS...AS COLD ADVECTION IN THE WAKE OF THE FRONT IS LOOKING A BIT
STRONGER THAN EARLIER MODEL RUNS HAD...WITH 925MB TEMPS PROGGED TO
BE DOWN AROUND ONLY +5C BY MONDAY AFTERNOON IN THE NORTHEAST CWA.
USED A MIX DOWN HEIGHT OF ONLY 900MB FOR THE MAIN INPUT INTO THE
FORECAST FOR HIGHS ON MONDAY...WHICH STILL ALLOWS FOR HIGHS UP INTO
THE 70S ALONG THE I-90 CORRIDOR...BUT AT THE NORTH END OF THE
CWA...IT MAY BE A STRUGGLE FOR 50. REGARDLESS OF THE FINAL
HIGH...GIVEN COOL EAST FLOW AND CLOUDS...EXPECT VERY LITTLE DIURNAL
RANGE WITH TEMPS ON MONDAY. FOR POPS...BEST FORCING FOR PRECIP WILL
BE ASSOCIATED WITH THE UPPER WAVE DRIVING THE FRONT...WHICH IS STILL
PROGGED TO GO ACROSS THE ARROWHEAD SOUTHEAST INTO MICHIGAN. TOOK
CHANCE POPS FROM THE END OF THE SHORT TERM PERIOD ACROSS CENTRAL MN
AND SLID THOSE TO THE SOUTHEAST MONDAY MORNING FOR LOCATIONS NORTH
OF I-94 /SIMILAR TO WHAT THE CAMS ARE SHOWING/. ALSO EXTENDED SLIGHT
CHANCE POPS ACROSS THE REST OF THE FORECAST AREA THROUGH THE DAY
MONDAY...AS MOST GUIDANCE SHOWS LIGHT QPF FOLLOWING THE STRATUS AND
WEAK FGEN IN THE WAKE OF THE COLD FRONT ACROSS SOUTHERN MN.

WE WILL HAVE A BRIEF BREAK IN PRECIP MONDAY NIGHT THROUGH TUESDAY
MORNING AS WE WAIT ON THE WRN THROUGH TO BEGIN TO MOVE OUT ON TO THE
HIGH PLAINS. MODEL AGREEMENT WITH THIS SYSTEM TUESDAY/TUESDAY NIGHT
IS FAIRLY HIGH...WITH THE ONLY SIGNIFICANT DIFFERENCE BEING WITH
TIMING AS THE GEM/ECMWF ARE ABOUT 6 HOURS SLOWER THAN THE GFS/NAM
WITH BRING PRECIP ACROSS MN/WI. GIVEN THE VERY DRY ATMO COLUMN
FORECAST TO BE ACROSS ERN MN AND WI TUESDAY...DID FAVOR POPS TOWARD
THE SLOWER SOLUTIONS. INTRODUCED SOME LIKELY POPS INTO WRN MN
TUESDAY AFTERNOON...GIVEN BROAD AGREEMENT IN PREFRONTAL PRECIP
CROSSING INTO MN DURING THE AFTERNOON. BEST INSTABILITY ON TUESDAY
LOOKS TO REMAIN ACROSS THE OMAHA/KC AREAS...WHICH IS GOOD...SINCE
DYNAMICS WITH NEGATIVELY TITLED TROUGH MOVING ACROSS THE ERN DAKOTAS
WOULD FAVOR THE THREAT FOR SEVERE WEATHER IF WE HAD MORE INSTABILITY.

TUESDAY NIGHT...THIS BAND OF SHOWERS THAT ARRIVES TUESDAY AFTERNOON
WILL WORK EAST ACROSS THE AREA AS THE COLD FRONT SLIPS INTO WRN MN.
HAVE WORKED LIKELY POPS EAST WITH TIME THROUGH THE NIGHT...THOUGH
WOULD EXPECT COVERAGE TO DIMINISH AFTER 6Z AND TREND TOWARD SRN
MN...CLOSER TO WHERE THE GREATEST ELEVATED INSTABILITY IS LIKELY TO
HEAD. AFTER THAT...BLENDING PROCEDURE USED CONTINUES TO PAINT POPS
ACROSS THE ENTIRE MPX CWA THROUGH FRIDAY...THOUGH THE GREATEST
POTENTIAL FOR PRECIP AFTER TUESDAY NIGHT WILL RESIDE MAIN EAST OF
I-35 THANKS TO THE STALLING OUT OF THE FRONT. THE PROLONGED AND
LIKELY OVERLY SPREAD OUT POPS ARE THE RESULT OF THE BROAD TROUGH
THAT WILL BE WORKING ACROSS THE UPPER MS VALLEY TUESDAY THROUGH
FRIDAY...WHICH WILL FEATURE NUMEROUS SHORTWAVES WORKING ACROSS THE
AREA DURING THESE DAY...SO EXPECT NEXT WEEK TO BE CONSIDERABLY DRY
THAN THE FORECAST PROBABLY MAKES IT SOUND. GIVEN THE SLOWER
PROGRESSION OF THE FRONT ACROSS THE ERN CWA...THE MEDIUM RANGE
MODELS CONTINUE TO BE IN GOOD AGREEMENT IN AROUND AN INCH OF QPF
FALLING ACROSS SE MN INTO WRN WI NEXT WEEK.

FOR FRIDAY...THE QUESTION FOR PRECIP COVERAGE REVOLVES AROUND THE
AMOUNT OF PHASING WE WILL SEE BETWEEN NRN AND SRN STREAM ENERGY NEXT
WEEK. THE GFS/ECMWF CONTINUE TO JUMP BACK AND FORTH ON THE DEGREE OF
PHASING THEY SHOW. WITH THE 28.00 RUNS...THE GFS IS THE MOST
AGGRESSIVE WITH PHASING...WITH A DEEP CLOSED LOW DEVELOPING OVER THE
U.P. OF MICHIGAN ON FRIDAY...WITH DEFORMATION PRECIP IMPACTING THE
ERN CWA FRIDAY. THE ECMWF AND GEM ARE FOLLOWING THE 28.12 ECMWF
SOLUTION WITH LESS PHASING AND A MORE OPEN WAVING WORKING ACROSS THE
GREAT LAKES ON FRIDAY...WITH PRECIP MOVING OUT OF THE MPX CWA BY
FRIDAY AFTERNOON. THE IMPACT OF THESE DIFFERENCES REALLY STARTS TO
SHOW UP WITH THE FORECAST ON SATURDAY. THE GFS CONTINUES TO KEEP US
IN THE COLD TROUGH ALOFT...WITH HIGHS STILL ONLY IN THE 50S. THE
ECMWF ON THE OTHER HAND HAS HIGHS IN THE MID 70S RETURNING TO SW
MN BY SATURDAY AFTERNOON.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 708 AM CDT SUN SEP 28 2014

PATCHY MVFR/IFR VSBYS/CIGS WILL DIMINISH BY 14Z ACROSS EASTERN MN
AND WESTERN WI AS SE WINDS INCREASE AND MIXING COMMENCES. VFR
CONDITIONS WILL THEN PREVAIL AT THE TAF SITES THROUGH THE
AFTERNOON. THERE WILL LIKELY BE A FEW SHRA/TSRA DEVELOP ACROSS
WEST CENTRAL MN DURING THE AFTERNOON AS HEATING PEAKS AND A COLD
FRONT APPROACHES FROM THE NORTHWEST WITH TEMPORARY LOWER
CONDITIONS. CONVECTIVE SIMULATIONS INDICATED MUCH OF THE ACTIVITY
BETWEEN KRWF AND KAXN. A COLD FRONT WILL SLIP SOUTHEAST INTO
CENTRAL MN THIS EVENING AND ACROSS THE REST OF THE TAF SITES BY
DAYBREAK MONDAY. MVFR OR LOWER CEILINGS ARE LIKELY BEHIND THE
FRONT ALONG WITH A FEW SHOWERS. IFR CIGS FORECAST FOR KAXN AND
KSTC AFTER 07Z WHERE CONFIDENCE WAS HIGHEST. THE IFR CIGS MAY PUSH
INTO THE REST OF THE TAF SITES MONDAY MORNING WHICH WILL BE
COVERED IN THE NEXT TAF ISSUANCE. LIGHT SE TO S WINDS THIS MORNING
BECOMING SW 10 KNOTS THIS AFTERNOON AND THEN NE AT 10 KNOTS
TONIGHT IN THE WAKE OF THE FRONT.

KMSP...MAIN CONCERN DURING THE TAF PERIOD IS MVFR CIGS SPREADING
IN MONDAY MORNING IN THE WAKE OF A COLD FRONT. THERE IS POTENTIAL
FOR A PERIOD OF IFR CIGS. CONFIDENCE WAS HIGHEST ON THE MVFR CIGS
BY 12Z WHICH WAS INDICATED IN THE TAF.

/OUTLOOK FOR KMSP/

TUE...VFR. MVFR/SHRA LIKELY OVERNIGHT. WINDS SE 10 KTS.
WED...MAINLY VFR. CHANCE MVFR IN SHRA/TSRA. WINDS S 10 KTS.
THU...MAINLY VFR. CHANCE MVFR IN SHRA. W WINDS 5-10 KTS BECOMING NW.

&&

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

$$

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




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