Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 252042
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
342 PM CDT THU JUN 25 2015

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 340 PM CDT THU JUN 25 2015

THE SHORT TERM WEATHER FEATURES SMALL CHANCES FOR SHOWERS AND WEAK
THUNDERSTORMS...BUT THE RAIN COVERAGE WILL BE FAIRLY SPARSE AND
THEREFORE MOST LOCATIONS WILL REMAIN DRY. THERE IS A WIDELY
SCATTERED LINE OF SHOWERS EXTENDING FROM SOUTH CENTRAL SD TO
WESTERN WI THIS AFTERNOON IN RESPONSE TO DIURNAL HEATING AND SBCAPE
VALUES BETWEEN 500-1000 J/KG. THERE REALLY ISN`T A CLEARLY DEFINED
BOUNDARY OR CONVERGENCE AREA...BUT IN GENERAL THE SHOWERS ARE
FORMING WHERE THE DEWPOINTS START TO CREEP UP INTO THE LOWER 60S.
NORTH OF THE SHOWERS...THE DEWPOINTS ARE IN THE 50S AND THE
CUMULUS GROWTH ISN`T AS DEEP. THE EFFECTIVE SHEAR IS SMALL WITH
ONLY 15 TO 25KTS...SO THE UPDRAFTS ARE BARELY STRONG ENOUGH TO
ACHIEVE GLACIATION...AS EVIDENT BY THE LACK OF IN-CLOUD ELECTRIC
ACTIVITY. THESE SHOWERS WILL DIMINISH EARLY THIS EVENING AS WE
LOSE THE SOLAR HEATING. TONIGHT...A SHORTWAVE WILL PASS THROUGH
THE MID/UPPER MISSISSIPPI RIVER VALLEY...BUT GIVEN HOW FAR SOUTH
THE WAVE IS EXPECTED TO TRACK...SOUTHERN IA AND NORTHERN MO WILL
BE IN THE FAVORABLE LOCATION TO SEE THUNDERSTORMS. LOCALLY...WEAK
NORTHERLY FLOW WILL KEEP MUCH OF THE AREA DRY. WE COULD SNEAK A
FEW SHOWERS OR RUMBLES OF THUNDER INTO FAR SOUTHERN MN...BUT EVEN
THAT MIGHT BE A STRETCH IF CONVECTION REALLY GETS GOING IN IA/MO.
MORE DIURNALLY DRIVEN SHOWERS ARE AGAIN POSSIBLE TOMORROW...BUT
THERE IS NO PRONOUNCED TRIGGER TO INDICATE WIDESPREAD CONVECTION
OR AN ENVIRONMENT THAT SUPPORTS STRONG CONVECTION.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 340 PM CDT THU JUN 25 2015

THE UPPER LEVEL PATTERN IN THE EXTENDED FORECAST RESEMBLES LATE
JANUARY MORE THAN LATE JUNE AS A COUPLE CLIPPER SYSTEMS EMBEDDED IN
NORTHWEST FLOW MOVE ACROSS THE REGION. HOWEVER THE DIABATIC HEATING
FROM THE SUMMER SUN WILL GREATLY DAMPEN THE TEMPERATURE CHANGE THAT
IS TYPICALLY ASSOCIATED WITH THESE SYSTEMS. SHOWERS AND
THUNDERSTORMS WILL DEVELOP AHEAD OF THE CLIPPERS...WITH CLEAR SKIES
AND DRY WEATHER BEHIND THEM.

THE TWO MAIN WINDOWS FOR PRECIP WILL BE LATE SATURDAY INTO
SUNDAY...AND AGAIN WEDNESDAY INTO THURSDAY. WITHIN THAT TIMEFRAME
THE POTENTIAL EXISTS ON MONDAY FOR ISOLATED LATE AFTERNOON/EVENING
SHOWERS AND THUNDERSTORMS...ESPECIALLY ACROSS EASTERN MN AND WESTERN
WI.

THE FIRST WAVE IS CURRENTLY OFF THE BRITISH COLUMBIA COAST ON THE
POLEWARD SIDE OF A 95-100KT UPPER LEVEL JET. THIS VORTICITY MAXIMA
WILL CROSS THE ROCKIES AND DIVE SOUTHEAST FROM CENTRAL ALBERTA
TOWARD THE ST CROIX RIVER VALLEY. 500MB HEIGHT FALLS ASSOCIATED WITH
THIS WAVE TOGETHER WITH WEAK 850MB THETA_E ADVECTION WILL LEAD TO A
FEW SHOWERS AND THUNDERSTORMS LATE SATURDAY...SPREADING SOUTHEAST
SATURDAY NIGHT INTO SUNDAY. THE DIRECTIONAL SHEAR PROFILE IN
NORTHWEST FLOW IS FAVORABLE FOR SUPERCELLS...AND THE 10KFT FREEZING
LEVELS WOULD SUPPORT A HAIL THREAT. THE BEST CHANCE FOR SEVERE
WEATHER WOULD BE LATE SATURDAY AFTERNOON SHORTLY AFTER INITIATION
WHEN STORMS ARE ABLE TO MAXIMIZE ANY AVAILABLE CAPE. THE THREAT IS
LOW...AND NOT EXPECTING ORGANIZED SEVERE WEATHER...BUT THE POTENTIAL
IS THERE FOR SOME COIN SIZE HAIL. THE SEVERE THREAT SHOULD TAPER OFF
OVERNIGHT AS THE LOWER LEVELS OF THE ATMOSPHERE STABILIZED.

SHOWERS AND THUNDERSTORMS WILL LINGER ACROSS EASTERN MN AND WESTERN
WI ON SUNDAY. MONDAY APPEARS DRY FOR THE MOST PART...BUT FORECAST
SOUNDINGS AGAIN SHOW AROUND 1000 J/KG OF UNCAPPED CAPE BY
AFTERNOON...SO SPLIT THE POPS UP INTO 6HR GRIDS TO BETTER DEPICT THE
TIMING. LOOKING AHEAD...THE UPPER LEVEL RIDGE TO THE WEST WILL
FLATTEN OUT TUESDAY NIGHT...AND ANOTHER WAVE WILL MOVE ACROSS THE
REGION BRINGING SHOWERS AND THUNDERSTORMS FOR WEDNESDAY AND
THURSDAY. THE TIMING OF THIS WAVE IS DURING THE OVERNIGHT
HOURS...WHICH SIMILAR TO THIS WEEKENDS WAVE WILL LIMIT THE SEVERE
THREAT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 152 PM CDT THU JUN 25 2015

THERE ARE JUST A FEW SHOWERS OUT THERE THIS AFTERNOON...BUT WE
HAVE HIGH CONFIDENCE THERE WILL BE LITTLE TO NO IMPACTS AT THE
LOCAL TAF SITES...PERHAPS A 5-10 MINUTE WINDOW WITH LIGHT RAIN.

KMSP...

NO AVIATION WEATHER IMPACTS ARE EXPECTED AT THERE
AIRPORT...PERHAPS A SPRINKLE OF RAIN THIS AFTERNOON.

/OUTLOOK FOR KMSP/
SUN...VFR. CHC OF TSRA. SW WINDS BCMG NW 5-10 KTS.
MON...VFR. SLIGHT CHC OF -TSRA. WINDS NNW 5 TO 10 KTS.

&&

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

$$

SHORT TERM...CLF
LONG TERM...JRB
AVIATION...CLF


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