Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 280756
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
256 AM CDT TUE OCT 28 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 245 AM CDT TUE OCT 28 2014

TODAY-TONIGHT...SFC ANALYSIS THIS MRNG PUTS A NOW-PHASED LOW PRES
CENTER OVER THE CENTRAL GREAT LAKES WITH CDFNT XTDNG SWWD THRU THE
OH RIVER VALLEY...MID-MISS RIVER VALLEY TO THE DEEP SOUTH. IN
ADDITION...A TRAILING SFC TROUGH XTNDS WNW ALONG THE INTERNATIONAL
BORDER OF MI/MN. ALOFT...A LARGE CUTOFF LOW IS ROTATING EWD OVER NRN
MN. THESE FEATURES ARE XPCTD TO SHIFT EWD TDA...BUT THE ISSUE IS THE
TRAILING SFC TROF. THIS TROF WILL SWING SEWD AROUND THE DEEPENING
SFC LOW...AND WILL AID IN MAINTAINING NOT ONLY EXTENSIVE CLOUD COVER
OVER MN/WI BUT ALSO SCATTERED TO NUMEROUS RAIN SHOWERS OVER NRN
MN...N OF THE WFO MPX CWFA. ONCE THIS TROF BEGINS TO ROTATE AROUND
THE DEPARTING LOW...COLD POOLING ALOFT COMBINED WITH WEAK LIFT MAY
BE ABLE TO SPREAD SOME OF THESE SHOWERS SWD INTO CENTRAL MN AND WRN
WI. NOT LOOKING FOR MUCH IN THE WAY OF COVERAGE...ONLY ISOLD TO
SCATTERED...AND ANY SHOWERS WILL PRODUCE LIGHT PRECIP.
NEVERTHELESS...THE WRAPAROUND FLOW WITH WEAK INSTABILITY WILL
WARRANT INCLUDING -RA MENTION FOR TDA INTO TNGT. ANY AND ALL PRECIP
WILL SHIFT OFF TO THE E THIS EVE WITH STEADILY CLEARING OVERNIGHT
INTO EARLY TUE MRNG AS THE STACKED LOW PRES SYSTEM DRIVES INTO ERN
CANADA AND SFC HIGH PRES ARRIVES FROM THE E.

AS FOR TEMPERATURES...CAA WILL COMMENCE IN FULL FORCE BY LATER TDA
INTO TNGT AS PRONOUNCED NW FLOW ALOFT WILL BRING IN COLDER CANADIAN
AIR TO THE AREA. VERY SMALL DIURNAL RANGE FROM THIS MRNG/S LOWS TO
THIS AFTN/S HIGHS ARE EXPECTED...WITH HIGHS THIS AFTN ONLY HITTING
THE MID-UPR 40S...AND POSSIBLY EVEN REMAINING IN THE LWR 40S IN NWRN
PORTIONS OF THE CWFA. WITH SKIES CLEARING OUT AND DEEP NW FLOW IN
PLACE FROM THE SFC ON UP...TEMPERATURES TNGT ARE EXPECTED TO DROP
INTO THE UPR 20S IN WRN MN TO THE MID 30S IN ERN MN AND WRN WI.

THE OTHER CONCERN FOR TDA IS STRONG WINDS DUE TO A TIGHTENING PRES
GRADIENT BEHIND THE DEPARTING LOW PRES SYSTEM AND INCOMING HIGH
PRES. WIND SPEEDS ARE EXPECTED TO INCRS TO THE 15-25 MPH RANGE WITH
GUSTS HITTING 30-40 MPH. THESE SPEEDS LOOK TO FALL JUST SHORT OF
WIND ADVY CRITERIA...BUT WILL STILL CERTAINLY MAKE FOR BREEZY CONDS.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 245 AM CDT TUE OCT 28 2014

MAIN THEME FOR THE EXTENDED PERIOD...
THE PROGRESSIVE PATTERN WILL REMAIN IN PLACE ACROSS NORTH AMERICA
WITH A HIGHLY AMPLIFIED TROUGH/RIDGE/TROUGH FROM WEST TO EAST BY
FRIDAY/SATURDAY. THE MAIN FORECAST CONCERN IS WHETHER THE
PROGRESSIVE PATTERN CONTINUES...OR A BLOCKING PATTERN STARTS.

AS TODAYS SYSTEM DEPARTS...ANOTHER AND MORE POTENT SHRTWV WILL
RIDE SSE ACROSS CANADA AND INTO THE GREAT LAKES BY FRIDAY MORNING.
A STRONG JET STREAM WILL DEVELOP ACROSS THE PLAINS...AND CONTINUE
TO DIG THIS SHRTWV FURTHER TO THE S/SE ACROSS THE DEEP SE CONUS BY
THE WEEKEND. WITH THE TROUGH IN THE WESTERN CONUS REFORMING AND
DIGGING FURTHER ACROSS CALIFORNIA...THIS WILL AMPLIFY THE UPPER
RIDGE IN THE CENTRAL CONUS FOR THE UPCOMING WEEKEND.

ALTHOUGH THE UPPER MIDWEST SHOULD REMAIN DRY THRU SUNDAY...A WEAK
SHRTWV WITH LIMITED MOISTURE AND JET ENERGY WILL BRUSH THE REGION
LATE WEDNESDAY/EARLY THURSDAY. MODELS HAVE BEEN TRENDING FOR A
STRONGER SHRTWV THEN IN THEIR PREVIOUS RUNS. THE DRIER AIR MASS
IN PLACE SHOULD PRECLUDE ANYTHING SIGNIFICANT IN TERMS OF
MEASURABLE PRECIPITATION. A FEW HUNDREDTHS IS NOT OUT OF THE
QUESTION...BUT MORE THAN LIKELY VIRGA OR SPRINKLES WILL DEVELOP.

THE COLDEST PERIOD WILL BE THURSDAY NIGHT THRU SATURDAY MORNING AS
BOTH THICKNESS VALUES BOTTOM OUT AND CAA SLOWLY LESSENS. HIGHS
NEAR 40 FRIDAY WILL REBOUND INTO THE 50S BY SUNDAY WHICH IS ABV
NORMAL FOR EARLY NOVEMBER.

NOT OVERLY CONFIDENT ON HOW THE UPPER RIDGE BEGINS TO BREAK DOWN
LATE IN THE WEEKEND AND A MORE SW FLOW DEVELOPS ALOFT. STILL CONCERN
WITH THE STRONG TROUGH/STORM SYSTEM AFFECTING THE EAST COAST THIS
WEEKEND AND HOW IT HOLDS BACK OR EVEN BLOCKS THE UPPER RIDGE FROM
MOVING TO FAR EAST. WILL CONTINUE TO LEAN TOWARD THE PROGRESSIVE
PATTERN IN THE MODELS...BUT CONFIDENCE STILL REMAINS
LOW...ESPECIALLY IN TERMS OF AN UNSETTLED WETTER PATTERN FOR THE
UPPER MIDWEST BY MONDAY/TUESDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1118 PM CDT MON OCT 27 2014

LOWER CEILINGS TO THE NORTH ACROSS CANADA AND THE DAKOTAS ARE
EXPECTED TO DROP SOUTH LATE TONIGHT AND AFFECT MINNESOTA EARLY
TOMORROW MORNING. WE ARE STILL SOMEWHAT UNSURE OF THE SPECIFIC
TIMING...BUT WE THINK MOST OR ALL THE MN TAF SITES SHOULD SEE SUB
3000FT CEILINGS BEFORE THE NOON HOUR. WESTERN WI SITES WILL BE A
BIT LATER WITH THE CEILINGS AND LIKELY NOT QUITE AS LOW.

KMSP...

NO AVIATION IMPACTS TONIGHT. LOWER /2000-2500FT/ CEILINGS ARE
MUCH MORE LIKELY JUST AFTER THE MORNING RUSH TOMORROW...ALONG WITH
A PRONOUNCED INCREASE IN WIND SPEED.

/OUTLOOK FOR KMSP/
WED...VFR WITH MVFR CIGS POSSIBLE EARLY. WINDS W AT 10KTS
THU...VFR. WINDS ST AT 10G15KTS.
FRI...VFR. WINDS NNE AT 10KTS.

&&

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

$$

SHORT TERM...JPC
LONG TERM...JLT
AVIATION...CLF




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