Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 280419
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1119 PM CDT MON OCT 27 2014

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 300 PM CDT MON OCT 27 2014

EARLY AFTERNOON WATER VAPOR IMAGERY SHOWED 3 DISTINCT AREAS OF
COOLER CLOUD TOPS. ONE WAS LOCATED OVER THE GREAT LAKES IN THE LEFT
EXIT REGION OF THE SUBTROPICAL JET. A SECOND WAS OVER NORTHWEST MN.
THIS AREA OF COOLING CLOUD TOPS ACROSS NORTHWEST MINNESOTA WAS
COINCIDENT WITH LIGHT PRECIP OVER THE NORTHWEST CWA. OBSERVED
RAINFALL TOTALS MAXED OUT AROUND A QUARTER OF AN INCH ALONG A LINE
FROM APPLETON TO GLENWOOD. FINALLY THE THIRD AREA OF COOLING CLOUD
TOPS WAS TO THE WEST OF LAKE WINNIPEG. THESE LAST TWO AREAS MATCHED
UP VERY WELL WITH THE REGIONS OF POSITIVE VORTICITY ADVECTION
EMBEDDED WITHIN THE SHORTWAVE TROUGH CENTERED OVER THE DAKOTAS.

OVER THE NEXT 24 HOURS THE SHORTWAVE WILL BECOME BETTER ORGANIZED AS
IT PHASES WITH THE SUBTROPICAL JET TO THE SOUTH. THE INCREASED
FORCING FOR ASCENT WILL BE REFLECTED IN THE SURFACE LOW THAT IS
FORECAST TO DEEPEN FROM THE CURRENT 999MB DOWN TO SUB 994 BY TUESDAY
AFTERNOON. BY THAT TIME QVECTOR CONVERGENCE WILL BE CENTERED OVER THE
NORTHERN SHORE OF LAKE SUPERIOR...AND CROSS SECTIONS REVEAL A TROWAL
IN THIS REGION AS WELL WHICH SUPPORTS THE HEAVY QPF GENERATED ACROSS
SOUTHERN ONTARIO. CLOSER TO HOME...A FEW SHOWERS MAY DEVELOP ACROSS
THE NORTHERN HALF OF THE CWA...MAINLY DUE TO THE SATURATION AND
INSTABILITY WITH THE LOW LEVEL COLD AIR ADVECTION. AS ALLUDED TO
EARLIER...THE UPPER LEVEL DYNAMICS ARE DISPLACED TO THE NORTH AND
EAST...BUT A FEW LIGHT SHOWERS ARE CERTAINLY POSSIBLE.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 300 PM CDT MON OCT 27 2014

PICKING UP THE FORECAST TOMORROW EVENING...WILL STILL BE
CONTENDING WITH WRAP AROUND MOISTURE UNDER UPPER LEVEL
CYCLONICALLY CURVED FLOW WITH THE STRONG UPPER LOW CENTERED OVER
LAKE SUPERIOR. SLIGHT CHANCE POPS REMAIN IN THE FORECAST TOMORROW
EVENING FOR A PORTION OF CENTRAL MN AND WEST CENTRAL WI...WHERE
LIGHT RAIN...POSSIBLY MIXING WITH A FEW PARTIALLY MELTED
SNOWFLAKES COULD REACH THE GROUND. HIGH PRESSURE WILL PUSH IN
BEHIND THIS SYSTEM AND TEMPERATURES ACROSS WESTERN MN SHOULD HAVE
NO PROBLEM DROPPING INTO THE 20S BY WEDNESDAY MORNING. A BIT MORE
WIND AND LONGER LASTING SKY COVER WILL HOLD THE EASTERN FA IN THE
MID 30S.

A VERY SUBTLE WAVE WILL MAKE ITS WAY SOUTHEAST THROUGH THE DAKOTAS
WEDNESDAY AND BOTH THE GFS AND EC AGREE THAT IT WILL HAVE ENOUGH
FORCING TO PRODUCE SOME VERY LIGHT QPF. IT WILL HAVE A DRY AIRMASS
TO CONTEND WITH BUT DUE TO THE AGREEMENT...INTRODUCED A SMALL AREA
OF SLIGHT CHANCE POPS ACROSS WESTERN MN IN CASE SOME RAINFALL IS
ABLE TO REACH THE GROUND. AMOUNTS WILL BE LIMITED TO UNDER ONE
TENTH OF AN INCH.

BEHIND THE AFOREMENTIONED SUBTLE WAVE...AN UPPER RIDGE WILL
AMPLIFY OVER THE WESTERN CONUS...PLACING THE UPPER MIDWEST SOLIDLY
IN NORTHWEST FLOW. A STRONG HIGH PRESSURE AREA WILL RIDE THE
DOWNSTREAM SIDE OF THE RIDGE AXIS ALMOST STRAIGHT SOUTH FROM
CANADA INTO THE UPPER MIDWEST BY FRIDAY MORNING. THE EC IS
CURRENTLY INDICATING 850H TEMPS OF COLDER THAN -10 ACROSS THE
EASTERN FA FRIDAY MORNING. ADJUSTED THE FRIDAY MORNING LOWS AND
HIGHS DOWNWARD...BUT THESE ADJUSTMENTS WERE CONSERVATIVE COMPARED
TO MUCH OF THE GUIDANCE SO DONT BE SURPRISED IF FORECAST TEMPS
CONTINUE TO GO DOWN AS HALLOWEEN APPROACHES.

OVER THE WEEKEND...THE UPPER RIDGE WILL PROGRESS EASTWARD AND BE
CENTERED OVER THE UPPER MIDWEST SATURDAY...BUT THE MORNING WILL
STILL START OUT QUITE COOL. MEANWHILE...A STRONG LOW PRESSURE
SYSTEM IS EXPECTED TO DEVELOP OVER THE MONTANA/WYOMING REGION AND
WILL PROGRESS EASTWARD WITH TIME. STRONG WARM AIR ADVECTION WILL
ENSUE FOR US AHEAD OF THIS SYSTEM...AND SATURDAY LOOKS QUITE
WINDY. ADJUSTED THE WIND SPEEDS UPWARD FROM GUIDANCE. CLOUD COVER
SHOULD BE ON THE INCREASE LATE SATURDAY WITH POPS COMING BACK INTO
THE PICTURE SUNDAY AS THE SYSTEM DRAWS NEARER.

&&

.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...JRB
LONG TERM...SPD
AVIATION...CLF







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