Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 240515
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1115 PM CST FRI JAN 23 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 333 PM CST FRI JAN 23 2015

GENERALLY QUIET SHORT TERM PERIOD...WITH THE WEEKEND SNOW EVENT
MAINLY OCCURRING IN THE LONG RANGE PERIOD.

AS THE TROUGH AXIS PUSHED THROUGH TODAY...DRIER MID AND LOW LEVEL
FLOW CLEARED SKIES ACROSS THE ENTIRE FA.  NEAR ST. CLOUD AND AREAS
NORTH...TEMPERATURES SHOT UP INTO THE LOW AND MID 40S THANKS TO THE
SUN AND SNOW-FREE GROUND. A VISIBLE SATELLITE LOOP SHOWS RAPID
MELTING OF THE SNOW PACK...ESPECIALLY ACROSS WESTERN MN...AND DEW
POINTS HAVE INCREASED INTO THE LOW 30S.

A STRATUS DECK IS SINKING SOUTHEAST THROUGH NORTHERN MN...BUT THE HI-
RES GUIDANCE IS BACKING OFF ON HOW FAR WEST THE CLOUD COVER WILL
EXTEND ONCE IT ARRIVES. MUCH OF WESTERN MN SHOULD REMAIN CLEAR
THROUGH THE EVENING.  MODEL SOUNDINGS DO INDICATE BLOSSOMING LOW
LEVEL CLOUDINESS OVERNIGHT HOWEVER AS TEMPERATURES COOL AND AMPLE
MOISTURE BECOMES TRAPPED IN THE BOUNDARY LAYER.

THERE REMAINS DIFFERENCES IN THE TIMING OF THE CLIPPER APPROACHING
THE AREA TOMORROW...BUT THE ECMWF DOES SPREAD LIGHT PRECIPITATION
INTO WESTERN MINNESOTA BY LATE AFTERNOON...SO STUCK WITH SOME SLIGHT
CHANCE TO CHANCE POPS THERE PRIOR TO 6PM SATURDAY.  LOW LEVEL
TEMPERATURES WILL BE WARM HOWEVER...SO ANY LIGHT PRECIP THAT DOES
REACH WESTERN MN BY THIS TIME WILL LIKELY BE A WINTRY MIX...BUT WILL
NOT TAKE LONG TO CHANGE TO SNOW.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 333 PM CST FRI JAN 23 2015

LIKE THE PENDULUM OF A CLOCK...THE MODELS CONTINUE MOVING BACK
AND FORTH ON THE TRACK OF THE HEAVIEST QPF WITH THE CLIPPER
DROPPING IN SATURDAY NIGHT. YESTERDAY IT WAS OFF THE EAST AND NOW
TODAY ITS BACK TO THE WEST. ITS TIED TO SHORT WAVES MOVING THROUGH
THE UPPER TROUGH OVER QUEBEC...WITH A DEEPER TROUGH PUSHING THE
CLIPPER BACK TO THE WEST. CONFIDENCE IS HIGH THAT IT WILL SNOW
ACROSS ALL OF OUR FA SATURDAY NIGHT...BUT THERE REMAINS QUITE A
BIT OF SPREAD IN THE TRACK OF THE HEAVIEST QPF. THE GFS WAS
FARTHEST WEST TODAY EXTENDING FROM CENTRAL ND THROUGH SW MN AND NW
IA. THE ECMWF IS ON A DIAGONAL FROM NW TO SE MN WHILE THE 12Z NAM
STRETCHED FROM NORTH CENTRAL MN THROUGH WESTERN WI. THE 18Z NAM
HAS ALREADY SHIFTED SOUTHWEST WITH THE AXIS FROM KAXN TO KRST. THE
WPC 24 HOUR PROBABILISTIC WINTER GUIDANCE...WHICH IS A 57 MEMBER
ENSEMBLE... FAVORS LIKELY PROBABILITIES FOR 2 OR MORE INCHES OF
SNOW ACROSS JUST ABOUT ALL OF CENTRAL AND SOUTHERN MN.
PROBABILITIES DROP OFF PRETTY QUICKLY HEADING EAST ACROSS WEST
CENTRAL WI. THERE ARE EVEN SOME LOW PROBABILITIES FOR 4 OR MORE
INCHES ACROSS THE METRO. HENCE...A FORECAST OF LIKELY TO
CATEGORICAL POPS IS IN PLACE FOR SATURDAY NIGHT WITH AROUND 2
INCHES OF ACCUMULATION IN THE AFOREMENTIONED AREAS. ONCE WE CAN
NAIL DOWN THE HEAVIER QPF TRACK...AN AREA OF 3 TO 4 INCHES WILL
LIKELY BE NEEDED.

THE SNOW WILL TAPER OFF QUICKLY ON SUNDAY...BUT ANOTHER CLIPPER
WILL COME OUR WAY FOR SUNDAY NIGHT AND MONDAY. THIS ONE CURRENTLY
HAS THE MOST SNOW OFF TO THE NORTH AND EAST OF THE METRO...BUT
THAT CAN CERTAINLY CHANGE. ONCE THIS FEATURE MOVES BY...UPPER
LEVEL RIDGING WILL SPREAD IN FROM THE ROCKIES... CONTINUING OUR
WELL ABOVE NORMAL TREND. HIGHS BY THE MIDDLE OF NEXT WEEK MAY BE
BACK TO LEVELS WE AREA SEEING THIS AFTERNOON...WHICH IS IN THE MIDDLE
30S TO MIDDLE 40S.

THERE IS SOME UNCERTAINTY TO THE STRENGTH OF A PACIFIC SYSTEM AS
IT MOVES THROUGH ON THURSDAY. THE GFS AND ECMWF ARE PRETTY
SIMILAR ON TIMING AND LOCATION...BUT NEITHER HAVE MUCH QPF.
BLENDED GUIDANCE RESULTED IN LOW CHANCE POPS ACROSS PARTS OF WEST
CENTRAL WI. THIS COULD END UP BEING A LIGHT WINTRY MIX DEPENDING
ON WHEN IT OCCURS. PLENTY OF TIME TO ADJUST WITH JUST LIGHT SNOW
MENTIONED NOW.

FINALLY...ANOTHER CLIPPER IS SHOWN BY BOTH THE GFS AND ECMWF TO
MOVE IN FRIDAY/FRIDAY NIGHT. AGAIN...TIMING AND LOCATION LOOK
GOOD. HIGH CHANCE POPS ALREADY IN PLACE FOR A GOOD PORTION OF THE
MN CWA BY FRIDAY NIGHT. IT CERTAINLY LOOKS COLDER FOR NEXT WEEKEND
AS THE FLOW ALOFT TURNS MORE NORTHERLY WITH A DEEPENING TROUGH
OVER THE EASTERN CONUS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1109 PM CST FRI JAN 23 2015

MVFR CEILINGS CONTINUE TO DROP SOUTH ACROSS MAINLY NORTHEASTERN
MN AND WESTERN WI...HOWEVER...KEAU/KRNH REALLY SHOULD BE THE ONLY
TWO TAF SITES AFFECTED BY THESE CLOUDS AND EVEN THESE SITES SHOULD
SEE A LOT OF VFR CEILINGS. OTHERWISE...STILL LOOKS LIKE VFR
TONIGHT. MVFR CEILINGS MOVE INTO THE TAF SITES LATE IN THE AFTERNOON
WITH THE SNOW TO FOLLOW. THE SNOW TRACK HAS SHIFTED A BIT TO THE
SOUTHWEST...WHICH MEANS MOST OF THE TAFS SHOULD GET LIFR
VISIBILITY WITH SNOW THIS EVENING/TONIGHT. HIGH CONFIDENCE IN AT
LEAST IFR CONDITIONS.

KMSP...
WE STILL DON`T EXPECT ANY AVIATION WEATHER IMPACTS UNTIL THE SNOW
MOVES IN THIS EVENING. STILL LOOKS LIKE 1-3" INCHES OF SNOW ACROSS
MUCH OF MN. IF THE SYSTEM SHIFTS ANY MORE SW THAN KMSP WILL LIKELY
BE ON THE LOWER END OF THE 1-3"...BUT AS IT STANDS NOW A COUPLE
INCHES IS A REASONABLE APPROXIMATION.

/OUTLOOK FOR KMSP/
SUNDAY...MVFR WITH -SN/IFR POSSIBLE IN THE MORNING. WIND NW 10G20
KTS.
MONDAY...VFR. WIND SW 5-10 KTS.

&&

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

$$

SHORT TERM...SPD
LONG TERM...RAH
AVIATION...CLF



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