000
FXUS63 KMPX 080527 AAB
AFDMPX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1127 PM CST SAT DEC 7 2013

.SHORT TERM...(TONIGHT)
ISSUED AT 325 PM CST SAT DEC 7 2013

1040 MB HIGH WAS CENTERED ALONG THE MN/IA BORDER. WATER VAPOR
IMAGERY THIS AFTERNOON SHOWS A COUPLE OF WAVES OF INTEREST BACK TO
THE SOUTHWEST. THERE IS A LEAD IMPULSE MOVING INTO SW KANSAS WITH
THE MAIN WAVE SPINNING ACROSS NEVADA. THE LEAD IMPULSE HAS INITIATED
WAA ACROSS THE PLAINS...WHICH HAS RESULTED IN CLOUD COVER RAPIDLY
EXPANDING ACROSS THE DAKOTAS. AS THIS WAVE MOVES INTO NEBRASKA...THE
HRRR SHOWS LIGHT SNOW RAPIDLY EXPANDING TO OUR SW THAT WILL START
MAKING INROADS INTO MN BETWEEN 6 AND 9Z. BIGGEST PROBLEM FOR THE
SNOW WILL BE THE DRY AIR IT NEEDS TO DISPLACE /SEE THE PWAT OF 0.06
INCHES ON THE LAST 3 KMPX SOUNDINGS/...SO THAT MAY RESULT IN THINGS
UNFOLDING A BIT SLOWER TONIGHT THAN WHAT WE CURRENTLY HAVE. FOLLOWED
THE IDEA OF THE NAM/HRRR WITH BRINGING SOME SNOW INTO THE SOUTHWEST
AFTER 6Z...WITH A BIG RAMP UP IN POPS BETWEEN 9 AND 12Z AS THE LEAD
IMPULSE MOVES INTO IOWA. THE PRIMARY UPPER WAVE OVER NEVADA WILL BE
WHAT IS RESPONSIBLE FOR THE LIGHT-MODERATE SNOW EXPECTED TO DOMINATE
OUR SUNDAY.

WITH THE HIGH PRESSURE SLIDING OFF TO OUR EAST TONIGHT...ALLOWING
FOR SOME RETURN FLOW TO SETUP LATE...ALONG WITH CLOUD COVER MOVING
UP FROM THE SOUTHWEST...IT IS A RATHER TRICKY NIGHT FOR FORECASTING
LOWS. HAVE A PRETTY AGGRESSIVE NON-DIURNAL TREND WITH HOURLY
TEMPERATURES THAT WAS BASED ON THE NAM TEMP TRENDS. THIS RESULTED IN
TEMPS WARMING ACROSS SOUTH CENTRAL MN AFTER 3Z...WITH THAT WARMING
TREND WORKING NORTH WITH THE CLOUDS THROUGH THE NIGHT. DEPENDING ON
HOW QUICKLY CLOUD COVER ARRIVES INTO CENTRAL MN...IT COULD BE
ANOTHER NIGHT OF WIDESPREAD LOWS OF 20 TO 25 BELOW ACROSS OUR
NORTH...BUT THAT WILL ALL BE DEPENDENT ON THE CLOUDS.

.LONG TERM...(SUNDAY THROUGH SATURDAY)
ISSUED AT 325 PM CST SAT DEC 7 2013

AS YOU PROBABLY NOTICED...MUCH OF SOUTHERN MN AND MOST OF WI IS
NOW UNDER A WINTER WEATHER ADVISORY FOR 2-5" SNOW EXPECTED SUNDAY
THROUGH EARLY MONDAY MORNING. AS IS TYPICAL...THE NAM/GFS/EC/GEM
HAVE ALL FALLEN PRETTY MUCH IN LINE WITH ONE ANOTHER IN TERMS OF
THE STRENGTH OF THE SURFACE TROUGH/LOW AND THE MOVEMENT WITH TIME.
THE NAM WAS THE HIGH OUTLIER YESTERDAY AND SUGGESTED THE POTENTIAL
FOR 5-7" IN SOUTHERN MN AND PORTIONS OF WESTERN WI. FORTUNATELY
FOR CONFIDENCE PURPOSES...THERE IS NO EVIDENCE OF THAT ANYMORE. WE
/NWS/ HAVE A FAIRLY UNIFORM 3-4" ACROSS THE ADVISORY AREA IN THE
FORECAST NOW AND WE ARE HAPPY WITH THIS FOR NOW. THE GOOD DENDRITE
GROWTH POTENTIAL AND HIGH SNOW RATIOS 25/30:1 SUGGEST WE COULD
EASILY STACK UP A FEW INCHES OVER THE COURSE OF THE DAY TOMORROW.
AT THE ONSET AND DURING THE FIRST FEW HOURS OF SNOWFALL...THERE
WILL BE A SOUTHEAST SURFACE WIND OF 10-15 MPH...STILL LIGHT ENOUGH
TO NOT BE CONCERNED ABOUT MUCH BLOWING OR DRIFTING AND THE WIND
SHOULD WEAKEN SUNDAY EVENING. RIGHT NOW WE HAVE THE TWIN CITIES
METRO RIGHT AT 3 INCHES. BEST GUESS IS IF WE`RE SLIGHTLY OFF WITH
THIS EVENT...WE`LL BE ON THE HIGH SIDE. WOULDN`T BE SURPRISED IF
MUCH OF THE METRO ENDS UP WITH 0.05-0.10" LIQUID AND AN 1.5" OF
SNOW. THE DERIVED REFLECTIVITY FROM NUMEROUS MESO-WRF RUNS MATCH
WELL WITH THE CURRENT ADVISORY. AT THIS POINT...THERE IS A MUCH
BETTER CHANCE FOR 3" RATHER THAN 5". THE LIMITING FACTOR IS THE
LACK OF FORCING AND OMEGA EVEN WITH THE FAVORABLE THERMAL PROFILE.
IMPACTS SHOULD BE LESS WITH THE SNOW FALLING ON SUNDAY AND ALSO
GIVEN THE SLOW RATE OF ACCUMULATION.

A CLIPPER SYSTEM DROPS DOWN ACROSS THE UPPER MISSISSIPPI RIVER
VALLEY MONDAY NIGHT INTO TUESDAY. BESIDES AN INCREASE IN THE
WIND...THERE WILL NOT BE MUCH CHANGE IN THE SENSIBLE WEATHER WITH
THIS SYSTEM. LIGHT SNOW LOOKS MORE FAVORABLE FOR NORTHERN MN. THE
CLIPPER WILL BRING ANOTHER ARCTIC BOUNDARY THROUGH TUESDAY NIGHT
INTO WEDNESDAY. SO...VERY COLD WIND CHILLS WILL CONTINUE TO BE A
CONCERN THROUGH AT LEAST MID WEEK. THERE IS A GLIMMER OF HOPE FOR
WARMER/CLOSER TO NORMAL TEMPS BY THE END OF NEXT WEEK WITH
BUILDING HEIGHTS AND A SLIGHTLY LESS AMPLIFIED FLOW OVER THE
WESTERN AND CENTRAL CONUS. WE MIGHT ACTUALLY BE ABLE TO MELT SOME
OF THE RESIDUAL ICE ON LOCAL ROADWAYS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1119 PM CST SAT DEC 7 2013

THE SNOW IS ADVANCING NORTH AND THE LEADING EDGE AT TAF ISSUANCE
TIME WAS NEAR THE MN/IA BORDER. THE SNOW WILL ENCOUNTER A LOT OF
DRY AIR WITH THE SURFACE HIGH OVERHEAD...SO THINK IT WILL STILL
TAKE SEVERAL HOURS BEFORE SNOW REACHES THE SURFACE AT MOST OF THE
AREA TAF SITES. ONCE IT DOES BEGIN REACHING THE GROUND...
VISIBILITY WILL QUICKLY DROP TO BETWEEN 1-3 MILES. A PROLONGED
PERIOD OF LIGHT SNOW WILL LAST INTO LATE AFTERNOON OR EVENING.
TOTAL ACCUMULATIONS WILL RANGE FROM AROUND AN INCH AT AXN TO 2 TO
5 INCHES ELSEWHERE...HEAVIEST TOWARD EAU.

KMSP...BEST TIMING AT THIS POINT IS VERY LIGHT SNOW WILL BEGIN
AROUND 10Z AND GRADUALLY BECOME HEAVIER INTO THE MID MORNING
HOURS. CONDITIONS WILL GRADUALLY IMPROVE THROUGH THE EVENING...BUT
SNOW IS LIKELY TO CONTINUE FALLING INTO LATE IN THE TAF PERIOD.

/OUTLOOK FOR KMSP/
MON...MVFR POSSIBLE EARLY...THEN VFR. WINDS W AT 15G25KTS.
TUE...VFR. WINDS W 15G25KTS.
WED...VFR. WINDS W 5-10KTS.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY FROM 4 AM SUNDAY TO 6 AM CST MONDAY FOR
     MNZ060-062-067>070-074>078-082>085-091>093.

     WINTER WEATHER ADVISORY FROM 6 AM SUNDAY TO 6 AM CST MONDAY FOR
     MNZ053-061-063.

WI...WINTER WEATHER ADVISORY FROM 6 AM SUNDAY TO 6 AM CST MONDAY FOR
     WIZ014>016-023>028.

&&

$$

SHORT TERM...MPG
LONG TERM...CLF
AVIATION...BORGHOFF