876
FXUS63 KMPX 092049
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
249 PM CST THU JAN 9 2025
KEY MESSAGES
- BAND OF LIGHT SNOW WILL CONTINUE TO TRANSLATE EAST THROUGH THE EARLY
EVENING HOURS. MINOR ACCUMULATIONS AND A FEW SLICK SPOTS
EXPECTED.
- A CLIPPER SYSTEM WILL BRING THE RETURN OF LIGHT SNOW TO THE REGION
LATE SATURDAY INTO SUNDAY. FEW INCHES OF ACCUMULATION LIKELY.
- MUCH COLDER EARLY NEXT WEEK, WITH SUB-ZERO LOWS EXPECTED.
DISCUSSION
ISSUED AT 242 PM CST THU JAN 9 2025
REGIONAL MRMS DISPLAY CAPTURES A NORTH TO SOUTH ORIENTED BAND OF
SNOW TRAVELING EAST ACROSS CENTRAL/SOUTHERN MINNESOTA THIS
AFTERNOON. THE HEAVIEST SNOW IS REPORTED ALONG AND NORTH OF I-94,
WHERE SURFACE OBSERVATIONS CAPTURE VISIBILITY BELOW 1 MILE.
MNDOT CAMERAS SHOW THE MINOR ACCUMULATION (GENERALLY AN INCH OR
LESS) ACROSS WESTERN COMMUNITIES. THE BEST FORCING IS LIFTING
INTO NORTHERN MINNESOTA, SUCH THAT SNOWFALL RATES WILL BECOME
LOWER WITH EASTERN EXTENT THIS AFTERNOON. THE GOING FORECAST
REMAINS ON TRACK THROUGH THIS EVENING, WITH ADDITIONAL SNOWFALL
EXPECTED TO REMAIN BELOW A HALF INCH ACROSS SOUTHEASTERN MINNESOTA
& WESTERN WISCONSIN. THE BEST CHANCE FOR SLIGHTLY HIGHER AMOUNTS
WILL BE NORTH OF I-94 IN EASTERN MINNESOTA, DUE TO THE BETTER
FORCING REFERENCED ABOVE. WHILE THIS IS A LOW IMPACT EVENT,
THERE WILL BE ENOUGH SNOW TO CREATE SLICK SPOTS ON AREA
ROADWAYS.
A VORTICITY LOBE CENTERED OVER CENTRAL MANITOBA IS PROGGED TO
PINWHEEL SOUTHEAST INTO NORTHERN MINNESOTA OVERNIGHT. THE
PRESENCE OF LIFT ASSOCIATED WITH THE VORT LOBE WILL WORK IN
TANDEM WITH THE NORTHWESTERLY FLOW REGIME TO PRODUCE FLURRIES
TONIGHT AND TOMORROW. TRADITIONALLY, THIS TYPE OF SETUP HAS
PRODUCED BURSTS OF SNOWFLAKES WITH BRIEF REDUCTIONS IN
VISIBILITY, THOUGH LITTLE TO NO ACCUMULATION. FORECAST SOUNDINGS
CAPTURE THIS SCENARIO WITH A SHALLOW, BUT SATURATED DGZ IN THE
LOWEST 5K FEET ALONG WITH MODERATE OMEGA FORCING. LOW-LEVEL
LAPSE RATES APPEAR TO BE TOO STABLE FOR THE DEVELOPMENT OF MORE
PRONOUNCED "CONVECTIVE" SNOW SHOWERS. A QUIET PERIOD IS ON TAP
FRIDAY INTO SATURDAY, AS WINDS GENTLY FLIP OUT OF THE SOUTH
AHEAD OF THE NEXT INCOMING SYSTEM.
NO MAJOR CHANGES WITH THE GOING TREND FOR A PERIOD OF ACCUMULATING
SNOW SATURDAY NIGHT INTO SUNDAY MORNING. WE'VE FOLLOWED THE TREND OF
THE OVERNIGHT SHIFT TO BUMP UP NBM POPS A TAD SO THAT LOCATIONS
GENERALLY ALONG AND NORTH OF I-94 (INCLUDING THE TC METRO) CARRY 70-
80% POPS. STORM TOTAL QPF CLOSELY REFLECTS THAT OF THE GLOBAL
ENSEMBLE MEANS, WITH ~0.1" ALONG AND NORTH OF I-94. LESSER AMOUNTS,
SAY NEAR 0.05" LIQUID ARE FOUND TO THE SOUTHWEST TOWARDS THE MINNESOTA
RIVER. A GLANCE AT THE 12Z EPS REVEALED A SLIGHT NORTHERN SHIFT,
WITH DRIER AMOUNTS ACROSS SOUTHERN MINNESOTA. WE'LL WATCH TO
SEE IF THE NORTHERN SHIFT BECOMES A TREND IN FORTHCOMING
FORECASTS, AS THAT WOULD LOWER THE POTENTIAL FOR HIGHER QPF
AMOUNTS CLOSER TO ~0.2" OR SO. NBM SLR'S BETWEEN 15-18:1 SEEM
REASONABLE FOR THIS CLIPPER SETUP AND A QUICK CALCULATION
REVEALS 1-2" OF SNOW FOR MOST LOCATIONS. COMMUNITIES NORTH OF
I-94 COULD SEE AMOUNTS CLOSER TO 3" GIVEN A LONGER DURATION
SNOWFALL NORTH OF THE SURFACE LOW.
GUSTY NORTHWESTERLY WINDS WILL USHER IN COLDER AIR FOLLOWING THE
DEPARTURE OF THE SYSTEM. LOWS ARE FORECAST TO DIP TO NEAR OR BELOW
ZERO MONDAY, WITH WIDESPREAD SUB-ZERO LOWS APPEARING MORE LIKELY
TUESDAY. WIND CHILLS WILL DROP INTO THE -15 TO -25 BELOW ZERO RANGE
EARLY IN THE WEEK. SINGLE DIGIT HIGHS MONDAY & TUESDAY WILL BEGIN TO
WARM BY MIDWEEK. THE WARMING TREND WILL PRECEDE THE NEXT ITERATION
IN THE PARADE OF WINTRY WAVES, WHICH IS SET TO SLIDE THROUGH
THE GREAT LAKES DURING THE MIDDLE TO END OF NEXT WEEK. CONFIDENCE
IS LOW THE CURRENT TRACK, HOWEVER I THINK MANY FOLKS WILL
WELCOME THE LOW 30S ON THURSDAY, AS CURRENTLY ADVERTISED BY THE
NBM.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1113 AM CST THU JAN 9 2025
THE TREND FOR THE 18Z TAF PERIOD IS TO GENERALLY INCREASE THE
VISIBILITY EXPECTED DURING THE SNOWFALL EXPECTED TO ARRIVE
AND END WITHIN THE FIRST 6-12 HOURS AS SNOWFALL RATES SHOULD BE
LOWER BASED ON RECENT GUIDANCE. SNOW IS STILL EXPECTED TO FALL
AT MOST/ALL SITES, HOWEVER RATES AND THEREFORE ACCUMULATIONS
WILL BE LOWER THAN PREVIOUSLY FORECAST. THE TIMING HAS ALSO
SLOWED BY AN HOUR OR TWO DEPENDING ON SITE BASED ON WHAT HAS
TAKEN PLACE THUS FAR TODAY. MVFR CIGS/VIS ARE EXPECTED AS THE
SNOW MOVES THROUGH, WITH A SLOW RETURN TO LOW VFR CIGS DURING
THE FINAL 6 HOURS OF THE PERIOD. WESTERN SITES COULD SEE A FEW
LINGERING SNOW SHOWERS BEHIND THE MAIN BAND OF SNOWFALL
OVERNIGHT.
KMSP...THE MAIN CHANGE HAS BEEN TO INCREASE EXPECTED VISIBILITY
AS SNOW FALLS WITH LOWER SNOWFALL RATES ALSO LEADING TO LOWER
ACCUMULATION. FOR NOW, TIMING OF 21Z-01Z IS THE EXPECTED
INTERVAL FOR ACCUMULATING SNOW, WITH ANY SNOW SHOWERS AFTER 01Z
FAILING TO ACCUMULATE OR REDUCE VISIBILITY LOWER THAN 6 MILES.
/OUTLOOK FOR KMSP/
SAT...VFR. IFR/SN OVERNIGHT. WIND S 5-10KTS.
SUN...MVFR/IFR/SN EARLY. WIND NW 10-15G25KTS.
MON...VFR. WIND NW 5-10KTS.
MPX WATCHES/WARNINGS/ADVISORIES
MN...NONE.
WI...NONE.
DISCUSSION...STRUS
AVIATION...TDH
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