518
FXUS63 KMPX 081654
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1054 AM CST THU DEC 8 2022
UPDATE
ISSUED AT 1050 AM CST THU DEC 8 2022
UPDATED FOR THE 18Z AVIATION DISCUSSION
SHORT TERM
(TODAY THROUGH FRIDAY)
ISSUED AT 534 AM CST THU DEC 8 2022
KEY MESSAGES
- WINTER WEATHER ADVISORY FOR SOUTHERN MINNESOTA. SNOW POSSIBLY
MIXED WITH RAIN/FREEZING RAIN THIS EVENING THROUGH EARLY FRIDAY.
WE WILL START OUT PARTLY CLOUDY TODAY BEFORE LOW CLOUDS MOVE IN AS A
DEVELOPING SURFACE LOW ACROSS THE PLAINS SENDS MOIST, SOUTHERLY FLOW
NORTHWARD. PW VALUES NEARING A HALF INCH OR BETTER WILL OVERSPREAD
THE SOUTHERN HALF OF MINNESOTA BY THIS EVENING AS THE SURFACE LOW
TRACKS ACROSS SOUTHERN IOWA. DESPITE BEING ON THE NORTHERN SIDE OF
THIS SYSTEM, P-TYPE HAS BEEN A FORECAST CHALLENGE. MODELS HAVE
BACKED OFF A BIT ON THE DURATION OF A WARM NOSE AS THE COLUMN COOLS
SHORTLY AFTER PRECIP ONSET, SO HAVE REDUCED FREEZING RAIN
ACCUMULATIONS TO AROUND TWO HUNDREDTHS OR LESS ALONG THE I-90
CORRIDOR. AS EXPECTED, THIS HAS LED TO A BUMP IN SNOWFALL TOTALS,
WITH 3-5 INCHES LOOKING LIKELY ALONG THE I-90 CORRIDOR WITH 1-3
INCHES NORTH OF US-14. WHILE THERE IS A CHANCE THAT SOME BANDING
COULD OCCUR AND LEAD TO TOTALS CLOSER TO THE 6 INCH MARK, DECIDED
THAT THERE IS STILL ENOUGH UNCERTAINTY WITH HOW MUCH PRECIP FALLS AS
FREEZING RAIN TO JUSTIFY STAYING WITH THE WINTER WEATHER ADVISORY.
ADDITIONALLY, THE OVERALL TIMING OF THE SYSTEM SEEMS A BIT SLOWER,
SO HAVE ADJUSTED THE ADVISORY TO BEGIN AT 00Z THIS EVENING. SNOW
WILL MOVE OUT BY LATE FRIDAY MORNING WITH TEMPERATURES WARMING TO
NEAR TO JUST ABOVE FREEZING.
LONG TERM
(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 534 AM CST THU DEC 8 2022
KEY MESSAGES
- A PERIOD OF FREEZING DRIZZLE IS POSSIBLE SATURDAY MORNING.
- A LARGE STORM SYSTEM WILL IMPACT THE NORTHERN PLAINS INTO THE
UPPER MS VALLEY MONDAY NIGHT THROUGH THURSDAY. IT WILL DRAW
SIGNIFICANT AMOUNTS OF MOISTURE NORTH. THE MPX AREA LOOKS TO BE IN A
MESSY TRANSITION ZONE OF RAIN AND WINTRY P-TYPES.
THE FIRST PROBLEM TO TACKLE WILL BE A TROUGH COMING OUT OF THE
ROCKIES FRIDAY NIGHT AND MOVING INTO THE GREAT LAKE THROUGH THE DAY
ON SATURDAY. THE COMBINATION OF STRONG ISENTROPIC LIFT AND PVA OUT
AHEAD OF THE WAVE WILL PROVIDE BACKGROUND SYNOPTIC LIFT FOR
PRECIPITATION. THE PROBLEM? THE DGZ WILL BE UP BETWEEN 12K AND 15K
FEET AGL, BUT THE SATURATED LAYER LOOKS TO BE ONLY 6K TO 9K FEET
DEEP. THIS LEAVES US WITH SOUNDINGS THAT DON'T SHOW MUCH SUPPORT FOR
ICE NUCLEATION, WHICH MEANS SUPER-COOLED WATER DROPS. THIS MEANS
PRIMARY P-TYPE SATURDAY MORNING INTO THE AFTERNOON WITH THIS WAVE
WOULD BE EITHER FZDZ OR DZ DEPENDING ON THE SURFACE TEMPERATURE. BY
THE AFTERNOON, DEEPER MOISTURE STARTS TO ARRIVE, WHICH MAY ALLOW FOR
BETTER SNOW CHANCES IN WESTERN WI. STILL, GIVEN THE FORECAST
SOUNDINGS, CONSIDERABLY UPPED THE MENTION OF FZDZ WITH THIS UPDATE
FROM WHAT WE HAD GOING. MOST GUIDANCE KEEPS QPF UNDER 0.05" ON
SATURDAY. THE LIGHT QPF, COMBINED WITH TEMPERATURES NEAR 30 AND
RISING AS THE PRECIP MOVES IN AND THROUGH WILL HOPEFULLY LIMIT THE
POTENTIAL IMPACTS TO TRAVEL FROM THIS SETUP, BUT THIS IS SOMETHING
WE'LL HAVE TO WATCH CLOSELY.
BEHIND THIS TROUGH, WE'LL QUICKLY SEE H5 HEIGHTS RISE ACROSS THE
CENTRAL CONUS IN RESPONSE TO H5 LOW DIGGING INTO THE GREAT BASIN.
THIS WILL RESULT IN BENIGN WEATHER SUNDAY AND MONDAY, WITH HIGHS
GETTING INTO THE 30S, WITH THE ONLY NOTICEABLE SENSIBLE WEATHER
BEING AN UPTICK IN SOUTHEAST WINDS ON MONDAY AS A STRONG AREA OF
LOW PRESSURE BEGINS TO TAKE SHAPE OVER NORTHEAST CO.
MONDAY NIGHT THROUGH THURSDAY LOOKS, MESSY... FOR THIS FAR OUT, THE
MODELS ARE ACTUALLY IN FAIRLY GOOD AGREEMENT ON THINGS LIKE WHERE
THE SURFACE AND H7 LOWS WILL TRACK. THE MAIN SHIFT WE SAW WITH THE
00Z MODELS IS A SLIGHT SOUTHERN SHIFT IN THE LOW TRACK. THIS STILL
LEAVES US A SCENARIO WHERE THE P-TYPE TRANSITION ZONE IS OVER OUR
CWA, BUT THERE ARE INCREASING CHANCES FOR A SIGNIFICANT SNOWFALL
EVENT NORTHWEST OF A MADISON TO MORA LINE.
THE CURRENT FORECAST FOR THE LOW TRACK TAKES IT OUT OF NORTHEAST CO
AND TO THE CENTRAL KS/NEB BORDER 12Z TUE, IT WILL BECOME OCCLUDED
ON TUESDAY AND BE OVER EASTERN SODAK 12Z WED, AND BY 12Z THU IT WILL
BE OVER CENTRAL WI, WITH THE LOW PASSING DIRECTLY OVER THE MPX AREA
ON WEDNESDAY. STRONG AND DEEP SOUTHERLY FLOW OUT AHEAD OF THIS
SYSTEM WILL TRANSPORT SIGNIFICANT AMOUNTS OF MOISTURE NORTH, WITH
PWATS POTENTIALLY PUSHING AN INCH IN THE MPX AREA, WHICH IS NEAR THE
CLIMATOLOGICAL MAX FOR THE MONTH OF DECEMBER. PRECIP LOOKS TO PUSH IN
RAPIDLY MONDAY NIGHT WITHIN A STRONG ZONE OF WAA. THE PROBLEM IS
THIS WAA LOOKS TO BRING IN A STRONG WARM NOSE ALOFT. THE RESULT OF
WHICH IS SEEN IN THE MODELS WITH A POTPOURRI OF WINTRY PRECIP TYPES
BEING POSSIBLE AS THIS PRECIP LIFTS INTO THE MPX AREA. TUESDAY
MORNING, SURFACE TEMPERATURES WILL RISE ABOVE FREEZING FOR MUCH OF
THE AREA, WHICH MEANS A TRANSITION TO RAIN FOR ALL BUT POSSIBLY THE
NORTHWEST CORNER OF OUR AREA. TUESDAY AFTERNOON, STRONG LIFT WITHIN
THE PRECIP BAND MOVING IN CAUSES THE WARM NOSE TO COLLAPSE, WITH P-
TYPES TUESDAY AFTERNOON THROUGH THE REST OF THE STORM LOOKING TO BE
RAIN OR SNOW DEPENDING ON LOW LEVEL TEMPERATURE PROFILES. TUESDAY
AFTERNOON, WE'LL SEE A TROWAL AND ASSOCIATED DRY SLOT MOVE IN BEHIND
THIS INITIAL BAND OF PRECIP, WITH IT LOOKING LIKE IT MAY BE
DIFFICULT TO GET MUCH MORE THAN DRIZZLE TUESDAY NIGHT THROUGH MUCH
OF WEDNESDAY. BY WEDNESDAY AFTERNOON, THE H7 LOW WILL BE MOVING
ALONG THE MN/IA BORDER AND AS IT DOES SO, WE'LL BEGIN TO SEE THE DRY
SLOT SHIFT EAST, WITH CHANCES FOR SNOW RETURNING AS THE LOW PUSHES
INTO THE GREAT LAKES ON THURSDAY. GIVEN THE AMOUNT OF MOISTURE
COMING IN, WE'RE SEEING SOME SIGNIFICANT QPF AMOUNTS FOR DECEMBER
STANDARDS, WITH THE EPS AND GEFS MEAN QPFS NEXT WEEK EXCEEDING 1"
FOR PRETTY MUCH OUR ENTIRE CWA. FOR REFERENCE, THE AVERAGE LIQUID
EQUIVALENT PRECIP IN DECEMBER FOR MSP IS 1.17", THERE A NUMEROUS
ENSEMBLE MEMBERS SHOWING QPF WITH THIS SYSTEM EXCEEDING WHAT WE
NORMALLY SEE FOR LIQUID FOR THE ENTIRE MONTH OF DECEMBER. THERE ARE
STILL MANY MOVING PARTS THIS FAR OUT, BUT ONE THING IS FOR SURE, WE
WILL BE DEALING WITH A SIGNIFICANT WINTER STORM NEXT WEEK, IT'S JUST
A MATTER OF PINNING DOWN WHERE THINGS LIKE THE RAIN/SNOW LINE AND
DRY SLOT SETUP.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1050 AM CST THU DEC 8 2022
VFR TO START THE PERIOD BEFORE LOW CLOUDS MOVE IN THIS AFTERNOON
AHEAD OF A SYSTEM THAT WILL BRING PRECIP TO OUR SOUTHERN SITES AFTER
03Z. TIMING OF PRECIPITATION HAVE BEEN PUSHED BACK TO MATCH MODEL
TRENDS. MODELS HINT AT SOME IFR CEILINGS MOVING IN AHEAD OF THE
SYSTEM BY THIS AFTERNOON, MAINLY FOR KEAU AND KMKT, WITH OBS
BEGINNING TO MATCH THAT. SNOW, POTENTIALLY MIXED WITH RAIN AT TIMES,
WILL SPREAD NORTH AND EASTWARD FROM SOUTH DAKOTA/IOWA THROUGH THE
OVERNIGHT WITH THE BULK OF THE PRECIP EXPECTED AFTER 05Z. SNOWFALL
RATES COULD NEAR 1"/HOUR AT TIMES, PARTICULARLY FOR KMKT, THROUGH THE
END OF THE PERIOD. WINDS REMAIN LIGHT AND TURN SOUTHEASTERLY TODAY
AHEAD OF THE SYSTEM AND GO EASTERLY ON THE BACKSIDE.
KMSP...TIMING HAS BEEN PUSHED BACK A BIT FROM THE PREVIOUS FORECAST
WITH THE HEAVIEST SNOW EXPECTED BETWEEN 09Z AND 13Z. HOWEVER, NOT
ANTICIPATING THE 1"/HOUR RATES TO MAKE IT AS FAR NORTH AS KMSP. SNOW
WILL TAPER OFF TOWARDS THE END OF THE PERIOD. THE TREND WITH
LATER/LIGHTER SNOWFALL CONTINUES AS THE SYSTEM TRENDS FURTHER SOUTH
WITH THE MAIN PRECIPITATION.
/OUTLOOK FOR KMSP/
SAT...VFR, CHC MVFR/-FZDZ. WIND SE 5-10KTS.
SUN...VFR. WIND SE 5-10KTS.
MON...VFR, CHC MVFR LATE. WIND SE 5-10KTS.
MPX WATCHES/WARNINGS/ADVISORIES
MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 9 AM CST FRIDAY
FOR BLUE EARTH-BROWN-FARIBAULT-FREEBORN-GOODHUE-LE SUEUR-
MARTIN-NICOLLET-REDWOOD-RICE-STEELE-WASECA-WATONWAN.
WI...NONE.
SHORT TERM...DYE
LONG TERM...MPG
AVIATION...BPH
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