455
FXUS63 KMPX 172039 CCA
AFDMPX
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
239 PM CST SUN NOV 17 2024
KEY MESSAGES
- WIDESPREAD SOAKING RAINFALL MONDAY AFTERNOON INTO TUESDAY MORNING.
AN INCH OR SO OF RAIN APPEARS LIKELY AT MOST LOCATIONS.
- COLDER AIR ARRIVES FOR THE MIDDLE OF THE WEEK, WITH SOME SNOW
ACCUMULATION POSSIBLE ACROSS WESTERN MINNESOTA TUESDAY NIGHT
THROUGH WEDNESDAY.
- TEMPERATURES WILL BE MUCH COLDER BY THE END OF THE WORK WEEK, WITH
HIGHS IN THE 30S AND LOWS IN THE 20S.
DISCUSSION
ISSUED AT 221 PM CST SUN NOV 17 2024
VISIBLE SATELLITE REVEALS CLEAR SKIES ACROSS SOUTH CENTRAL MINNESOTA
AND WESTERN WISCONSIN. AFTERNOON HIGHS ARE ON TRACK TO TOP OUT WELL
ABOVE NORMAL, IN THE UPPER 40S TO LOW 50S. WSW WINDS WILL
OCCASIONALLY GUST TO AROUND 20 MPH THROUGH THE AFTERNOON, HOWEVER
THEY ARE EXPECTED TO DIMINISH HEADING INTO THE EVENING. DESPITE
CLEAR SKIES TONIGHT, LIGHT SOUTHERLY WINDS WILL SUPPORT
TEMPERATURES FROM FALLING BELOW THE FREEZING MARK IN MANY SPOTS.
RAP FORECAST SOUNDINGS HAVE HINTED AT THE POSSIBILITY OF PATCHY
FOG GENERALLY ALONG AND NORTH OF I-94 WHERE WINDS ARE FORECAST TO
BE THE LIGHTEST AND RELATIVE HUMIDITY CLIMBS ABOVE 90 PERCENT FROM
JUST AFTER MIDNIGHT THROUGH DAYBREAK. CONFIDENCE IS LOW IN THE
DEVELOPMENT OF FOG, BUT IT WILL BE SOMETHING TO KEEP AN EYE ON
OVERNIGHT. MONDAY WILL BEGIN CALM AND DRY. TEMPERATURES ARE
FORECAST TO CLIMB INTO THE LOW TO MID 50S PRIOR TO THE ARRIVAL OF
SOAKING RAIN THROUGH THE SECOND HALF OF THE DAY.
CONUS WATER VAPOR IMAGERY AND 500MB ANALYSIS REVEAL A CLOSED UPPER-
LOW CURRENTLY LOCATED OVER ARIZONA. THE CLOSED LOW WILL BECOME
NEGATIVELY TILTED AS IT LIFTS NORTHEAST OVER THE SOUTHERN GREAT
PLAINS. BROAD ASCENT EAST OF THE UPPER-LOW WILL SPAWN A DEVELOPING
SURFACE CYCLONE ACROSS TEXAS TONIGHT. THE ~980S MB SURFACE LOW
PRESSURE SYSTEM IS PROGGED TO RACE NORTH MONDAY AND WILL BRING A
PERIOD OF REGION-WIDE RAINFALL MONDAY AFTERNOON THROUGH TUESDAY
MORNING. FAVORABLE MOISTURE TRANSPORT AND ISENTROPIC ASCENT WILL
WORK IN TANDEM TO PRODUCE A WIDESPREAD SHIELD OF RAINFALL TO THE
NORTH OF THE SURFACE LOW. EXPECTED MOISTURE RETURN INTO THE UPPER
MIDWEST REMAINS QUITE REMARKABLE, WITH PWATS (1-1.25") NEAR RECORD
VALUES PER MPX SOUNDING CLIMATOLOGY. OUR LATEST FORECAST
ILLUSTRATES THE ARRIVAL OF THE RAIN ACROSS SOUTHERN MINNESOTA BY
EARLY AFTERNOON. RAIN WILL CONTINUE TO LIFT NORTHWARD TOWARDS THE
I-94 CORRIDOR THROUGH LATE AFTERNOON, SETTING THE STAGE FOR A
SOGGY EVENING COMMUTE. THE RAIN WILL BE MODERATE TO HEAVY AT TIMES
THROUGH EARLY TUESDAY, PRIOR TO THE ARRIVAL OF THE SYSTEM'S DRY
SLOT WHICH WILL BRING AN END TO THE RAIN FROM SOUTH TO NORTH
TUESDAY MORNING. MOST LOCATIONS ARE EXPECTED TO SEE AN INCH OR SO
OF RAIN, WITH UP TO AN INCH AND A HALF POSSIBLE. WESTERLY GUSTS
WILL REACH SPEEDS BETWEEN 30-40 MPH ACROSS WESTERN MINNESOTA
TUESDAY.
FORECAST GUIDANCE CONTINUES TO COME INTO BETTER AGREEMENT WITH THE
RANGE OF POSSIBLE OUTCOMES REGARDING WRAP AROUND PRECIPITATION AND
POTENTIAL SNOWFALL ON WEDNESDAY. THE LATEST RUNS OF THE EPS/GEM
SUITES REMAIN STEADFAST ON A DUE NORTH/NORTHWEST TRACK AND CESSATION
OF THE OCCLUDING SURFACE LOW ACROSS SOUTHERN MANITOBA. NEW GEFS
SUITE HAS TRENDED FURTHER WEST ACROSS THE ENSEMBLE MEMBERSHIP, WHICH
IS REFLECTED IN THE DETERMINISTIC RUN AS WELL. THE AFOREMENTIONED
STALL OF THE SURFACE LOW WILL ALLOW FOR NORTHWESTERLY FLOW TO
TRANSPORT COLDER AIR FROM SOUTHERN CANADA INTO THE UPPER MIDWEST,
ALLOWING FOR WRAP AROUND PRECIPITATION TO TRANSITION TO LIGHT SNOW.
IT LOOKS LIKE THE BEST CHANCE FOR SEVERAL INCHES OF ACCUMULATING
SNOW WILL BE FOR LOCATIONS NEAR THE SURFACE LOW, SAY ACROSS
NORTH DAKOTA, DUE TO BETTER DYNAMICS. HOWEVER, CURVATURE VORTICITY
SHOULD PROVIDE ENOUGH LIFT TO PRODUCE SNOW SHOWERS LOCALLY. THE
BEST CHANCE FOR A FEW INCHES OF SNOW ACCUMULATION WILL BE ACROSS
WESTERN MINNESOTA. WE DON'T EXPECT AS MUCH IN TERMS OF ACCUMULATION
IN EASTERN MINNESOTA AND WESTERN WISCONSIN, THOUGH THE COMBINATION
OF STRONG NORTHWESTERLY WINDS AND SNOW SHOWERS WILL MAKE FOR A
RATHER UNPLEASANT DAY OUTDOORS. WE HAVE REFLECTED THIS POTENTIAL
WITH 40-60% POPS IN THE GRIDS. THE 12Z NAM IS AN OUTLIER IN THE
DATA SET, WITH AN ELONGATED SURFACE LOW LOCATED FURTHER TO THE
NORTH AND EAST THAN THE SCENARIO CAPTURED ABOVE. IN THIS SOLUTION,
THE WRAP AROUND PRECIPITATION/SNOWFALL ARE MORE LIKELY ACROSS
NORTH CENTRAL MINNESOTA, WITH DRY WEATHER IN THE SOUTH.
THE UPPER-LOW IS PROGGED TO TRANSLATE SOUTHEAST OVER THE GREAT
LAKES ON THURSDAY. WE'LL KEEP THE CHANCE FOR A FEW SNOWFLAKES
AROUND EARLY THURSDAY MORNING, BEFORE THE UPPER-LEVEL FEATURES
MOVE OFF TO THE EAST. NORTHWESTERLY FLOW WILL BECOME THE
DOMINATING FEATURE IN THE UPPER AIR PATTERN THROUGH THE UPCOMING
WEEKEND, WHICH WILL DROP TEMPERATURES INTO THE 30S FOR HIGHS
AND 20S FOR LOWS. THE FORECAST APPEARS QUIET THROUGH SATURDAY,
BUT GLOBAL MODELS HAVE STARTED TO HINT AT A CLIPPER-TYPE SYSTEM
MOVING ACROSS THE NORTHERN CONUS ROUGHLY A WEEK FROM NOW. THERE
IS A LONG WAY TO GO BEFORE WE CAN LOCK IN ANY SPECIFICS, BUT
THE EXPECTED ENVIRONMENT SHOULD BE COLD ENOUGH FOR SNOW TO BE IN
THE DISCUSSION IF A WEATHER SYSTEM WERE TO TAKE SHAPE.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1126 AM CST SUN NOV 17 2024
MORNING STRATUS HAS LIFTED NORTH OF THE TERMINALS, BEGINNING
WHAT WILL BE AN EXTENDED PERIOD OF CLEAR SKIES AND VFR
CONDITIONS FOR MOST OF THE 18Z TAF PERIOD. WEST/SOUTHWESTERLY
WINDS WILL GRADUALLY SUBSIDE THIS EVENING, BEFORE TURNING
SOUTHERLY BY DAYBREAK. FORECAST GUIDANCE TEASES THE IDEA OF
PATCHY FOG DEVELOPING AROUND 12Z AT A FEW OF THE TERMINALS,
HOWEVER THIS IS A LOW CONFIDENCE SCENARIO AT THIS TIME, SO DID
NOT INCLUDE IN THE TAFS. A BROAD SHIELD OF MODERATE TO HEAVY
RAIN, STRONG EASTERLY WINDS, AND MVFR/IFR OR LOWER CEILINGS AND
VISIBILITY WILL IMPACT ALL TERMINALS MONDAY EVENING INTO
TUESDAY. FORTHCOMING TAFS WILL BEGIN TO ADDRESS THE EXPECTED
CONDITIONS.
KMSP...CONDITIONS WILL BEGIN TO DETERIORATE MONDAY AFTERNOON,
WITH RAIN, LOW CEILINGS/VISIBILITY, AND GUSTY WINDS OUT OF THE
SOUTHEAST. WE HAVE INCLUDED A PROB30 AT THE END OF THE 18Z TAF
TO ADDRESS THIS POTENTIAL.
/OUTLOOK FOR KMSP/
TUE...MVFR/IFR. RA EARLY. WIND SE 10-15KTS BCMG W 20-25G35 KTS.
WED...MVFR. CHANCE -SHSN/IFR. WIND WNW 15-20G25-30KTS.
THU...MVFR CEILINGS POSSIBLE. WIND NW 15-20G25-30KTS.
MPX WATCHES/WARNINGS/ADVISORIES
MN...NONE.
WI...NONE.
DISCUSSION...STRUS
AVIATION...STRUS
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