624
FXUS63 KMPX 220457
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1057 PM CST THU NOV 21 2024
KEY MESSAGES
- PATCHY FREEZING FOG POSSIBLE TONIGHT AND FRIDAY NIGHT.
- ONE LAST CHANCE TO GET SOME OUTDOOR WORK DONE ON SUNDAY WITH
HIGHS IN THE 40S.
- TURNING MUCH COLDER NEXT WEEK, WITH OUR FIRST TASTE OF ARCTIC
AIR LOOKING INCREASINGLY LIKELY FOR THANKSGIVING WEEKEND.
- NO SIGNIFICANT WINTER SYSTEMS EXPECTED TO IMPACT THE REGION
OVER THE NEXT WEEK.
DISCUSSION
ISSUED AT 401 PM CST THU NOV 21 2024
A SURFACE LOW AS BEEN TRACKING SOUTH ACROSS LAKE MICHIGAN THROUGH
THE DAY, WITH HIGH PRESSURE OVER THE DAKOTAS KEEPING THE CEASELESS
NORTHWEST WINDS GOING THROUGH THIS AFTERNOON. THE GOOD NEWS IS THAT
THROUGH SATURDAY MORNING, THE DAKOTAS HIGH WILL BE SLOWLY WORKING
ACROSS THE MPX AREA. THIS MEANS WE FINALLY LOSE THE WINDS ON FRIDAY,
BUT THE BIG UNCERTAINTY IS WHAT HAPPENS WITH THE CLOUD COVER.
LOOKING AT RAP SOUNDINGS, WE LOOK TO HAVE A SCENARIO WHERE WE HAVE A
THIN MOISTURE LAYER THAT GETS TRAPPED BENEATH AN INVERSION. THIS
TIME OF YEAR, THAT TRANSLATES INTO VERY STUBBORN STRATUS LAYERS THAT
ARE POORLY RESOLVED BY THE MODELS. AS THE HIGH PRESSURE MOVES IN ON
FRIDAY, THE LOSS OF CYCLONIC FLOW SHOULD START TO CLEAR OUT THE LOW
CLOUDS, BUT THOSE LOW CLOUDS LOOK TO BE REPLACED BY MID AND UPPER
LEVEL CLOUDS. THE BIGGEST ISSUE WITH CLOUD COVER WILL COME DURING
THE OVERNIGHT PERIODS THE NEXT TWO NIGHTS. WINDS WILL BECOME LIGHT
AND VARIABLE OVERNIGHT IN WESTERN MN AND THEN ACROSS THE ENTIRE AREA
FRIDAY NIGHT AS THE SURFACE RIDGE AXIS MOVES THROUGH. WITH THIS
SETUP, ANYWHERE THAT SEES CLEAR SKIES TONIGHT IN WESTERN MN WILL
LIKELY HAVE THAT CLEARING FILLED IN WITH FREEZING FOG, WITH THAT
FREEZING FOG THREAT SPREADING ACROSS PRETTY MUCH THE ENTIRE AREA
FRIDAY NIGHT. AGAIN, THE BIG UNCERTAINTY IS WHAT CLOUD COVERAGE WILL
LOOK LIKE THE NEXT TWO NIGHTS. GIVEN THE UNCERTAINTY WITH CLOUD
COVER, WE DON'T HAVE MUCH FOG MENTION, BUT ANYONE THAT MANAGES TO
GET LIGHT WINDS AND CLEAR SKIES OVER THE NEXT TWO NIGHT WILL HAVE
THE THREAT OF FREEZING FOG.
FOR THE WEEKEND, MODELS CONTINUE TO SHOW A SHORTWAVE WORKING ACROSS
THE INTERNATIONAL BORDER SUNDAY NIGHT/MONDAY. THIS SHORTWAVE WILL
DRAG AN INVERTED SURFACE TROUGH ACROSS THE AREA SUNDAY INTO MONDAY
MORNING. THE BEST FORCING AND SIGNAL FOR PRECIPITATION CONTINUES TO
BE ACROSS THE INTERNATIONAL BORDER AND LAKE SUPERIOR, THOUGH WE
COULD SEE SOME LIGHT RAIN/SNOW ACROSS CENTRAL MN AND NORTHWEST WI
LATE SUNDAY INTO MONDAY. THE MAIN IMPACT LOCALLY OF THIS INVERTED
TROUGH WILL BE THE WAA OUT AHEAD OF IT. THIS WAA WILL SEND HIGHS
INTO THE 40S FOR MUCH OF THE MPX AREA ON SUNDAY, GIVING US ONE LAST
CHANCE TO GET SOME OUTDOOR WORK DONE BEFORE SOME REAL WINTER COLD
COMES SLAMMING IN FOR THE END OF NOVEMBER.
AS FOR NEXT WEEK, THE MEAN 200MB FLOW FROM THE EPS SHOWS THE PRIMARY
JET BEING A SOUTHERN STREAM FEATURE THAT WILL BE WELL TO OUR SOUTH.
THIS MEANS THE PRIMARY STORM TRACK WILL BE TO OUR SOUTH. HOWEVER,
THERE WILL BE A NORTHERN STREAM JET OF THE NORTHWEST VARIETY COMING
DOWN FROM NORTHWEST CANADA INTO THE DAKOTAS. THIS NORTHWEST JET IS
WHAT WILL OPEN US UP TO GETTING OUR FIRST REAL SHOT OF ARCTIC AIR OF
THE SEASON OVER THE EXTENDED THANKSGIVING HOLIDAY WEEKEND. THIS IS A
COLD A DRY PATTERN, SO IT LOOKS UNLIKELY WE'LL SEE ANY SIGNIFICANT
WEATHER SYSTEMS UP THIS FAR NORTH, BUT GIVEN THE MULTIPLE STREAMS OF
FLOW NEAR US, WE WILL HAVE TO POTENTIAL FOR SEEING SOME QUICK
HITTING WAVES CAPABLE OF PRODUCING SOME LIGHT PRECIP. GIVEN THE
TEMPERATURES WE WILL HAVE NEXT WEEK, ANY PRECIPITATION WE SEE WILL
COME IN THE FORM OF SNOW. AT THIS POINT THOUGH, DETERMINISTIC AND
ENSEMBLE SYSTEMS WOULD FAVOR ANY SNOW WE SEE NEXT WEEK BEING MORE OF
THE COSMETIC/NUISANCE VARIETY AS OPPOSED TO A BIG DUMP OF SNOW.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1057 PM CST THU NOV 21 2024
THE MAIN THEME OF THE FORECAST IS PERSISTENT STRATUS. MVFR WILL
BE THE PRIMARY CEILING HEIGHT FOR THE PERIOD. THERE ARE SOME
CHANCES FOR IFR AT MOST TERMINALS AND MAYBE EVEN LIFR AT AXN
OVERNIGHT. AXN WILL ALSO BE THE SPOT WITH THE BEST CHANCE FOR
MIST OR FOG TO FORM. OVERALL THE FOG CHANCES APPEAR PATCHY
OVERNIGHT, SO I HAVE ONLY ADDED IT TO TERMINALS WHERE IT IS MOST
LIKELY. HOWEVER IF RWF REMAINS CLEAR FOR MUCH LONGER THE
RESULTING COOLING COULD MAKE A STRONG CASE FOR RADIATION FOG TO
OCCUR AND BE ADDED TO THE TAF. WINDS WILL REMAIN LIGHT AND
COULD APPROACH CALM TO LIGHT AND VARIABLE AS WE HEAD INTO
TOMORROW NIGHT. TOMORROW NIGHT, FOR THIS REASON, COULD BE THE
BETTER FOG NIGHT.
KMSP...NO ADDITIONAL CONCERNS.
/OUTLOOK FOR KMSP/
SAT...CHC MVFR CIGS. WIND NW 5-10 KTS.
SUN...VFR. WIND SE 5-10 KTS.
MON...VFR/MVFR W/ CHC -SHSN. WIND NW 10-15G20 KTS.
MPX WATCHES/WARNINGS/ADVISORIES
MN...NONE.
WI...NONE.
DISCUSSION...MPG
AVIATION...NDC
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