397
FXUS63 KGRR 030028
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
728 PM EST SUN FEB 2 2025
KEY MESSAGES
- AREAS OF FOG TONIGHT AND MONDAY MORNING
- LIGHT MIX NEAR U.S. 10 MONDAY
- WINTRY MIX WEDNESDAY NIGHT; BREEZY THURSDAY
UPDATE
ISSUED AT 727 PM EST SUN FEB 2 2025
WE DECIDED TO HOIST A DENSE FOG ADVISORY FOR TONIGHT AND THROUGH
NOON (17Z) ON MONDAY.
VISIBILITIES ARE MOSTLY BELOW 2 MILES ACROSS THE AREA, WITH QUITE
A FEW SITES SITTING AT 1/2 MILE OR LESS ALREADY THIS EVENING. WITH
THE LOSS OF DAYLIGHT, WINDS UNDER 5 MPH, AND DEW POINTS ONLY
RISING THROUGH THE NIGHT, COMBINED WITH THE NEW SNOWPACK, FOG WILL
ONLY BECOME MORE DENSE OVERNIGHT.
ANOTHER CONCERN AS MENTIONED IN THE PREVIOUS DISCUSSION, IS
POSSIBLE BLACK ICE FORMATION NORTH OF INTERSTATE 96 OVERNIGHT.
ROAD TEMPS ARE MAINLY AT OR BELOW FREEZING FOR THOSE AREAS.
TEMPERATURES ARE ALREADY BELOW FREEZING, BUT SHOULD RISE A LITTLE
OVERNIGHT. WE DID MENTION IT IN THE DENSE FOG ADVISORY PRODUCT,
AND WILL MONITOR TO SEE IF ANY OTHER ACTIONS WILL BE NEEDED FOR
THAT.
DISCUSSION
ISSUED AT 344 PM EST SUN FEB 2 2025
- AREAS OF FOG TONIGHT AND MONDAY MORNING
A FRESH 1-2" WET SNOW COVER PUT DOWN BY THIS MORNING'S QUICK-
HITTING SYSTEM IS IN PLACE AND TEMPS/DEW POINTS WILL CONTINUE TO
SLOWLY RISE TONIGHT. WITH LIGHT WINDS EXPECTED THE RESULT WILL BE
FOR AREAS TO FOG TO FORM, SOME OF WHICH COULD BECOME DENSE.
VISIBILITIES BELOW ONE HALF MILE ARE ALREADY OCCURRING NEAR THE
MI/IN BORDER. WE MAY NEED TO CONSIDER A DENSE FOG ADVISORY FOR
THE MONDAY MORNING COMMUTE TIME DEPENDING ON TRENDS LATER TONIGHT.
SOME LOCATIONS NORTH OF ABOUT M-46 MAY STAY JUST COLD ENOUGH FOR
FREEZING FOG/BLACK ICE TO EVEN OCCUR TONIGHT.
- LIGHT MIX NEAR U.S. 10 MONDAY
ELONGATED BUT NARROW BAND OF ACCUMULATING, FGEN-FORCED SNOW ALONG
A TIGHT MID LEVEL BAROCLINIC ZONE OVER THE NORTH CENTRAL U.S.
LOOKS TO STAY JUST NORTH OF THE GRR CWFA AREA MONDAY. HOWEVER ON
THE SOUTHERN FLANK OF THAT BAND THERE MAY BE A BIT OF LIGHT MIXED
PRECIPITATION NEAR THE U.S. 10 CORRIDOR. FORECAST SOUNDINGS
INDICATE THAT SNOW AND RAIN (OR A MIX THEREOF) ARE EQUALLY
POSSIBLE IN THIS AREA AND THERE IS ALSO A LOW RISK FOR A PERIOD OF
LIGHT FREEZING RAIN IF/WHERE TEMPS STAY COLD ENOUGH SUCH AS
AROUND CLARE/HARRISON.
- WINTRY MIX WEDNESDAY NIGHT; BREEZY THURSDAY
SPECIFIC DETAILS OF THE MIDWEEK SYSTEM ARE STILL NOT VERY CLEAR.
THIS SYSTEM IS AIDED BY A COUPLED JET STRUCTURE ALOFT, WITH A 150
KT PACIFIC JET STRETCHING EAST FROM CA PROVIDING LFQ LIFT WHILE
ANOTHER 120KT JET SITUATED FROM NORTH OF LAKE SUPERIOR TO NEW
ENGLAND PROVIDES COINCIDENT RRQ LIFT.
MODELS/ENSEMBLES HAVE VARYING SOLUTIONS OF HOW THIS ALL PLAYS
OUT, WITH ONE CAMP (MAINLY THE GFS/GEFS) KEEPING THE HEAVIER QPF
DOWN THROUGH THE OHIO VALLEY AND A COLDER SOLUTION OVER MI WITH
MORE OF A LIGHT SNOW THREAT (AND SOME RISK OF FREEZING RAIN IN THE
SOUTH). ANOTHER CAMP (MAINLY THE ECWMF/ECE) HAS A MORE NRN SFC
LOW TRACK WHICH PULLS THE BETTER WAA QPF FARTHER NORTH WITH A
STRONGER RISK OF FREEZING RAIN AS THE PREDOMINANT P-TYPE.
OBVIOUSLY THE EC SOLUTION WOULD BE MORE IMPACTFUL ESPECIALLY IF
THE PRECIP IS CONVECTIVE AS SUGGESTED BY ITS MUCAPE PROGS AND IF
IT IS MOSTLY FREEZING RAIN. THE PRIMARY TIME OF CONCERN LOOKS TO
BE LATE WED AFTERNOON AND WED EVENING WHEN THE LOW LEVEL JET WILL
BE AIMED AT THE AREA. MID LEVEL DRY SLOT THEN PUNCHES IN QUICKLY
LATE WED NIGHT/EARLY THURSDAY BRINGING AN ABRUPT DIMINISHING TREND
TO THE PRECIP. THE EC SOLUTION ALSO SUPPORTS SOME FAIRLY STRONG
WIND GUSTS IN THE DRY SLOT ON THURSDAY, POSSIBLY EXCEEDING 40/45
MPH PER ENSEMBLE MEANS.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 705 PM EST SUN FEB 2 2025
IFR AND LOWER CIGS AND VSBYS CONTINUE TO DEVELOP OVER SOUTHERN
LOWER MICHIGAN THIS EVENING. WHILE THERE ARE SOME BREAKS, WITH
BIV AND LAN UP TO MVFR, THESE WILL BE TEMPORARY. THE CALM
OVERNIGHT WINDS COUPLED WITH WARM OVERNIGHT LOWS AND A WET,
MELTING SNOWPACK AND IT IS A RECIPE FOR WINTER TIME FOG
DEVELOPMENT. THE MODELS DO INDICATE A SLIGHT RESPITE FOR A FEW
HOURS, FROM 03Z TO 06Z, HOWEVER GIVEN THE LOW LEVEL MOISTURE
AVAILABLE THIS SHOULDN'T MATERIALIZE. A SYSTEM MOVING THROUGH
NORTHERN LOWER MICHIGAN EARLY TOMORROW COULD MIX IN SOME LIGHT
RAIN TO MKG AND PERHAPS GRR. DUE TO THE ADDED MOISTURE AND THAT
SFC WINDS WILL REMAIN OUT OF THE SOUTH, DON' EXPECT CIGS AND VSBYS
TO IMPROVE UNTIL LATE MONDAY. IFR AND LOWER VSBYS SHOULD SLOWLY
IMPROVE AFTER 18Z, HOWEVER IFR TO LIFR CIGS SHOULD PERSIST THROUGH
MONDAY AFTERNOON, FINALLY IMPROVING WEST TO EAST AFTER 22Z
MONDAY.
GRR WATCHES/WARNINGS/ADVISORIES
MI...DENSE FOG ADVISORY UNTIL NOON EST MONDAY FOR MIZ037>040-043>046-
050>052-056>059-064>067-071>074.
MARINE...NONE.
UPDATE...NJJ
DISCUSSION...MEADE
AVIATION...CERU
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