477
FXUS63 KGRR 081209
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
709 AM EST THU JAN 8 2026
KEY MESSAGES
- PERIODS OF RAIN TONIGHT INTO FRIDAY
- SNOW THIS WEEKEND
- SMALL CHANCES FOR PRECIPITATION EARLY NEXT WEEK
DISCUSSION
ISSUED AT 348 AM EST THU JAN 8 2026
- PERIODS OF RAIN TONIGHT INTO FRIDAY
A COLORADO LOW HAS DEVELOPED IN THE LEE OF THE ROCKIES AS OF
YESTERDAY EVENING. THE LOW IS SITUATED IN SOUTHEAST COLORADO AT
THE PRESENT TIME (08Z) AND IT WILL BE ON THE MOVE TODAY NORTHEAST
ACROSS THE PLAINS STATES. THE LOW WILL DEEPEN TO AROUND 990MB
TONIGHT AS IT SLIDES ACROSS WISCONSIN OFF TO OUR WEST. A SURGE OF
WARMTH AND MOISTURE WILL MOVE INTO MICHIGAN AHEAD OF THE LOW.
MODELS ARE CONSISTENT IN BRINGING IN A SWATH OF RAIN THIS EVENING
WITH PERIODS OF RAIN AND EVEN SOME EMBEDDED THUNDER THROUGH THE
COURSE OF TONIGHT.
PWAT VALUES ARE STILL EXPECTED TO BE ABOVE THE CLIMATOLOGICAL MAX
FOR THE DAY, WHICH IS AROUND 1 INCH, REACHING 1.2 INCHES IN OUR
SOUTH TONIGHT. 850MB LOW LEVEL JET WINDS ARE EXPECTED TO REACH
60-70 KNOTS SO AS ONE WOULD EXPECT GIVEN THE PARAMETER SPACE, 850
MOISTURE TRANSPORT IS OFF THE CHARTS. BRIEFLY HEAVY RAIN RATES ARE
EXPECTED WITH RAINFALL TOTALS FROM TONIGHT AND FRIDAY REACHING
0.30 TO 0.75 IN MANY AREAS. HREF PRECIPITATION GUIDANCE WOULD
SUGGEST THAT LOCAL SWATHS OF 1-2 INCHES ARE PROBABLE. MUCAPE
VALUES REACH 600 J/KG TONIGHT WITH 850MB LIS AROUND -2C.
DEFINITELY EXPECTING A FEW RUMBLES OF THUNDER TONIGHT.
WE WILL NEED TO KEEP AN EYE ON WIND GUSTS BOTH SYNOPTICALLY GIVEN
A TIGHT PRESSURE GRADIENT IN PLACE AND VIA CONVECTIVE DOWNDRAFTS
GIVEN THE STRENGTH OF THE WIND IN THE PROFILE. SOME HIGH
RESOLUTION MODELS ARE SUGGESTING 50+ MPH WINDS TONIGHT. GIVEN THIS
IS A WARM AIR ADVECTION WIND AT NIGHT THOUGH WE ARE NOT EXPECTING
TO REACH WIND ADVISORY HEADLINE CRITERIA. WE WILL BE MONITORING
TRENDS TODAY GIVEN WE HAVE 45 KNOTS AT 1K FEET AND 60 KNOTS AT 2K
FEET WHICH IS STRONG FOR ANY TIME OF THE YEAR.
- SNOW THIS WEEKEND
FOCUS ONCE WE GET PAST THE RAIN, STORMS AND WIND OF THE NEXT 24
HOURS WILL SHIFT TO A DEVELOPING UPPER TROUGH AS A SUBSTANTIAL MID
LEVEL SHORTWAVE DIGS INTO THE GREAT LAKES REGION FROM THE NORTHERN
PLAINS. A MIX OF RAIN AND SNOW ON SATURDAY ASSOCIATED WITH THIS
UPPER TROUGH AND DEVELOPING SURFACE LOW WILL CHANGE TO ALL SNOW
SATURDAY NIGHT. MODELS HAVE NOT SETTLED IN ON THE EXACT EVOLUTION
OF A DEVELOPING SURFACE LOW ASSOCIATED WITH THE UPPER TROUGH, BUT
THEY ARE BEGINNING TO SHOW SIGNS OF A SWATH OF POSSIBLY 2-4 INCHES
OF SNOW ACROSS OUR CENTRAL OR NORTHERN FORECAST AREA (NEAR AND
NORTH OF I-96) SATURDAY INTO SATURDAY NIGHT. THE SYNOPTIC SNOW
WILL BE FOLLOWED BY A PERIOD OF LAKE ENHANCED OR LAKE EFFECT SNOW
SATURDAY NIGHT INTO SUNDAY. THE UP AND DOWN WEATHER CONTINUES.
- SMALL CHANCES FOR PRECIPITATION EARLY NEXT WEEK
SMALL CHANCES FOR RAIN AND SNOW WILL EXIST EARLY NEXT WEEK AS A
COUPLE SHORTWAVES MOVE THROUGH THE NORTHWEST FLOW ALOFT. THE WAVES
ARE CENTERED ON MONDAY AND TUESDAY WITH WEAK SURFACE COLD FRONTS
ASSOCIATED. AT THIS POINT WE HAVE SMALL CHANCES FOR RAIN AND SNOW
SHOWERS IN THE FORECAST. AS WE HEAD INTO THE MIDDLE OF NEXT WEEK
IT LOOKS LIKE NORTHERLY FLOW WILL BRING IN A SURGE OF COLDER AIR.
TEMPERATURES NEXT WEDNESDAY AND THURSDAY WILL COOL TO NEAR AND
BELOW NORMALS FOR THIS TIME OF YEAR. HIGHS TREND BACK INTO THE 20S
FOR NEXT THURSDAY.
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 709 AM EST THU JAN 8 2026
ACTIVE WEATHER IS EXPECTED DURING THE 12Z THU TO 12Z FRI TAF
WINDOW. A LOW IN COLORADO THIS MORNING WILL LIFT NORTHEAST ACROSS
THE CENTRAL PLAINS STATES TODAY MOVING INTO WISCONSIN TONIGHT.
THIS WILL PUSH A WARM FRONT INTO THE AREA THIS EVENING. THE LOW
WILL BE FAIRLY STRONG AS IT MAKES ITS APPROACH TO THE GREAT LAKES
AND THEREFORE STRONG WINDS CAN BE EXPECTED BOTH AT THE SURFACE AND
ALOFT. WINDS WILL REACH 10-20 KNOTS TODAY FROM THE SOUTH
INCREASING TO 15-25 KNOTS TONIGHT. WIND GUSTS AT THE SURFACE TO 30
KNOTS WILL BE POSSIBLE ESPECIALLY TONIGHT. LOW LEVEL WIND SHEAR
IS A THREAT TONIGHT AS WINDS AT 2000 FEET INCREASE TO 50-55 KNOTS
FROM THE SOUTHWEST. THE WARM FRONT WILL PUSH A SURGE OF RAIN INTO
THE AREA THIS EVENING BETWEEN 21Z AND 03Z. SOME EMBEDDED
THUNDERSTORMS ARE POSSIBLE TONIGHT, BUT THE CHANCE WAS TOO SMALL
TO INCLUDE IN THE TAFS AT THIS TIME.
VFR WEATHER IS EXPECTED TO PERSIST TODAY NOW THAT THE LOW CLOUDS
AND FOG HAVE CLEARED TO THE EAST FOR THE MOST PART. WE MAY SEE
ANOTHER HOUR OR TWO OF LIGHT/MVFR FOG BUT THAT SHOULD END BY 14Z.
MVFR CEILINGS WILL SPREAD IN AFTER 00Z, LOWERING TO IFR BY 06Z.
VISIBILITIES WILL FOLLOW THE SAME TREND TONIGHT FROM MVFR AFTER
00Z TO IFR AFTER 06Z.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST FRIDAY
FOR LMZ844>849.
DISCUSSION...DUKE
AVIATION...DUKE
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