509
FXUS63 KGRR 081746
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1246 PM 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 /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1234 PM EST THU JAN 8 2026
VFR CONDITIONS TO START THE PERIOD WILL GO DOWNHILL OVER THE NEXT
6 HOURS AS A LARGE AND FAST-MOVING STORM MOVES INTO THE GREAT
LAKES REGION. THIS WEATHER SYSTEM HAS ALREADY PUSHED A STRONG WARM
FRONT NORTHWARD THROUGH SOUTHWEST MICHIGAN, WITH WINDS A FEW
THOUSAND FEET ABOVE GROUND LEVEL ALREADY CLIMBING PAST THE 30 TO
40 KT RANGE. BY THIS EVENING, LOW-LEVEL WIND SHEAR WILL BE
WIDESPREAD IN THE 50+ KT RANGE OUT OF THE SOUTHWEST AT ALL
LOCATIONS, WITH ROUNDS OF RAIN SHOWERS MOVING THROUGH THE AREA.
THIS WILL BRING CONDITIONS DOWN TO IFR AND POSSIBLY EVEN LIFR AT
TIMES THROUGH THE NIGHT. SOME OF THE GUSTY WINDS WILL EVENTUALLY
BE WORKING DOWN TO THE SURFACE, BUT THE STRONGEST WINDS WILL
REMAIN ALOFT WITH LLWS CONDITIONS CONTINUING THROUGH FRIDAY
MORNING. BY MID-MORNING ON FRIDAY, WINDS SHIFT TO THE WEST AND
WINDS SLOWLY DECREASE AS TEMPERATURES ONCE AGAIN DROP AND CIGS
LIKELY IMPROVE ONLY TO MVFR.
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...AMD
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