797
FXUS63 KGRR 311949
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
349 PM EDT MON MAR 31 2025
KEY MESSAGES
- ROUND OF WINTER WEATHER TUESDAY NIGHT INTO WEDNESDAY MORNING
- SEVERE POTENTIAL WEDNESDAY AFTERNOON AND EVENING
- HEAVY RAINS MISS US OFF TO THE SOUTH THIS WEEKEND
DISCUSSION
ISSUED AT 349 PM EDT MON MAR 31 2025
- ROUND OF WINTER WEATHER TUESDAY NIGHT INTO WEDNESDAY MORNING
A POTENT UPPER LEVEL LOW IS PUSHING INTO THE WEST COAST AT THIS
TIME WITH A STRONG UPPER JET ROTATING THROUGH THE BASE OF THE
TROUGH. THIS UPPER WAVE MOVES INTO THE INTER MOUNTAIN WEST AND
PUSHES AN INITIAL UPPER WAVE INTO THE PLAINS TUESDAY WHICH WORKS
INTO THE WESTERN GREAT LAKES ON WEDNESDAY.
THE INITIAL SURGE OF WARM AIR ADVECTION RESULTS IN SNOW BREAKING
OUT ACROSS CENTRAL LOWER MICHIGAN TOWARDS MIDNIGHT TUESDAY NIGHT.
THE SNOW WILL TRANSITION TO FREEZING RAIN LATE IN THE NIGHT AS WE
HEAD TOWARDS DAYBREAK ACROSS CENTRAL LOWER. FURTHER TO THE SOUTH
FROM I-96 SOUTHWARD THE PRECIPITATION SHOULD BE ALL RAIN AS THE
WARM AIR ADVECTION IS STRONG.
THE MIXTURE OF PRECIPITATION WILL CONTINUE INTO WEDNESDAY MORNING
ACROSS CENTRAL LOWER BEFORE THE WARM AIR TAKES OVER WHICH WILL
FLIP ALL PRECIPITATION OVER TO RAIN.
AT THIS POINT WE ARE THINKING THAT THE MOST SUBSTANTIAL ICE/SNOW
WILL OCCUR ACROSS OUR TWO NORTHERN MOST ROWS OF COUNTIES OR
ROUGHLY NORTH OF A WHITEHALL TO HOWARD CITY TO ALMA LINE. WE ARE
NOT EXPECTING BIG TOTALS BUT SNOW UP TO AN INCH OR TWO IS POSSIBLE
ALONG WITH ICING OF ONE TO TWO TENTHS. IF THE CURRENT FORECAST
HOLDS, WE ARE LIKELY LOOKING AT A WINTER WEATHER ADVISORY UP THERE
FOR TUESDAY NIGHT AND WEDNESDAY MORNING. CONFIDENCE IS NOT HIGH
ENOUGH AT THIS POINT TO ISSUE ANY WINTER HEADLINES.
- SEVERE POTENTIAL WEDNESDAY AFTERNOON AND EVENING
SEVERE POTENTIAL CERTAINLY EXISTS ON WEDNESDAY, BUT THERE ARE SOME
ISSUES WITH THE SYSTEM WHICH WE WILL SPEAK TO HERE. FIRST OFF, THE
SPC HAS OUR AREA IN A SLIGHT RISK FOR SEVERE WEATHER NORTH OF I-96
AND AN ENHANCED RISK TO THE SOUTH OF I-96. IN THE POSITIVE FOR
THIS EVENT, THE UPPER WAVE IS STRONG, MOVING IN WEDNESDAY
AFTERNOON AND EVENING. WIND FIELDS ARE VERY STRONG WITH A 50-60KT
LOW LEVEL JET AND A 100+ KT UPPER JET. THIS PUSHES DEEP LAYER
SHEAR TO SIGNIFICANT LEVELS OF 60-80 KNOTS. ON THE NEGATIVE SIDE
FOR SEVERE STORMS THE SURFACE LOW IS LOCATED WELL TO OUR WEST AND
IT IS WEEKENDING AND OCCLUDING AS IT MOVES INTO OUR AREA. THE
QUESTION IS IN THE CAPE / SHEAR BALANCE, HOW MUCH CAPE/INSTABILITY
WILL WE ACTUALLY HAVE. THE TIME FRAME OF CONCERN WILL LIKELY BE
BETWEEN 4PM AND MIDNIGHT ON WEDNESDAY, BUT MOISTURE RETURN INTO
OUR AREA ONLY MAKES A GLANCING BLOW. MOST MODELS HAVE ONLY MODEST
CAPE. THIS IS LIKELY DUE TO THE FACT THAT THERE WILL BE PLENTY OF
CLOUDS AND RAIN SHOWERS IN THE MORNING AND MIDDAY LEADING INTO THE
EVENT. SO, WHILE THERE IS A SEVERE THREAT ON WEDNESDAY IT IS VERY
CONTINGENT ON BETTER INSTABILITY SHOWING UP. CONFIDENCE IN THE
EVENT FOR NOW IS A BIT TEMPERED. TONIGHT THE EVENT WILL MAKE IT
INTO THE HREF WINDOW AND WE WILL HAVE A MORE LOCKED IN CONFIDENCE
AT THAT POINT.
- HEAVY RAINS MISS US OFF TO THE SOUTH THIS WEEKEND
MULTIPLE ROUNDS OF SHOWERS AND STORMS LOOK TO OCCUR OFF TO OUR
SOUTH LATE IN THE WEEK AND INTO THE WEEKEND. AT THIS POINT THE
PRECIPITATION LOOKS TO MAINLY STAY OFF TO OUR SOUTH, BUT WE WILL
NEED TO MONITOR TO SEE IF IT TRENDS NORTH AT ALL. AT THIS POINT,
THERE IS NO INDICATION OF THAT WITH THE RAIN REPEATEDLY OCCURRING
ACROSS THE OHIO VALLEY. TEMPERATURES THROUGH THE FORECAST PERIOD
WILL GENERALLY BE NEAR NORMALS FOR THIS TIME OF YEAR.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1258 PM EDT MON MAR 31 2025
MVFR IS EXPECTED TO LAST THROUGH LATE AFTERNOON OR EVENING BEFORE
CLOUDS EXIT THE REGION AND VFR BEGINS. BASES AROUND 1800-2000 FT
WILL SCATTER OUT AND LIFT SLIGHTLY AS WE APPROACH SUNSET. WINDS
DECREASE AFTER 00Z AND THEN VEER EASTERLY TUESDAY MORNING.
HYDROLOGY
ISSUED AT 250 PM EDT MON MAR 31 2025
WITH ANOTHER ROUND OF WIDESPREAD RAIN COMING UP ON WEDNESDAY, WE
NEED TO BE THINKING ABOUT THE CAPACITY OF OUR RIVERS TO HANDLE ALL
THIS WATER. AS OF MONDAY AFTERNOON, THE MUSKEGON RIVER IS ALREADY AT
NEAR OR SLIGHTLY ABOVE-NORMAL LEVELS, WHILE THE GRAND AND KALAMAZOO
RIVERS ARE AT NEAR TO SLIGHTLY BELOW NORMAL LEVELS FOR THIS TIME OF
YEAR. ENSEMBLE GUIDANCE IS IN PRETTY GOOD AGREEMENT ON AT LEAST
ANOTHER INCH OR SO OF RAIN COMING UP ACROSS A LARGE PORTION OF OUR
BIG 3 WATERSHEDS. IF THIS COMES TO PASS, OUR RIVERS SHOULD BE ABLE
TO HANDLE THINGS RELATIVELY SMOOTHLY, WITH ONLY THE LOWER MUSKEGON
RIVER (NEWAYGO AND BRIDGETON) LOCATIONS RISING TO BANKFULL BUT NOT
REACHING MINOR FLOOD LEVELS LATER THIS WEEK.
HOWEVER, BECAUSE MUCH OF THIS PRECIPITATION WILL BE DRIVEN BY
CONVECTION, WE FULLY EXPECT SOME BULLSEYES/LOCALIZED AREAS TO
APPROACH 2 INCHES OF RAIN DURING THE WEDNESDAY AND WEDNESDAY NIGHT
TIMEFRAMES. IF RAIN TOTALS APPROACH 2 INCHES OVER THE GRAND OR
KALAMAZOO BASINS, THE MAINSTEM RIVERS SHOULD STILL MOSTLY BE OK, BUT
SOME OF THE SMALLER TRIBUTARY STREAMS - ESPECIALLY AROUND THE
LANSING AREA, SUCH AS THE RED CEDAR AND SYCAMORE CREEK - WOULD
APPROACH FLOOD LEVELS. SIMILARLY, IF THESE 2 INCH RAIN TOTALS FALL
UP OVER THE MUSKEGON RIVER, WE'D LIKELY PUSH BRIDGETON AND NEWAYGO
WELL INTO MINOR FLOOD STAGE.
WE'LL BE CLOSELY MONITORING EXPECTED RAIN TOTALS OVER THE NEXT 36
HOURS BEFORE THE STORM BEGINS, BUT NOW IS THE TIME FOR ANY FOLKS
LIVING OR PLAYING NEAR WEST MICHIGAN RIVERS TO PREPARE FOR LIKELY
RISING WATER LEVELS LATER THIS WEEK.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT TUESDAY FOR LMZ844>849.
DISCUSSION...DUKE
AVIATION...HOVING
HYDROLOGY...AMD
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