219
FXUS63 KGRR 310609
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
ISSUED BY NATIONAL WEATHER SERVICE HASTINGS NE
209 AM EDT TUE MAR 31 2026
KEY MESSAGES
- STRONG POSSIBLY SEVERE STORMS OVERNIGHT INTO TUESDAY MORNING
- POTENTIAL SEVERE STORMS TUESDAY AFTERNOON AND EVENING
- WINTRY MIX,RAIN MIDWEEK WITH RAIN THIS WEEKEND
DISCUSSION
ISSUED AT 252 PM EDT MON MAR 30 2026
- STRONG POSSIBLY SEVERE STORMS OVERNIGHT INTO TUESDAY MORNING
HIGH LEVEL CLOUDS CONTINUE TO STEAM THROUGH THE NORTHERN GREAT
LAKES TODAY WITH WARM AIR POURING INTO LOWER MICHIGAN. THAT WARM
AIR AND WESTERLY FLOW WILL SET THE STAGE FOR OVERNIGHT CONVECTION.
LATEST GUIDANCE CONTINUES TO HAVE ZONAL FLOW THROUGH THE UPPER
LEVELS AND A NEGATIVELY TILTED MID LEVELS THERE HAS BEEN AN UPTICK
IN POTENTIAL OVERNIGHT INTO TUESDAY MORNING. THIS CORRESPONDS TO
THE STRENGTH OF THE JET AND THE WARM AIR ADVECTION OUT AHEAD OF
IT. TEMPERATURES TODAY ARE INTO THE 70S ACROSS MUCH OF SOUTHERN
LOWER MICHIGAN. WHILE DEWPOINTS ARE ONLY IN THE MID 40S, THOSE
WILL INCREASE AS THE EVENING CONTINUES. SO WARM DAYTIME TEMPS,
ALONG WITH WARM AIR ADVECTION THIS EVENING WILL BRING A BETTER AIR
MASS FOR CONVECTION OVERNIGHT. GIVEN THOSE ABOVE FEATURES, THAT
SHOULD ALLOW FOR MORE CAPE WHICH, WITH STRONG MID LEVEL SHEAR,
SHOULD ALLOW FOR ANY STORMS TO FILTER DOWN WINDS. THERE REMAINS
SOME QUESTION ON TIMING. SOME OF THE CAMS WANT TO BRING
CONVECTION IN LATER, SOME SOONER AND THERE IS SOME VARIANCE IN
WHERE THE BOUNDARY SETS UP. SEVERAL RUNS OF THE NAM HAVE IT NORTH
OF I 96 AND SOME VERSIONS OF THE HREF HAS THE BOUNDARY FURTHER
SOUTH. BEST CHANCES FOR OVERNIGHT STORMS WILL BE BETWEEN 2 AM AND
7 AM. THE MAIN THREAT IS DAMAGING WINDS AND LARGE HAIL. WHILE
THERE IS SOME CAP IN PLACE GIVEN THE TIME OF DAY, THE SURFACE
TEMPS AND STRONG WINDS ALOFT SHOULD BE ABLE TO OVERCOME ANY
CAPPING INVERSION.
- POTENTIAL SEVERE STORMS TUESDAY AFTERNOON AND EVENING
MUCH OF THE FORECAST FOR TOMORROW REMAINS THE SAME. THERE ARE
QUESTIONS OF WHETHER OR NOT THE ATMOSPHERE WILL BE ABLE TO
RECHARGE IN THE WAKE OF THE OVERNIGHT CONVECTION. IF SKIES CLEAR
OUT AND TEMPS GET BACK INTO THE MID TO UPPER 60S, THEN THERE
SHOULD BE ENOUGH CAPE TO GO ALONG WITH THE SHORT WAVE THAT ARRIVES
EARLY TO MID AFTERNOON. BEST SHEAR, 40 TO 50 KTS, AND HELICITY
SHOULD BE AFTER 19Z AS THE FRONT DRAPES ACROSS THE REGION FROM THE
NORTHEAST TO THE SOUTHWEST. THAT FAVORS THE POTENTIAL FOR SUPER
CELL DEVELOPMENT TOMORROW AFTERNOON AND EVENING. DAMAGING WINDS
AND LARGE HAIL ARE THE PRIMARY CONCERN. HOWEVER GIVEN THE SHEAR
AND THE SHAPE OF THE HODOGRAPHS, THERE IS THE POTENTIAL FOR
TORNADOES, ESPECIALLY ALONG THE FRONTAL BOUNDARY. DEPENDING ON THE
SPEED OF THE FRONT, STORM THREAT COULD LINGER THROUGH THE FIRST
HALF OF THE EVENING.
- WINTRY MIX,RAIN MIDWEEK WITH RAIN THIS WEEKEND
WEDNESDAY REMAINS DRY THOUGH THERE COULD BE SOME LINGERING RAIN
SHOWERS EARLY WEDNESDAY IN FAR SOUTHERN MICHIGAN. OTHERWISE, COLD
NORTHWESTERLY FLOW WILL FILTER IN BEHIND THE FRONT WITH OTHERWISE
DRY CONDITIONS WITH HIGHS IN THE 40S. COLDER TEMPERATURES
WEDNESDAY NIGHT WILL SET THE STAGE FOR RAIN AND FREEZING RAIN. THE
0C LINE AT 850 MB HAS SHIFTED SOUTHWARD . HERE WILL BE A
SIGNIFICANT WARM NOSE AT 850MB THAT WOULD MELT ANY SNOW/ICE, BUT
SURFACE TEMPERATURES CONTINUE TO TREND AROUND 32 ALONG I-96 WITH
TEMPERATURES BELOW 32 NORTH. AREAS ALONG THE LAKESHORE MAY REMAIN
WARM ENOUGH LIMIT ICE ACCUMULATIONS. THE WARM FRONT THEN MOVES
NORTH THURSDAY WITH AREAS TRANSITIONING TO RAIN DURING THE MORNING
AND AFTERNOON. THERE IS STILL SOME UNCERTAINTY WITH THE EXACT
AMOUNTS, BUT ICE AMOUNTS ARE TRENDING UPWARD AND WOULD BE HIGHEST
ON ELEVATED SURFACES. KEEP UP TO DATE WITH THE FORECAST AS ANY ICE
ACCUMULATIONS COULD BE IMPACTFUL.
RAIN CONTINUES INTO THURSDAY WITH DECENT RAINFALL, UPWARDS OF AN
ADDITIONAL INCH ON THURSDAY. AFTER A BREAK ON FRIDAY THERE
REMAINS GOOD AGREEMENT ON A DEEP TROUGH MOVING THROUGH THE REGIONS
SATURDAY INTO SUNDAY. SOME DIFFERENCES IN TIMING, BUT OVERALL
RAIN AND MAYBE A FEW THUNDERSTORMS MOVE IN SATURDAY WITH A COLD
FRONT MOVING THROUGH SATURDAY NIGHT INTO SUNDAY. COLD AIR WILL
ADVECT IN ON THE BACKSIDE OF THE LOW WITH THE POTENTIAL FOR SNOW
TO MIX IN AS SUNDAY MORNING AS TEMPERATURES FALL. COLD, BLUSTERY
NORTHWESTERLY FLOW WILL GREET SOUTHERN LOWER MICHIGAN EASTER
MORNING.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 159 AM EDT TUE MAR 31 2026
OVERVIEW: COMPLEX AVIATION FORECAST WITH MULTIPLE AVIATION
CONCERNS WITHIN THE NEXT 24 HOURS, INCLUDING: ONGOING LOW LEVEL
WIND SHEAR (LLWS), MULTIPLE ROUNDS OF SHOWERS/STORMS - SOME OF
WHICH COULD BE STRONG/SEVERE, MVFR TO IFR CEILINGS AND
VISIBILITIES (ESP. WITHIN STRONGER STORMS), AND FINALLY, A WIND
SHIFT LATE IN THE PERIOD WITH A COLD FRONT.
NEXT 6 HOURS: TRIED TO HONE IN ON SHOWER/STORM POTENTIAL A BIT
MORE, SPECIFICALLY REMOVING THE MENTION FOR MKG GIVEN THE CURRENT
GAP...AS WELL AS INDICATE A LIKELY BREAK AFTER 08-10Z BETWEEN THIS
ROUND AND THE NEXT ROUND TOWARDS MID TO LATE AM. BELIEVE LLWS WILL
PERSIST ALL SITES THROUGH DAWN (GIVEN STRONG 45-55KT LOW LEVEL
JET)- DESPITE RATHER BREEZY SFC WINDS OUT OF THE SW AT 15-20KT AND
GUSTS 20-30KT. CONFIDENCE: LLWS & SFC WINDS - HIGH, SHOWERS/STORMS
AND RESULTANT CEILINGS/VISIBILITIES/FLIGHT CAT - MEDIUM.
REST OF THE PERIOD: EXPECT ANOTHER ROUND OF CONVECTION TO DEVELOP
AND/OR MOVE IN FROM THE W BY MID TO LATE MORNING, AND CONTINUE
INTO THE AFTERNOON. SOME OF THIS ACTIVITY COULD BE STRONG TO
SEVERE, BUT WILL REALLY DEPEND ON HOW DETAILS EVOLVE THROUGH THE
MORNING. MODELS SUGGEST LOWERING CEILINGS, ESP. FOR MKG, BUT
PROBABLY ELSEWHERE, AS WELL. HOWEVER, CONFIDENCE ON SPECIFIC
TIMING AND MAGNITUDE OF CEILING AND VISIBLITIE DROP IS QUITE LOW.
AGAIN...WILL DEPEND ON SPECIFIC CONVECTIVE TRENDS, BUT
PROBABILITIES FOR AT LEAST MVFR CONDITIONS ARE 50-70%, AND
CHANCES FOR IFR CONDITIONS ARE 20-50%, HIGHEST AT MKG. EXPECT
SHOWERS AND STORMS TO DISSIPATE FROM NW TO SE LATE AFTERNOON INTO
EARLY EVENING WITH THE PASSAGE OF A COLD FRONT. THIS FRONT WILL
TURN WINDS FROM PRIMARILY SWRLY DURING THE DAY, TO NWRLY BY MID TO
LATE EVENING. MVFR TO IFR CONDITIONS ARE FAVORED TO CONTINUE
BEHIND THE COLD FRONT. CONFIDENCE: LOW TO MEDIUM.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...CERU
AVIATION...THIES
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