608
FXUS63 KGRR 231938
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
338 PM EDT WED APR 23 2025
KEY MESSAGES
- OCCASIONAL SHOWERS AND STORMS THROUGH FRIDAY
- COOLER AND DRY THIS WEEKEND
- WARMER WITH STORMS RETURNING MONDAY INTO TUESDAY
DISCUSSION
ISSUED AT 337 PM EDT WED APR 23 2025
- OCCASIONAL SHOWERS AND STORMS THROUGH FRIDAY
A STATIONARY FRONT WILL BE IN PLACE ACROSS THE SOUTHERN GREAT
LAKES FROM THIS AFTERNOON INTO FRIDAY AFTERNOON. CHANCES FOR
SHOWERS AND STORMS WILL OCCUR DURING THAT TIME FRAME AS THE FRONT
AND PERIODIC WEAK SHORTWAVES MOVE THROUGH IN THE ZONAL UPPER FLOW.
THE FIRST TIME FRAME WILL BE THIS EVENING AS SHOWERS AND STORMS
TRY TO FIRE UPSTREAM IN WISCONSIN AND MOVE ACROSS THE LAKE INTO
CENTRAL LOWER MICHIGAN. THE SPC HAS A MARGINAL RISK FOR SEVERE
WEATHER WHICH IS BASED ON INSTABILITY DRIVEN BY A WEAK LOW LEVEL
JET AIDING IN INSTABILITY. MUCAPE VALUES IN SOME OF THE MODELS
EXCEED 1,000 J/KG THIS EVENING WHICH IN THE STRONGER STORMS MAY
RESULT IN SOME HAIL IN THE HALF INCH TO ONE INCH IN DIAMETER
RANGE. DEEP LAYER SHEAR IS ON THE ORDER OF 50 KNOTS, SO IF WE
REALIZE THE MUCAPE FORECAST BY THE MODELS IT IS NOT OUT OF THE
REALM OF POSSIBILITIES TO SEE SOME SEVERE HAIL THIS EVENING INTO
TONIGHT.
MUCH OF THURSDAY AND THURSDAY NIGHT APPEAR TO BE A LULL IN THE
ACTIVITY WITH MID LEVEL FLAT RIDGING TAKING OVER FOR A TIME. THE
PATTERN GETS ACTIVE ONCE AGAIN INTO FRIDAY AS A STRONGER MID LEVEL
SHORTWAVE MOVES OUR DIRECTION IN SOUTHWEST FLOW ALOFT FROM THE
PLAINS. THE STATIONARY FRONT WILL BE ON THE MOVE ON FRIDAY,
BECOMING A COLD FRONT PUSHING INTO AN UNSTABLE AIR MASS. A SURFACE
LOW ASSOCIATED WITH THE MID LEVEL WAVE WILL SLIDE NORTHEAST
THROUGH THE AREA ALLOW INSTABILITY TO CONSOLIDATE IN OUR SOUTHEAST
CWA FRIDAY AFTERNOON AND EARLY EVENING. 1000-2000 J/KG MUCAPE
VALUES WILL BE IN PLACE FROM LWA TO GRR TO MOP AND POINTS SOUTH
AND EAST. WE ARE CURRENTLY IN A GENERAL THUNDER OUTLOOK FROM THE
SPC ON FRIDAY AND CANNOT REALLY ARGUE GIVEN LESS THAN IDEAL DEEP
LAYER (0-6KM) SHEAR NUMBERS ON THE ORDER OF 20-30 KNOTS.
DEFINITELY NOT A ZERO THREAT OF SEVERE AND WE WILL NEED TO WATCH
THIS TIME FRAME IS SHEAR INCREASES AT ALL.
- COOLER AND DRY THIS WEEKEND
A COOLER AND DRIER AIRMASS MOVES IN FOR THE WEEKEND ON NORTHERLY
WINDS AHEAD OF AN ADVANCING HIGH PRESSURE SYSTEM. BUFKIT OVERVIEWS
WITH REGARD TO RELATIVE HUMIDITY LOOK PRETTY DRY THROUGH THE
COLUMN SO WE SHOULD SEE QUITE A BIT OF SUNSHINE. HIGH TEMPERATURES
WILL BE IN THE 60S.
- WARMER WITH STORMS RETURNING MONDAY INTO TUESDAY
SOUTHERLY FLOW INCREASES ONCE AGAIN EARLY NEXT WEEK ON THE
BACKSIDE OF THE HIGH WHICH WILL PROPEL MOISTURE AND INSTABILITY
BACK INTO THE AREA. 850MB DEW POINTS SURGE INTO THE 10-12C RANGE
AND SURFACE DEW POINTS RISE INTO THE 60S. MUCAPE VALUES ON TUESDAY
ESPECIALLY ARE FORECAST TO RISE TO IN EXCESS OF 2000 J/KG. DEEP
LAYER SHEAR WILL BE ON THE ORDER OF 50-60 KNOTS SO THE COMBINATION
OF SHEAR AND INSTABILITY WILL MAKE SEVERE STORMS A THREAT. WE ARE
IN AN OUTLOOK FOR SEVERE WEATHER ON TUESDAY VIA THE SPC WHICH
CERTAINLY LOOKS WARRANTED AT THIS POINT.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 136 PM EDT WED APR 23 2025
WE ARE STARTING THIS FORECAST PACKAGE OUT WITH LOTS OF MID LEVEL
CLOUDS BASED AROUND 7-10K FT AGL, AND SOME LIGHT RAIN SHOWERS
SCATTERED AROUND. THE CURRENT BATCH OF SHOWERS AND THE NEXT BATCH
OVER THE LAKE SHOULD MOVE THROUGH THE TERMINALS THROUGH ABOUT
21-23Z. VFR CONDITIONS WILL DOMINATE, BUT CAN'T RULE OUT A BRIEF
ISOLATED BOUT OF MVFR UNDER HEAVIER PARTS OF SHOWERS.
ADDITIONAL SHOWERS OCCURRING OVER SOUTHERN WI WILL TEND TO LIFT TO
THE NE, AND ARE LOOKING MORE LIKELY TO MISS THE TERMINALS LATER
THIS EVENING AND OVERNIGHT. WE HAVE ADDED IN SOME VCSH AT KMKG TO
ACCOUNT FOR THIS. THE OTHER TERMINALS ARE EXPECTED TO MISS OUT ON
THE SHOWERS LATER, AND COULD EVEN POTENTIALLY CLEAR OUT
OVERNIGHT.
MARINE
ISSUED AT 337 PM EDT WED APR 23 2025
WINDS WILL REMAIN FAIRLY LIGHT THE NEXT DAY OR SO, WHICH WILL KEEP
WAVES IN CHECK. WE ARE EXPECTING WAVES TO REMAIN AT OR BELOW 2
FEET THROUGH MIDDAY ON FRIDAY. FRIDAY AFTERNOON AND FRIDAY NIGHT
WINDS INCREASE OUT OF THE NORTH BEHIND THE PASSAGE OF A LOW
PRESSURE SYSTEM. SMALL CRAFT CONDITIONS ARE VERY LIKELY AND THERE
IS A GOOD CHANCE WE REACH GALE FORCE. WAVES WILL LIKELY REACH THE
3 TO 6 FOOT RANGE IN THE NEARSHORE WATERS AND NEAR 7 FEET OFF
SHORE. OCCASIONAL THUNDERSTORMS ARE EXPECTED THROUGH FRIDAY WITH
WINDS AND WAVES LOCALLY HIGHER IN AND NEAR THUNDERSTORMS.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...NONE.
DISCUSSION...DUKE
AVIATION...NJJ
MARINE...DUKE
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