Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000 FXUS63 KGRR 031136 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 736 AM EDT SUN MAY 3 2015 LATEST UPDATE... AVIATION .SYNOPSIS... ISSUED AT 337 AM EDT SUN MAY 3 2015 ONE MORE FINE DAY TODAY WITH PARTLY SUNNY SKIES AND TEMPERATURES REACHING THE UPPER 70S INLAND FROM LAKE MICHIGAN. THEN A COLD FRONT APPROACHES TONIGHT AND WILL BRING SHOWERS AND THUNDERSTORMS. MOST OF THE PRECIPITATION WILL BE NORTH OF I-96 TONIGHT...THEN SPREAD INTO SOUTHERN LOWER MICHIGAN ON MONDAY. THE FRONT MOVES SOUTH INTO NORTHERN INDIANA BY MONDAY NIGHT AND STALLS THERE. THIS WILL CAUSE THE SHOWERS A FEW STORMS TO LINGER MAINLY ALONG AND SOUTH OF I-96 MONDAY NIGHT AND TUESDAY. MEANWHILE AREAS NORTH OF I-96 SHOULD ONLY SEE SCATTERED SHOWERS INTO TUESDAY. DAYTIME TEMPERATURES WILL COOL SLIGHTLY TO THE UPPER 60S TO AROUND 70 FOR MONDAY AND TUESDAY. IT APPEARS WE WILL DRY OUT TOWARD MID WEEK...WITH ANOTHER CHANCE OF STORMS ARRIVING FRIDAY INTO SATURDAY. DAYTIME HIGHS SHOULD RETURN INTO THE 70S AND MAY APPROACH 80 THURSDAY AND FRIDAY. && .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 337 AM EDT SUN MAY 3 2015 ANOTHER VERY NICE SPRING DAY TODAY...THEN RAIN CHANCES RETURN TONIGHT AND LINGER INTO TUESDAY. SEVERE THREAT STILL LOOKS MINIMAL AND EXCESSIVE RAIN CHANCES ALSO LOOK REMOTE. INCREASED MAX TEMPS FORECAST AGAIN DUE TO VERY DRY AIR MASS AND FAVORABLE MIXING. FEEL UPPER 70S WILL BE COMMON AND AN ISOLATED 80 IS NOT OUT OF THE QUESTION. WE SHOULD SEE A FEW SOME DEBRIS CLOUDS ROLL IN BY MID AFTERNOON WHICH TAPER THE MIXING AND HEATING AFTER 18Z. A COLD FRONT MOVING ACROSS MN THIS MORNING WILL REACH SOUTHWEST MI ON MONDAY. THE FRONT WILL HAVE FAVORABLE JET DYNAMICS TO OUR WEST LATER THIS AFTERNOON AND EXPECT WIDESPREAD PCPN SPREADING ACROSS WISCONSIN. THE UPPER JET BRINGS IN WEAK UPPER DIVERGENCE INTO THE NW CWA TONIGHT. SO SOME OF THE WISCONSIN CONVECTION SHOULD HOLD TOGETHER AND MOVE INTO CENTRAL LOWER TONIGHT. EXPECTING OF THIS ACTIVITY TO REMAIN NORTH OF I-96 AS AREAS SOUTH OF THERE WILL BE TOO FAR REMOVED FROM THE UPPER JET. SO GENERALLY WILL CARRY LIKELY POPS NORTH AND CHC POPS SOUTH OF I-96. THE SHOWERS AND STORMS GRADUALLY SHIFT SOUTH ON MONDAY AS THE FRONT COMES THROUGH. DECENT INSTABILITY COULD BE REALIZED SOUTH OF I-96 BY AFTERNOON WHERE WE MAY SEE AN ISOLATED STRONGER STORM...BUT THIS WILL DEPEND ON THE EXTENT OF THE MORNING CLOUD COVER. THE FORCING DOES NOT LOOK STRONG ENOUGH TO BE TOO CONCERNED THOUGH...AS THE FRONT BECOMES MORE PARALLEL TO THE UPPER FLOW. THE FRONT MOVES THROUGH BY MONDAY EVENING AND STALLS OVER NORTHERN INDIANA MONDAY NIGHT AND TUESDAY. DECENT OVER RUNNING FORCING IS SHOWN FOR AREAS SOUTH OF I-96...SO THE SHOWERS SHOULD CONTINUE WITH A FEW EMBEDDED STORMS. THE CONVECTIVE NATURE OF THE PCPN COULD LEAD LOCALIZED HEAVY RAIN...BUT OVERALL EXPECT AROUND A QUARTER INCH FOR CENTRAL...AND UP TO THREE QUARTER OF AN INCH FOR THE I-94 REGION THROUGH TUESDAY. .LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY) ISSUED AT 337 AM EDT SUN MAY 3 2015 PRIMARY FOCUS IS ON THE CHANCE FOR SCATTERED SHOWERS/STORMS TUESDAY NIGHT AND WEDNESDAY AND ALSO THE DEGREE OF WARMTH FOR THURSDAY AND FRIDAY. STATIONARY BOUNDARY ACROSS FAR SOUTHERN LOWER MI TUESDAY NIGHT BEGINS LIFTING NORTH AS A WARM FRONT WITH UPPER LEVEL RIDGE AMPLIFICATION OCCURRING ACROSS THE OHIO VALLEY AND GREAT LAKES REGIONS. THIS FRONT WILL SERVE AS A SOURCE OF LIFT AND PROVIDE OPPORTUNITY FOR SOME SCATTERED SHOWER/STORM DEVELOPMENT COINCIDENT WITH RISING DEW POINTS INTO THE UPPER 50S/NEAR 60 ON WEDNESDAY. MODEL QPF IS NOT OVERLY BULLISH ON WEDNESDAY...BUT WOULD EXPECT SOME CONVECTIVE DEVELOPMENT AFTER MORNING H925 TEMP INVERSION IS MIXED OUT AND SFC BASED CAPE OF A FEW HUNDRED JOULES/KG ARE REALIZED ALONG WITH LI VALUES SLIGHTLY NEGATIVE. THAT SAID...WITH WINDS AT OR BELOW 20 KTS FROM THE LCL TO THE EL AND MARGINAL CAPE IN THE -10C TO -20C LAYER...THERE IS NO REAL THREAT FOR SEVERE WEATHER. BY THURSDAY...MOSTLY DRY CONDITIONS ARE EXPECTED WITH A FEW STRAY SHOWERS OR STORMS POSSIBLE...BUT WITH A LACK OF ANY TRIGGER VERY LITTLE CONVECTIVE ACTIVITY IS FORESEEN. H850 TEMPS OF 13C BY 00Z FRI SUPPORT HIGHS AROUND 80. FOR FRIDAY...A SFC COLD FRONT SHOULD BE PUSHING THROUGH WISCONSIN DURING THE AFTERNOON HOURS...AND WE MAY HAVE A CHANCE TO MIX DOWN 14C AIR...WHICH WOULD SUPPORT HIGHS IN THE LOWER 80S. GIVEN INCREASING CLOUD COVER AND POSSIBLE SHOWER/STORM DEVELOPMENT AHEAD OF THIS FRONT...WE MAY NOT QUITE GET THERE BUT IT IS STILL A DECENT POSSIBILITY. FOR NEXT WEEKEND...NEED TO CONTINUE THE MENTION FOR SHOWER/STORM POSSIBILITIES AS UPPER LEVEL RIDGING MAY RELAX SOMEWHAT BUT WITH CONTINUED MOIST LOW LEVEL FLOW AND POSSIBLE SFC BOUNDARY IN PLAY ONCE AGAIN ACROSS THE GREAT LAKES. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 730 AM EDT SUN MAY 3 2015 INCREASING MID LEVEL CLOUDS TODAY WITH VFR CONDITIONS BUT INCREASING SW BREEZE. A FEW POCKETS OF LIGHT SHOWERS COULD AFFECT ANY OF THE TAF SITES DURING THE MID TO LATE AFTERNOON HOURS...BUT MORE LIKELY THAT ANY SHOWERS/STORMS WILL HOLD OFF UNTIL EARLY MONDAY MORNING AS A LINE OF THUNDERSTORMS FROM WISCONSIN SHOULD MOVE OVER LAKE MICHIGAN AND WEAKEN PRIOR TO SUNRISE MONDAY. BEYOND 12Z MONDAY...ADDITIONAL SHOWERS/STORMS ARE POSSIBLE JUST ABOUT ANYWHERE BUT ESPECIALLY FOR AZO/BTL/JXN MONDAY AFTERNOON/EVE...WITH ACTIVITY LIKELY PRESSING INTO NORTHERN INDIANA AND OHIO BY LATE IN THE DAY. && .MARINE... ISSUED AT 337 AM EDT SUN MAY 3 2015 SOUTH WINDS WILL CAUSE WAVES TO INCREASE THIS AFTERNOON MAINLY NORTH OF HOLLAND. EXPECT SOME 3 FOOTERS...BUT OVERALL A SMALL CRAFT ADVISORY IS NOT EXPECTED TO BE NEEDED. THESE WAVES WILL DIMINISH LATE TONIGHT/EARLY MONDAY AS THE FRONT MOVES IN. && .FIRE WEATHER... ISSUED AT 337 AM EDT SUN MAY 3 2015 WITH TEMPS INTO THE UPPER 70S AND A DRY AIR MASS...THE FIRE DANGER WILL BE AT ELEVATED LEVELS TODAY. HOWEVER WINDS ARE NOT EXPECTED TO BE TOO HIGH TODAY...GENERALLY REMAINING UNDER 15 MPH. && .HYDROLOGY... ISSUED AT 250 PM EDT SAT MAY 2 2015 RIVERS MAY RISE A BIT BY THE MIDDLE OF NEXT WEEK AS AS ABOUT AN INCH OF QPF IS POSSIBLE BY NEXT WEDNESDAY. SINCE RIVER LEVELS ARE RUNNING A BIT BELOW AVERAGE...THIS SHOULD NOT CAUSE MANY IMPACTS. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS...JK SHORT TERM...JK LONG TERM...HOVING AVIATION...HOVING FIRE WEATHER...JK HYDROLOGY...OSTUNO MARINE...JK

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