Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 060050
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
850 PM EDT TUE MAY 5 2015

LATEST UPDATE...
UPDATE

.SYNOPSIS...
ISSUED AT 223 PM EDT TUE MAY 5 2015

A WARM FRONT IN NORTHERN INDIANA WILL LIFT NORTHWARD THROUGH
MICHIGAN TONIGHT AND WEDNESDAY. THIS COULD LEAD TO SOME SHOWERS
AND EVEN A THUNDERSTORM. A SOUTHERLY FLOW OF MILD AIR WILL THEN
DEVELOP SUPPORTING A WARM UP FOR THE REGION. A COLD FRONT ARRIVES
FOR FRIDAY. THIS SYSTEM COULD TRIGGER A FEW THUNDERSTORMS.

&&

.UPDATE...
ISSUED AT 848 PM EDT TUE MAY 5 2015

ADJUSTED THE POP GRIDS TO REFLECT CURRENT RADAR TRENDS. ALSO
TRIMMED THE AREA OF TSRA TO I-94 AND SOUTH. INSTABILITY IS PRETTY
WEAK AND NOT EXPECTED TO INCREASE OVERNIGHT.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 223 PM EDT TUE MAY 5 2015

THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH HOW MUCH IF ANY
RAIN AND THUNDERSTORM ACTIVITY FOR TONIGHT.

OVERALL THE PRECIPITATION TREND THROUGH THE DAY HAS BEEN FOR
WEAKENING SHOWERS. THUS I DID GENERALLY LOWER THE POTENTIAL FOR
RAIN TONIGHT. HOWEVER SOME ELEVATED INSTABILITY SHOWS UP ACROSS
ROUGHLY THE SOUTHERN HALF OF THE CWA. THUS I DID KEEP THE MENTION
OF A FEW THUNDERSTORMS GOING. SURFACE BASED INSTABILITY IS SHOWN
FOR WEDNESDAY...HOWEVER ANY LIFT IS SHOWN TO BE WEAK. BASED ON
THAT WILL FEATURE LOW POPS FOR A COUPLE OF THUNDERSTORMS FOR
WEDNESDAY.

DEEP LAYER WARM AIR ADVECTION CONTINUES INTO THURSDAY. WE SHOULD
LIKELY SEE TEMPERATURES ABOVE 80 DEGREES. 925 MB TEMPERATURES INTO
THE UPPER TEENS TO LOW 20S SUPPORT THAT. A FEW THUNDERSTORMS COULD
DEVELOP THURSDAY AS THE INSTABILITY BUILDS. DEEP LAYER SHEAR IS
SHOWN TO BE WEAK...THUS ANY STORMS SHOULD BE PULSE IN NATURE.

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 223 PM EDT TUE MAY 5 2015

TEMPERATURES WILL AVERAGE ABOVE TO MUCH ABOVE NORMAL FRIDAY THROUGH
THE WEEKEND BEFORE RETURNING TO NEAR TO EVEN A LITTLE BELOW NORMAL
BY NEXT TUESDAY THROUGH THE MIDDLE OF NEXT WEEK.

THERE WILL BE AN INCREASING POTENTIAL FOR SCATTERED SHOWERS AND
THUNDERSTORMS FRIDAY THROUGH NEXT WEEKEND. AN APPROACHING FRONTAL
BOUNDARY FROM THE WEST WILL BRING A CHANCE OF SHOWERS AND
THUNDERSTORMS FRIDAY. BOTH GFS AND ECMWF GUIDANCE SUGGEST SB CAPE
VALUES COULD REACH AT LEAST 1000-1500 J/KG ACROSS MUCH OF OUR FCST
AREA FRIDAY. 12Z ECMWF GUIDANCE INDICATES CONVECTION COULD LINGER
THROUGH FRIDAY NIGHT.

THE BOUNDARY WILL LIKELY STALL OUT IN THE LOWER GREAT LAKES REGION
AND RESULT IN A CONTINUED CHANCE FOR SHOWERS AND THUNDERSTORMS THIS
WEEKEND WITH A WARM AND FAIRLY HUMID AIRMASS IN PLACE OVER LWR MI.

THE MAIN LOW PRESSURE SYSTEM AND UPPER TROUGH AXIS WILL SLOWLY
APPROACH FROM THE WEST SUNDAY NIGHT AND MONDAY BRINGING A CONTINUED
CHANCE FOR SHOWERS AND STORMS. FAIR BUT SIGNIFICANTLY COOLER WEATHER
IS THEN ANTICIPATED TOWARD THE MIDDLE PORTION OF NEXT WEEK AS THAT
LOW PRESSURE SYSTEM MOVES EAST AND HIGH PRESSURE BUILDS INTO THE
GREAT LAKES REGION.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 736 PM EDT TUE MAY 5 2015

CONDITIONS AT 00Z RANGE FROM IFR TOWARDS KLAN AND KJXN TO VFR AT
KMKG AND KGRR. CEILINGS ARE CURRENTLY TRYING TO IMPROVE THIS
EVENING IN THE WAKE OF THE RAIN WHICH IS WINDING DOWN. THIS TREND
SHOULD BE SHORT LIVED...WITH LOWER CEILINGS AND VISIBILITIES
SETTLING BACK IN. A WARM FRONT IS SITUATED ACROSS NORTHERN INDIANA
THIS EVENING AND IT SHOULD REMAIN THERE TONIGHT. THIS WILL PLACE
SOUTHWEST LOWER MICHIGAN IN A COOL/DAMP EASTERLY FLOW WHICH SHOULD
PROMOTE THE EXPANSION OF LOWER CEILINGS AND VISIBILITIES. HAVE
ALL SITES DROPPING BACK INTO IFR CONDITIONS OVERNIGHT.

ON WEDNESDAY THE WARM FRONT WILL LIFT THROUGH THE AREA WITH
CONDITIONS IMPROVING...ESPECIALLY IN THE MID TO LATE AFTERNOON
HOURS. IFR CONDITIONS WILL PERSIST INTO THE MORNING HOURS HOWEVER.


&&

.MARINE...
ISSUED AT 223 PM EDT TUE MAY 5 2015

WINDS REMAIN LOW THROUGH THURSDAY SO NO HEADLINES AT THIS TIME.
WILL NEED TO MONITOR THE FOG RISK WITH A WARM MOIST AIRMASS HEADED
OUR WAY FOR THE END OF THE WEEK...COMBINED WITH THE COLD WATERS OF
LAKE MI.  SO A RISK FOR FOG EXISTS.


&&

.HYDROLOGY...
ISSUED AT 1149 AM EDT TUE MAY 5 2015

TODAYS PRECIPITATION IS IN THE IMMEDIATE SCOPE OF ATTENTION WHILE
THE NEXT BIG CHALLENGE IS KEYING IN ON NEXT WEEKENDS RAIN
POTENTIAL. ANY RIVER CONCERNS WOULD BE IN THE LATE WEEK AND
WEEKEND TIMEFRAME.

PRECIPITATION MATERIALIZED FAIRLY WELL THIS MORNING WHICH IS
PROVIDING
SOME NEEDED RELIEF TO AREAS RECENTLY CONSIDERED ABNORMALLY DRY.
ADDITIONAL RAINFALL IS POSSIBLE THROUGH THE AFTERNOON WITH LOCALIZED
MODERATE TO HEAVY RAINFALL. LOCATIONS ALONG AND SOUTH OF I-94 HAVE
THE GREATEST CHANCE FOR SEEING CONVECTIVE TYPE RAINFALL...BUT LOWER
INSTABILITY WOULD LIMIT THE THREAT.

THE FORECAST GETS A BIT TRICKY GOING INTO LATE WEEK AND NEXT WEEKEND.
A SYSTEM WILL DEVELOP OUT OVER THE PLAINS AND IS EXPECTED TO
TRAVEL NORTH AND EAST. THE GULF OF MEXICO OPENS UP TO ALLOW FOR
ABUNDANT MOISTURE TO FEED NORTHWARD AS WELL. MEANWHILE...THE
SYSTEM OVER THE SOUTHEAST OFF THE CAROLINA COAST COULD PLAY A PART
IN HOW THE PATTERN RESPONDS. INLAND MOTION OF THE SOUTHEAST SYSTEM
COULD AID IN DRAPING A STATIONARY BOUNDARY THROUGH THE OHIO VALLEY
OR SOMEWHERE THROUGH THE MIDWEST. THE RESULT COULD VERY WELL END
UP BEING PERIODS OF RAINFALL...POSSIBLY HEAVY...SPANNING FROM
LATE FRIDAY ON THROUGH MONDAY. THIS IS SOMETHING THAT BARES
WATCHING AS WE HEAD INTO THURSDAY AND FRIDAY. IF THE SCENARIO WERE
TO PLAY OUT THE BIGGEST CONCERN WOULD THEN BECOME MULTIPLE ROUNDS
OF HEAVIER RAIN. THOUGH RIVERS AND STREAMS ARE WELL WITHIN
BANKS...FORECASTS WILL BE MONITORED FOR THIS POTENTIAL.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

UPDATE...04
SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...LAURENS
AVIATION...DUKE
HYDROLOGY...JAM
MARINE...MJS





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