Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 250331
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1131 PM EDT THU JUL 24 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 PM EDT THU JUL 24 2014

AFTER DRY CONDITIONS THROUGH FRIDAY...AN APPROACHING WARM FRONT WILL
PROVIDE THE NEXT OPPORTUNITY FOR SHOWERS AND THUNDERSTORMS FRIDAY
NIGHT INTO SATURDAY. AFTER ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS SUNDAY...COOLER THAN WEATHER WILL PREVAIL MUCH OF NEXT
WEEK WITH HIGHS IN THE 70S.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 330 PM EDT THU JUL 24 2014

MAIN CONCERN IS THUNDERSTORM POTENTIAL/INTENSITY SATURDAY AND
SATURDAY NIGHT. OVERALL FORECAST WAS CHANGED VERY LITTLE.

THE DAY3 OUTLOOK FROM SPC VALID FROM SATURDAY MORNING THROUGH SUNDAY
MORNING INDICATES A SLIGHT RISK FOR SEVERE WEATHER FROM THE I-94
CORRIDOR SOUTH. SATURDAY AFTERNOON IS A CANDIDATE FOR SEVERE STORMS
WITH MODERATE INSTABILITY /1000+ J PER KG MLCAPE/ OCCURRING OVER THE
EASTERN FORECAST AREA IN THE LEE OF THE LAKE SHADOW. THIS WILL BE
CO-LOCATED WITH STRONG DEEP LAYER SHEAR /50KT IN 0-6KM LAYER/.

ANOTHER ROUND OF THUNDERSTORMS WITH MARGINAL SEVERE POTENTIAL IS
EXPECTED TO NOSE INTO THE FORECAST AREA FROM THE SOUTHWEST SATURDAY
NIGHT WITH ATTENANT LOW LEVEL MOIST TRANSPORT THAT WILL AID
DESTABILIZATION. ASSOCIATED BOUNDARY WILL BE LIFTING FAIRLY QUICKLY
SO DO NOT EXPECT A FLASH FLOOD THREAT YET...BUT WILL NEED TO MONITOR
THIS.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 330 PM EDT THU JUL 24 2014

LONG TERM PERIOD WILL BEGIN WITH A STRONG SHORTWAVE (CURRENTLY SEEN
SPINNING FROM BRITISH COLUMBIA INTO ALBERTA) DRIVING INTO THE GREAT
LAKES REGION. THIS WAVE WILL HAVE SOME MOISTURE TO WORK WITH TO MAKE
SHOWERS AND THUNDERSTORMS LIKELY. A THREAT FOR SEVERE WEATHER
CERTAINLY EXISTS GIVEN THE STRENGTH OF THE SHORTWAVE AND DECENT
INSTABILITY LINGERING ACROSS THE GREAT LAKES. SATURDAY NIGHT/S
CONVECTIVE TRENDS AND ASSOCIATED CLOUDS WILL DICTATE OUR SEVERE
THREAT ON SUNDAY. A BIT TOO EARLY TO NAIL ANYTHING DOWN YET...BUT A
TIME FRAME OF CONCERN FOR SURE SUNDAY AFTERNOON.

THE PASSAGE OF THE SUNDAY SHORTWAVE WILL LEAD TO THE DEVELOPMENT OF
A FAIRLY DEEP TROUGH ACROSS THE AREA. TODAY/S MODEL RUNS HAVE
SHIFTED A LITTLE BIT TO THE NORTHEAST WITH THE CENTER OF THE UPPER
TROUGH...BUT ARE STILL SOLIDLY UNDER THE INFLUENCE OF IT. EARLY TO
MID NEXT WEEK WILL FEATURE COOLER THAN NORMAL WEATHER FOR JULY AND
SOME AFTERNOON SHOWERS AND STORMS. HIGH ON MONDAY WILL LIKELY TOP
OUT AROUND 70...GRADUALLY WARMING TO AROUND 80 BY THURSDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1127 PM EDT THU JUL 24 2014

AT THIS TIME...IT LOOKS LIKE VFR WEATHER WILL PREVAIL THROUGH THE
FORECAST PERIOD. TOWARD THE END...FROM ROUGHLY 02Z TO 06Z SHOWERS
WILL BE ARRIVING FROM THE WEST. THERE IS A SUGGESTION THAT EVEN A
FEW THUNDERSTORMS WILL BE POSSIBLE. CONFIDENCE IS NOT HIGH ENOUGH
TO ADD THUNDER TO THE FORECAST AT THIS TIME. ALSO CEILINGS AND
VISIBILITIES ARE FORECASTED TO REMAIN AT VFR LEVELS...UNLESS
HEAVIER RAIN MOVES IN...GENERALLY AFTER 02Z. MVFR LOOKS LIKELY FOR
BY 12Z SAT...MOVING IN FROM THE WEST.

&&

.MARINE...
ISSUED AT 330 PM EDT THU JUL 24 2014

MAIN CONCERN IS WINDS AND WAVES RAMPING UP FRIDAY EVENING INTO
SATURDAY MORNING. ALTHOUGH THIS MIGHT JUSTIFY A BEACH HAZARDS
STATEMENT...WILL LIKELY NOT ISSUE AT THIS TIME DUE TO UNCERTAINTY
THIS FAR OUT AND A LIMITED EXPECTED BEACH POPULATION DURING THE PEAK
THREAT TIME.


&&

.HYDROLOGY...
ISSUED AT 1121 AM EDT THU JUL 24 2014

NO SIGNIFICANT RAINFALL IS ANTICIPATED AS HIGH PRESSURE WILL
PROVIDE QUIET CONDITIONS TODAY AND MUCH OF FRIDAY. DUE TO
RECENT...MOSTLY DRY STRETCH OF WEATHER...ALL RIVERS AND STREAMS
REMAIN WELL BELOW ADVISORY CRITERIA.

SHOWERS AND THUNDERSTORMS MAY DEVELOP LATE FRIDAY EVENING AND
EARLY SATURDAY MORNING TO PROVIDE A QUICK SHOT OF PRECIPITATION.
ANOTHER...MORE SIGNIFICANT WAVE WILL PASS THROUGH SUNDAY AFTERNOON
AND EVENING. THIS SECOND ROUND COULD PROVIDE A BETTER CHANCE OF
LOCALIZED HEAVY RAINFALL IN AND AROUND THUNDERSTORMS.

&&

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

$$

SYNOPSIS...TJT
SHORT TERM...TJT
LONG TERM...DUKE
AVIATION...MJS
HYDROLOGY...JAM
MARINE...TJT






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