Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 290343
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1143 PM EDT MON JUL 28 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 PM EDT MON JUL 28 2014

BELOW NORMAL TEMPERATURES WILL LINGER THROUGH MID WEEK BEFORE
RECOVERING TO CLOSER TO NORMAL VALUES TOWARD THE END OF THE WEEK AND
NEXT WEEKEND. A FEW SCATTERED SHOWERS OR THUNDERSTORMS ARE POSSIBLE
EACH DAY THIS WEEK... PARTICULARLY INLAND FROM LAKE MICHIGAN.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 330 PM EDT MON JUL 28 2014

HUDSON BAY VORTEX/NORTHWEST FLOW ALOFT WILL KEEP COOL TEMPS LOCKED
IN FOR THE NEXT FEW DAYS. COLD TEMPS ALOFT OF AROUND -17C AT H5 WILL
SUPPORT DIURNAL FLARE UPS OF CONVECTION... ESPECIALLY EAST OF
HIGHWAY 131 INLAND FROM THE STABILIZING EFFECTS OF LAKE MICHIGAN AND
IN AREA OF BETTER LOW LEVEL CONVERGENCE ON THE LEADING EDGE OF THE
LOW LEVEL WESTERLY FLOW/LAKE BREEZE.

MODELS SHOW DECENT COVERAGE OF LOW TOPPED CONVECTION ON TUESDAY
AFTERNOON AROUND CLARE/MT PLEASANT/ALMA/LAN/JXN AREAS. GFS FCST
SOUNDINGS A BIT MORE UNSTABLE THAN THE NAM... SHOWING 1000-1500 J/KG
SB CAPE WHILE NAM IS MORE LIKE 500-1000. EITHER WAY THAT IS ENOUGH
TO HAVE A MENTION OF THUNDER IN THE FCST. THE LOW FREEZING LEVELS
AROUND 9300 FT SUPPORTS THE POSSIBILITY OF SOME SMALL HAIL (PEA TO
PERHAPS MARBLE SIZE) IN ANY STRONGER STORMS. HOWEVER THE CAPE IS
THIN... ESPECIALLY ON THE NAM... SUGGESTING WEAK UPDRAFTS.

WILL HAVE LOWER POPS ON WEDNESDAY AS INSTABILITY IS PROGGED TO BE
LESS (ONLY A COUPLE HUNDRED JOULES OF CAPE). MODELS ALSO FOCUS BEST
SFC CONVERGENCE ALONG/SOUTH OF I-94 DUE TO THE LOW LEVEL FLOW BEING
MORE NORTHWESTERLY THAN WEST.

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 330 PM EDT MON JUL 28 2014

THE UPPER LEVEL TROUGH WILL REMAIN OVER THE GREAT LAKES REGION
THURSDAY THROUGH FRIDAY BEFORE SLOWLY MOVING OUT AND DEAMPLIFYING AS
IT MOVES EAST. TEMPS WILL AVERAGE NEAR OR JUST A LITTLE BELOW NORMAL
THURSDAY THROUGH FRIDAY WITH A CONTINUED CHANCE OF DIURNALLY DRIVEN
MAINLY AFTERNOON AND EARLY EVENING SHOWERS AND PERHAPS ISOLATED
THUNDERSTORMS.

HOWEVER THE LARGE SCALE PATTERN WILL NOT CHANGE TOO MUCH WITH THE
WESTERN CONUS HIGH AMPLITUDE RIDGE IN THE WEST THROUGH THE WEEKEND
INTO EARLY NEXT WEEK THAT WILL BE CONDUCIVE TO REDEVELOPMENT OF A
TROUGH OVER OUR REGION EARLY NEXT WEEK. TEMPERATURES THIS WEEKEND
INTO EARLY NEXT WEEK SHOULD AVERAGE FAIRLY CLOSE TO NORMAL.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1143 PM EDT MON JUL 28 2014

THE CLOUDS ASSOCIATED WITH THE NEXT SYSTEM DROPPING SOUTH INTO
LOWER MICHIGAN ARE COMING IN SLOWER THAN EXPECTED SO I DELAYED THE
ARRIVAL OF THOSE CLOUDS BY A FEW HOURS. THAT MEANS CLEAR SKIES AND
LIGHT WIND MOST OF THE EARLY MORNING HOURS OF TUESDAY.

MODEL SOUNDING LOOK RATHER UNSTABLE FOR TUESDAY DURING THE DAY.
GIVEN THE MOSTLY WESTERLY LOW LEVEL WINDS IT WOULD SEEM THE RISK
FOR THUNDERSTORMS WOULD LARGELY BE WEST OF US-131 SO I DO NOW HAVE
VCTS FOR ALL OF THE TAF SITES EXCEPT GRR AND MKG. I ALSO INCREASE
THE CIGS TO VFR AS MODEL SOUNDINGS SUGGEST CLOUD BASES AROUND 4000
FT AGL. SOME CLEARING IS EXPECTED TUESDAY NIGHT.

&&

.MARINE...
ISSUED AT 959 PM EDT MON JUL 28 2014

WE CONTINUE TO MONITOR THE STEADY DROP IN WINDS AND WAVES ACROSS
THE NEARSHORE WATERS THIS EVENING. THE GRADIENT HAS WEAKENED
CONSIDERABLY AS EXPECTED...AND WAVES ARE LAGGING...BUT FOLLOWING
SUIT. MOST OF THE NEARSHORE HAS DROPPED BELOW SMALL CRAFT ADVISORY
CRITERIA...EXCEPT FOR THE ST. JOSEPH BUOY WHICH IS AT 5+ FT AT
0140Z SOUTH OF THE NEARSHORE WATERS. EVEN THIS BUOY IS COMING DOWN
STEADILY...AND WE EXPECT THAT IT SHOULD CONTINUE TO DO SO ENOUGH
THAT WE CAN CANCEL ALL MARINE HEADLINES BY 03Z.


&&

.HYDROLOGY...
ISSUED AT 330 PM EDT MON JUL 28 2014

NO HYDRO CONCERNS AT THIS TIME GIVEN ISOLATED TO SCATTERED NATURE OF
THE CONVECTION OVER THE NEXT FEW DAYS. SOME BRIEF LOCALLY HEAVY
DOWNPOURS WITH SMALL HAIL MAY OCCUR EAST OF HIGHWAY 131 AND
ESPECIALLY EAST OF U.S. 127 ON TUESDAY.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR LMZ844.

&&

$$

SYNOPSIS...MEADE
SHORT TERM...MEADE
LONG TERM...LAURENS
AVIATION...WDM
HYDROLOGY...MEADE
MARINE...NJJ






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