Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 212240
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
640 PM EDT MON JUL 21 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 334 PM EDT MON JUL 21 2014

MAINLY CLEAR SKIES ARE EXPECTED TONIGHT WITH INCREASING CLOUDINESS
ON TUESDAY. IT WILL CONTINUE TO BE WARM INTO TUESDAY WITH READINGS
PUSHING INTO THE UPPER 80S IF NOT REACHING 90 IN SPOTS. SHOWERS AND
THUNDERSTORMS SHOULD WORK THROUGH THE AREA TUESDAY EVENING AND
TUESDAY NIGHT ALONG AND AHEAD OF A COLD FRONT. THE SHOWERS AND
STORMS SHOULD EXIT THE REGION WEDNESDAY MORNING WITH DRY AND COOLER
AIR WORKING IN BEHIND THE FRONT FOR LATER IN THE WEEK. HIGHS ON
THURSDAY AND FRIDAY WILL REMAIN IN THE 70S IN MOST AREAS.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 334 PM EDT MON JUL 21 2014

MAIN FOCUS OF THE SHORT TERM IS ON THE EXTENT OF THUNDERSTORMS
TUESDAY AFTERNOON THOUGH TUESDAY NIGHT AND THE CHANCES FOR SEVERE
STORMS.

THE TIMING OF THE FRONT HAS CHANGED A LITTLE BIT IN TODAY/S MODEL
RUNS...A BIT QUICKER. WHAT THIS DOES IS BRING THE FRONT CLOSER TO
THE AREA AT MAX HEATING. STRONG MOISTURE ADVECTION WILL OCCUR
THROUGH THE DAY WITH VERY HIGH DEW POINTS POOLING UPSTREAM OVER
WI/IL DURING THE AFTERNOON. EXPECT SHOWERS/STORMS TO FIRE AHEAD OF
THE FRONT FROM NORTHWEST LOWER MICHIGAN TO NEAR MADISON WI IN THE
LATE AFTERNOON/EARLY EVENING. THESE STORMS UPSTREAM WILL HAVE
SIGNIFICANT INSTABILITY TO WORK WITH AND WILL LIKELY BE AIDED BY AN
MCV FROM TONIGHT/S CONVECTION AS WELL AS A SHORTWAVE DROPPING INTO
THE AREA. A SLIGHT RISK IS POISED UPSTREAM IN EASTERN WI. LAKE
MICHIGAN IS ALWAYS THE WILDCARD AND LOOKS TO BE AGAIN TOMORROW. FEEL
THAT STORMS MAY NOT COMPLETELY ROOT IN THE BOUNDARY LAYER OVER THE
LAKE THOUGH WITH A LATE SPRING FEEL TO THE AIR TEMPS OUT THERE.

SO...THE STORMS MAY FIRE UPSTREAM AND MAINTAIN A GOOD DEAL OF THERE
STRENGTH AS THE ROLL EAST INTO WESTERN LOWER MICHIGAN TUESDAY
EVENING. MEAN LAYER CAPES SHOW 2000 J/KG TO WORK WITH AROUND 00Z
TOMORROW EVENING. THE 850MB LLJ IS ON THE ORDER OF 30-40 KNOTS WITH
40-50 KNOTS UP IN THE MID LEVELS. FOR A SHORT TIME 0-6KM SHEAR
INCREASES TO 30-40 KNOTS ACROSS WEST CENTRAL LOWER MICHIGAN. FEEL
THIS AREA...NORTH AND WEST OF GRAND RAPIDS...TOWARDS LUDINGTON
STANDS THE BEST CHANCE AT SEVERE WEATHER TOMORROW EVENING. NOT A
SLAM DUNK BY ANY MEANS...BUT WE WILL NEED TO MONITOR CONVECTION THAT
GOES UP UPSTREAM AND THAT MAY DEVELOP OVERHEAD. MAIN THREAT WOULD BE
DAMAGING WINDS CENTERED IN THE 6PM THROUGH 2AM TIME FRAME.
AGAIN...BEST PARAMETERS COME TOGETHER ACROSS WEST CENTRAL INTO
CENTRAL LOWER MICHIGAN.

OTHERWISE...LIMITED CONCERNS THROUGH THE SHORT TERM. SHOWERS AND
STORMS SHOULD EXIT EARLY ON WEDNESDAY IN THE FAR SOUTHEAST. MAINLY
CLEAR SKIES EXPECTED TONIGHT AND AGAIN WEDNESDAY NIGHT.

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 334 PM EDT MON JUL 21 2014

NO NOTABLE CHANGES TO THE GOING LONG TERM FORECAST RUNNING THROUGH
NEXT MONDAY. WE WILL SEE A QUIET AND COMFORTABLE PERIOD FOR THE END
OF THE WORK WEEK. THE WEATHER THEN LOOKS TO BECOME A BIT UNSETTLED
FOR NEXT WEEKEND AND INTO NEXT WEEK.

THERE IS HIGH CONFIDENCE THAT WE WILL SEE DRY CONDITIONS FOR THU
THROUGH FRI. WE CONTINUE TO EXPECT TO BE DOWNSTREAM OF THE FAIRLY
AMPLIFIED UPPER RIDGE CENTERED ACROSS THE PLAINS STATES. TEMPS WILL
BE COOL FOR THIS TIME OF THE YEAR AS NRLY FLOW AHEAD OF THE SFC
RIDGE WILL BRING A CANADIAN AIR MASS INTO THE AREA. AS THE SFC HIGH
PASSES EAST...WE WILL SEE SRLY FLOW START TO ADVECT IN AND THE AIR
MASS WILL MODERATE A BIT.

THE WEATHER LOOKS UNSETTLED FOR THE WEEKEND AND EARLY NEXT WEEK. THE
PLAINS RIDGE WILL NEVER GET HERE AS IT GETS CLIPPED OFF BY THE
STRONG PACIFIC JET EXPECTED TO COME ONSHORE OVER THE PACIFIC NW MID
WEEK. TROUGHING THEN DEVELOPS OVER THE AREA AS THE JET PHASES WITH
THE UPPER LOW ACROSS ERN CANADA. WE CAN EXPECT TO BE ON THE NORTH
SIDE OF THE JET WITH SHORT WAVES POSSIBLE. THIS WILL KEEP A CHC OF
SHOWERS/STORMS POSSIBLE...BUT NOT THE WHOLE PERIOD. TEMPS WILL NOT
BE TOO COLD AS THE CORE OF THE COLD AIR ALOFT REMAINS NORTH OF THE
AREA.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 640 PM EDT MON JUL 21 2014

QUIET WEATHER EXPECTED FOR THE NEXT 24 HOURS...WITH SOME
CONVECTION MOVING THROUGH JUST BEYOND THIS FCST CYCLE.

DIURNAL CUMULUS CLOUDS ARE IN THE PROCESS OF DISSIPATING ACROSS
THE AREA EARLY THIS EVENING. WINDS WILL BE DIMINISHING ALSO. THE
MORE HUMID AIR IN PLACE WILL BRING THE POTENTIAL OF SOME FOG/HAZE
LATER TONIGHT...EVEN AS WINDS DO NOT GO ENTIRELY CALM. WE ARE
GOING WITH SOME MVFR HZ FOR NOW...BUT WE CAN NOT RULE OUT SOME
LOCAL IFR.

ANY FOG/HZ WILL GRADUALLY MIX OUT TUE MORNING...ESPECIALLY AS
WINDS INCREASE AHEAD OF THE INCOMING FRONT. NOT EXPECTING A LOT OF
CU THROUGH MOST OF THE DAY AS THE ATMOSPHERE WILL BE CAPPED/TOO
WARM ALOFT. SOME MID LEVEL CLOUDS WILL GRADUALLY FLOAT IN FROM
CONVECTION TO OUR WEST. CONVECTION SHOULD HOLD OFF AT THE
TERMINALS UNTIL AFTER 00Z AND THEN MOVE IN FROM THE NW.

&&

.MARINE...
ISSUED AT 334 PM EDT MON JUL 21 2014

HAVE ISSUES A SMALL CRAFT ADVISORY AND A BEACH HAZARDS STATEMENT FOR
AREAS FROM GRAND HAVEN NORTH ON TUESDAY. EXPECTING THE STRONGEST
WINDS AND HIGHEST WAVES FROM MID MORNING THROUGH MID
EVENING...ENCOMPASSING THE BULK OF THE SWIMMING/BOATING DAY. WAVES
OF 3 TO 5 FEET LOOK LIKE A SOLID BET ESPECIALLY THE FURTHER NORTH
YOU GO.

WINDS AND WAVES WILL COME DOWN FOR A BIT TUESDAY NIGHT WITH ANOTHER
SCA/BHS EXPECTED ON WEDNESDAY. GIVEN THE 12 HR BREAK OR SO...DECIDED
TO LET THIS SECOND TIME FRAME GO FOR NOW AND WE CAN ISSUE THAT ONE
ON TUESDAY OR EVEN TUESDAY EVENING. THE WAVES ON TUESDAY WILL BE
SOUTHERLY FLOW. ON WEDNESDAY THE FLOW WILL BE NORTHERLY. SO
WEDNESDAY/S LARGER WAVES WILL BE THE SOUTHERN HALF OF THE FORECAST
AREA...SOUTH OF GRAND HAVEN.

AREAS OF FOG LOOK LIKE A DECENT BET TUESDAY AFTERNOON INTO TUESDAY
NIGHT AS HIGH DEW POINT AIR IS ADVECTED OUT OVER THE COOLER LAKE
WATERS.


&&

.HYDROLOGY...
ISSUED AT 334 PM EDT MON JUL 21 2014

WIDESPREAD SIGNIFICANT RAINFALL LOOKS UNLIKELY TUESDAY NIGHT AND
WEDNESDAY. GENERALLY WE ARE EXPECTING A QUARTER TO THREE QUARTERS
OF AN INCH OF RAINFALL WITH HIGHER AMOUNTS POSSIBLE IN HEAVIER
THUNDERSTORMS. NOT ALL LOCATIONS ARE EXPECTED TO RECEIVE RAINFALL
WITH THIS COLD FRONT. WITH A FAIRLY QUICK MOVING LINE OF CONVECTION
ALONG THE FRONT...FLOODING IS A GREATLY MITIGATED THREAT. RIVERS
HAVE BEEN FALLING STEADILY AND ASIDE FROM A TEMPORARY BUMP IN SOME
LEVELS ON WEDNESDAY THIS TREND SHOULD CONTINUE FOR THE REST OF THE
WEEK.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT FROM TUESDAY MORNING THROUGH TUESDAY
     EVENING FOR MIZ037-043-050.

LM...SMALL CRAFT ADVISORY FROM 10 AM TO 11 PM EDT TUESDAY FOR
     LMZ847>849.

&&

$$

SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...NJJ
AVIATION...NJJ
HYDROLOGY...HOVING
MARINE...DUKE






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