Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 041914
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
314 PM EDT SAT JUL 4 2015

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/MARINE

.SYNOPSIS...
ISSUED AT 314 PM EDT SAT JUL 4 2015

THE REST OF THE HOLIDAY WEEKEND CONTINUES TO LOOK MOSTLY DRY AND
WARM FOR LOWER MICHIGAN. THE ONLY EXCEPTION WILL BE A LOW CHANCE OF
A SHOWER OR STORM INTO EARLY THIS EVENING ACROSS CENTRAL LOWER
MICHIGAN AWAY FROM LAKE MICHIGAN.

MOST OF MONDAY WILL BE DRY AND VERY WARM. CHANCES OF MORE WIDESPREAD
SHOWERS AND STORMS WILL INCREASE MONDAY NIGHT AND EARLY TUESDAY WITH
THE APPROACH OF A STRONGER COLD FRONT. RAIN SHOULD CLEAR OUT BY
TUESDAY NIGHT AND DRY AND COOLER CONDITIONS WILL PREVAIL MID WEEK
NEXT WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 314 PM EDT SAT JUL 4 2015

CU FIELD IS DEVELOPING ACROSS INTERIOR PORTIONS OF CENTRAL LOWER
MICHIGAN EARLY THIS AFTERNOON AS EXPECTED ALONG AND AHEAD OF A
WEAKENING COLD FRONT. WE EXPECT A FEW OF THESE CUMULUS TO GROW SOME
VERTICAL DEVELOPMENT AND BECOME ISOLATED SHOWERS AND MAYBE A STORM.
CAPES OF A FEW HUNDRED J/KG ARE STILL EXPECTED...WITH ONE OR TWO
INVERSIONS TO LIMIT THE UPDRAFT STRENGTH. THIS WILL ALSO LIMIT
SEVERE WX POTENTIAL. ANY SHOWERS/STORMS THAT DO DEVELOP WILL
DISSIPATE BY MID EVENING.

WE ARE THEN EXPECTING DRY CONDITIONS FROM MID EVENING TONIGHT
THROUGH MOST OF THE DAY ON MONDAY. AN UPPER RIDGE BUILDING OVER THE
AREA THIS EVENING WILL HOLD OVER THE AREA THROUGH SUN. A DRY DEEP
LAYER AIR MASS IN PLACE COMBINED WITH WARM TEMPS ALOFT AROUND 700-
500 MB WILL KEEP THE AREA DRY. THE RIDGE TRIES TO MOVE EAST BY
MON...BUT THE NEXT TROUGH AND MOISTURE RETURN HOLDS WEST OF THE AREA
THROUGH THE DAY. H850 TEMPS OF MID TO UPPER TEENS C WILL SUPPORT MID
80S ON SUN AND UPPER 80S ON MON FOR MAX TEMPERATURES.

THE BEST CHANCE OF SHOWERS AND STORMS WILL COME OVERNIGHT MON NIGHT
INTO TUE. WE WILL SEE A NICE 40-45 KT LLJ SHIFT INTO THE AREA LATE
MON HELPING TO INCREASE THE MOISTURE ADVECTION. THE NOSE OF IT
HOWEVER IS UP IN CANADA CLOSER TO THE SFC LOW. UPPER LEVEL JET
DYNAMICS ARE NOT REALLY CLOSE ENOUGH TO HELP THE CAUSE EITHER.
SEVERE WEATHER IS NOT LOOKING LIKELY AT THIS TIME DUE TO THE TIMING
OF THE FRONT DURING THE EARLY MORNING HOURS. THERE IS NOT A
SIGNIFICANT AMOUNT OF INSTABILITY AVAILABLE DURING FROPA...AND WHAT
INSTABILITY THERE IS IS THIN AND ELEVATED. BEST DEEP LAYER SHEAR
LOOKS TO BE LAGGING BEHIND THE FRONT ALSO.

THE SEVERE THREAT FROM THIS FRONT COULD INCREASE SOME ACROSS THE SE
SECTION OF THE CWFA IF IT ENDS UP SLOWING UP A BIT AND CAN TAP SOME
INSTABILITY TUE AFTERNOON BEFORE IT PASSES.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 314 PM EDT SAT JUL 4 2015

PRECIPITATION CHANCES THURSDAY LOOK LESS CERTAIN. ALTHOUGH THERE
WILL BE A WEAK UPPER SHORTWAVE TROUGH CROSSING THE AREA...BEST LOW
LEVEL MOISTURE AND CONVERGENCE STAY SOUTH OF THE AREA WITH THE MOST
RECENT MODEL RUNS.

THE NEXT REAL PROSPECTS FOR PRECIPITATION ARRIVE SATURDAY WITH BOTH
THE ECMWF AND GFS HINTING AT A WEAK UPPER SHORTWAVE TROUGH
APPROACHING THE AREA. THE FIM ALSO SHOWS THIS...BUT WITH SLIGHTLY
EARLIER TIMING. THIS SUBTLE TROUGH IS WITHIN A SIMILARLY WEAK SUMMER-
LIKE SYNOPTIC ENVIRONMENT...WHICH MODELS HAVE GREAT DIFFICULTY
REPRESENTING AT THIS TIME RANGE. WOULD THEREFORE WANT TO SEE MORE
MODEL CONTINUITY WITH THIS FEATURE BEFORE ASSIGNING MUCH CERTAINTY.

TEMPERATURES THROUGH THE PERIOD WILL BEGIN SLIGHTLY BELOW NORMAL
(MID 70S) BEFORE WARMING INTO THE 80S BY THE WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 132 PM EDT SAT JUL 4 2015

MOSTLY LIGHT RAIN SHOWERS ARE POSSIBLE THIS AFTERNOON OVER
CENTRAL LOWER MICHIGAN...MOST LIKELY AFFECTING THE GRR AND LAN
TERMINALS. THUNDERSTORMS ARE NOT ANTICIPATED.

AS NOTED ALREADY...WE EXPECT A RETURN TO MVFR VSBY AT MOST TERMINALS
EARLY SUNDAY MORNING. DISSIPATION SHOULD BE RAPID...MOST LIKELY
AROUND 12Z.

&&

.MARINE...
ISSUED AT 314 PM EDT SAT JUL 4 2015

WE CONTINUE TO EXPECT THAT THERE SHOULD BE MINIMAL ISSUES WITH
REGARDS TO THE WEATHER FOR THE NEARSHORE WATERS THROUGH SUNDAY. A
LIGHT GRADIENT OVERHEAD WILL KEEP WINDS UNDER 15 KNOTS AND WAVES
UNDER 2 FEET. WATER TEMPS VARY FROM THE 40S NEAR GRAND HAVEN TO THE
LOWER 60S NEAR SOUTH HAVEN AND LUDINGTON.

WINDS ARE STILL EXPECTED TO INCREASE ON MON OUT AHEAD OF A STRONGER
COLD FRONT MOVING TOWARD THE AREA. WE ARE LOOKING AT SOME POSSIBLE
SMALL CRAFT ADVISORY CONDITIONS DEVELOPING MONDAY AFTERNOON.

&&

.HYDROLOGY...
ISSUED AT 1124 AM EDT SAT JUL 4 2015

THERE ARE NO EXISTING ADVISORIES ON AREA RIVERS. IMPROVEMENT IS
EXPECTED TO CONTINUE AT LEAST THROUGH THE WEEKEND.

OVERALL...DRY CONDITIONS WILL DOMINATE THE PATTERN THROUGH THE
FIRST HALF OF MONDAY. THERE IS A SLIGHT CHANCE OF AN ISOLATED
STORM THIS AFTERNOON THROUGH INTERIOR PORTIONS OF LOWER MICHIGAN.
BETTER CHANCES OF RAIN EXIST LATE MONDAY INTO EARLY TUESDAY WHEN A
COLD FRONT SWEEPS THROUGH THE AREA. A DECENT RAINFALL IS POSSIBLE
MONDAY BUT GIVEN THE RECENT PERIOD OF DRY WEATHER THIS SHOULD NOT
BE MUCH OF A CONCERN. AMOUNTS IN THE REALM OF ONE- HALF TO THREE-
QUARTERS OF AN INCH ARE POSSIBLE. AMOUNTS MAY VARY IN OR NEAR
THUNDERSTORMS.

&&

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

$$

SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...TJT
AVIATION...TJT
HYDROLOGY...JAM
MARINE...NJJ


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