Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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904
FXUS63 KGRR 181930
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
310 PM EDT MON MAY 18 2015

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

.SYNOPSIS...
ISSUED AT 330 PM EDT MON MAY 18 2015

A COLD FRONT WILL TRAVERSE THE AREA THIS EVENING AND USHER IN MUCH
COOLER AND DRIER AIR. A FEW SHOWERS AND STORMS ARE POSSIBLE THIS
EVENING TOWARDS LANSING AND JACKSON. OTHERWISE...MAINLY DRY
CONDITIONS ARE EXPECTED THE REMAINDER OF THE WORK WEEK...WITH THE
EXCEPTION BEING A FEW SHOWERS POSSIBLE ON THURSDAY WITH A WEAK
SYSTEM MOVING THROUGH THE SOUTHERN GREAT LAKES. FROST AND EVEN SOME
FREEZING TEMPERATURES ARE POSSIBLE WEDNESDAY MORNING WITH SURFACE
HIGH PRESSURE NOSING INTO THE REGION. AFTER A COOL DOWN THIS WEEK
THE HOLIDAY WEEKEND LOOKS TO BRING A WARM UP WITH CHANCES FOR
SHOWERS AND STORMS TOWARDS MEMORIAL DAY.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 330 PM EDT MON MAY 18 2015

TWO MAIN ITEMS OF NOTE IN THE SHORT TERM ARE THE CHANCES FOR SHOWERS
AND STORMS THIS EVENING AND THE THREAT OF FROST AND FREEZING
TEMPERATURES TUESDAY NIGHT.

AS FOR THE STORMS...INSTABILITY HAS POOLED ALONG AND AHEAD OF THE
COLD FRONT ON THE ORDER OF 1000 J/KG CAPE VALUES AND -4 LI/S.
ISOLATED STORMS HAVE FIRED ON THE BOUNDARY WITH LIGHTNING NOTED IN
THE THUMB. STILL THINKING A FEW SHOWERS AND STORMS WILL MOVE THROUGH
THE SOUTHEAST CWA ACROSS SOUTH CENTRAL LOWER MICHIGAN. NOT EXPECTING
ANYTHING SEVERE...BUT SOME LOCALLY HEAVY RAIN AND LIGHTNING.

THREAT FOR FROST TUESDAY NIGHT LOOKS DECENT AS HIGH PRESSURE WILL BE
NOSING ALONG WITH A VERY DRY AIRMASS. THINKING LOWER 30S TEMPS ARE
GOING TO BE COMMON WITH AROUND 3O AND EVEN UPPER 20S POSSIBLE IN THE
TYPICALLY COLDER SPOTS. WE MAY NEED TO CONSIDER HEADLINES AS EARLY
AS OVERNIGHT SINCE IT WILL BE A PERIOD 2 EVENT AT THAT POINT.

OTHERWISE...QUIET WEATHER WITH COLD AIR STRATOCUMULUS SLIDING IN
TONIGHT WITH THE UPPER LOW.

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 330 PM EDT MON MAY 18 2015

THE LATTER HALF OF THE WEEK CONTINUES TO LOOK QUIET AND COOL.  H8
TEMPS HOLD AROUND +3 TO +6C THURSDAY THROUGH SATURDAY WITH NW UPPER
FLOW DOMINATING.  THIS WILL KEEP DAYTIME MAX TEMPS BELOW
NORMAL...MOSTLY IN THE MID AND UPPER 60S.  A BACK COLD FRONT IS
STILL SHOWN TO COME THROUGH THURSDAY OR THURSDAY NIGHT WHICH SHOULD
COME THROUGH DRY AND ONLY RESULT IN A REINFORCING SHOT OF COOL AIR.

WE WILL FINALLY SEE A WARM UP SATURDAY NIGHT INTO MONDAY AS H8 TEMPS
CLIMB TO AROUND +12C.  HOWEVER WITH THE WARM AIR COMES GULF MOISTURE
AS THE SOUTHWESTERLY UPPER FLOW OPENS UP.  THERE APPEARS TO BE GOOD
CHANCES FOR SHOWERS AND STORMS SUNDAY INTO MONDAY AS A WARM FRONT
LIFTS OUT OF THE OHIO VALLEY AND MOVES OVER SOUTHERN LOWER.  THE
FRONT APPEARS TO STALL OR AT LEAST SLOWS OVER SOUTHERN LOWER AND
THIS COULD RESULT IN SOME HEAVIER RAINS WITH THE RICH GULF MOISTURE
COMING INTO PLAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 131 PM EDT MON MAY 18 2015

VFR CONDITIONS ARE EXPECT FOR MUCH OF THE NEXT 24 HOURS. A COLD
FRONT WAS CROSSING SW MI AS OF 17Z AND THERE COULD BE ISOLATED
SHOWERS OR A THUNDERSTORM ALONG IT THAT MAY AFFECT LAN AND/OR JXN
THROUGH 20Z. BUT LEFT THIS OUT OF THE TAFS DUE TO THE EXPECTED
LOW COVERAGE.

WSW WINDS WILL OCCASIONALLY GUST TO AROUND 25 KTS THIS AFTERNOON
INTO EARLY EVENING BEFORE DIMINISHING SOMEWHAT AFTER 01Z.

COLD AIR AND WRAP AROUND MOISTURE WILL BRING LOWERING CLOUDS INTO
THE AREA AFTER 06Z. MKG AND GRR COULD BRIEFLY SEE MVFR CEILINGS
AROUND DAYBREAK TUESDAY THAT MIGHT LAST UNTIL MID MORNING.


&&

.MARINE...
ISSUED AT 330 PM EDT MON MAY 18 2015

MAINTAINED THE DENSE FOG ADVISORY NORTH OF HOLLAND WITH THE MUSKEGON
WEBCAM STILL SOCKED IN WITH NEAR ZERO VISIBILITY. 1 MIN VISIBLE
IMAGERY ALSO SHOWS QUITE A BIT OF FOG AS WELL OVER THE LAKE BUT IT
IS STARTING TO THIN. STILL EXPECTING A RAPID IMPROVEMENT IN THE NEXT
FEW HOURS AS DRIER AIR BEGINS TO FILTER IN. SO...THE MARINE DENSE
FOG ADVISORY CONTINUES THROUGH 600PM.

EXTENDED THE SMALL CRAFT ADVISORY THROUGH 500 PM ON TUESDAY WITH A
NORTHWEST FLOW COLD AIR ADVECTION EVENT SET TO OCCUR FROM TONIGHT
INTO TUESDAY. EXPECTING NORTHWEST WINDS OF 15 TO 25 KNOTS AND 3 TO 5
FOOTERS.

&&

.HYDROLOGY...
ISSUED AT 140 PM EDT MON MAY 18 2015

IN GENERAL...RIVER LEVELS ACROSS SOUTHWEST LOWER MICHIGAN ARE
GRADUALLY FALLING. THAT WILL CONTINUE TO BE THE CASE WITH LIMITED
QPF. ONLY A FEW SCATTERED SHOWERS/STORMS ARE POSSIBLE THIS AFTERNOON
ALONG AND AHEAD OF A COLD FRONT SWEEPING THROUGH THE STATE. FAIR
WEATHER WILL DOMINATE FOR THE REST OF THE WEEK INTO SATURDAY. THE
NEXT SIGNIFICANT CHANCE FOR WIDESPREAD RAINFALL WILL BE LATE IN THE
HOLIDAY WEEKEND INTO NEXT WEEK. 00Z ECMWF EPS PROBABILITY
INDICATES A 30 TO 40 PERCENT CHANCE FOR GREATER THAN HALF AN INCH
OF RAIN SOUTH OF I-96 IN A 24-HOUR PERIOD ENDING MONDAY
AFTERNOON.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...DENSE FOG ADVISORY UNTIL 6 PM EDT THIS EVENING FOR LMZ846>849.

     SMALL CRAFT ADVISORY UNTIL 5 P
M EDT TUESDAY FOR LMZ844>849.

&&

$$

SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...JK
AVIATION...JK
HYDROLOGY...EBW
MARINE...DUKE



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