Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 211031
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
631 AM EDT MON APR 21 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 318 AM EDT MON APR 21 2014

LOW PRESSURE MOVING ACROSS WISCONSIN AND LOWER MICHIGAN WILL BRING
LIGHT RAIN TO SW LOWER TODAY AND TONIGHT. THIS IS A VERY SLOW MOVING
SYSTEM AND GIVEN THE DRY AIR ALREADY IN PLACE...WE/RE NOT LOOKING AT
TOO MUCH RAIN...PERHAPS A QUARTER INCH. TEMPERATURES WILL CLIMB INTO
THE LOWER TO MID 70S AGAIN TODAY EXCEPT FOR AREAS NORTH OF US-10
WHERE 60S ARE EXPECTED. COOLER WEATHER CAN BE EXPECTED FOR THE
REMAINDER OF THE WEEK WITH MORE RAIN POSSIBLE THURSDAY INTO FRIDAY.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 318 AM EDT MON APR 21 2014

FORECAST CONCERNS DEAL WITH RAIN CHANCES TODAY AS A SLOW MOVING LOW
CROSSES WISCONSIN AND MICHIGAN.

THE LOW IN WISCONSIN WILL SLOWLY MOVE ACROSS NRN LWR TODAY. AHEAD OF
IT...WARM AIR WITH TEMPS IN THE 70S WILL BE NOTED. THE WARMER AIR
WILL BRING SOME ELEVATED INSTABILITY WITH IT...BUT NOTHING TOO
SIGNIFICANT. MUCAPE AROUND 500 J/KG AND LI/S SLIGHTLY BELOW 0C MAY
BE ENOUGH TO GENERATE A FEW STORMS. KEPT THE CHC OF THUNDER IN THE
GRIDS. FORECAST SOUNDINGS THIS AFTERNOON SHOW THE PRESENCE OF SOME
DRIER AIR IN THE LOWER TROP. THIS MAY RESULT IN SOME GUSTY WINDS AS
SHOWERS/STORMS MOVE ACROSS THE CWA.

THE LOW SHOULD MOVE OVER LAKE HURON BY MIDNIGHT AND COOLER AIR WILL
BEGIN TO FLOW BACK INTO THE CWA AS HIGH PRESSURE BUILDS INTO THE
GREAT LAKES. SUNSHINE WILL RETURN TUESDAY AND WEDNESDAY BUT HIGHS
WILL ONLY BE IN THE LOWER TO MID 50S.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 318 AM EDT MON APR 21 2014

MODELS ARE IN FAIRLY GOOD AGREEMENT IN TRACKING A COLD FRONT THROUGH
THE REGION THU NIGHT.  A SOUTHERLY LOW LEVEL JET MOVES IN AHEAD OF
THE COLD FRONT.  THAT WILL ACT TO DEVELOP A BAND OF SHOWERS.  THESE
SHOWERS WILL CROSS THE FORECAST AREA...WITH MOST LOCATIONS EXPECTED
TO SEE SOME PRECIPITATION.  WILL KEEP POPS RELATIVELY HIGH THEN.
SOME INSTABILITY IS SHOWING UP IN THE MODELS WITH THIS RUN...SO WE
MAY NEED TO ADD THUNDER TO THE FORECAST.

BEHIND THE COLD FRONT IT WILL TURN WINDY ON FRIDAY.  GUSTS OVER 35M
MPH LOOK LIKELY.  AS THE UPPER LOW APPROACHES...SHOWERS SHOULD
DEVELOP ESPECIALLY IN THE AFTERNOON.   THE HIGH RES EURO DOES SHOW A
MORE NORTHERLY TRACK TO THE IS UPPER LOW WITH THE 00Z MON RUN.  THE
GFS IS STRONGER AND FURTHER SOUTH WITH THIS FEATURE AS COMPARED TO
THE HIGH RES EURO. FORECAST SOUNDINGS SHOW SOME CAPE DURING THE
AFTERNOON.  MAY NEED TO ADD THUNDER TO THE FORECAST.  SHOWERS LOOK
HIGH BASED GIVEN THE LARGE T/TD SPREAD AT THE SURFACE.  I WILL
MAINTAIN THE RISK FOR SHOWERS IN THE FORECAST.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 626 AM EDT MON APR 21 2014

VFR WEATHER TO START THE PERIOD...BUT LATER THIS AFTERNOON AND
INTO TONIGHT WE WILL SEE MVFR CLOUDS/VSBYS AS A COLD FRONT ARRIVES.
SOME INSTABILITY WILL BE AROUND...AND THAT COULD SUPPORT A FEW THUNDERSTORMS.
AS THE MOISTURE BECOMES SHALLOWER TONIGHT...WE MAY SEE SOME ICING
SHOWING UP IN THE MVFR CLOUD DECK.

&&

.HYDROLOGY...
ISSUED AT 1153 AM EDT SUN APR 20 2014

MINOR FLOODING EXISTS ON THE MUSKEGON RIVER AT CROTON AND EVART.
THE DOWNWARD TREND CONTINUES ON ALL AREA RIVERS AND TRIBUTARIES.
WE SHOULD SEE A FEW MORE ADVISORIES DROP OFF THE LIST OVER THE
NEXT 24 HOURS OR SO. HOWEVER...LOCAL IMPACTS MAY STILL BE EVIDENT
OVER THE NEXT SEVERAL DAYS ALONG THE MUSKEGON RIVER.

LIGHT RAIN IS POSSIBLE TONIGHT AHEAD OF A SLOW MOVING COLD FRONT.
BEST CHANCES TONIGHT SHOULD REMAIN ALONG AND NORTH OF HIGHWAY 10.
THE FRONT WILL FINALLY PUSH THROUGH MONDAY AFTERNOON AND THATS
WHEN RAIN IS MORE LIKELY THROUGHOUT THE AREA. PRECIPITATION
AMOUNTS WILL BE RATHER LIGHT AND SHOULD NOT HAVE ANY ADVERSE
AFFECTS ON RIVERS. ANOTHER SHOT OF RAIN WILL MOVE IN LATER IN THE
WORK WEEK BUT IT LOOKS LIKE THE HEAVIEST SHOULD REMAIN WEST OF
LOWER MICHIGAN.

&&

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

$$

SYNOPSIS...93
SHORT TERM...93
LONG TERM...MJS
AVIATION...MJS
HYDROLOGY...JAM






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