Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 211821
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
221 PM EDT MON APR 21 2014

LATEST UPDATE...
HYDRO

.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.

&&

.UPDATE...
ISSUED AT 925 AM EDT MON APR 21 2014

UPDATED FORECAST TO CUT POPS FOR THIS AFTERNOON BASED ON RADAR AND
LATEST HRRR WHICH SHOWS SHOWERS JUST ENTERING NORTHERN ILLINOIS
ATTM AND NOT ARRIVING UNTIL LATE AFTERNOON.

&&

.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 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 122 PM EDT MON APR 21 2014

SHOWERS WILL GRADUALLY DEVELOP THIS AFTERNOON AND EVENING AND
CONDITIONS WILL GRADUALLY DETERIORATE FROM VFR TO MVFR AS LOWER
CLOUDS AND SHOWERS MOVE IN. CANNOT RULE OUT AN ISOLATED STORM LATE
THIS AFTERNOON AND EVENING BUT THERE IS NOT ENOUGH CONFIDENCE IN
CONVECTIVE POTENTIAL TO WARRANT INCLUSION IN THE TERMINAL FCSTS AT
THIS TIME. CONDITIONS WILL IMPROVE TO VFR TUESDAY AND WNW WINDS
WILL RAMP UP TO AROUND 15 TO 20 KTS WITH GUSTS TO 25 KTS BY LATE
MORNING.


&&

.HYDROLOGY...
ISSUED AT 220 PM EDT MON APR 21 2014

WARNINGS NO LONGER EXIST ON ANY OF THE AREA RIVERS OR STREAMS. ALL
HAVE SINCE BEEN DOWNGRADED TO ADVISORIES...WHICH ARE EVEN NUMBERED
THEMSELVES. SCOTTVILLE...CROTON AND EVART ARE THE HOLD OUTS WITH
THE ONGOING ADVISORIES. CONDITIONS CONTINUE TO IMPROVE WITH
DROPPING RIVER LEVELS BUT SOME LOCALIZED AFFECTS ARE STILL POSSIBLE.

WE WILL SEE A QUICK HIT OF RAINFALL THIS AFTERNOON THROUGH LATE THIS
EVENING. TOTAL RAINFALL AMOUNTS SHOULD REMAIN WELL SHY OF CREATING
ANY CONCERN FOR RIVERS AND STREAMS. THE NEXT CHANCE OF RAIN MOVES
IN BY THURSDAY AND FRIDAY.

&&

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

$$

UPDATE...OSTUNO
SYNOPSIS...93
SHORT TERM...93
LONG TERM...MJS
AVIATION...LAURENS
HYDROLOGY...JAM








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