Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 291923
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
322 PM EDT FRI MAY 29 2015

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

.SYNOPSIS...
ISSUED AT 322 PM EDT FRI MAY 29 2015

THE NEXT 24 TO 36 HOURS COULD BE RATHER WET AS SEVERAL OPPORTUNITIES
FOR SHOWERS AND THUNDERSTORMS EXIST. A FAIRLY STRONG COLD FRONT WILL
MOVE THROUGH LOWER MICHIGAN SATURDAY AND TEMPERATURES WILL FALL INTO
THE UPPER 50S TO LOWER 60S BEHIND IT. SUNDAY WILL ALSO BE COOL WITH
HIGHS IN THE LOWER 60S DESPITE SUNSHINE. PATCHY FROST IS POSSIBLE
NORTH OF M-46 SATURDAY NIGHT AND SUNDAY NIGHT. WARMER WEATHER WILL
DEVELOP EARLY NEXT WEEK WITH 70S BY TUESDAY AND 80S BY THURSDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 322 PM EDT FRI MAY 29 2015

FORECAST CONCERNS DEAL WITH PCPN TRENDS TONIGHT THROUGH SATURDAY
NIGHT.

SCATTERED CONVECTION CONTINUES TO DEVELOP ACROSS THE MIDWEST THIS
AFTERNOON, BUT SO FAR IT/S BEEN LOW-TOPPED WITH LIMITED LIGHTNING.
THE STRONGER CELLS ARE CLOSER TO ST LOUIS MO BUT ARE MOVING
NORTHEAST. WE SHOULD SEE A GENERAL INCREASE IN COVERAGE TONIGHT BUT
MORE SHOWERS THAN STORMS. SHOWERS HAVE BEEN DEVELOPING AND
DISSIPATING ALONG THE LAKE BREEZE.  MESOANALYSIS SHOWS LI/S NEAR
-3 ACROSS THE WESTERN CWA ATTM COUPLED WITH 1K J/K SBCAPE BUT NOT
MUCH TO FOCUS CONVECTION.

AN APPROACHING COLD FRONT WILL WITH HELP TO FOCUS PCPN LATER TONIGHT
AND SATURDAY. THE COLD FRONT WILL MOVE THROUGH THE CWA BY EARLY TO
MID AFTERNOON. MUCH OF THE SHOWERS WILL OCCUR POST FRONTAL. A 300 MB
JETLET SEEMS TO BE THE CAUSE OF THIS AS IT UNDERCUTS THE MAIN UPPER
JET FARTHER NORTH. WE ALSO INCREASED POPS SATURDAY NIGHT AS A WAVE
THAT IS CURRENTLY IN TEXAS MOVES NORTHEAST ALONG THE FRONT. THIS
WAVE WILL CAUSE MORE PCPN OVER THE SRN CWA.

CHANCES FOR SEVERE WEATHER APPEAR SMALL ATTM DUE TO LIMITED
INSTABILITY NEAR THE FRONT LATE TONIGHT AND SATURDAY.

SKIES WILL CLEAR OUT SUNDAY AND IT SHOULD BE A BIT CHILLY WITH HIGHS
IN THE 60S. PATCHY FROST IS EXPECTED OVER THE NRN CWA SUNDAY NIGHT.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 322 PM EDT FRI MAY 29 2015

FAIRLY QUIET WEATHER IN THE EXTENDED. CANADIAN SFC HIGH MOVES EAST
EARLY IN THE WEEK WITH A MOIST RETURN FLOW SETTING UP BY WEDNESDAY.
DESPITE INCREASING MOISTURE AND INSTABILITY ...THERE IS LITTLE TO
FOCUS ANY CONVECTION AND ONLY SLIGHT CHANCE POPS ARE INCLUDED FROM
WEDNESDAY THROUGH FRIDAY.

ZONAL FLOW WILL PREVAIL MOST OF THE WEEK AS THE GREAT LAKES WILL BE
IN BETWEEN AN UPPER LOW ACROSS THE GULF COAST THAT SLOWLY OPENS UP
AND FILLS AND A COUPLE NORTHERN STREAM SHORTWAVE TROUGHS PROGRESSING
ACROSS CENTRAL CANADA. THE SECOND TROUGH MAY FORCE A COLD FRONT
THROUGH BY THE END OF THE WEEK THAT WILL BRING SOME BETTER CHANCES
FOR RAIN...BUT PROBABLY NOT UNTIL FRIDAY NIGHT OR SATURDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 211 PM EDT FRI MAY 29 2015

THERE WILL BE A FEW SHOWERS AND THUNDERSTORMS AROUND THIS
AFTERNOON AND INTO THIS EVENING THAT COULD BRING SOME ISOLATED
AREAS OF IFR BUT COVERAGE WILL BE LOW ENOUGH TO KEEP PREVAILING
VFR CONDITIONS IN THE FORECAST THROUGH THE EVENING. STEADIER RAIN
WILL MOVE IN LATE TONIGHT WITH IFR CONDITIONS BECOMING WIDESPREAD
AFTER 12Z ON SATURDAY. WINDS WILL BE SOUTHWEST THIS AFTERNOON WITH
SOME GUSTS TO 20 KNOTS.


&&

.MARINE...
ISSUED AT 322 PM EDT FRI MAY 29 2015

LIGHT WINDS EXPECTED UNTIL SATURDAY. LOOK FOR WAVES TO BUILD FROM
NORTH TO SOUTH AS COLDER AIR ADVECTS SOUTH ACROSS THE LAKE. A SCA
MAY BE NEEDED SATURDAY.

&&

.HYDROLOGY...
ISSUED AT 322 PM EDT FRI MAY 29 2015

RIVER LEVELS RANGE FROM ABOVE NORMAL IN OUR NORTHERN HYDROLOGIC
SERVICE AREA TO BELOW NORMAL SOUTHEAST. BASIN-AVERAGE RAINFALL
THROUGH SATURDAY EVENING IS LIKELY TO BE AROUND A HALF TO THREE-
QUARTERS INCH. PER NCRFC ENSEMBLE GUIDANCE... BASIN-AVERAGE TOTALS
OF ABOUT 2 INCHES WOULD BE NECESSARY TO PUSH SEVERAL OF THE MID-
MICHIGAN RIVERS ABOVE BANKFULL.

&&

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

$$

SYNOPSIS...04
SHORT TERM...04
LONG TERM...OSTUNO
AVIATION...OSTUNO
HYDROLOGY...CAS
MARINE...04



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