Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 041555
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1155 AM EDT WED MAY 4 2016

LATEST UPDATE...
HYDRO

.SYNOPSIS...
ISSUED AT 312 AM EDT WED MAY 4 2016

A SYSTEM DROPPING INTO THE AREA TODAY WILL BRING SHOWERS TO ALL OF
THE AREA. THE BEST CHANCES OF RAIN WILL GRADUALLY SHIFT TO ALONG AND
EAST OF U.S.-131 THIS AFTERNOON INTO THIS EVENING. WINDS WILL BECOME
A BIT GUSTY...AND TEMPERATURES WILL REMAIN COOL WITH HIGHS NO WARMER
THAN THE MID 50S WITH CLOUDS AND RAIN SHOWERS.

CONDITIONS WILL IMPROVE ON THURSDAY AS THE SYSTEM MOVES OUT OF THE
AREA. HIGH PRESSURE WILL GRADUALLY BUILD IN THROUGH FRIDAY BRINGING
DRIER AND WARMER WEATHER TO THE AREA.

THE NEXT CHANCE OF RAIN WILL THEN COME ON SATURDAY AS ANOTHER SYSTEM
SLIPS SOUTH THROUGH THE AREA.

&&

.UPDATE...
ISSUED AT 1024 AM EDT WED MAY 4 2016

BUMPED UP QPF TO ACCOUNT FOR HI RES MODEL TRENDS THROUGH TONIGHT.
THE HRRR-X...WRF ARW...NAM 4KM...AND REG GEM ARE SHOWING
ADDITIONAL AMOUNTS OF 0.50"-1.00" TODAY AND TONIGHT WHERE THE RAIN
IS STEADIEST. THIS AXIS OF RAIN...PRESENTLY RIGHT OVER U.S. 131
AND NEARBY AREAS...WILL NOT MOVE MUCH AT ALL TODAY. SOME OF THE
RAIN COULD RETROGRADE BACK TOWARD THE LAKESHORE THIS AFTERNOON. IT
MAY NOT BE UNTIL MIDNIGHT OR SO WHEN THE RAIN FINALLY STOPS FOR
MANY AREAS.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 312 AM EDT WED MAY 4 2016

OUR MAIN CHALLENGE WITH THE FCST THIS MORNING IS DETERMINING RAIN
TRENDS INTO THU. THE FCST THEN QUIETS DOWN A BIT FOR THU NIGHT AND
FRI.

SHOWER ACTIVITY IS MOVING INTO THE AREA PRETTY MUCH AS EXPECTED THIS
MORNING. WE SEE SCATTERED SHOWERS ACROSS THE SE COUNTIES AHEAD OF
THE COLD FRONT WHERE SOME MODEST MOISTURE TRANSPORT IS TAKING PLACE.
THE MAIN BAND OF RAIN SHOWERS IS RIGHT ALONG AND BEHIND THE COLD
FRONT AS OF 07Z. THIS PCPN IS PROGRESSING SLOWLY S AND E FOR THE
TIME BEING.

WE EXPECT THAT THE RAIN SHOWERS WILL PROGRESS TO THE EAST UNTIL THEY
GET TO AROUND OR JUST EAST OF U.S.-131 LATE THIS MORNING/EARLY THIS
AFTERNOON. THEY WILL CONTINUE TO MOVE EAST UNTIL THE UPPER WAVE
DIVING SE WILL CLOSE OFF JUST SOUTH OF THE AREA. THE RAIN SHOWERS
WILL TEND TO ROTATE A LITTLE BIT BACK TO THE WEST LATE THIS
AFTERNOON/EARLY THIS EVENING AS THE LOW CLOSES OFF BEFORE SLIPPING
SOUTH WITH THE LOW OVERNIGHT.

WE HAVE LEFT THUNDER OUT OF THE FCST FOR TODAY AND TONIGHT. MODELS
HAVE BEEN DOING WELL IN INDICATING WHERE THUNDER THREAT HAS BEEN.
SUFFICIENT INSTABILITY IS REMAINING NEAR THE WAVE ITSELF...WHICH
LINES UP WELL WITH THE TRACK OF THE LIGHTNING ACROSS WISCONSIN. THE
INSTABILITY ALOFT IS EXPECTED TO STAY WEST OF THE AREA THIS
MORNING...AND THEN TRACK SOUTH OF THE AREA THIS AFTERNOON.

WE HAVE ADDED A FEW SPRINKLES INLAND FOR THE DAYLIGHT HOURS OF THU.
UPPER FLOW WILL BE TRANSITIONING FROM CYCLONIC TO ANTI-CYCLONIC THU
AFTERNOON AS THE UPPER LOW MOVES FAR ENOUGH AWAY. JUST ENOUGH
MOISTURE MAY LINGER TO COMBINE WITH DIURNAL CU FOR SOME SPRINKLES.
FCST SOUNDING INDICATES THAT THE CU WILL NOT BECOME VERY TALL...
LIMITING THE RAIN CHCS. HIGH PRESSURE BUILDING IN ON FRI WILL BRING
A DRY AND WARM DAY AS H850 TEMPS WARM TO DOUBLE DIGITS C.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 312 AM EDT WED MAY 4 2016

A SFC LOW MOVING ACROSS SOUTHERN CANADA WILL BRING A TRAILING COLD
FRONT THROUGH SATURDAY INTO EARLY SUNDAY. THE FRONT SHOULD CLEAR
LOWER MICHIGAN BY SUNDAY BUT A VORT MAX ROUNDING THE BASE OF THE
UPPER TROUGH COULD BRING SOME DIURNALLY ENHANCED SHOWERS ON SUNDAY.

A SURFACE HIGH BUILDING IN SUNDAY NIGHT SHOULD ALLOW SKIES TO CLEAR
WITH THE POTENTIAL FOR TEMPERATURES TO DROP INTO THE 30S BY MONDAY
MORNING. THEN THE SFC HIGH YIELDS TO MOIST RETURN FLOW WITH SHOWERS
ADVANCING FROM THE SOUTHWEST IN OVERRUNNING PATTERN LATER MONDAY.

SHORTWAVE RIDGING AHEAD OF SLOWLY ADVANCING WESTERN CONUS CUTOFF LOW
SHOULD PREVENT MUCH IN THE WAY OF RAIN UNTIL IT BREAKS DOWN LATER
TUESDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1124 AM EDT WED MAY 4 2016

A MIX OF MVFR AND IFR CONDITIONS WILL CONTINUE AT ALL THE
TERMINALS THIS AFTERNOON AND EVENING DUE TO LOW CLOUDS AND
SHOWERS. CONDITIONS WILL GRADUALLY IMPROVE TO MVFR LATE THIS
EVENING AS SHOWERS FINALLY BEGIN TO TAPER OFF AND CIGS IMPROVE A
BIT. CONDITIONS WILL CONTINUE TO IMPROVE TO VFR EARLY THURSDAY
MORNING THROUGH THURSDAY AFTERNOON.

&&

.MARINE...
ISSUED AT 312 AM EDT WED MAY 4 2016

WE WILL BE UPGRADING THE SMALL CRAFT ADVISORY UP TO A GALE WARNING
WITH THE FCST PACKAGE THIS MORNING. WINDS LOOK TO START INCREASING
JUST PRIOR TO SUNRISE THIS MORNING...AND WILL PEAK THIS EVENING. THE
COLD AIR COMING IN ON THE BACKSIDE OF THE SYSTEM AND TIGHT GRADIENT
LOOK TO BRING 35 TO 40 KNOTS OF WIND TO THE NEARSHORE WATERS. WINDS
WILL THEN DIMINISH BELOW GALES AROUND MIDNIGHT TONIGHT.

&&

.HYDROLOGY...
ISSUED AT 1155 AM EDT WED MAY 4 2016

RIVER FLOOD ADVISORIES ARE CURRENTLY POSTED FOR SYCAMORE CREEK NEAR
HOLT AND THE GRAND RIVER AT IONIA. BOTH ARE RISING BACK ABOVE
BANKFULL LEVELS AND SHOULD CREST THURSDAY OR FRIDAY BELOW FLOOD
STAGE. A FEW OTHER SITES ARE FORECAST TO CREST AROUND BANKFULL
THURSDAY OR FRIDAY.

RAINFALL TOTALS OF UP TO A HALF INCH FELL THROUGH THIS MORNING WITH
ANOTHER HALF INCH TO INCH EXPECTED THROUGH TONIGHT. THIS SHOULD HELP
TO KEEP RIVER LEVELS ELEVATED. THUNDERSTORMS ARE POSSIBLE
SATURDAY... SO RIVERS WILL NEED TO BE MONITORED INTO EARLY NEXT
WEEK.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...GALE WARNING UNTIL 2 AM EDT THURSDAY FOR LMZ844>849.

&&

$$

UPDATE...HOVING
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...OSTUNO
AVIATION...LAURENS
HYDROLOGY...63
MARINE...NJJ



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