Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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940
FXUS63 KGRR 211111
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
711 AM EDT THU MAY 21 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 259 AM EDT THU MAY 21 2015

SCATTERED SHOWERS MAY DRIFT FROM NORTH TO SOUTH LATE THIS
AFTERNOON INTO TONIGHT AS A COLD FRONT APPROACHES. AFTER A MILD
DAY WITH HIGHS IN THE 60S...TEMPS WILL BE SEVERAL DEGREES COOLER
ON FRIDAY. AREAS OF FROST ARE ONCE AGAIN POSSIBLE FRIDAY MORNING
AND SATURDAY MORNING...ESPECIALLY FOR CENTRAL LOWER MICHIGAN. A
WARMER AND MORE HUMID PATTERN LOOKS TO TAKE SHAPE FOR EARLY NEXT
WEEK WITH RAIN CHANCES RETURNING.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 259 AM EDT THU MAY 21 2015

PRIMARY FOCUS IS ON SHOWER POTENTIAL LATER TODAY ALONG WITH FROST
POTENTIAL FRIDAY AND SATURDAY MORNINGS. SFC COLD FRONT IS FORECAST
TO REACH NORTHERN WISCONSIN AND INTO THE STRAITS AREA BY 18Z
TODAY. THE ONLY MOISTURE AVAILABLE IS IN THE MID LEVELS...H500 TO
H800...WITH BUFKIT SOUNDINGS INDICATING AN INVERTED V SHAPE.

WHILE ANY SFC BASED INSTABILITY WILL BE CONFINED TO WISCONSIN...SOME
OF THESE DIURNALLY DRIVEN SHOWERS MAY SURVIVE THE NIGHTTIME HOURS
AS THEY PROGRESS ALONG THE FRONT...REACHING LDM BETWEEN 21Z-00Z
AND GRR BY 03Z OR SO. GIVEN THE NEARLY DRY ADIABATIC LAPSE RATES
DOWN LOW...SOME GUSTY WINDS OF 30 TO 40 MPH ARE POSSIBLE WITH THE
SHOWERS...ALTHOUGH COVERAGE WILL BE SCATTERED IT APPEARS. THE HI
RES CAMS SUGGEST THE ACTIVITY FIZZLES AFTER 06Z FRIDAY.

FRIDAY MORNING FROST POTENTIAL LOOKS BETTER THAN THIS MORNING FOR
CENTRAL LOWER. CLOUD COVER SHOULD BE LESS OF AN ISSUE AND WITH CAA
UNDERWAY THERE COULD CERTAINLY BE AREAS OF FROST MAINLY FOR THE
ROUTE 10 CORRIDOR. SATURDAY MORNING MAY FEATURE A MORE SIGNIFICANT
FROST UNFORTUNATELY FOR AREAS NEAR/NORTH OF A BIG RAPIDS TO MOUNT
PLEASANT LINE.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 259 AM EDT THU MAY 21 2015

RETURN FLOW SETS UP SATURDAY NIGHT BUT PRECIP SHOULD HOLD OFF UNTIL
SUNDAY WHEN AN AREA OF ISENTROPIC ASCENT NORTH OF THE SFC WARM FRONT
BRINGS SHOWERS AND A POSSIBLY A RUMBLE OF THUNDER. THE WARM FRONT
MOVES NORTH SUNDAY NIGHT WITH THE HEAVIER SHOWERS LIFTING NORTH WITH
IT...BUT A DEEP SOUTHERLY FLOW OF GULF MOISTURE CONTINUES THROUGH
MONDAY. INSTABILITY IS FAIRLY WEAK SO THUNDER THREAT IS LIMITED.

COVERAGE OF SHOWERS SHOULD DECREASE TUESDAY AND WEDNESDAY AS THE
STRONGER MOISTURE TRANSPORT MOVES EAST. GIVEN THERMAL PROFILES THE
MAX TEMPS IN THE 70S FOR TUESDAY AND WEDNESDAY MAY BE UNDERDONE BUT
WERE LEFT ALONE FOR NOW WITH THE POSSIBILITY THAT CLOUDS AND SHOWERS
THOSE DAYS COULD BE WIDESPREAD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 711 AM EDT THU MAY 21 2015

VFR CONDITIONS THROUGH TONIGHT...WITH SOME SCATTERED SHOWERS
POSSIBLE THIS EVENING. WINDS WILL BE WEST AROUND 10 KNOTS TODAY
WITH SOME GUSTS TO 20 KNOTS THIS AFTERNOON.

&&

.MARINE...
ISSUED AT 259 AM EDT THU MAY 21 2015

NO SIGNIFICANT WAVE ACTION NOR FOG IS ON THE HORIZON FOR THE
NEARSHORE WATERS. SOME WAVES COULD APPROACH 2 TO 3 FEET AT TIMES
TODAY BUT REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA.


&&

.HYDROLOGY...
ISSUED AT 1139 AM EDT WED MAY 20 2015

NO REAL IMPACTS ARE EXPECTED IN THE NEAR FUTURE. RIVERS ARE STABLE
OR SLOWLY FALLING. ONLY SLIGHT CHANCES OF RAIN EXIST LATE THURSDAY
INTO EARLY FRIDAY. ANY MEANINGFUL PRECIPITATION IS EXPECTED TO
HOLD OFF UNTIL AT LEAST SUNDAY.

BY SUNDAY...CHANCES FOR PRECIPITATION WILL INCREASE AS A WARM
FRONT LIFTS NORTH AND BECOMES STATIONARY SOMEWHERE OVER THE GREAT
LAKES REGION. THE PLACEMENT OF THIS BOUNDARY...AND THE POSSIBILITY
OF IT MEANDERING A BIT...MAY PROVIDE MULTIPLE CHANCES FOR RAIN
THROUGH MUCH OF NEXT WEEK. THIS WILL BE SOMETHING TO MONITOR AND
UPDATES WILL BE PROVIDED AS WE GET CLOSER TO THE WEEKEND.

&&

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

$$

SYNOPSIS...HOVING
SHORT TERM...HOVING
LONG TERM...OSTUNO
AVIATION...OSTUNO
HYDROLOGY...JAM
MARINE...HOVING



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