Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 261827
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
227 PM EDT WED AUG 26 2015

LATEST UPDATE...
HYDRO

.SYNOPSIS...
ISSUED AT 330 AM EDT WED AUG 26 2015

ONE MORE COOL AND OVERCAST DAY WITH SCATTERED LIGHT SHOWERS CAN
BE EXPECTED AS A LARGE SLOW MOVING AREA OF LOW PRESSURE CONTINUES
TO IMPACT THE GREAT LAKES REGION.

THE LOW WILL FINALLY DEPART TONIGHT AND HIGH PRESSURE WILL MOVE
IN FOR THURSDAY... BRINGING BACK SOME SUNSHINE AND MILDER
TEMPERATURES. MORE CLOUDS AND SHOWERS WILL RETURN FOR THE
WEEKEND...ALTHOUGH TEMPERATURES WILL BE NEAR NORMAL.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 330 AM EDT WED AUG 26 2015

THE BEST CHANCE OF ANY MEASURABLE PRECIP WILL BE THIS MORNING AS
FINAL VORTICITY MAXIMA DROP THROUGH THE BACK SIDE OF THE
DEPARTING UPPER TROUGH. STILL ONLY A FEW HUNDREDTHS OF AN INCH
EXPECTED... ESPECIALLY WEST AND SOUTHWEST OF GRR WHERE NW FLOW OFF
THE WARM WATERS OF LAKE MICHIGAN IS CREATING SOME LAKE
ENHANCEMENT. DELTA T/S BETWEEN THE LAKE AND H8 ARE STILL IN THE
MID TEENS THIS MORNING.

CHALLENGING SKY FCST TONIGHT AS GUIDANCE SUGGESTS CLEARING SKIES
DUE TO INCOMING SUBSIDENCE WITH THE SFC RIDGE. TIMING AND EXTENT
OF CLEARING OF THE CURRENT CLOUD DECK IS LOW CONFIDENCE ATTM AND
EVEN IF IT DOES CLEAR WE RUN THE RISK OF SOME RADIATION LOW
STRATUS/FOG DEVELOPING OVERNIGHT. CURRENT SFC DEW POINTS IN THE
MID 50S PROBABLY WILL NOT FALL OFF MUCH TONIGHT AND WINDS WILL BE
LIGHT/CALM. STRONG RADIATIONAL COOLING WHERE SKIES CLEAR COULD
LEAD TO STRONG LOW LEVEL INVERSIONS SETTING UP WITH SFC TEMPS
FALLING BELOW THE CROSSOVER TEMP.

WILL MAINTAIN A MOSTLY SUNNY FCST FOR THURSDAY BUT AM A LITTLE
CONCERNED WE WILL SEE A FAIR AMOUNT OF SHALLOW DIURNAL CUMULUS
DEVELOPMENT AS A POCKET OF COOL H8 AIR AROUND 10C HANGS OVER THE
AREA. SUBSIDENCE UNDER THE RIDGE MAY OFFSET THIS SO WILL REMAIN
OPTIMISTIC FOR NOW.

SHORTWAVE APPROACHING FROM THE CENTRAL PLAINS WILL SEND A FAIR
AMOUNT OF MID AND HIGH LEVEL CLOUDINESS INTO THE AREA ON FRIDAY...
WITH PERHAPS EVEN SOME LIGHT SHOWERS/SPRINKLES ARRIVING BY LATE IN
THE DAY.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 330 AM EDT WED AUG 26 2015

THE FOCUS DURING THE LONG TERM IS THE EVOLUTION OF A SFC LOW OVER
IOWA AND ITS MOVEMENT EASTWARD OVER THE WEEKEND.

BOTH THE GFS AND ECMWF ARE IN PRETTY GOOD AGREEMENT THAT A SFC
LOW WILL DEVELOP OVER THE PLAINS THURSDAY NIGHT AND THEN MOVE EAST
ACROSS IOWA AND WISCONSIN FRIDAY NIGHT AND SATURDAY. THE ECMWF IS
A BIT MORE DEVELOPED THAN THE GFS, LIKELY DUE TO BETTER SUPPORT
ALOFT. HOWEVER...BOTH MODELS FILL THE LOW AS IT MOVES TOWARD THE
CWA LATE SATURDAY. NOT REAL IMPRESSED WITH THIS SYSTEM, ALTHOUGH
IT`LL PROVIDE THE BEST CHANCE OF RAIN DURING THE LONG TERM.
THUNDERSTORM CHANCES ARE HIGHEST SATURDAY AFTERNOON WHEN LI/S FALL
TO AROUND -2C BUT WITHOUT STRONG INFLOW...LLJ IS LESS THAN 20
KTS...CAN`T SEE ANYTHING STRONG WITH THIS SYSTEM, THUS THE CHC
POPS.

AS THE SFC HIGH RETREATS THIS WEEKEND TEMPS WILL BEGIN TO WARM AGAIN
AND SUMMER WEATHER WILL RETURN BY LATE WEEKEND INTO EARLY NEXT WEEK.
HIGHS WILL CLIMB INTO THE MID 80S MONDAY AND TUESDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 150 PM EDT WED AUG 26 2015

CONFIDENCE ON EXTENT AND TIMING OF CLEARING IS LOW. CURRENTLY...AT
18Z...WIDESPREAD CEILINGS OF 2500-3500FT ARE IN PLACE ACROSS THE
LOWER PENINSULA. SOME GUIDANCE INDICATES THE CLOUDS MAY HANG ON
INTO THURSDAY MORNING...WHILE OTHER ITEMS POINT TOWARD CLEARING
OUT THIS EVENING. ONE FACTOR LOOKED AS IT THAT THE WINDS IN THE
CLOUD LAYER GO NORTH-NORTHEAST TONIGHT. GIVEN THIS
DIRECTION...FEEL WHAT BREAKS DO DEVELOP THIS AFTERNOON OR EVENING
WILL LIKELY FILL BACK IN GIVEN THE FLOW. FINALLY SCATTERED THE
CLOUDS OUT OF THE TAFS AT MID MORNING ON THURSDAY. WINDS FROM THE
NORTHWEST THIS AFTERNOON AT 5-15 KNOTS WILL GO NEARLY CALM
OVERNIGHT.

&&

.MARINE...
ISSUED AT 330 AM EDT WED AUG 26 2015

WINDS AND WAVES HAVE SUBSIDED AND ALL HEADLINES HAVE EXPIRED. WINDS
WILL REMAIN ON THE LIGHT SIDE THE NEXT FEW DAYS SO NO NEW HEADLINES
EXPECTED.

&&

.HYDROLOGY...
ISSUED AT 227 PM EDT WED AUG 26 2015

WITH DRY WEATHER EXPECTED TONIGHT THROUGH FRIDAY AND ONLY LIGHT RAIN
FRIDAY NIGHT INTO SATURDAY... RIVER LEVELS SHOULD REMAIN LOW INTO
NEXT WEEK WITH NO FLOODING CONCERNS.

&&

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

$$

SYNOPSIS...MEADE
SHORT TERM...MEADE
LONG TERM...04
AVIATION...DUKE
HYDROLOGY...63
MARINE...MEADE



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