Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 012340
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
740 PM EDT TUE SEP 1 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 328 PM EDT TUE SEP 1 2015

HAZY HOT AND HUMID WEATHER WILL CONTINUE FOR MUCH OF THIS WEEK AS A
PERSISTENT UPPER RIDGE REMAINS ENTRENCHED OVER THE GREAT LAKES.
HIGHS IN THE MID TO UPPER 80S COUPLED WITH DEWPOINTS AROUND 70 WILL
FEEL MORE LIKE EARLY AUGUST USUALLY DOES. LOW CHANCES FOR SHOWERS AN
STORMS EXIST HOWEVER BUT SEVERE STORMS ARE NOT EXPECTED.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 328 PM EDT TUE SEP 1 2015

FORECAST CONCERNS DEAL WITH MINOR CHANCES FOR STORMS WEDNESDAY NIGHT
THROUGH THURSDAY NIGHT.

LATEST WV LOOP SHOWS A WELL DEFINED UPPER LOW SPINNING OVER CENTRAL
INDIANA. THERE HAS BEEN PERSISTENT CONFECTION DEVELOPING AROUND THE
LOW BUT ALL OF IT HAS REMAINED SOUTH OF THE CWA AND WILL CONTINUE TO
DO SO TONIGHT. ABUNDANT CAPE HAS DEVELOPED OVER THE CWA WITH
MESOANALYSIS SHOWING 3000 J/KG ACROSS THE CWA. HOWEVER...WITH NOT
MUCH OF A KICKER OUTSIDE OF THE LAKE BREEZE THERE ISN`T ENOUGH LIFT
TO TAKE ADVANTAGE OF THE INSTABILITY. INSTEAD...DEWPOINTS WILL
REMAIN HIGH OVERNIGHT AND AREAS OF FOG ARE EXPECTED.

A SHORT WAVE CURRENTLY OVER NORTHEAST NEBRASKA WILL SLOWLY MOVE
TOWARD EASTERN WISCONSIN AND THEN ACROSS LAKE MICHIGAN WEDNESDAY
NIGHT AND THURSDAY. AFTER A DRY DAY TOMORROW ISOLATED TO SCATTERED
STORMS ARE EXPECTED WEDNESDAY NIGHT AND THURSDAY AS THIS WAVE MOVES
ACROSS. CLOUDS ASSOCIATED WITH THE WAVE WILL LIKELY HOLD HIGHS IN
THE MID VS UPPER 80S THURSDAY. SHORT RANGE MODELS SHOW THIS WAVE
VERY SLOW TO MOVE OUT OF THE CWA SO WE/LL CONTINUE WITH LOW POPS
THURSDAY NIGHT TOO.

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 328 PM EDT TUE SEP 1 2015

LABOR DAY WEEKEND WILL CONTINUE TO FEATURE UNSEASONABLY WARM AND
HUMID CONDITIONS ALONG WITH A DAILY RISK OF A FEW POP UP SHOWERS OR
NON SEVERE THUNDERSTORMS.

LATEST MEDIUM RANGE GUIDANCE INDICATES THAT THE SHORTWAVE WHICH
COMES INTO THE STATE ON THURSDAY STALLS AND ACTUALLY BECOMES A WEAK
CUTOFF LOW OVER MICHIGAN ON FRIDAY... UNDERNEATH THE BUILDING UPPER
RIDGE. THIS FEATURE LOOKS TO LIFT BACK TO THE NORTH SATURDAY AND
GETS ABSORBED WITH THE STRONGER WESTERLIES OVER CANADA DUE TO
DEVELOPING SOUTH FLOW ALOFT AROUND A STRENGTHENING UPR HIGH CENTER
OVER NEW YORK. HOWEVER ADDITIONAL WEAK VORTICITY MAXIMA ARE SENT OUR
WAY OVER THE HOLIDAY WEEKEND FROM THE MID ATLANTIC REGION ON THE SRN
AND WRN PERIPHERY OF THE AFOREMENTIONED UPR HIGH CENTER.

THESE WEAK VORTICITY MAXIMA ALOFT... COMBINED WITH DAILY MESOSCALE
FEATURES WHICH MANAGE TO CREATE SFC CONVERGENCE SUCH AS THE LAKE
BREEZE OR OUTFLOW BOUNDARIES... COULD BE AN IMPETUS FOR CONVECTION.
SFC COLD FRONT APPROACHING FROM THE WEST LATE MONDAY MAY PROVIDE A
BETTER FOCUS FOR STORMS BUT THE TIMING AND STRENGTH OF THE FRONT IS
QUESTIONABLE AT THIS TIME.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 738 PM EDT TUE SEP 1 2015

CURRENTLY ALL TAF SITES ARE VFR... BUT LIKE LAST NIGHT THE
QUESTION IS WILL THERE BE IFR VISIBILITY FOG AGAIN? AT THIS POINT
IT IS HARD TO BE SURE... THERE IS MORE WIND IN THE BOUNDARY LAYER
THAN LAST NIGHT AS THE SURFACE HIGH IS FARTHER EAST THAN LAST
NIGHT. THE STRONGER WINDS ABOVE 1000 FT AGL MAY BE ENOUGH TO KEEP
IFR VISIBILITIES FROM OCCURRING. HOWEVER...GIVEN THE LACK OF
SIGNIFICANT CLOUD COVER AND LIGHT SURFACE WINDS (BELOW 1000 FT
AGL) I HAVE GONE WITH IFR FOG ONCE AGAIN. THIS SHOULD MIX OUT
QUICKLY TOMORROW MORNING. THERE COULD BE A FEW
SHOWERS/THUNDERSTORMS IN THE AFTERNOON LIKE TODAY BUT THE COVERAGE
SHOULD BE TO LIMITED TO PUT IN THE TAFS AT THIS POINT.

&&

.MARINE...
ISSUED AT 328 PM EDT TUE SEP 1 2015

UPPER RIDGE WILL KEEP WINDS UNDER 20KTS RESULTING IN WAVES 1-3 FEET
FOR THE NEXT FEW DAYS.


&&

.HYDROLOGY...
ISSUED AT 302 AM EDT TUE SEP 1 2015

ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS MAY OCCUR OVER THE
NEXT SEVERAL DAYS. THERE REMAINS A BIT OF UNCERTAINTY WITH THEIR
COVERAGE AND INTENSITY. WIDESPREAD HEAVY RAINFALL IS NOT EXPECTED...
BUT AS IS THE CASE WITH SUMMER THUNDERSTORMS... LOCALLY HEAVY RAIN
AND MINOR FLOODING IMPACTS ARE NOT OUT OF THE QUESTION.

&&

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

$$

SYNOPSIS...04
SHORT TERM...04
LONG TERM...MEADE
AVIATION...WDM
HYDROLOGY...CAS
MARINE...04


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