Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KGRR 010414
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1214 AM EDT TUE SEP 1 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 327 PM EDT MON AUG 31 2015

HIGH PRESSURE WILL BE IN CONTROL OF THE AREAS WEATHER OVER THE NEXT
FEW DAYS.  THIS WILL KEEP THE REGION WARM WITH HIGHS IN THE 80S AND
MAINLY DRY.  THERE WILL BE THE CHANCE FOR SCATTERED SHOWERS AND
STORMS HOWEVER WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT.

SHOWER CHANCES APPEAR TO REMAIN LOW THROUGH THE WEEKEND.  IT SHOULD
STAY WARM WITH HIGHS IN THE 80S...WITH A FEW TEMPERATURES NEAR 90.

&&

.UPDATE...
ISSUED AT 1112 PM EDT MON AUG 31 2015

MUCH LIKE LAST NIGHT WE ARE WATCHING FOG FORMATION ACROSS
SOUTHWEST LOWER MICHIGAN. CONDITIONS SO FAR TONIGHT ARE HIGHLY
VARIABLE RANGING FROM A 1/4 MILE VISIBILITY IN A FEW SPOTS TO 10
MILES IN LANSING. NOT CONVINCED AT THIS POINT THAT ALL AREAS ARE
GOING TO SEE VERY LOW VISIBILITIES TO THE POINT WHERE A DENSE FOG
ADVISORY WOULD BE NEEDED. AN ADVISORY IS CERTAINLY POSSIBLE
THOUGH...BUT CONFIDENCE IS NOT HIGH ENOUGH RIGHT NOW.

TWO THINGS THAT MAY CHANGE CONDITIONS JUST A BIT TONIGHT ARE WINDS
IN THE 1000-3000FT LAYER THAT INCREASE TO 10-20 KNOTS. THIS MAY BE
JUST ENOUGH TO TEMPER RADIATIONAL COOLING TO THE POINT WHERE
WIDESPREAD DENSE FOG DOES NOT FORM. THE OTHER FACTOR IS THAT WE
HAD A GOOD AMOUNT OF SUNSHINE THIS AFTERNOON WHICH MAY HAVE TENDED
TO DRY OUT THE BOUNDARY LAYER JUST A BIT.

BOTTOM LINE...AREAS OF FOG TONIGHT...SOME OF WHICH THAT MAY BE
LOCALLY DENSE. LOWS IN THE LOWER TO MIDDLE 60S ACROSS THE AREA.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 327 PM EDT MON AUG 31 2015

AN UPPER RIDGE WILL DOMINATE THE WEATHER INTO TUESDAY...BUT THEN IT
SLOWLY BREAKS DOWN.  A SHORT WAVE TRIES TO MOVE INTO THE RIDGE
WED/WED NIGHT THAT COULD BE ENOUGH TO PRODUCE ISOLATED OR WIDELY
SCATTERED SHOWERS AND STORMS.

LITTLE CHANGE TO THE FORECAST FOR TONIGHT AND TUESDAY WITH THE UPPER
RIDGE IN PLACE.  THERE WILL BE A WEAK UPPER LOW OVER CENTRAL INDIANA
IN THE MEANTIME...BUT ANY ISOLATED CONVECTION ASSOCIATED WITH THIS
FEATURE SHOULD REMAIN SOUTH.  AREAS OF FOG ARE LIKELY AGAIN
TONIGHT...BUT A BIT MORE MIXING SHOULD LEAD TO LESS AREAS OF DENSE
FOG.  HIGHS ON TUESDAY AWAY FROM THE LAKE MAINLY IN THE MID 80S...
WITH A FEW UPPER 80S WELL INLAND.

AS THE UPPER RIDGE BREAKS DOWN SOME OF THE MOISTURE FROM THE INDIANA
UPPER LOW MAY CREEP INTO THE SOUTHERN CWA TUESDAY NIGHT.  HAVE 20
POPS IN CASE A STRAY SHOWER OR STORM MOVES IN.  INCREASED MIN TEMPS
TUESDAY NIGHT AS SOUTHERLY WINDS AND HIGH DEW POINTS PRODUCE A
WARM/MUGGY NIGHT.

THE INCREASED MOISTURE INTO WEDNESDAY COULD PRODUCE DIURNAL SHOWERS
AND STORMS...MAINLY EAST OF U.S. 131.  THEN THERE IS NOT GOOD
AGREEMENT IN THE MODELS AS TO HOW SUCCESSFUL THE NEXT SHORT WAVE
MOVES THROUGH THE WEAKENING UPPER RIDGE BY WEDNESDAY NIGHT.  BUT IT
WOULD SEEM THAT THIS RIDGE WEAKNESS AND SHORT WAVE SHOULD LEAD TO AN
MCS MOVING ALONG THE WESTERN EDGE OF THE RIDGE.  ADDED CHANCE POPS
FOR THIS MCS TO IMPACT THE NW CWA.

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 327 PM EDT MON AUG 31 2015

THE MAIN STORY IN THE LONG TERM IS THAT VERY WARM TEMPERATURES AND
HUMID CONDITIONS WILL CONTINUE THROUGH THE HOLIDAY WEEKEND. THE
DAILY RISK OF RAIN IS QUITE LOW WITH LIMITED COVERAGE OF CONVECTION
EXPECTED.

A FEW SHOWERS OR THUNDERSTORMS ARE POSSIBLE ON THURSDAY DUE TO THE
COMBINATION OF A MID LEVEL SHORTWAVE PASSING THROUGH AND A WEAK
BACKDOOR COLD FRONT SLIPPING DOWN FROM THE NORTHEAST AND STALLING.
THIS ILL-DEFINED SFC BOUNDARY MAY STILL BE SITUATED NW-SE OR N-S
ACROSS THE AREA ON FRIDAY AND WEAK CONVERGENCE ALONG IT... OR THE
LAKE BREEZE... COULD FOCUS A FEW ISOLATED SHOWERS OR STORMS.

ON SATURDAY AND SUNDAY THE UPPER RIDGE RE-AMPLIFIES IN RESPONSE TO
THE UPPER LOW/TROUGH DROPPING SOUTH THROUGH THE PACIFIC NORTHWEST.
THE RIDGE DOES BEGIN TO FLATTEN OUT ON LABOR DAY AS SHORTWAVE ENERGY
EJECTS OUT OF THE WESTERN TROUGH. THE SHOWER AND TSTM POTENTIAL MAY
INCREASE AS THIS HAPPENS... ALTHOUGH CONFIDENCE IS LOW AS TO WHEN
(AND IF) THE COLD FRONT WILL ARRIVE.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1204 AM EDT TUE SEP 1 2015

A MIX OF VFR/MVFR CONDITIONS WILL GRADUALLY DETERIORATE TO MIXED
MVFR/IFR CONDITIONS OVERNIGHT THROUGH MID MORNING DUE TO
DEVELOPMENT OF PATCHY FOG. SOME PATCHY LIFR CONDITIONS ARE ALSO
POSSIBLE DUE TO LOCALLY DENSER FOG.

PATCHY FOG WILL GRADUALLY DISSIPATE DURING THE MID MORNING HOURS
AND ALLOW CONDITIONS TO GRADUALLY IMPROVE TO MVFR LATE TUESDAY
MORNING AND THEN VFR FOR TUESDAY AFTERNOON AND EVENING.

&&

.MARINE...
ISSUED AT 327 PM EDT MON AUG 31 2015

RATHER QUIET REGIME ON THE LAKE WITH RIDGING OVERHEAD.  THE PRESSURE
GRADIENT SHOULD TIGHTEN A BIT INTO TUESDAY NIGHT AND SSW WINDS SHOULD
PICK UP.  IT CAUSE THE LAKE TO BECOME A BIT ROUGH WITH SOME 2-3 FOOT
WAVES.


&&

.HYDROLOGY...
ISSUED AT 327 PM EDT MON AUG 31 2015

HYDRO CONCERNS ARE LOW THIS WEEK. THERE ARE SMALL CHANCES FOR A
SHOWER IN ANY GIVEN LOCATION FROM MID WEEK INTO THE WEEKEND.
EXCESSIVE RAINFALL IS UNLIKELY.

&&

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

$$

UPDATE...DUKE
SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...MEADE
AVIATION...LAURENS
HYDROLOGY...CAS/JK
MARINE...JK



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.