Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 311756
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
156 PM EDT MON AUG 31 2015

LATEST UPDATE...
AVIATION

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

DENSE FOG WILL GRADUALLY LIFT THIS MORNING WITH FAIR AND WARM
WEATHER EXPECTED THIS WEEK. THERE MAY BE AN ISOLATED SHOWER OR
THUNDERSTORM TUESDAY AND INTO THE WEEKEND BUT MOST PLACES WILL
STAY DRY.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 327 AM EDT MON AUG 31 2015

FORECAST ISSUES IN THE NEAR TERM INCLUDE FOG THIS MORNING AND
AGAIN TONIGHT AS WELL AS CHANCES FOR A FEW SHOWERS AND STORMS
TUESDAY AND WEDNESDAY AFTERNOON.

THE FOG CONTINUES TO BE HIGHLY VARIABLE IN SPACE AND TIME WHICH IS
TYPICAL IN THIS SITUATION WHERE LOW STRATUS IS ALSO PRESENT. THERE
SHOULD BE ENOUGH BREAKS IN THE LOW CLOUD TO SEE AREAS OF DENSE FOG
FORM AND PERSIST...SO WILL KEEP THE ADVISORY GOING. EXPECT MORE
OF THE SAME TONIGHT AS LOW LEVEL RH PROFILES AND WINDS ARE
SIMILAR.

AS FOR TUESDAY AND WEDNESDAY...LOOKS LIKE THERE WILL BE A SLIGHT
CHANCE FOR STORMS TO FIRE TUESDAY AFTERNOON AS MOISTURE MOVES UP
FROM THE SOUTH. DESPITE OVERALL RIDGING IN CONTROL...THE FORECAST
GUIDANCE HAS BEEN SHOWING A SMALL UPPER LOW...APPARENTLY THE
REMNANT OR REMNANTS OF CUT OFF LOWS THAT PINCHED OFF FROM THE
UPPER TROUGH THAT WERE ACROSS THE EASTERN CONUS A COUPLE DAYS AGO.
FOLLOWED THE SUPERBLEND POPS PRETTY CLOSELY ON TUESDAY. DECIDED TO
HAVE WEDNESDAY DRY AS THE REMNANT LOW IS OUT OF THE PICTURE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 327 AM EDT MON AUG 31 2015

A CONSENSUS OF LATEST MEDIUM RANGE GUIDANCE CONTINUES TO INDICATE
THAT TEMPERATURES WILL AVERAGE MUCH ABOVE NORMAL LATE THIS WEEK AND
FOR NEXT WEEKEND WITH AN UPPER LEVEL RIDGE IN PLACE IN THE EASTERN
CONUS. MAX TEMPS WILL REACH THE MID 80S TO AROUND 90 DEGREES DAILY
WITH MINS IN THE 60S. IT WILL ALSO BE RATHER HUMID WITH DEW POINTS
IN THE 60S.

DRY WX WILL PREVAIL THE VAST MAJORITY OF THE TIME LATE IN THE WEEK
THROUGH THE WEEKEND. HOWEVER THERE IS STILL POTENTIAL FOR DIURNALLY
DRIVEN ISOLATED SHOWERS OR STORMS LATE THIS WEEK WHEN INSTABILITY
FROM DAYTIME HEATING WILL BE MAXIMIZED.

NO STRONG FORCING MECHANISMS EXIST FOR CONVECTIVE INITIATION TO
OCCUR THROUGH THE LONG RANGE FCST PERIOD BUT MESOSCALE PROCESSES
SUCH AS LAKE BREEZE CONVERGENCE MAY BE SUFFICIENT ENOUGH TO CAUSE
A FEW SHOWERS AND STORMS TO DEVELOP. A MUCH BETTER CHANCE FOR
SHOWERS AND STORMS SHOULD COME SUNDAY NIGHT AND MONDAY AS A COLD
FRONT MOVES IN FROM THE NW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 156 PM EDT MON AUG 31 2015

WE WILL PROBABLY SEE A REPEAT OF IFR/LIFR FOG AND STRATUS AGAIN
LATE TONIGHT AND EARLY TUESDAY. THE LATEST GUIDANCE IS NOT QUITE
AS AGGRESSIVE ON DEVELOPING FOG TONIGHT...SHOWING DRIER BOUNDARY
LAYER CONDITIONS AND A BIT MORE WIND JUST ABOVE THE SFC. HOWEVER
SINCE THE OVERALL SYNOPTIC REGIME AND AIR MASS IS LARGELY
UNCHANGED... DECIDED TO GO WITH PERSISTENCE AND FCST IFR FOG AT
ALL THE TAF SITES FROM 09Z TO 14Z. THIS WILL BE FOLLOWED BY
QUICKLY IMPROVING CONDITIONS BY MID TO LATE MORNING DUE TO THE
SHALLOW NATURE OF THE FOG/STRATUS.

&&

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

WINDS AND WAVES WILL CONTINUE TO BE RELATIVELY LIGHT THROUGH
TUESDAY ALTHOUGH THERE WILL BE AREAS OF FOG AT TIMES.


&&

.HYDROLOGY...
ISSUED AT 315 PM EDT SUN AUG 30 2015

HYDRO CONCERNS ARE LOW THIS WEEK. THERE SMALL CHANCES FOR A SHOWER
IN ANY GIVEN LOCATION DURING THE LATTER HALF OF THE WEEK. EXCESSIVE
RAINFALL IS UNLIKELY.

&&

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

$$

SYNOPSIS...OSTUNO
SHORT TERM...OSTUNO
LONG TERM...LAURENS
AVIATION...MEADE
HYDROLOGY...CAS
MARINE...OSTUNO


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