Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 310005
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
805 PM EDT SUN AUG 30 2015

LATEST UPDATE...
AVIATION

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

MUCH OF THE UPCOMING WEEK LOOKS TO BECOME VERY WARM AND HUMID ACROSS
THE REGION. MUCH OF THE TIME DRY CONDITIONS LOOK TO PREVAIL WITH
HIGH PRESSURE SETTLING IN AND NO MAJOR SYSTEMS EXPECTED TO AFFECT
THE AREA. THERE ARE SOME OPPORTUNITIES FOR AN ISOLATED SHOWER OR
STORM...BUT THESE WILL BE VERY FEW AND FAR BETWEEN.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 315 PM EDT SUN AUG 30 2015

OUR MAIN CHALLENGES IN THE SHORT TERM ARE FOG/STRATUS POTENTIAL EACH
NIGHT...AND THEN SHOWER/STORM CHCS FOR TUE.

CLOUDS HAVE BEEN FAIRLY STUBBORN TO CLEAR OUT EARLY THIS AFTERNOON
THUS FAR WITH A LACK OF DRY AIR ADVECTION INTO THE AREA...AND THE
DECENT THICKNESS OF THE STRATUS CLOUDS IN PLACE. THE CLOUDS ARE
TRYING TO MIX OUT AND BECOME MORE CELLULAR AS THE MOISTURE THICKNESS
DIMINISHES. WE ARE ALSO SEEING A FEATURE COME IN FROM THE NW THAT
LOOKS TO HELP MORE WITH DIMINISHING THE CLOUD COVER. WE EXPECT MORE
CLEARING TO TAKE PLACE THROUGH MID EVENING...BEFORE CLOUDS START TO
REFORM AND SOME FOG DEVELOPS IN THE MOIST AIR MASS AND LIGHT WIND
REGIME.

WE EXPECT THE FOG AND ANY STRATUS TO MIX OUT A BIT QUICKER ON MON AS
IT SHOULD BE MUCH MORE SHALLOW IN NATURE. WE WILL HAVE A GOOD DEAL
OF SUBSIDENCE AROUND UNDER THE UPPER RIDGE WHICH WILL LIMIT THE
VERTICAL EXTENT OF ANY CU DEVELOPMENT. THIS WILL ALLOW TEMPS TO WARM
INTO THE MID 80S WITH H850 TEMPS IN THE MID TEENS C.

FOG POTENTIAL MON NIGHT LOOKS TO STILL BE POSSIBLE WITH DEW POINTS
REMAINING WELL INTO THE 60S. IT SHOULD NOT BE AS BAD AS THIS MORNING
OR WHAT IS EXPECTED MON MORNING. WINDS ALOFT WILL BE A LITTLE
STRONGER KEEPING THINGS MIXED A LITTLE BETTER...AND THE DEEPER
MOISTURE IN PLACE NOW WILL HAVE MIXED OUT BETTER ON MON AFTERNOON.

WE ARE STILL LOOKING AT A SMALL CHC OF A FEW SHOWERS/STORMS ACROSS
THE SOUTH DURING THE AFTERNOON HOURS ON TUE. THE MODELS ARE ALL
HOLDING ON TO A WEAK UPPER WAVE ACROSS INDIANA THAT WAS LEFT BY THE
CURRENTLY DEPARTING UPPER TROUGH. THIS IS EXPECTED TO DRIFT NORTH
INTO THE SRN PORTION OF THE CWFA ALONG WITH SOME BETTER MOISTURE ON
A SRLY LOW LEVEL FLOW. CAPE PROFILES ON FCST SOUNDINGS ARE RATHER
LIMITED AS ARE WIND FIELDS ALOFT. MOST LOCATIONS SHOULD REMAIN
DRY...AND ANY SHOWERS/STORMS WILL REMAIN WEAK.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 315 PM EDT SUN AUG 30 2015

MUCH ABOVE NORMAL TEMPERATURES ARE EXPECTED FROM MID WEEK THROUGH
LABOR DAY WEEKEND DUE TO A HIGHLY AMPLIFIED UPPER PATTERN OVER THE
U.S. FEATURING A TROUGH IN THE WEST AND RIDGE IN THE EAST. THE BULK
OF THE PERIOD WILL BE DRY HOWEVER A FEW ISOLATED DIURNAL SHOWERS OR
TSTMS MAY DEVELOP DURING PEAK HEATING EACH DAY.

WITH LITTLE SYNOPTIC FORCING UNDER THE UPPER RIDGE... PRIMARY
FORCING MECHANISM FOR ANY CONVECTION WOULD BE FROM MESO/MICRO SCALE
EFFECTS SUCH AS LAKE BREEZE CONVERGENCE.

HUMID AIR MASS WITH DEW POINTS IN THE MID TO UPR 60S COMBINED WITH
LIGHT WINDS/STAGNANT PATTERN AND LONGER NIGHTS WILL CONTINUE TO
SUPPORT THE POSSIBILITY OF NIGHTTIME FOG/STRATUS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 805 PM EDT SUN AUG 30 2015

EXPECTING A REPEAT PERFORMANCE OF THE STRATUS AND FOG TONIGHT.
MOST OBSERVATION SITES CURRENTLY HAVE A TEMPERATURE/DEW POINT
SPREAD OF 10 DEGREES OR LESS AND IT WON/T TAKE MUCH FOR THE
READINGS TO CONVERGE AFTER SUNSET.

LOOKING FOR MVFR VISIBILITIES IN FOG TO DEVELOP BETWEEN 03Z AND
05Z...WITH STRATUS SHOWING UP AFTER 08Z OR SO. LOOKING FOR THE
WORST OF THE CONDITIONS BETWEEN 09Z AND 14Z....WHERE IFR SHOULD BE
PREVALENT. CONFIDENCE IN IFR CONDITIONS IS MEDIUM AT THIS
POINT...BUT ENOUGH TO INCLUDE IN THE TAFS.

CEILINGS AND VISIBILITIES WILL IMPROVE THROUGH THE COURSE OF
MONDAY MORNING. COULD SEE SOME OF THE STRATUS HANGING ON INTO THE
MIDDAY HOURS THOUGH. MONDAY AFTERNOON SHOULD BRING VFR WEATHER.

&&

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

WE ARE LOOKING AT RATHER BENIGN CONDITIONS FOR MUCH OF THIS WEEK FOR
MARINE INTERESTS. WINDS SHOULD REMAIN BELOW 20 KNOTS THROUGH THE
WEEK...WITH MON/THU-FRI LOOKING LIKE WINDS COULD BE 10 KNOTS OR LESS
WITH A VERY WEAK GRADIENT IN PLACE THOSE DAYS.

WE COULD BE LOOKING AT SOME FOG ISSUES IN THE LATE NIGHT/EARLY
MORNING HOURS WITH A MOIST AIR MASS IN PLACE.


&&

.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...NJJ
SHORT TERM...NJJ
LONG TERM...MEADE
AVIATION...DUKE
HYDROLOGY...CAS
MARINE...NJJ



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