Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 310426
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1226 AM EDT MON AUG 31 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.

&&

.UPDATE...
ISSUED AT 958 PM EDT SUN AUG 30 2015

DEW POINT DEPRESSIONS ARE NOW ABOUT 5 DEGREES F OR LESS AS OF
930PM...AND CORRESPONDINGLY FOG IS ALREADY FORMING. VISIBILITIES
APPROACHING 1 MILE ARE ALREADY BEING REPORTED AT SEVERAL
SITES...WITH STRATUS BELOW 1000FT SHOWING UP AS WELL.

GIVEN MAINLY CLEAR SKIES...LIGHT WINDS AND MUCH OF THE NIGHT
AHEAD OF US...THINKING THE GOING FORECAST OF FAIRLY WIDESPREAD FOG
AND STRATUS DEVELOPING IS SOLID. THREAT FOR DENSE FOG IS A
POSSIBILITY...BUT NOT CONFIDENT ENOUGH TO HOIST ANY HEADLINE YET.
WE WILL BE MONITORING TRENDS.


&&

.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 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1217 AM EDT MON AUG 31 2015

CONDITIONS GENERALLY RANGE FROM MVFR TO LIFR AND CONDITIONS WILL
CONTINUE TO GRADUALLY DETERIORATE TO PRIMARILY IFR/LIFR THROUGH
THE EARLY TO MID MORNING HOURS AS FOG BECOMES MORE DENSE AND
WIDESPREAD.

CONDITIONS WILL THEN GRADUALLY IMPROVE TO MVFR LATE THIS MORNING
AS FOG GRADUALLY DISSIPATES AND CIGS IMPROVE. CONDITIONS WILL
CONTINUE TO IMPROVE TO VFR THIS AFTERNOON WITH VFR THEN CONTINUING
THROUGH THIS EVENING.

&&

.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.
&&

$$

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


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