Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 170727
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
327 AM EDT SUN AUG 17 2014

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/MARINE

.SYNOPSIS...
ISSUED AT 327 AM EDT SUN AUG 17 2014

PARTLY SUNNY SKIES WITH TEMPERATURES IN THE MID AND UPPER 70S CAN BE
EXPECTED TODAY AND MONDAY.  SHOWERS AND A FEW THUNDERSTORMS WILL
ARRIVE MONDAY NIGHT AND CONTINUE INTO TUESDAY AS AN AREA OF LOW
PRESSURE SLOWLY MOVES ACROSS THE REGION.

TEMPERATURES SHOULD WARM INTO THE LATTER HALF OF THE WEEK...WITH 80S
BEING COMMON.  SCATTERED SHOWERS AND STORMS MAY LINGER INTO
THURSDAY...WITH DRIER WEATHER POSSIBLE BY FRIDAY AND SATURDAY.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 327 AM EDT SUN AUG 17 2014

A COLD FRONT CONTINUES TO WORK SOUTH ACROSS THE SOUTHERN CWA EARLY
THIS MORNING.  SCATTERED SHOWERS LINGER SOUTH OF I-96...BUT MOST OF
THESE ARE EXPECTED TO BE EXITING THE CWA TOWARD 12Z WITH THE FRONT.
A DRIER PUSH OF AIR MOVES IN FROM THE NORTH WITH HIGH PRESSURE
CENTERED OVER THE SUPERIOR REGION.  THIS WILL GIVE US A DRY NE FLOW
AND GRADUALLY SCOUR OUT SOME OF THE CLOUDS TOWARD MID DAY.  WITH THE
DRIER AIR ARRIVING...PULLED POPS OUT OF THE FORECAST FOR THIS
AFTERNOON IN THE FAR SOUTH.

EXPECT A DRY NIGHT TONIGHT AS THE SUPERIOR HIGH CONTINUES TO FEED IN
THE DRY AIR.  THE LOW LEVELS DO MOISTEN...SO FEEL WE WILL CLOUD
OVER...ESPECIALLY SOUTH...BUT THIS MOISTURE LOOKS TOO SHALLOW FOR
ANY PCPN TO OCCUR.  SAME STORY INTO MONDAY WHERE WE MAY STRUGGLE TO
GET RID OF THE LOW CLOUDS AS THE MIXING APPEARS TO BE MINIMAL.  THIS
LEADS TO A TRICKY HIGH TEMP FORECAST.  HAVE GONE WITH TEMPS SLIGHTLY
COOLER THEN GUIDANCE...BUT CLOSER TO WHAT THE NAM HAS.  THE MOISTURE
BEGINS TO DEEPEN LATE IN THE DAY AND WE COULD SEE A FEW SHOWERS
DEVELOP OVER THE WESTERN CWA...BUT HAVE LEFT THESE OUT OF THE
FORECAST FOR NOW.

AN OPEN UPPER WAVE OVER THE UPPER MIDWEST MOVES TOWARD SW MI BY
MONDAY NIGHT AND TUESDAY.  DECENT AGREEMENT IN THE MODELS SHOWING
THIS WAVE BECOMING A CUT OFF LOW OVER WRN LAKE SUPERIOR INTO
TUESDAY.  SO THIS WILL BE A SLOW MOVING SYSTEM...BRINGING SCATTERED
SHOWERS MONDAY NIGHT...AND EVEN MORE WIDESPREAD SHOWERS AND A FEW
STORMS INTO TUESDAY.  INCREASED POPS FOR EARLY MONDAY NIGHT AS THE
DEEPER MOISTURE ARRIVES THROUGH THE EVENING.  ALSO INCREASED POPS
FOR TUESDAY AS THE UPPER LOW MOVES IN WITH AMPLE MOISTURE THROUGHOUT
THE DAY.  NOT EXPECTING ANY SEVERE STORMS AS THE INSTABILITY SHOULD
ONLY BE MARGINAL.


.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 327 AM EDT SUN AUG 17 2014

PRIMARY FORECAST ISSUE IN THE EXTENDED IS TRYING TO PIN DOWN THOSE
PERIODS THAT POPS CAN BE DROPPED. TUESDAY NIGHT AND WEDNESDAY SHOULD
SEE THE HIGHEST CHANCES OF SHOWERS AND THUNDERSTORMS AS AN UPPER LOW
WITH SFC REFLECTION MOVES THROUGH. THINGS SHOULD CLEAR OUT AS
SHORTWAVE RIDGING MOVES IN WEDNESDAY NIGHT AND EARLY THURSDAY. THEN
WARM ADVECTION BEGINS WITH SHOWERS AND THUNDERSTORMS EXPECTED NORTH
OF THE SFC WARM FRONT THURSDAY NIGHT AND FRIDAY...MOSTLY CLUSTERED
ACROSS THE SOUTHERN FORECAST AREA.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1129 PM EDT SAT AUG 16 2014

THAT BAND OF SHOWERS CONTINUES TO SINK SOUTH WITH TIME. STILL THE
RAP...HRRR AND NAM SUGGEST MORE SHOWERS ARE POSSIBLE BETWEEN 06Z
AND 09Z OVER ALL OF OUR TAF SITES. I CONTINUED THE VCSH AS A
RESULT.

THE AREA MVFR/IFR CIGS/VSBY ARE NOW JUST NORTH OF I-96 AND SLOWLY
SINKING SOUTH WITH TIME. IT IS JUST A MATTER OF TIME BEFORE THE
SPREAD OVER THE TAF SITES. I EXPECT IFR CIGS /VSBY AT ALL TAF
SITES AT 12Z. AS THE FRONT CONTINUES TO MOVE SOUTH WITH TIME THE
CIGS/VSBY SHOULD BECOME VFR AT ALL SITES BY 18Z OR SO.

&&

.MARINE...
ISSUED AT 327 AM EDT SUN AUG 17 2014

OFFSHORE NE TO E WINDS WILL PREVAIL OVER THE NEXT 24 TO 36 HOURS.
THIS COULD PRODUCE 1-3 FOOT WAVES NEAR THE POINTS TODAY...OTHERWISE
EXPECT WAVES STAYING UNDER 2 FEET FOR THE REST OF THE SHORT TERM.
WINDS GRADUALLY BECOME S TO SE AS THE STACKED LOW MOVES IN MONDAY
NIGHT AND TUESDAY.

&&

.HYDROLOGY...
ISSUED AT 327 PM EDT SAT AUG 16 2014

HYDRO ISSUES ARE NOT ANTICIPATED THE NEXT FEW DAYS. RAINFALL SO FAR
TODAY ACROSS THE GRR FORECAST AREA HAS BEEN SPOTTY AND SOMEWHAT
LIGHT AS EXPECTED ACROSS CENTRAL LOWER. SCATTERED SHOWERS AND A FEW
EMBEDDED STORMS WILL SLIDE SOUTH THROUGH THE AREA TONIGHT. WHILE
SOME LOCALLY HEAVY RAIN MAY BE POSSIBLE THIS EVENING...NOT EXPECTING
ANYTHING WIDESPREAD. RIVERS WILL EASILY BE ABLE TO ABSORB TONIGHT/S
SCATTERED RAIN WITHOUT ANY PROBLEMS.

&&

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

$$

SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...OSTUNO
AVIATION...WDM
HYDROLOGY...DUKE
MARINE...JK








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