Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 150535
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
135 AM EDT MON SEP 15 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 327 PM EDT SUN SEP 14 2014

LIGHT RAIN SHOWERS WILL MOVE INTO AREAS NORTH OF I-96 LATE
TONIGHT...THEN SPREAD INTO SOUTHERN LOWER MICHIGAN ON MONDAY AND
BECOME STEADIER.  RAIN IS EXPECTED MUCH OF MONDAY WITH THE RAIN
EXITING FROM WEST TO EAST LATE MONDAY AFTERNOON AND INTO THE
EVENING.  HIGH PRESSURE ARRIVES LATER MONDAY NIGHT GIVING THE REGION
A DRY PERIOD INTO TUESDAY NIGHT.  IT WILL REMAIN COOL WITH DAYTIME
HIGHS BOTH MONDAY AND TUESDAY ONLY 60 TO 65...WHICH IS ABOUT 10
DEGREES BELOW NORMAL.

MUCH OF THE REMAINDER OF THE WEEK APPEARS TO BE DRY...WITH THE NEXT
CHANCE OF RAIN HOLDING OFF UNTIL FRIDAY NIGHT INTO NEXT WEEKEND.
TEMPERATURES WILL MODERATE...WARMING TO 65 TO 75 FOR THE LATTER PART
OF THE WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 327 PM EDT SUN SEP 14 2014

A STEADIER/HEAVIER RAIN IS NOW EXPECTED FOR MONDAY AS A COLD FRONT
COMES THROUGH ALONG WITH GOOD JET DYNAMICS AND FGEN FORCING.

FAVORABLE FGEN FORCING DEVELOPS OUT AHEAD OF THE COLD FRONT BY LATE
THIS EVENING.  EXPECT A SLIGHTLY QUICKER ONSET TO THE PCPN SO ADDED
POPS TO THE NW CWA STARTING THIS EVENING.  WE WILL HAVE TO OVERCOME
SOME FAIRLY DRY LOW LEVELS...SO THESE INITIAL SHOWERS SHOULD WILL BE
LIGHT.  THE LIGHT SHOWERS SHOULD SPREAD EAST AS THE FGEN EXPANDS
OVER THE AREAS NORTH OF I-96 LATE TONIGHT.

THE FGEN FORCING TONIGHT WILL PRIME THE LOW LEVELS WITH MOISTURE AND
SHOULD MAKE THE COLD FRONT THAT COMES IN ON MONDAY THAT MUCH MORE
PROFICIENT.  WE WILL ALSO SEE THE RIGHT ENTRANCE REGION OF THE UPPER
JET AND A WEAK LOW LEVEL JET COME ACROSS THE SE HALF OF THE CWA
MONDAY AFTERNOON.  INCREASED POPS ACROSS THE ENTIRE CWA TO
CATEGORICAL AND ALSO INCREASED QPF AMOUNTS TO AROUND OR SLIGHTLY
OVER
A QUARTER INCH.

THE SHOWERS WILL LIGHTEN UP AND EXIT QUICKLY MONDAY EVENING FROM
WEST TO EAST AS THE FRONT AND UPPER DYNAMICS EXIT.  SKIES SHOULD AT
LEAST PARTIALLY CLEAR AND THERE COULD BE THE RISK OF ISOLATED FROST
OVER THE INTERIOR NORTH...BUT IT DOES NOT APPEAR IT WILL BE
WIDESPREAD ENOUGH TO WARRANT A HEADLINE.

TUESDAY WILL BE QUIET AND WILL BECOME MOSTLY SUNNY.  TEMPS SHOULD
BE SLIGHTLY WARMER.  ANOTHER COLD FRONT IS PROGGED TO DROP SOUTH
INTO NORTHERN LOWER TUESDAY NIGHT.  THIS LOOKS LIKE A PRETTY WEAK
FRONT...BUT THE CLOUDS SHOULD INCREASE ACROSS THE NORTHERN CWA WITH
MAYBE SOME SPRINKLES TOWARD HIGHWAY 10.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 327 PM EDT SUN SEP 14 2014

VERY LITTLE IMPACTS EXPECTED DURING THIS PERIOD AS INITIALLY
NORTHWEST FLOW ALOFT GRADUALLY TRANSITIONS TO ZONAL FLOW AND WARMING
TEMPERATURES. MODELS SHOWING SOME CONSISTENCY WITH SHOWERS AND
THUNDERSTORMS SPREADING INTO THE AREA EARLY SATURDAY AND EXITING
SUNDAY. THE LATEST 12Z ECMWF SHOWS A HASTIER EXIT SUNDAY THAN THE
00Z RUN...SO TIMING THE END OF PRECIPITATION IS PROBABLY THE BIGGEST
FORECAST CHALLENGE AT THIS POINT.

AS NOTED IN THE PREVIOUS DISCUSSION...HIGHS IN THE 70S ARE EXPECTED
LATE WEEK INTO THE WEEKEND AHEAD OF THIS SYSTEM.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 135 AM EDT MON SEP 15 2014

VFR CONDITIONS PREVAIL FIRST THING THIS MORNING ACROSS THE ENTIRE
AREA. ALL AREAS WILL SEE DETERIORATION OF CIGS AND VBSYS LATER THIS
MORNING AND THIS AFTERNOON AS RAIN WILL SPREAD IN FROM THE NORTH
AND WEST TODAY. WITH A WAVE OF LOW PRESSURE. WE EXPECT LOTS OF
LOW SCALE MVFR TO RULE AS THE LOWER CLOUDS AND RAIN MOVES IN. IFR
AND LOWER CONDITIONS WILL BE POSSIBLE.

WE EXPECT THAT THE RAIN SHOULD MOVE OUT THIS EVENING. RESIDUAL LOW
CLOUDS COULD HOLD ON ACROSS THE I-94 TERMINALS FOR A BIT. CLOUDS
WILL TRY TO CLEAR OUT FROM THE NW LATE IN THE EVENING AND OVERNIGHT.

&&

.MARINE...
ISSUED AT 327 PM EDT SUN SEP 14 2014

WAVES WILL CONTINUE TO BUILD LATE THIS AFTERNOON INTO THIS EVENING
WITH A BRISK SW FLOW.  SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED
FOR THE REST OF TODAY AND LINGER INTO MID MORNING ON MONDAY NORTH OF
HOLLAND.  THEREAFTER WINDS AND WAVES LIGHTEN UP AS A COLD FRONT
COMES IN...FOLLOWED BY HIGH PRESSURE INTO TUESDAY NIGHT.


&&

.HYDROLOGY...
ISSUED AT 327 PM EDT SUN SEP 14 2014

MOST AREAS SHOULD SEE AROUND A QUARTER INCH OF RAIN FROM LATE
TONIGHT INTO MONDAY EVENING.  RIVERS ARE RUNNING A BIT HIGHER THAN
NORMAL...BUT THIS AMOUNT OF RAIN SHOULD NOT AFFECT THEM TOO MUCH.
EXPECT A MOSTLY DRY PERIOD TUESDAY THROUGH FRIDAY.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR LMZ846>849.

&&

$$

SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...TJT
AVIATION...NJJ
HYDROLOGY...JK
MARINE...JK






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