Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 041730
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
130 PM EDT TUE AUG 4 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 328 AM EDT TUE AUG 4 2015

GENERALLY FAIR WEATHER IS EXPECTED THROUGH THE NEXT FEW DAYS WITH
TEMPERATURES IN THE 70S DURING THE DAY AND 50S AT NIGHT AND LOW
HUMIDITY. THERE COULD BE A FEW SHOWERS NORTH OF GRAND RAPIDS THIS
AFTERNOON. THE NEXT CHANCE FOR RAIN WILL COME LATE THURSDAY AND
FRIDAY.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 328 AM EDT TUE AUG 4 2015

FORECAST ISSUES IN THE NEAR TERM INCLUDE POPS TODAY AND THURSDAY.
FOR TODAY...WENT WITH SLIGHT CHANCE TO CHANCE POPS ACROSS ROUGHLY THE
NORTHEAST QUARTER OF THE FORECAST AREA. LIGHT SHOWERS WERE ACROSS
THE UP OF MICHIGAN AT 07Z WITH SOME LIGHT RADAR RETURNS MOVING
INTO NORTHWEST LOWER MICHIGAN. THESE SHOWERS ARE ASSOCIATED WITH A
VORT MAX ROTATING AROUND THE BIG UPPER LOW ACROSS EASTERN CANADA.

GIVEN THE PROXIMITY OF THE UPPER LOW AND THE RESULTING MID LEVEL
LAPSE RATES...SOME DIURNAL ENHANCEMENT OF THE SHOWERS ARE EXPECTED
THIS AFTERNOON ACROSS NORTHERN INTERIOR ZONES. LEFT OUT THUNDER
FOR NOW...BUT THERE MAY BE ENOUGH INSTABILITY TO SEE A COUPLE
LIGHTNING STROKES THIS AFTERNOON.

AS FOR THURSDAY...THEIR SEEMS TO BE A DEVELOPING CONSENSUS THAT
THE FORECAST AREA WILL REMAIN IN BETWEEN TWO AREAS OF SHOWERS
ASSOCIATED WITH TWO LOWS...ONE MOVING ACROSS THE OHIO VALLEY AND
ANOTHER ACROSS THE UPPER MIDWEST...WHICH SHOULD MOVE IN THURSDAY
NIGHT.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 328 AM EDT TUE AUG 4 2015

MEDIUM RANGE MODELS HAVE TRENDED TO A SOMEWHAT WETTER AND NOT AS
COOL PATTERN FOR THE END OF THE WEEK INTO EARLY NEXT WEEK.

THE FLOW BECOMES MORE ZONAL INTO THURSDAY NIGHT/FRIDAY WITH A SHORT
WAVE COMING THROUGH THE MEAN FLOW ON FRIDAY.  THE MODELS ARE ALSO
SHOWING A BETTER SURFACE COLD FRONT WITH THIS WAVE.  BEST MOISTURE
SEEMS TO POOL ACROSS CENTRAL LOWER WHERE POPS WHERE INCREASED FOR
BOTH THURSDAY NIGHT AND FRIDAY.  ENOUGH INSTABILITY AROUND ON FRIDAY
TO MENTION THUNDER AS THE COLD FRONT COMES THROUGH.

THE PATTERN REMAINS PROGRESSIVE WITH ANOTHER UPPER WAVE COMING
THROUGH SATURDAY OR SATURDAY NIGHT.  THIS SHOULD BRING ANOTHER ROUND
OF SCATTERED SHOWERS AND STORMS...FAVORING CENTRAL LOWER AGAIN...AND
THERE MAY A BIT OF A LAKE SHADOW OVER THE WESTERN CWA WITH A SW LOW
LEVEL FLOW.

TEMP TREND APPEARS TO BE A BIT WARMER.  I RAISED BOTH THURSDAY AND
FRIDAY NIGHT LOWS DUE TO MORE EXPECTED CLOUD COVER.  DAYTIME HIGHS
SHOULD BE UPPER 70S TO AROUND 80 EACH DAY...BUT IT MAY COOL A BIT BY
MONDAY WITH NORTHWEST UPPER FLOW RETURNING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY MORNING) ISSUED
AT 130 PM EDT TUE AUG 4 2015

VFR CONDITIONS WITH AREAS OF BKN060 THROUGH THIS AFTERNOON. CIGS AND
VIS UNLIMITED (CAVU) FROM THIS EVENING THROUGH WEDNESDAY. LAKE
BREEZE WIND GUSTS OF 25KTS ALONG ROUTE 131 WILL CONTINUE TO SLOWLY
PUSH FURTHER EAST (INLAND) AND THEN WILL DIMINISH TOWARDS SUNSET.
EXPECT VERY LIGHT NORTHWEST OR LIGHT AND VARIABLE WINDS
OVERNIGHT INTO EARLY AFTERNOON WEDNESDAY. ALSO COULD BE SOME SHALLOW
LAKE...RIVER...OR VALLEY FOG AROUND DAYBREAK WEDNESDAY.

OUTLOOK...VFR WITH LIGHT WINDS INTO THURSDAY...CHANCE OF SHOWERS
WITH PATCHY MVFR FRIDAY NIGHT.

 &&

.MARINE...
ISSUED AT 1035 AM EDT TUE AUG 4 2015

WE HAVE INCREASED THE WAVES A LITTLE FOR TODAY BASED ON CURRENT
COASTAL OBS AND REPORTS FROM THE STATE PARKS. WE EXPECT WAVES TO
PEAK OUT AROUND 2-3 FEET INTO EARLY THIS AFTERNOON BEFORE WINDS
SHOULD THEN DIMINISH SOME LATER THIS AFTERNOON.


&&

.HYDROLOGY...
ISSUED AT 1233 PM EDT TUE AUG 4 2015

NO FLOODING ISSUES ARE EXPECTED AS A RELATIVELY DRY PATTERN SETS
UP OVER LOWER MICHIGAN. SOME SHOWERS WILL BE POSSIBLE OFF AND
ON THROUGH THE WEEKEND...BUT NO SIGNIFICANT RAINFALL EVENTS ARE
EXPECTED AT THIS TIME.

&&

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

$$

SYNOPSIS...OSTUNO
SHORT TERM...OSTUNO
LONG TERM...JK
AVIATION...COBB
HYDROLOGY...MACZKO
MARINE...NJJ



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