Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 280534
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
134 AM EDT TUE JUL 28 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 324 PM EDT MON JUL 27 2015

VERY WARM TEMPERATURES CONTINUE INTO TUESDAY WITH HIGHS IN THE
UPPER 80S TO LOW 90S. WEAKENING SHOWERS AND A FEW STORMS MAY CROSS
THE LAKE WEDNESDAY MORNING...MAINLY IMPACTING THE LAKESHORE
REGION. SOME SCATTERED THUNDERSTORMS MAY DEVELOP ACROSS CENTRAL
AND EASTERN LOWER MI WEDNESDAY AFTERNOON...A FEW POSSIBLY STRONG.
COOLER AND DRIER AIR WORKS IN FOR THE SECOND HALF OF THE WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 324 PM EDT MON JUL 27 2015

PRIMARY CONCERN CENTERS ON THE CHANCE FOR RAINFALL LATE TUESDAY
NIGHT THROUGH WEDNESDAY AFTERNOON. WHILE SOME SHOWERS AND PERHAPS
A THUNDERSTORM ARE POSSIBLE LATE TUESDAY NIGHT/EARLY WEDNESDAY
MORNING FOR THE LAKESHORE...ANY RISK FOR STRONGER THUNDERSTORMS
WOULD HOLD OFF UNTIL THE AFTERNOON FOR THE EASTERN CWA.
OVERALL...THE THREAT FOR SEVERE WEATHER REMAINS LOW.

A DEEP UPPER LOW MOVING TOWARD HUDSON BAY WILL DRAG A SFC COLD
FRONT INTO THE STATE WEDNESDAY. THE BEST UPPER LEVEL DIVERGENCE
RESIDES CLOSER TO THIS SYSTEM ACROSS THE U.P. AND POINTS NORTH.
THE LLJ WILL BE WEAKENING AS IT MOVES THROUGH OUR REGION. DEEP
LAYER SHEAR IS MAXIMIZED IN THE 30-35 KTS RANGE OVER LAKE MICHIGAN
BY 12Z WED AS SHOWN BY THE ECMWF...GFS...AND GEM. WHATEVER FLOATS
IN FROM WISCONSIN WEDNESDAY MORNING MAY SURVIVE PART OF THE
JOURNEY ACROSS THE LAKE BUT THEN RAPIDLY WEAKEN. HI RES MODELS
INCLUDING THE NAMDNG AND WRF-ARW (EAST) REVEAL THIS TREND NICELY
WITH THE SIM Z PLOTS FOR EARLY WEDNESDAY MORNING. AS A
RESULT...THE HIGHEST POPS WILL BE ACROSS THE FAR WESTERN CWA FOR
THE LATE TUESDAY NIGHT/WEDNESDAY MORNING TIME FRAME. PROBABLY MORE
SHOWERS THAN ANYTHING ELSE WITH ONLY ISOLATED TSRA MENTIONED AT
THIS TIME...THOUGH LOCALLY HEAVY DOWNPOURS ARE POSSIBLE.

AFTER THE DECAYING MORNING CONVECTION...FOCUS TURNS TOWARD THE
EARLY TO MID AFTERNOON PERIOD PRIOR TO FROPA FOR THE EASTERN HALF
OF THE CWA. THE FRONT WILL LIKELY BE OVERHEAD GRR AROUND 18Z OR
SO. WHILE SEVERE WEATHER IS NOT EXPECTED...THE TIMING OF FROPA MAY
AFFORD THE EASTERN CWA TIME TO DESTABILIZE FOR A FEW STRONGER
STORMS TO OCCUR...BUT LEADING HIGH/MID LEVEL CLOUD COVER MAY
DAMPEN INSTABILITY. THE STRONGEST CELLS MAY FEATURE SOME HAIL AND
BRIEF GUSTY WINDS ALONG WITH LOCALLY HEAVY DOWNPOURS.

OUTSIDE OF THIS WEATHER...EXPECTING ANOTHER VERY WARM DAY TUESDAY
WITH HIGHS MAINLY IN THE UPPER 80S TO AROUND 90. SOME HIGH CLOUDS
MAY BE PRESENT THOUGH THEY SHOULDN`T IMPACT TEMPERATURES MUCH.

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 324 PM EDT MON JUL 27 2015

THINK COOLER WITH PERIODS OF SHOWERS FRIDAY THROUGH MONDAY AND WELL
BEYOND THAT ACTUALLY. THURSDAY WILL LIKELY BE THE ONLY DRY DAY.

THIS IS A TRANSITIONAL PERIOD WITH A DEEPENING EASTERN
TROUGH...WHICH IT WOULD SEEM TO ME... SHOULD BE AROUND FOR ABOUT
AT LEAST TWO WEEKS. OVER TIME IT WILL TURN SIGNIFICANTLY COOLER
THAN NORMAL TOO. THERE WILL BE A SERIES OF SHORTWAVES ROTATING
AROUND THE DEVELOPING CLOSED UPPER LOW OVER SOUTHERN HUDSON BAY.
EACH OF THESE SHORTWAVES WILL DEEPEN THE EASTERN TROUGH JUST A
LITTLE MORE. THEY ALSO WILL BRING PERIODS OF SHOWERS AND
THUNDERSTORMS AND EACH COLD FRONT WILL HAVE SLIGHTLY COOLER AIR
BEHIND IT.

TIMING EACH WAVE AT THIS POINT IS QUESTIONABLE AT BEST. THERE ARE
SIGNIFICANT DIFFERENCES FROM RUN TO RUN ON EACH OF THE MODELS AS TO
WHICH SHORT WAVES RESULT IN SHOWERS AND WHICH DO NOT AND HOW MUCH
COOL AIR FOLLOWS EACH SHORTWAVE. IT MAY BE THAT NOT ONLY WILL WE
SEE A TREND TOWARD COOLER TEMPERATURES (MODELS SEEM TOO WARM TO ME
FOR SURFACE TEMPERATURES) BUT A TREND TOWARD WETTER WEATHER TOO. I
COULD SEE RAIN FALLING NEARLY EVERY DAY OVER OUR CWA STARTING
FRIDAY. THESE PERIODS OF SHOWERS WILL LAST WELL PAST THE FORECAST
TIME FRAME TOO. AT THIS POINT I DO NOT SEE ANY ONE SYSTEM GIVING
US A LARGE AMOUNT OF RAIN...JUST THAT EACH DAY THERE WILL BE
SHOWERS AROUND. BOTTOM LINE THINK COOLER WITH SHOWERS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 134 AM EDT TUE JUL 28 2015

WE ARE NOT EXPECTING MUCH IN THE WAY OF IMPACTS TO AVIATION
INTERESTS THROUGH 06Z WED. THE ONLY THING OF POSSIBLE SIGNIFICANCE
WILL BE ANOTHER CHC OF SOME FOG EARLY THIS MORNING FOR MAINLY BTL
AND KJXN. CONDITIONS LOOK SIMILAR TO LAST NIGHT WHEN SOME FOG WAS
EXPERIENCED THERE. ALSO...KBTL IS ALREADY DOWN TO 7SM AS OF 0530Z.

AFTER ANY FOG DISSIPATES AFTER SUNRISE THIS MORNING...WE ARE ONLY
LOOKING AT MAINLY SOME HIGH CLOUDS. SE WINDS UNDER 10 KNOTS WILL
RULE. A LAKE BREEZE WILL DEVELOP AT KMKG IN THE EARLY AFTERNOON
HOURS AND THEN DIMINISH TOWARD SUNSET TUE EVENING.

&&

.MARINE...
ISSUED AT 324 PM EDT MON JUL 27 2015

WAVES WILL BUILD INTO THE 1 TO 3 FOOT RANGE TUESDAY NIGHT AND
WEDNESDAY AS A COLD FRONT APPROACHES. MARINERS CAN EXPECT
SOUTHERLY WINDS TUESDAY/TUESDAY NIGHT VEERING WEST BY WEDNESDAY
AFTERNOON. LIGHTNING MAY POSE A THREAT MAINLY WEDNESDAY MORNING.


&&

.HYDROLOGY...
ISSUED AT 149 PM EDT MON JUL 27 2015

RIVER LEVELS ARE FALLING AND ARE WELL BELOW BANKFULL. WITH UNDER
AN INCH OF PRECIPITATION EXPECTED THROUGH THE WEEK... THESE
CONDITIONS SHOULD CONTINUE.

&&

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

$$

SYNOPSIS...HOVING
SHORT TERM...HOVING
LONG TERM...WDM
AVIATION...NJJ
HYDROLOGY...63
MARINE...HOVING


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