Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 281135
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
735 AM EDT SUN JUN 28 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 317 AM EDT SUN JUN 28 2015

EXPECT ABUNDANT SUNSHINE TODAY WITH PLEASANT TEMPERATURES. THERE
COULD BE AN LATE DAY THUNDERSTORM NORTH OF LANSING. THE NEXT STORM
SYSTEM WILL PASS JUST SOUTH OF MICHIGAN MONDAY HEADING TOWARD
WESTERN LAKE ERIE FOR TUESDAY. THIS WILL BRING PERIODS OF SHOWERS
AND ISOLATED THUNDERSTORMS DURING THE DAY TIME HOURS OF BOTH
DAYS. MOST OF THE SHOWERS FROM THIS SYSTEM WILL BE NEAR AND EAST
OF US-131. HIGH PRESSURE WILL BRING SUNSHINE BACK FOR WEDNESDAY
AND THURSDAY. ANOTHER STORM SYSTEM...ALSO PASSING SOUTH OF
MICHIGAN... MAY BRING MORE SHOWERS TO THE AREA LATE IN THE WEEK.
TEMPERATURES WILL CONTINUE TO BE COOLER THAN NORMAL THROUGH THIS
COMING WEEK.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 317 AM EDT SUN JUN 28 2015

THE ISSUES EARLY THIS MORNING FOR THE NEXT FEW DAYS IS THE RISK
OF ISOLATED LATE DAY THUNDERSTORMS NEAR AND EAST OF US-127
(LANSING TO MT PLEASANT) TODAY. THEN THERE IS A MORE WIDESPREAD
ISSUE FOR SHOWERS AND ISOLATED THUNDERSTORMS FOR MONDAY AND
TUESDAY AS A STORM SYSTEM TRACKS JUST SOUTH OF LOWER MICHIGAN
TOWARD WESTERN LAKE ERIE BY TUESDAY MORNING.

OUR UPPER AIR PATTERN FEATURES A PERSISTENT EASTERN TROUGH
THROUGH THE SHORT TERM PERIOD. BOTH THE 200 MB AND 500 MB HEIGHTS
ARE ABOUT 2 STANDARD DEVIATIONS BELOW NORMAL FOR THIS TIME OF
YEAR. THIS RESULTS IN THE POLAR JET STREAM BEING SOUTH OF MICHIGAN
THROUGH THE PERIOD. THAT IN TURN CUTS OFF GULF MOISTURE TO OUR
REGION. THUS ANY CONVECTION HAS TO WORK OF LOCAL MOISTURE AND
UPPER AIR DYNAMICS. ALSO WITH THE POLAR JET WELL SOUTH OF MICHIGAN
JET DYNAMICS ARE ALSO OUT OF THE PICTURE. SO WHAT WE HAVE TO WORK
WITH IS LOCAL HEATING...VERTICAL INSTABILITY DUE TO THE COLD AIR
ALOFT WITH THE UPPER TROUGH AND SOME DEFORMATION STRETCHING. THE
BEST Q VECTOR CONVERGENCE IN THE 500 TO 300 MB LAYER IS OF COURSE
NEAR THE POLAR JET CORE...OR WELL SOUTH OF MICHIGAN.

SO WHAT I AM THINKING IS SINCE THERE ARE TWO SHORTWAVES...ONE FOR
MONDAY AND ONE FOR TUESDAY... THE GREATEST RISK FOR SHOWERS AND
THUNDERSTORMS WILL BE SOUTH OF MICHIGAN BOTH DAYS. EVEN SO...WITH
THE COLD AIR AT MID TO UPPER LEVELS...DAY TIME HEATING WILL
GENERATE SOME CONVECTION BUT WITH WEST WINDS AT THE SURFACE THE
GREATEST RISK OF THESE STORMS WILL BE NEAR AND EAST OF US-131. I
RE CONFIGURED TO POP BOTH DAYS TO SHOW THAT. INSTABILITY IS NOT
ALL THAT GREAT SO I DO NOT SEE SEVERE STORMS AS A THREAT EITHER
DAY.

BEING SO DEEP IN THE COLDER AIR WILL LIMIT HOW WARM WE CAN GET
EACH DAY...HIGHS IN THE 70S WILL BE THE BEST WE CAN DO.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 317 AM EDT SUN JUN 28 2015

A CONSENSUS OF LATEST MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST A
BROAD UPPER LEVEL TROUGH WILL REMAIN ENTRENCHED OVER OUR REGION
THROUGH THE LONG RANGE FORECAST PERIOD. THIS WILL RESULT IN SLIGHTLY
BELOW NORMAL TEMPERATURES THROUGH THE PERIOD WITH MAX TEMPS
WEDNESDAY THROUGH SATURDAY IN THE 70S.

A FEW SHOWERS MAY LINGER INTO TUESDAY NIGHT BEFORE DRY WX RETURNS
WEDNESDAY AND THURSDAY AS A SFC HIGH PRESSURE RIDGE BUILDS IN FROM
THE NORTH. THE COMBINATION OF A WEAK LOW PRESSURE SYSTEM MOVING
THROUGH OUR REGION AND UPPER LEVEL SYSTEM MOVING IN FROM THE NW WILL
BRING ANOTHER CHANCE FOR SHOWERS VERY LATE THIS WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 735 AM EDT SUN JUN 28 2015

HIGH PRESSURE OVER LOWER MICHIGAN TODAY SHOULD RESULT IN MOSTLY
CLEAR SKIES AND LIGHT WINDS. I WOULD EXPECT SOME CU TO DEVELOPED
(HIGH BASED) BY LATE MORNING. TONIGHT A SYSTEM COMING TOWARD THE
GREAT LAKES WILL SPREAD RAIN AND LOW CLOUDS TOWARD LOWER MICHIGAN
BY 12Z MONDAY. WITH THE TRACK OF THE SYSTEM GOING SOUTH OF
MICHIGAN...THE RAIN WILL SPREAD NORTHWARD INTO LOWER MICHIGAN
TOWARD SUNRISE. AT THIS POINT IT WOULD SEEM THE TAF SITES SHOULD
STAY VFR THROUGH 12Z. ONLY THE TAF SITES ALONG INTERSTATE 94 HAVE
A CHANCE TO SEEM SOME RAIN PRIOR TO 12Z MONDAY...BUT ANY RAIN
WOULD BE RATHER LIGHT PRIOR TO 12Z.


&&

.MARINE...
ISSUED AT 317 AM EDT SUN JUN 28 2015

LIGHT WINDS AND LOW DEW POINTS WILL KEEP THE NEAR SHORE QUIET FOR
THE NEXT FEW DAYS. ANY THUNDERSTORMS WOULD MORE THAN LIKELY BE
WELL INLAND TOO.


&&

.HYDROLOGY...
ISSUED AT 1110 AM EDT SAT JUN 27 2015

RIVER FLOOD ADVISORIES REMAIN IN EFFECT AS RUNOFF OF RAINFALL MAKES
ITS WAY THROUGH THE RIVER SYSTEM. RAIN ACCUMULATIONS THROUGH THE
NEXT WEEK ARE EXPECTED TO BE A HALF INCH IN MOST AREAS WITH UP TO
AN INCH AND A HALF IN THE SOUTH. SIGNIFICANT FLOODING IS NOT
EXPECTED... BUT MINOR FLOODING ALONG RIVERS AND IN LOW-LYING AREAS
MAY PERSIST THROUGH THE WEEK.

&&

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

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...LAURENS
AVIATION...WDM
HYDROLOGY...63
MARINE...WDM



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