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000
FXUS63 KGRR 201839
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
239 PM EDT MON MAY 20 2013

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/FIRE WEATHER/MARINE/HYDROLOGY

.SYNOPSIS...
ISSUED AT 238 PM EDT MON MAY 20 2013
THUNDERSTORMS AT TIMES THIS AFTERNOON THROUGH WEDNESDAY EVENING WITH
SOME SEVERE WEATHER POSSIBLE. COOLER TEMPERATURES EXPECTED THURSDAY
THROUGH MUCH OF THE HOLIDAY WEEKEND...WITH OVERNIGHT LOWS ON THE
WEEKEND POSSIBLY DROPPING INTO THE UPPER 30S.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 238 PM EDT MON MAY 20 2013

THUNDERSTORM WATCH IN EFFECT THROUGH 8PM. STORMS SHOULD CONTINUE TO
DEVELOP MAINLY ALONG A LINE OF MID LEVEL MOISTURE THAT IS MOVING
INTO MICHIGAN FROM THE WEST/SOUTHWEST. LARGE HAIL APPEARS TO BE THE
MAIN THREAT SO FAR FROM ANY STORMS...ALONG WITH HEAVY RAINFALL.
WOULD EXPECT THOSE SAME THREATS THIS AFTERNOON...ALONG WITH SOME
DAMAGING WIND POTENTIAL AS WELL. FOCUS THIS AFTERNOON SEEMS TO BE
NEAR US131...SOME PROGRESSION EAST/NORTHEAST WITH THE THREAT
SHOULD BE EXPECTED THROUGH THIS EVENING.

ADDITIONAL ROUNDS OF STORMS POSSIBLE THIS EVENING AND
OVERNIGHT...ESPECIALLY NEAR AND NORTH OF THE WARM FRONT THAT IS
STRETCHING ACROSS NORTHERN LOWER MICHIGAN.  STORM POSSIBILITIES ALSO
REMAIN TUESDAY AFTERNOON THOUGH SEVERE POTENTIAL FOR TUESDAY
AFTERNOON DOES SEEM TO BE SOMEWHAT LIMITED...AND WOULD BE MORE SO IF
MORNING ACTIVITY LIMITS AMOUNT OF WARMING THAT COULD OCCUR DURING
THE DAY.

THE MAIN PUSH OF THE UPPER SYSTEM WORKS TOWARD THE GREAT LAKES
WEDNESDAY BRINGING COLD AIR ALOFT TO THE REGION AND RAMPING UP THE
INSTABILITY. MODELS ARE TRENDING MORE TOWARD THIS BEING MORE OF A
RAIN EVENT THAN A SEVERE EVENT.

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 238 PM EDT MON MAY 20 2013

COOLER END OF THE WEEK AND WEEKEND STILL THE FOCUS OF THE LONG
TERM...WITH SOME FROST THREAT REMAINING FOR FRIDAY MORNING...AND
ESPECIALLY SATURDAY MORNING.  NORTHERN MOST COUNTIES REMAIN THE MOST
THREATENED BY FROST...ESPECIALLY NORTH OF US-10 ON SATURDAY MORNING.
WILL MONITOR FOR POTENTIAL HEADLINES LATER IN THE WEEK BUT FROST
POTENTIAL IS CERTAINLY THERE FOR THE FIRST HALF OF THE WEEKEND.

OTHERWISE...SOME LINGERING LIGHT RAIN SHOWERS THROUGH THE DAY
THURSDAY THE ONLY NOTABLE WEATHER IN THE LONG TERM. NO SIGNIFICANT
IMPACTS EXPECTED FROM THIS LINGERING RAIN ON THURSDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 116 PM EDT MON MAY 20 2013

THE MAIN FOCUS OF THE 18Z SET OF FCSTS IS CONVECTION TRENDS
THROUGH THE PERIOD.

A FEW ISOLATED STORMS ARE GOING UP AS OF 1715Z THIS AFTERNOON.
THESE FORMED JUST EAST OF KMKG AND ARE MOVING NORTHEAST AND
STAYING NORTH OF THE REMAINDER OF THE TERMINALS. THERE COULD BE
MORE STORMS THAT FORM NEAR THE LAKESHORE AND MOVE INLAND...BUT
CONFIDENCE IS STILL LIMITED AS TO WHERE ADDITIONAL STORMS...IF ANY
WILL FIRE THIS AFTERNOON. WE HAVE VCTS TO ADDRESS THE CONVECTION
CHCS AND UNCERTAINTY. WE WILL UPDATE THE FCSTS AS NECESSARY IF
CONVECTION IS HEADING TOWARD A SITE. MVFR CONDITIONS CAN BE
EXPECTED UNDER ANY STORMS WITH SOME BRIEF BOUTS OF IFR POSSIBLE.

THE NEXT ROUND OF STORMS SHOULD COME IN AS EARLY AS LATER THIS
EVENING...AND MORE SO OVERNIGHT. THESE STORMS LOOK LIKE THEY WILL
BE MORE WIDESPREAD AND AFFECT ALL OF THE SITES. AGAIN MVFR SHOULD
BE EXPECTED UNDER ANY STORMS WITH BRIEF PERIODS OF IFR ALSO
LIKELY. WE WILL CONTINUE TO FINE TUNE THE CONVECTION OVERNIGHT.


&&

.MARINE...
ISSUED AT 238 PM EDT MON MAY 20 2013

THUNDERSTORMS WILL POSE HAZARDS TO MARINERS THIS EVENING THROUGH
WEDNESDAY. FOG IS ALSO EXPECTED TO BE A HAZARD AS WELL TONIGHT AND
TUESDAY NIGHT.

&&

.FIRE WEATHER...
ISSUED AT 238 PM EDT MON MAY 20 2013

WARM AND FAIRLY HUMID WEATHER IS EXPECTED THROUGH WEDNESDAY.
THUNDERSTORMS WILL BRING LIGHTNING AND GUSTY WINDS AT TIMES TODAY
THROUGH WEDNESDAY.  COOLER WEATHER WITH A DRIER AIR MASS FOR THE END
OF THE WEEK THROUGH THE WEEKEND.

&&

.HYDROLOGY...
ISSUED AT 238 PM EDT MON MAY 20 2013

SOME LOCALIZED FLOODING COULD OCCUR THROUGH WEDNESDAY AS SEVERAL
ROUNDS OF THUNDERSTORMS MAY BRING HEAVY RAINFALL TO SOME AREAS.
PLACES THAT SEE MULTIPLE SHOWERS/THUNDERSTORMS IN QUICK SUCCESSION
WOULD BE PARTICULARLY VULNERABLE TO LOCALIZED FLOODING.

&&

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

$$

SYNOPSIS...MACZKO
SHORT TERM...MACZKO
LONG TERM...MACZKO
AVIATION...NJJ
FIRE WEATHER...MACZKO
HYDROLOGY...LAURENS
MARINE...MACZKO