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000
FXUS63 KGRR 160411
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1211 AM EDT THU MAY 16 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 331 PM EDT WED MAY 15 2013

A LARGE AREA OF HIGH PRESSURE FROM CENTRAL CANADA WILL CONTINUE
TO BUILD SOUTHEAST INTO SOUTHWEST LOWER MICHIGAN INTO THURSDAY NIGHT.
THIS WILL BRING IN DRIER AND SLIGHTLY COOLER AIR INTO FRIDAY. ONCE
THE HIGH MOVES EAST OF THE AREA THE RETURN FLOW OF MORE MOIST AIR WILL
BRING A SLIGHT CHANCE OF SHOWERS TO THE AREA. A STORM SYSTEM FROM
THE PACIFIC WILL MOVE INTO SOUTHWEST MICHIGAN EARLY NEXT WEEK.
THAT WILL SIGNIFICANTLY INCREASE THE CHANCES OF GETTING SHOWERS
AND THUNDERSTORMS.

&&

.UPDATE...
ISSUED AT 752 PM EDT WED MAY 15 2013

HAD TO ADD MORE CLOUDINESS TO THE FORECAST THIS EVENING AS A BAND
OF THICK MID LEVEL CLOUDS IS IMPACTING MUCH OF THE CWFA. THERE MAY
EVEN BE A SPRINKLE OR TWO OUT OF THESE CLOUDS...BUT LEFT THAT OUT
OF THE FCST. THE CLOUDS ARE RELATED TO A MID LEVEL JET STREAK NOW
ZIPPING THROUGH THE REGION... AND SHOULD DISSIPATE OR EXIT THE
REGION BY 03Z.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 331 PM EDT WED MAY 15 2013

LITTLE IN THE WAY OF WEATHER ISSUES TONIGHT THROUGH FRIDAY. THERE
IS SOME POTENTIAL FOR SHOWERS AND THUNDERSTORMS FRIDAY NIGHT.

THE COLD FRONT HAS MOVED SOUTH OF MICHIGAN AND WILL STALL JUST
OVER THE OHIO VALLEY FRIDAY INTO SATURDAY. MEANWHILE THE POLAR JET
WILL REMAIN IN PLACE OVER UPPER MICHIGAN INTO NORTHERN LOWER
MICHIGAN INTO SATURDAY. THIS CREATES A SET UP FOR JET ENTRANCE
REGION CONVECTION FOR THIS AREA. ONE SUCH SPEED MAX CROSSES NORTH
OF THE AREA THURSDAY INTO THURSDAY NIGHT BUT SOUTHWEST MICHIGAN IS
TO FAR EAST OF THE LOW LEVEL JET TO CREATE ANY CONVECTIVE THREAT.

HOWEVER... ON FRIDAY NIGHT A WEAKENING LOW LEVEL JET IS JUST
STRONG ENOUGH THAT I HAVE CONTINUED LOW CHANCE POPS FOR LEFT OVER
CONVECTION CROSSING THE SOUTHWEST PART OF OUR AREA DURING THE
NIGHT. THE NAM PLAYS THIS UP BUT EVEN ON THE NAM THE LOW LEVEL
INFLOW TO THIS EVENT IS WEAK AND WEAKENING WITH TIME SO AT THIS
POINT IS DOES NOT SEEM LIKE MUCH OF A REAL THREAT.

WITH THE DRY AIR IN PLACE I EXPECT HIGHS WILL BE WARMER THAN MOS
DURING THE DAY TOMORROW AND COOLER THAN MOS TONIGHT AND THURSDAY
NIGHT. THERE SHOULD BE ENOUGH MID AND HIGH CLOUDS FRIDAY INTO
FRIDAY NIGHT TO LIMIT THAT EFFECT.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 331 PM EDT WED MAY 15 2013

TWEAKED THE SATURDAY FORECAST AS THE SHORT WAVE MOVES AWAY SLOWER.
IT NOW APPEARS IT WILL BE OVER LAKE MICHIGAN BY 12Z SAT AND SLIDING
ACROSS SW MI THROUGH THE MORNING HOURS.  THEREFORE A FEW LINGERING
SHOWERS WILL BE POSSIBLE IN THE MORNING.  ALSO LOWERED MAX TEMPS AS
ANY CLEARING/SUNSHINE APPEARS TO NOT OCCUR UNTIL LATE IN THE DAY.

THE UPPER RIDGE OVER THE EASTERN U.S. TAKES OVER FOR THE REST OF THE
WEEKEND.  THE EURO AND GFS AGREE IT SHOULD HOLD THROUGH SUNDAY
NIGHT...SO DELAYED POPS UNTIL MONDAY....AND ITS NOT OUT OF THE REALM
OF POSSIBILITY WE MAY NEED TO DELAY EVEN FURTHER GIVEN THE SLOWER
TREND.

A GENERAL WEAKENING OF THE RIDGE OCCURS INTO THE FIRST HALF OF THE
WORK WEEK NEXT WEEK.  HOWEVER THE PATTERN REMAINS RATHER BLOCKED SO
THE MOVEMENT OF THE WESTERN U.S TROUGH SHOULD ONLY EASE INTO THE
GREAT LAKES REGION.  GULF MOISTURE SHOULD GRADUALLY INCREASE...AND
ALONG WITH A WARM FRONT LIFTING THROUGH THE CWA...SHOWERS AND STORMS
WILL BECOME INCREASINGLY POSSIBLE.  SURFACE LOW PRESSURE IS EXPECTED
TO BE IN THE EASTERN DAKOTAS ON MONDAY DRIFTING TO THE SOUTHERN
GREAT LAKES BY WEDNESDAY.  THIS SHOULD RESULT IN A WET PERIOD.

TEMPS WILL REMAIN TOASTY AND SOMEWHAT HUMID MONDAY AND TUESDAY...
THEN A BIT COOLER BY WEDNESDAY AS THE LOW REACHES THE REGION.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1211 AM EDT THU MAY 16 2013

WIDESPREAD VFR CONDITIONS CONTINUING OVERNIGHT AND THURSDAY. THIS
IS A VERY HIGH CONFIDENCE FORECAST. DEEP MIXED LAYER ON THURSDAY
AFTERNOON MAY RESULT IN A FEW SFC WINDS GUSTS CLOSE TO 20 KTS.

&&

.MARINE...
ISSUED AT 331 PM EDT WED MAY 15 2013

WITH HIGH PRESSURE IN THE AREA WINDS WILL BE LIGHT AND AS DRY AS
THIS AIR IS I SEE LITTLE THREAT FOR FOG SO NO NEED FOR HEADLINES
IN THE NEAR SHORE OVER THE NEXT FEW DAYS.


&&

.FIRE WEATHER...
ISSUED AT 331 PM EDT WED MAY 15 2013

IT WOULD SEEM THE RH WILL GET CLOSE TO 25 PCT THURSDAY AFTERNOON
BUT WINDS SHOULD BE LIGHT SO THAT SHOULD MITIGATE HAVING TO ISSUE
A RED FLAG WARNING.

&&

.HYDROLOGY...
ISSUED AT 331 PM EDT WED MAY 15 2013

NO SIGNIFICANT RAINFALL EXPECTED UNTIL EARLY NEXT WEEK SO RIVER
LEVELS SHOULD CONTINUE TO FALL THROUGH THE WEEKEND.

&&

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

$$

UPDATE...MEADE
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...JK
AVIATION...MEADE
FIRE WEATHER...WDM
HYDROLOGY...WDM
MARINE...WDM