Special Marine Warning 13, NWS Grand Rapids, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
755 PM EDT MON MAY 28 2012

.SYNOPSIS...
ISSUED AT 300 PM EDT MON MAY 28 2012

A COLD FRONT WILL TRACK EASTWARD THROUGH THE REGION TONIGHT
PRODUCING SHOWERS AND THUNDERSTORMS. A COOLER HIGH PRESSURE SYSTEM
THEN BUILDS IN FOR THE MIDDLE PART OF THE WEEK. A SLOW MOVING AREA
OF LOW PRESSURE WILL LIFT NORTHWARD INTO THE GREAT LAKES REGION
RESULTING IN UNSETTLED WEATHER FOR THE END OF THE WEEK.

&&

.UPDATE...
ISSUED AT 754 PM EDT MON MAY 28 2012

THE GRIDDED FCST DATABASE WAS RECENTLY UPDATED TO REFLECT THE
DELAYED ARRIVAL TIME OF THE CONVECTION WITH THE APPROACHING COLD
FRONT. HAVE MAINTAINED LIKELY POPS FOR TONIGHT... BUT HAVE PLACED
THE EMPHASIS ON THE 03Z-09Z /11PM-5AM EDT/ TIME FRAME.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 217 PM EDT MON MAY 28 2012

THE MAIN ISSUE DEALS WITH THE TIMING AND STRENGTH OF ANY STORMS.

THE ATMOSPHERE REMAINS UNSTABLE HERE IN MI AHEAD OF THE COLD FRONT
THAT WAS TRACKING INTO IN MN. THAT ATMOSPHERE HERE REMAINS CAPPED
AND HIGHER CLOUDS WERE FILTERING THE SUN SOMEWHAT. AS THE FRONT
NEARS LATER THIS AFTERNOON THE LIFT SHOULD OVERCOME THE WARMER AIR
ALOFT AND PRODUCE SCATTERED TO NUMEROUS SHOWERS AND THUNDERS. IT
APPEARS THAT THIS WILL MOST LIKELY HAPPEN AFTER 6 PM. MOISTURE
REMAINS POOLED UP AROUND CAD...PERHAPS AS A RESULT OF THE HEAVIER
RAIN SAT INTO SUN. SO IF A STORM DOES POP UP AHEAD OF THE MAIN
LINE IT LOOKS LIKE IT WOULD BE FOR THE REGION NORTH OF A MT
PLEASANT TO BIG RAPIDS LINE. THE MOVEMENT WOULD BE NORTHEAST
QUICKLY AT OVER 30 MPH.

MODELS CONTINUE TO SHOW THE DEEP LAYER SHEAR INCREASING THIS
EVENING. THIS WOULD ACT TO ORGANIZED THE STORMS WHICH INCREASES
THE SEVERE THREAT. DAMAGING WINDS AND LARGE HAIL APPEAR TO BE THE
MAIN THREATS. THE BULK OF THE STORMS SHOULD MOVE EAST OF KLAN AS
THE COLD FRONT ADVANCES EAST.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 300 PM EDT MON MAY 28 2012

HIGH PRESSURE WILL BRING FAIR AND COOL WX WEDNESDAY WITH MAX TEMPS
ONLY REACHING THE LOW TO MID 60S. LOW PRESSURE TRACKING NE THRU THE
OH VALLEY REGION WILL BRING A CHANCE OF SHOWERS AS EARLY AS THURSDAY
AFTERNOON BUT MAINLY FOR THURSDAY NIGHT AND FRIDAY. ALL OF OUR FCST
AREA COULD GET SOME RAINFALL FROM THIS SYSTEM BUT THE BEST CHC FOR
RAIN WILL BE SE OVER TOWARD LAN AND JXN.

SIGNIFICANT MEDIUM RANGE DIFFERENCES EXIST REGARDING TRACK OF THE
LOW AND TIMING OF RAINFALL INTO OUR AREA. 12Z GFS GUIDANCE IS MUCH
SLOWER/FURTHER WEST THAN THE 00Z ECMWF AND SUGGESTS THAT RAINFALL
WOULD NOT REACH OUR AREA UNTIL FRIDAY MORNING. SO AT THIS TIME WE
DID NOT MAKE ANY SIGNIFICANT CHANGES TO OUR PREVIOUS FCST WHICH
FEATURES LOW POPS THURSDAY AFTERNOON AND HIGHER POPS FOR THURSDAY
NIGHT INTO FRIDAY.

TEMPS WILL CONTINUE TO AVERAGE ABOUT FIVE TO TEN DEGREES BELOW
NORMAL THROUGH THE LONG RANGE FCST PERIOD..

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 754 PM EDT MON MAY 28 2012

LATEST TIMING/EXTRAPOLATION TOOL HAS THE LINE OF CONVECTION OVER
WI AT 00Z REACHING THE MKG TERMINAL AROUND 02Z AND THE LAN/JXN
TERMINALS TOWARD 06Z. THE LINE IS RATHER NARROW... SO WENT WITH
ONLY ABOUT TWO HOURS OF THUNDER AT EACH TAF SITE. OTHERWISE VFR
CONDITIONS ARE EXPECTED AHEAD OF... AND BEHIND... THE COLD FRONT
TONIGHT AND TUESDAY.

GUSTY SW SFC WINDS SHOULD DIMINISH AFTER SUNSET HOWEVER THE LOW
LEVEL JET WILL BE OVERHEAD THIS EVENING SO WINDS ABV 1K FT AGL
WILL MAINTAIN AT 35-45 KTS THROUGH ABOUT 06Z. SFC WINDS WILL
BECOME STRONG/GUSTY AGAIN ON TUESDAY AFTER ABOUT 15Z OUT OF THE
WEST-SOUTHWEST /APPROX 250 DEGREES/.

&&

.MARINE...
ISSUED AT 147 PM EDT MON MAY 28 2012

SOUTHWEST WINDS 15 TO 25 KTS EXPECTED TODAY RESULTING IN WAVES 2
TO 4 FEET. FORECAST WAS UPDATED BY 9 AM TO REFLECT THE HIGHER
WAVES AND INCREASED RISK FOR RIP CURRENTS.  MAIN HAZARD WILL BE
THUNDERSTORMS LATE THIS AFTERNOON AND EVENING.

WILL NEED TO MONITOR THE RISK FOR A SMALL CRAFT ADVISORY TUE NIGHT
OR WED.

&&

.HYDROLOGY...
ISSUED AT 300 PM EDT MON MAY 28 2012

STORMS COULD PRODUCE LOCALLY HEAVY RAINFALL TONIGHT. ANY PROBLEMS
APPEAR TO BE LIMITED TO URBAN AND POOR DRAINAGE AS THE STORMS WILL
ONLY LAST AN HOUR OR SO GIVEN THE FAST FLOW. RUNOFF INTO THE
RIVERS IS NOT EXPECTED TO CAUSE SIGNIFICANT RISES.

&&

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

UPDATE...MEADE
SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...LAURENS
AVIATION...MEADE
HYDROLOGY...MJS
MARINE...MJS

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
259 PM EDT MON MAY 28 2012

MIZ037>040-043>046-050>052-056>059-064>067-071>074-291900-
MASON-LAKE-OSCEOLA-CLARE-OCEANA-NEWAYGO-MECOSTA-ISABELLA-MUSKEGON-
MONTCALM-GRATIOT-OTTAWA-KENT-IONIA-CLINTON-ALLEGAN-BARRY-EATON-
INGHAM-VAN BUREN-KALAMAZOO-CALHOUN-JACKSON-
259 PM EDT MON MAY 28 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST LOWER
MICHIGAN.

.DAY ONE...TODAY AND TONIGHT

STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED EVENING INTO TONIGHT. THE
MAIN THREAT WITH THESE STORMS IS LARGE HAIL AND DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON OR EVENING.

LMZ844>849-291900-
ST JOSEPH TO SOUTH HAVEN MI-SOUTH HAVEN TO HOLLAND MI-
HOLLAND TO GRAND HAVEN MI-GRAND HAVEN TO WHITEHALL MI-
WHITEHALL TO PENTWATER MI-PENTWATER TO MANISTEE MI-
259 PM EDT MON MAY 28 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST LOWER
MICHIGAN.

.DAY ONE...TODAY AND TONIGHT

A MODERATE RISK FOR RIP CURRENTS WILL EXIST NORTH OF VAN BUREN
COUNTY THROUGH TONIGHT.

STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED THIS AFTERNOON OR
EVENING. THE MAIN THREAT WITH THESE STORMS IS LARGE HAIL AND
DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON OR EVENING.

OSTUNO MJS