Severe Thunderstorm Warning 22, NWS Grand Rapids, MI

590 
WWUS53 KGRR 111341
SVSGRR

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
941 AM EDT WED MAY 11 2011

MIC105-111400-
/O.CON.KGRR.SV.W.0022.000000T0000Z-110511T1400Z/
MASON MI-
941 AM EDT WED MAY 11 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR NORTHEASTERN
MASON COUNTY UNTIL 1000 AM EDT...

AT 937 AM EDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE TRACKING
A CLUSTER OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING LARGE HAIL UP 
TO GOLFBALL SIZE.  THESE STORMS EXTENDED FROM MANISTEE TO 
FREESOIL...AND WERE MOVING EAST AT 20 MPH.

LOCATIONS IMPACTED INCLUDE...
  FREESOIL...           MEADE TWP...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS CAN PRODUCE DAMAGING WIND IN EXCESS OF 60 MILES
PER HOUR...DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN.
FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF
YOUR HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT
DRIVE INTO AREAS WHERE WATER COVERS THE ROAD.

&&

LAT...LON 4418 8636 4417 8604 4411 8604 4405 8629
      4413 8637 4417 8640 4418 8636 4419 8639
      4420 8637
TIME...MOT...LOC 1340Z 258DEG 16KT 4417 8630 4407 8621
WIND...HAIL 60MPH 1.00IN

$$

TJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
822 AM EDT WED MAY 11 2011

LATEST UPDATE...AVIATION...

.SYNOPSIS...(400 AM EDT WED MAY 11 2011)
IT WILL BE UNSEASONABLY MILD WITH A CHANCE OF THUNDERSTORMS TODAY
THROUGH FRIDAY. TEMPERATURES WILL UNDERGO A GRADUAL COOLING TREND
THIS WEEKEND WITH RAIN SHOWERS. TEMPERATURES WILL CONTINUE ON A
COOLING TREND TO BELOW NORMAL FOR THE EARLY PART OF NEXT WEEK.

&&

.SHORT TERM...(400 AM EDT WED MAY 11 2011)
(TODAY THROUGH FRIDAY AFTERNOON)

OUR PRIMARY FORECAST CHALLENGE INVOLVES DETERMINING PROBABILITIES
AND COVERAGE OF CONVECTION THROUGH THE SHORT TERM FCST PERIOD.

UNSEASONABLY MILD WX ANTICIPATED TODAY WITH MAX TEMPS REACHING THE
UPPER 70S TO LOWER 80S ALONG WITH AN INCREASE IN HUMIDITY AS DEW PTS
CLIMB UP INTO THE 50S. BOTH 00Z GFS AND 00Z NAM GUIDANCE ARE IN GOOD
AGREEMENT IN SHOWING AN AXIS OF ENHANCED INSTABILITY (SB CAPES
AROUND 2000 J/KG) WILL DEVELOP FROM NEAR GRR SOUTH TO AZO BY LATE
AFTN/EARLY EVE. I RAISED POPS SLIGHTLY FOR THE CHC FOR TSTORMS
TODAY.

ALSO RAISED POPS TO HIGH CHC ACROSS OUR AREA FOR TONIGHT. 00Z 4KM
WRF-NMM SIM Z GUIDANCE SUGGESTS THAT CONVECTION WHICH WILL DEVELOP
ACROSS WI/IL THIS AFTN WILL TRACK ENE ACROSS LWR MI OVERNIGHT. GIVEN
THE INSTABILITY AND STRONG WARM FRONT NEAR OUR AREA WE WILL HAVE TO
MONITOR THIS CLOSELY FOR POTENTIAL FOR STRONG TO A FEW LOCALLY
SEVERE STORMS PARTICULARLY FROM MID TO LATE AFTN THRU THE EVENING.

MORE SCATTERED SHOWERS AND STORMS ARE ANTICIPATED THURSDAY
(PARTICULARLY IN THE AFTERNOON/EVENING) AS INSTABILITY RAMPS BACK UP
WITH MAX TEMPS EXPECTED TO REACH THE LOW TO MID 80S AND DEW PTS INTO
THE LOWER 60S. SB CAPES SHOULD ONCE AGAIN REACH THE 1000-2000 J/KG
RANGE IN THE AFTN/EARLY EVE. WIND FIELDS/SHEAR VALUES THURSDAY
THROUGH THURSDAY NIGHT LOOK VERY WEAK THOUGH. SCATTERED SHOWERS AND
STORMS REMAIN IN THE FCST INTO FRIDAY AND IT WON/T BE QUITE AS WARM
BUT STILL ABOVE NORMAL.

&&

.LONG TERM...(400 AM EDT WED MAY 11 2011)
(FRIDAY NIGHT THROUGH TUESDAY)

THE MAIN CHALLENGE IN THE LONG TERM DEALS WITH THE RISK FOR RAIN FRI
NIGHT INTO SAT.  COMPLICATED AND UNUSUAL MID TO UPPER LEVEL PATTERN
FOR FRI NIGHT INTO SAT.  ONE UPPER LOW DOWN IN ARKANSAS TRIES TO
LIFT NORTH TOWARD LOWER MI AS A SECOND UPPER LOW OVER IN NEBRASKA
DIVES TOWARD THE GULF.  GIVEN THE FALLING HEIGHTS HERE IN LOWER
MI...ALONG WITH DECENT MOISTURE AROUND...SUSPECT AN EXPANDING AREA
OF RAIN WILL BE DEVELOPING ON SATURDAY. PWAT VALUES ARE WELL ABOVE
NORMAL 12Z SAT.  I INCREASED THE POPS TO ACCOUNT FOR THIS.
TEMPERATURES WILL ALSO BE A CHALLENGE WITH A STRENGTHENING NORTHEAST
FLOW.  I LOWERED TEMPS ON SAT FOR THIS REASON.  I SUSPECT WITH 850
MB WINDS OVER 35 KNOTS FOR PARTS OF THE REGION SAT INTO SUN SHOWN BY
THE ECMWF...THAT IT WILL END UP BLUSTERY AS WELL.

&&

.AVIATION...(822 AM EDT WED MAY 11 2011)
THE MAIN CHALLENGE IN THE AVIATION FORECAST DEALS WITH THE RISK FOR
STORMS TODAY.   THE ATMOSPHERE IS UNSTABLE AND MOISTURE WILL BE ON
THE INCREASE...BUT A WEAK CAP WILL BE PRESENT.  WITH SOME LIFT
ARRIVING WE MAY SEE A FEW STORMS DEVELOPING THROUGH THE AFTERNOON
AND EVENING.  NOT CONFIDENT ENOUGH TO FEATURE THEM IN THE
TAFS...BUT WILL NEED TO MONITOR THE TRENDS CLOSELY THROUGH THE
DAY.   PRIMARILY VFR OUTSIDE OF ANY STORMS TODAY...BUT OVERNIGHT WE
COULD SEE VISIBILITIES DROPPING IN SOME LIGHT FOG.

&&

.MARINE...(400 AM EDT WED MAY 11 2011)
VISIBILITY ISSUES RELATED TO FOG AND HAZE WILL LIKELY BECOME AN
ISSUE LATER TODAY THROUGH THURSDAY INTO FRIDAY. IN ADDITION THE
THREAT OF THUNDERSTORMS WILL POSE A HAZARD TO MARINERS FROM THIS
AFTERNOON THROUGH MIDDAY FRIDAY.

&&

.HYDROLOGY...(400 AM EDT WED MAY 11 2011)
ONLY ONE RIVER FLOOD ADVISORY REMAINS. COVERAGE/INTENSITY OF
SCATTERED THUNDERSTORMS TODAY THROUGH FRIDAY SHOULD BE TOO LOW TO
HAVE A SIGNIFICANT IMPACT ON RIVER LEVELS.

&&

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

&&

SYNOPSIS:    LAURENS
SHORT TERM:  LAURENS
LONG TERM:   MJS
AVIATION:    MJS
MARINE:      LAURENS
HYDROLOGY:   LAURENS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
557 AM EDT WED MAY 11 2011

MIZ037>040-043>046-050>052-056>059-064>067-071>074-121000-
MASON-LAKE-OSCEOLA-CLARE-OCEANA-NEWAYGO-MECOSTA-ISABELLA-MUSKEGON-
MONTCALM-GRATIOT-OTTAWA-KENT-IONIA-CLINTON-ALLEGAN-BARRY-EATON-
INGHAM-VAN BUREN-KALAMAZOO-CALHOUN-JACKSON-
557 AM EDT WED MAY 11 2011

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

.DAY ONE...TODAY AND TONIGHT

A FEW THUNDERSTORMS ARE POSSIBLE THROUGH TONIGHT. AN ISOLATED
SEVERE THUNDERSTORM COULD DEVELOP WITH DAMAGING WINDS AND LARGE HAIL THE
PRIMARY THREAT.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

SCATTERED THUNDERSTORMS ARE POSSIBLE INTO SATURDAY. AN ISOLATED
SEVERE THUNDERSTORM MAY OCCUR...WITH DAMAGING WINDS AND LARGE
HAIL THE PRIMARY RISKS. LOCALLY HEAVY RAINFALL IS POSSIBLE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED.

LMZ844>849-121000-
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-
557 AM EDT WED MAY 11 2011

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

.DAY ONE...TODAY AND TONIGHT

A FEW THUNDERSTORMS ARE POSSIBLE THROUGH TONIGHT. CLOUD TO WATER
LIGHTNING STRIKES...GUSTY WINDS AND HAIL ARE THE PRIMARY HAZARDS.

FOG COULD LEAD TO AREAS OF LOW VISIBILITY.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

A RISK FOR THUNDERSTORMS WILL EXIST INTO SATURDAY. IN ADDITION
WINDS AND WAVES WILL BE ON THE INCREASE THIS WEEKEND.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED.

MJS

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
914 AM EDT WED MAY 11 2011

MIZ037-111415-
MASON-
914 AM EDT WED MAY 11 2011

...SIGNIFICANT WEATHER ADVISORY...

AT 909 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM OVER EXTREME NORTHWEST MASON COUNTY...MOVING
NORTHEAST AT 25 MPH.

WINDS GREATER THAN 40 MPH...FREQUENT CLOUD TO GROUND LIGHTNING...
BRIEF HEAVY DOWNPOURS...ARE POSSIBLE WITH THIS STORM.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

GUSTY WINDS MAY CAUSE SMALL OBJECTS SUCH AS TRASH BINS TO BLOW
AROUND. STAY AWAY FROM HIGH OBJECTS OUTDOORS SUCH AS TREES. SEEK
SHELTER IN A STURDY STRUCTURE UNTIL THIS STORM HAS PASSED.

&&

LAT...LON 4419 8637 4418 8637 4417 8607 4404 8645
      4409 8648 4412 8644 4417 8640 4418 8637
      4419 8639 4420 8637
TIME...MOT...LOC 1313Z 244DEG 21KT 4417 8638

93