Hail and Damaging Winds in Michigan, May 22, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
157 PM EDT SUN MAY 22 2011

.SYNOPSIS.../ISSUED AT 315 AM/

MILD...AND RATHER WET...PERIOD OF WEATHER EXPECTED TO CONTINUE INTO
THE BEGINNING OF THE NEW WORK WEEK AS ORGANIZING LOW PRESSURE OFF TO
OUR WEST PUSHES INTO...AND THROUGH...THE REGION LATER TONIGHT AND
MONDAY. THIS SYSTEM WILL GENERATE PERIODIC BOUTS OF SHOWERS AND
THUNDERSTORMS THROUGH MONDAY...ALONG WITH MUCH ABOVE NORMAL
TEMPERATURES. CONDITIONS WILL TREND SHARPLY COOLER...BUT QUIETER...
BEHIND THIS SYSTEM...WITH THE NEXT CHANCE OF RAIN ARRIVING LATER IN
THE WEEK.

&&

.SHORT TERM.../ISSUED AT 1139 AM/...THIS AFTERNOON

...SCT TSTMS COULD TURN SEVERE OVER PARTS OF NE LOWER THIS AFTN...

ALL LATE MORNING PRODUCTS POSTED. ONLY CHANGE WAS RECONFIGURATION
OF POPS. HWO HAS BEEN UPDATED BASED ON LATE MORNING ASSESSMENT.

THE 1ST SHRTWV TROF /AND ITS INITIAL SURGE OF COOL AIR ALOFT/ IS
EXITING THE FCST AREA ATTM. MSTR CHANNEL IMAGERY AND ANALYZED 700
MB ANALYSIS REVEALS A 2ND SHRTWV TROF RACING NE THRU WI/IL. THIS
TROF WAS ASSOCIATED WITH AN ARC OF NOCTURNAL TSTMS THAT HAS FALLEN
APART SAVE FOR A FEW DISSIPATING SHWRS/TSTMS LIFTING NWD INTO THE
MN ARROW-HEAD AND WRN LAKE SUP. AWIPS TIMING TOOL BRINGS THIS TROF
INTO NW LOWER BY 16Z AND EXIT E OF THE FCST AREA BY 21Z.

LOW-LEVEL WIND PROFILE HAS BACKED IN THE WAKE OF THE EXITING SHRTWV
TROF. LOW-LEVELS ARE DRY ON DVN/ILX RAOBS AND THIS DRY AIR WILL
ADVECT INTO NRN MI ON SW WINDS.

VIS SAT IMAGERY SHOWS LARGELY CLEAR SKIES FROM NRN MI WSW TO THE
NEXT SURGE OF LOW-LEVEL MSTR APPROACHING DVN/ILX...WITH 2-5K FT
CIGS. THIS IS WHERE THE TAIL END OF THE OUTFLOW BOUNDARY FROM LAST
NIGHT'S TSTMS IS LIFTING NEWD. TIMING TOOL BRINGS LEADING EDGE TO
MBL AROUND 02Z. THIS WILL BE A LOCATION FOR CONVECTIVE INITIATION
(CI) SW OF THE FCST AREA THIS AFTN.

LOOKING AT 12Z RUC/06Z NAM SOUNDINGS...THIS GUIDANCE IS NOT
HANDLING THE ADVECTION OF DRY AIR FROM THE SW. THIS HAS BEEN USED
TO REMOVE POPS OVER MOST OF NW LOWER THIS AFTN.

GRB 88D AND VIS IMAGERY SHOW NEWLY DEVELOPING SHWRS FROM IMT-MNM
ASSOCIATED WITH APPROACHING TROF. HIGH-RES MODELS SUGGEST THIS
BLOSSOMS SEWD INTO AN ARC OF TSTMS FROM THE U.P. INTO THE TIP OF
THE MITT. WORST CASE SCENARIO SUGGESTS SE DEVELOPMENT COULD EXTEND
AS FAR S AS THE THUMB. 6 HR SPAGHETTI PLOTS OF MULTI-MODEL QPF ARE
ON BOARD INDICATING THE ERN U.P. AND NE LOWER.

IT WILL BE A RACE AGAINST TIME THO AS DRIER AIR ADVECTS IN FROM THE
SW.

HAVE ADJUSTED POPS TO LIKELY N OF A LINE FROM WRN MACKINAC COUNTY
TO HARRISVILLE. A RIBBON OF CHANCE POPS TO THE SW AND NO POPS S OF
GRAND TRAVERSE BAY.

MLCAPE FROM MODIFIED SOUNDINGS OFFER 1000-1500 K/KG BASED ON 80/58.
DEEP LAYER SHEAR WILL BE AROUND 35 KTS. WHILE LOW-LEVEL WIND
SPEEDS ARE NOT STRONG...PROFILES ARE STILL VEERING. WITH 0-3 KM
SRH AVERAGING 150 M2/S2..."IF" CI OCCURS OVER NE LOWER..THIS WILL
SUPPORT POSSIBLE SUPERCELL DEVELOPMENT. NON-ROTATING STORM MOTION
23035KT.

THREATS: DRYING MID-LEVELS SUPPORTS POTENTIAL FOR MICROBURST
WINDS. CAPE IN THE HAIL GROWTH ZONE NOT SIGNIFICANT...WITH
MARGINAL LAPSE RATES. MULTICELL STORM STRUCTURES WOULD SUPPORT
LOW-END SVR HAIL. WITH BACKED LOW-LEVEL FLOW...ESPECIALLY ALONG
THE LAKE HURON COAST...AN ISOLD TORNADO IS POSSIBLE CONTINGENT
UPON TSTMS DEVELOPING.

50 DBZ TO 37K FT WILL BE MULTICELL HAIL THREASHOLD.

BASED ON COOL/OVC CONDITIONS OVER THE ERN U.P. ANY STORMS THAT
MOVE SHOULD BE ELEVATED.

HAVE INTRODUCED MENTION OF SEVERE INTO THE FCST FOR NE LOWER.

JH

&&

.LONG TERM.../ISSUED AT 315 AM/...TONIGHT AND BEYOND

VERTICALLY STACKED LOW WILL MOVE INTO THE UPPER MISSISSIPPI VALLEY
TONIGHT AND THEN SLIDE THRU LAKE SUPERIOR ON MONDAY. CHANCE OF
STRONG/SVR CONVECTION WILL LIKELY INCREASE LATER TONIGHT AS A 50 KT
LOW LEVEL JET PUNCHES INTO NRN LWR MICHIGAN BY 06Z MONDAY. 850 MB
THETA E RIDGING AND INSTABILITY AXIS WILL ACCOMPANY THIS LOW LEVEL
JET. ANY DIURNAL ENHANCEMENT TO INSTABILITY WILL BE GONE BY THIS
TIME...BUT ARRIVAL OF THE 500 MB COLD POOL SHOULD PROVIDE SUFFICIENT
INSTABILITY. WINDS BECOME NEARLY UNIDIRECTIONAL BY THIS TIME...WHILE
WET-BULB ZERO HEIGHTS APPROACHING 11 KFT. THUS...PRIMARY SVR WX
THREAT WILL BE DAMAGING WINDS...AND TO A LESSER EXTENT...LARGE HAIL.
BEST INSTABILITY AND MAXIMUM IMPACT OF THE LOW LEVEL JET WILL TARGET
OUR SOUTHERN COUNTIES...SO WILL KEEP LIKELY POPS FOR THIS AREA
OVERNIGHT...WITH HIGH CHANCE POPS FOR THE REST OF NRN LWR AND ERN
UPR MICHIGAN. CHANCES OF THUNDER WILL PERSIST INTO MONDAY AS THE LOW
SLIDES TO OUR NORTH...BUT WILL WANE AS THE DAY PROGRESSES AND
COOLER/MORE STABLE AIR BEGINS TO FILTER INTO THE REGION FROM NW TO
SE. OUR FAR SE COUNTIES MAY HAVE A FINAL SHOT AT SOME STRONGER
CONVECTION MONDAY AFTERNOON BEFORE THE COLD FRONT MOVES THRU...BUT
WITH MODELS STILL DIFFERING ON THE TIMING OF FROPA...WILL SIMPLY
CONTINUE TO ADVERTISE THUNDER CHANCES FOR LOCATIONS SOUTH OF A LINE
FROM APN TO CAD MONDAY AFTERNOON...WITH ONLY SHOWERS NORTH OF THAT
LINE.

DRY WX WILL RETURN TO NORTHERN MICHIGAN MONDAY NIGHT AS COOL
CANADIAN HIGH PRESSURE BUILDS INTO THE REGION. HIGH PRESSURE...
SUBSIDENCE AND DRY AIR WILL REMAIN IN CONTROL THRU TUESDAY NIGHT.
UNSEASONABLY COLD AIRMASS IN PLACE COMBINED WITH MOSTLY CLEAR SKIES
AND LIGHT WINDS WILL ALLOW TEMPS TO CLOSE TO AND POSSIBLY BELOW
FREEZING IN SOME LOCATIONS LATE TUESDAY NIGHT. THOSE WHO HAVE
ALREADY PLANTED OUTDOOR GARDENS AND SENSITIVE FLOWERS WILL NEED TO
KEEP A CLOSE EYE ON THE FORECAST FOR TUESDAY NIGHT.

LAST VESTIGES OF THE DEPARTING COLD FRONT WILL STALL OVER THE OHIO
VALLEY ON TUESDAY...AS ANOTHER AREA OF LOW PRESSURE DEVELOPS OVER
THE CENTRAL PLAINS ALONG THIS BOUNDARY. RAIN CHANCES WILL AGAIN
INCREASE FOR OUR SOUTHERN COUNTIES WEDNESDAY AND THURSDAY AS
MICHIGAN FINDS ITSELF IN A SQUEEZE PLAY BETWEEN STRONG CANADIAN HIGH
PRESSURE TO THE NORTH AND DEVELOPING LOW PRESSURE TO OUR SW. WILL
KEEP A CHANCE OF SHOWERS IN THE FORECAST FOR THURSDAY AND FRIDAY...
BUT ITS HARD TO SAY JUST HOW FAR NORTH THESE SHOWERS WILL BE ABLE TO
REACH WITH THE STRONG HIGH HOLDING TO OUR NORTH. ONE THING IS FOR
SURE...OUR TEMPS WILL REMAIN BELOW NORMAL FOR THE LAST HALF OF THE
WEEK...WITH AFTERNOON HIGHS IN THE UPPER 50S AND LOWER 60S AND
OVERNIGHT LOWS IN THE 40S.

&&

.MARINE.../ISSUED AT 315 AM/

LOW PRESSURE APPROACHING THE REGION WILL SUPPLY SEVERAL ROUND OF
SHOWERS AND THUNDERSTORMS TO THE WATERS FROM TODAY THROUGH
MONDAY...THOUGH OVERALL...WINDS WILL REMAIN LIGHT (15 KNOTS OR LESS)
AS PLENTIFUL OVER-WATER STABILITY REMAINS. OF COURSE...GUSTY
CONDITIONS ARE POSSIBLE AROUND ANY THUNDERSTORMS. A COLD FRONT
CROSSING THE WATERS LATER MONDAY WILL END THE THREAT FOR SHOWERS AND
STORMS...BUT PROVIDE A QUICK SHIFT IN WINDS TO A NORTHERLY
DIRECTION...WITH SOME BRIEF GUSTS TO 25 KNOTS POSSIBLE MONDAY NIGHT.
THEREAFTER...HIGH PRESSURE WILL BUILD THROUGH THE NORTHERN LAKES
FROM ONTARIO INTO MIDWEEK WITH A RETURN TO LIGHT WINDS AND LOW WAVES.

LAWRENCE/RUNYAN

&&

.AVIATION.../ISSUED AT 157 PM/...VALID FOR 18Z TAFS

THRU 00Z: VFR WITH S-SE WINDS. A TSTM IS POSSIBLE PLN APN. ISOLD
MVFR IN ANY SHWRS/TSTMS. TVC EXPECTED TO REMAIN DRY THRU DAYLIGHT
HRS.

TNGT: VFR TO START WITH SCT SHWRS/TSTMS DEVELOPING WITH ISOLD
POCKETS OF MVFR-IFR CIGS/VSBYS. LLWS DEVELOPED 03Z-10Z.

MON THRU 18Z: ANY IFR MIST/STRATUS LIFTS INTO BKN CU BY 14Z.
UPPER-LOW MOVES IN WITH SCT SHWRS AND ISOLD THUNDER. WINDS BECOME
GUSTY FROM SW.

JH

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.

&&

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE GAYLORD MI
1106 AM EDT SUN MAY 22 2011

LHZ345>349-LMZ323-341-342-344>346-LSZ321-322-MIZ008-015>036-041-042-
231200-
STRAITS OF MACKINAC-ST IGNACE TO FALSE DETOUR CHANNEL-
MACKINAC BRDG TO PRESQUE ISLE LT-PRESQUE ISLE LT TO STURGEON PT-
STURGEON PT TO ALABASTER-GRAND TRAVERSE BAY-
SEUL CHOIX PT TO MACKINAC BRDG-NORWOOD TO MACKINAC BRDG-
SLEEPING BEAR PT TO GRAND TRAVERSE LT-PT BETSIE TO SLEEPING BEAR PT-
MANISTEE TO PT BETSIE-WHITEFISH BAY-ST. MARYS RIVER-CHIPPEWA-
MACKINAC-EMMET-CHEBOYGAN-PRESQUE ISLE-CHARLEVOIX-LEELANAU-ANTRIM-
OTSEGO-MONTMORENCY-ALPENA-BENZIE-GRAND TRAVERSE-KALKASKA-CRAWFORD-
OSCODA-ALCONA-MANISTEE-WEXFORD-MISSAUKEE-ROSCOMMON-OGEMAW-IOSCO-
GLADWIN-ARENAC-
1106 AM EDT SUN MAY 22 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHERN LOWER MICHIGAN...
EASTERN UPPER MICHIGAN...AND ADJACENT NEARSHORE WATERS OF LAKE
MICHIGAN...LAKE HURON AND LAKE SUPERIOR.

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON...OVER THE
EASTERN U.P. AND PARTS OF NORTHEAST LOWER MICHIGAN...MAINLY NORTH OF
A LINE FROM PELLSTON TO OSCODA. SOME OF THE STORMS OVER NORTHEAST
LOWER COULD BE SEVERE.

SCATTERED THUNDERSTORMS ARE POSSIBLE OVER ALL OF NORTHERN MICHIGAN
TONIGHT. SOME STORMS COULD BE SEVERE.

THE MAIN SEVERE WEATHER THREATS TODAY AND TONIGHT WILL BE DAMAGING
WINDS IN EXCESS OF 60 MPH...AND LARGE HAIL ONE INCH IN DIAMETER OR
GREATER.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THE CHANCE OF THUNDERSTORMS WILL CONTINUE INTO MONDAY. SEVERE
WEATHER IS NOT EXPECTED.

FROST AND/OR FREEZE CONDITIONS ARE POSSIBLE LATER TUESDAY NIGHT
THROUGHOUT ALL OF NORTHERN MICHIGAN...ESPECIALLY FOR INLAND
LOCATIONS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND TONIGHT.

JH