Severe Thunderstorm Warning 123, NWS Gaylord, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1040 AM EDT FRI SEP 8 2006

.UPDATE...COLD FRONT PROGRESSING THIS MORNING TO THE STRAITS AROUND
SUNRISE. THE SUNSHINE THEN BEGAN TO BLUNT THE NOSE OF THE COLD AIR
INITIALLY, BUT THE CLOUD COVER ASSOCIATED WITH THE 850 FRONT HAS
BEEN POWERING THROUGH UPPER MICHIGAN SO THAT LOWER CLOUDS ARE
BEGINNING TO MAKE THEIR MOVE SOUTH OF THE STRAITS. A TIMING OF THE
PROGRESSION CURRENTLY GIVE THE CLOUD LINE ROUGHLY JUST NORTH OF KAPN
TO KGLR TO KFKS BY 18Z. THE 500 MB VORTMAX SUPPORTING THE COLD FRONT
IS THE MAJOR PLAYER WITH THE SYSTEM AND IS LOCATED IN N MINNESOTA.
CURRENT 88D (BOTH MQT AND APX) SHOW SHOWERS AND A FEW THUNDERSTORMS
PUSHING THROUGH UPPER MICHIGAN JUST BEHIND THE MAIN COLD FRONT.
SO...NORTH OF M-72, FORECAST LOOKS GOOD WITH RAIN SHOWERS AND
ISOLATED THUNDER. SOUTH OF M-72 WILL PROBABLY SCALE BACK THE THUNDER
POTENTIAL IF NOT BY 11 AM PROBABLY BY 1 PM, ONCE I AM CONVINCED THAT
THE CLOUDS WILL LIMIT THE INSOLATION TO THE SOUTHERN COUNTIES OF THE
FORECAST AREA AND THUS THE THUNDER.

LUTZ

&&

.PREV DISCUSSION...ISSUED 430 AM EDT FRI SEP 8 2006
LATEST SURFACE/SATELLITE/RUC ANALYSIS SHOWING ENERGETIC NORTHERN
STREAM FLOW ACROSS THE NORTHERN TIER OF STATES INTO CANADA. POTENT
SHORTWAVE IS DROPPING SOUTHEAST ACROSS SOUTHERN ONTARIO BETWEEN MID
LEVEL RIDGE AXIS STRETCHING FAR NORTH INTO THE NORTHWEST TERRITORIES
AND CLOSED CIRCULATION NORTH OF QUEBEC. AT THE SURFACE...COLD FRONT
ASSOCIATED WITH ONTARIO SHORTWAVE MAKING STEADY PROGRESS SOUTH
ACROSS LAKE SUPERIOR AND THE WESTERN UPPER AS A 1022MB CANADIAN
BUILDS IN BEHIND FRONT. LATEST RADAR TRENDS SHOWING A DECAYING LINE
OF SHOWER AND STORMS ALONG AND SLIGHTLY BEHIND FRONT WITH NEW
DEVELOPMENT ACROSS MUCH OF THE EASTERN UPPER AND NORTHERN LAKE
MICHIGAN AHEAD OF FRONT. FORECAST CONCERNS CENTERED ON TIMING OF
SHOWERS AND STORMS WITH FRONTAL PASSAGE...THREAT OF SEVERE
WEATHER...POST FRONTAL COLD AIR MASS...AND POSSIBLE MARINE HEADLINES.

TODAY...BASED OFF EARLY MORNING RADAR TRENDS HAVE SCALED BACK
PRECIPITATION TO SCATTERED COVERAGE ACROSS THE EASTERN UPPER AND THE
TIP OF THE MITT. UNFAVORABLE MORNING TIMING IN THESE AREAS SHOULD
PRECLUDE MUCH OF A THUNDER THREAT. HOWEVER...WILL KEEP MENTION OF
ISOLATED THUNDER PER REGIONAL LIGHTNING PLOT SHOWING SOME REMAINING
THUNDERSTORMS NEAR THE KEWEENAW PENINSULA AND OVER WESTERN LAKE
SUPERIOR. ELSEWHERE...WILL KEEP CHANCE POPS THIS MORNING TO ACCOUNT
FOR THUNDERSTORMS FIRING ACROSS CENTRAL WISCONSIN IN AREA OF
ENHANCED LOW LEVEL JET AND SHOWERS AND STORMS FILLING IN ACROSS LAKE
MICHIGAN. FRONT WILL SAG SOUTH THROUGH THE DAY AND CONTINUE TO
TAKE ON ANAFRONT CHARACTERISTICS WITH THE MAJORITY OF THE
PRECIPITATION FALLING BEHIND THE FRONT IN THE COOL AIR. COVERAGE
SHOULD INCREASE THIS AFTERNOON OVER OUR SOUTH AND SOUTHEASTERN ZONES
WITH FAVORABLE DIURNAL TIMING. AS FOR SEVERE WEATHER...LATEST SPC
DAY ONE OUTLOOK HAS ALL AREAS FROM MACKINAW COUNTY SOUTH IN SLIGHT
RISK. KINEMATICS RATHER UNIMPRESSIVE AS BEST MID LEVEL WIND FIELDS
AND SHEAR PASS NORTH WITH SHORTWAVE. 0-6 KM BULK SHEAR OVER THE CWA
IS ONLY ABOUT 20 KNOTS WITH 500 MB WIND SPEEDS OF ONLY 25 TO 30
KNOTS. THERMODYNAMICS MORE IMPRESSIVE...ESPECIALLY SOUTH. SB CAPE
APPROACHES 1700 J/KG WITH ML CAPE OF NEARLY 800 J/KG. IN
ADDITION...WET BULB HEIGHTS ARE ONLY 10.3 KM WITH A FREEZING LEVEL
OF 11.1 KM. BASED OFF THE ABOVE...FEEL HAIL WOULD BE THE PRIMARY
THREAT. THAT BEING SAID...EXTREME SHALLOW NATURE OF FRONTAL ZONE MY
INHIBIT DEEP MOIST CONVECTION IN MORE FAVORABLE UNSTABLE AREAS AHEAD
OF FRONT. AS FOR TEMPERATURES...WILL FOLLOW A NON-DIURNAL TREND AND
SPREAD COOLER AIR SOUTH BEHIND FRONT.

TONIGHT...FRONT WILL BE SLOW TO CLEAR THE AREA AS IT ALIGNS ITSELF
PARALLEL TO MID LEVEL WIND FIELD AND WITH BEST UPPER LEVEL DYNAMIC
PASSING NORTH. REGION IS ALSO IN FAVORABLE RIGHT ENTRANCE REGION OF
80 KNOT 300 MB JET WITH UPPER LEVEL DIVERGENCE NOTED OVER THE AREA.
GIVEN THIS AND PAST HISTORY OF FRONT WITH PRECIPITATION WELL NORTH
OF FRONTAL ZONE WILL KEEP GOING FORECAST OF POPS ACROSS THE NORTHERN
LOWER...TAPERED FROM NORTH TO SOUTH. LINGERING INSTABILITY THIS
EVENING MAY LEAD TO SOME THUNDERSTORMS SO WILL KEEP IN FORECAST.

SATURDAY...WILL LINGER CHANCE POPS FAR SOUTH AS GFS HAS BEEN
CONSISTENT IN SHOWING SOME LIGHT PRECIPITATION WELL NORTH OF FRONT.
ELSEWHERE...850 MB CAA CONTINUES WITH READINGS DROPPING TO 2C BY
EVENING. THIS WILL LEAD TO IMPRESSIVE SHALLOW OVER WATER INSTABILITY
WITH DELTA TS APPROACHING 18C. NORTHEAST WINDS SHOULD BRING IN LAKE
GENERATED STRATUS TO MUCH OF THE NORTHEASTERN LOWER.
ELSEWHERE...EXPECT MORNING MOSTLY CLOUDY CONDITIONS GIVING WAY TO
PARTLY CLOUDY SKIES. IT WILL BE MUCH COOLER WITH HIGHS ONLY REACHING
THE 50S IN MOST AREAS.

REST OF FORECAST LEFT UNCHANGED.

MARINE...GUSTY NORTH AND NORTHEAST WINDS BEING OBSERVED DIRECTLY
BEHIND FRONT THIS MORNING IN THE WESTERN UPPER AND LAKE SUPERIOR.
WILL START SCA FOR WHITEFISH BAY AND THE SAINT MARYS RIVER AT NOON
TO ACCOUNT FOR THESE GUSTY WINDS. NORTH WINDS WILL SPREAD SOUTH OVER
NORTHERN LAKE MICHIGAN EARLY THIS AFTERNOON AND WILL HOIST SCA NORTH
OF SLEEPING BEAR POINT STARTING EARLY THIS AFTERNOON.

MSB

&&

.APX...WATCHES/WARNINGS/ADVISORIES...NONE.

&&

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE GAYLORD MI
1043 AM EDT FRI SEP 8 2006

LHZ345>349-361-362-LMZ323-341-342-344-345-363-LSZ321-322-MIZ008-
015>036-041-042-091000-
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-MICHIGAN WATERS OF NORTHERN LAKE HURON-
MICHIGAN WATERS OF CENTRAL LAKE HURON-GRAND TRAVERSE BAY-
SEUL CHOIX PT TO MACKINAC BRDG-NORWOOD TO MACKINAC BRDG-
SLEEPING BEAR PT TO GRAND TRAVERSE LT-MANISTEE TO SLEEPING BEAR PT-
MICHIGAN WATERS OF NORTHERN LAKE MICHIGAN-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-
1043 AM EDT FRI SEP 8 2006

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

.DAY ONE...THIS AFTERNOON AND TONIGHT...

SCATTERED THUNDERSTORMS ARE EXPECTED THIS AFTERNOON ACROSS EASTERN
UPPER AND NORTHERN LOWER MICHIGAN. SOME THUNDERSTORMS MAY BECOME
SEVERE TODAY...ESPECIALLY ALONG AND SOUTH OF M-72. THE PRIMARY RISK
WILL BE HAIL UP TO PENNY SIZE.

THERE IS AN INCREASED RISK OF RIP CURRENTS THIS AFTERNOON ON LAKE
MICHIGAN BEACHES OF NORTHERN LOWER MICHIGAN AND WHITEFISH BAY OF
EASTERN UPPER MICHIGAN.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

PATCHY FROST IS POSSIBLE SATURDAY NIGHT...WITH TEMPERATURES DIPPING
INTO THE LOWER AND MIDDLE 30S ACROSS THE INTERIOR REGIONS OF
NORTHERN MICHIGAN.  THESE TEMPERATURES COULD BE COLD ENOUGH TO HARM
TENDER VEGETATION...AND YOU SHOULD BE PREPARED TO PROTECT PLANTS
SATURDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS POSSIBLE TODAY.

MSB/LUTZ