Tornadoes and Hail in Michigan, June 13, 2004

AREA FORECAST DISCUSSION...CORRECTED TYPOS
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
945 AM EDT SUN JUN 13 2004

.UPDATE...

SEVERE STORMS ANTICIPATED THIS AFTERNOON/EARLY EVENING.
PLANNING ON 18Z UPPER AIR SOUNDING.

WARM FRONT SLOWLY PUSHING THROUGH SOUTHEAST MICHIGAN THIS MORNING.
CONTINUED BREAKS IN THE LOW CLOUDS EXPECTED...ALLOWING THE AIRMASS
TO DESTABILIZE MODERATELY TO STRONGLY. WITH MAXES IN THE LOWER 80S
AND SURFACE DEW POINTS NEAR 70 DEGREES...SURFACE BASED CAPES WILL
EXCEED 3000 J/KG. UNFORTUNATELY...MID LEVEL WAVE OVER THE UPPER
MISSISSIPPI VALLEY LOOKS TO BE PUSHING INTO WESTERN LOWER MICHIGAN
DURING THE PEAK HEATING OF THE DAY. WIND FIELDS INCREASE NICELY AS
55 KNOT JET AT 500 MB MOVE INTO THE CENTRAL LAKES...INCREASING THE
0-6 KM SHEAR TO AROUND 40 KNOTS. LARGE HAIL AND DAMAGING WINDS
APPEAR LIKELY WITH A FEW STORMS.

AS FAR AS TORNADIC DEVELOPMENT...WILL HAVE TO WATCH THE TRI-CITIES
AND THUMB REGION CLOSELY BY EARLY TO MID-AFTERNOON. SOUTHEAST/BACKED
FLOW NEAR THE WARM FRONT WITH SUFFICIENTLY LOW LCL HEIGHTS. 00Z 4KM
WRF INDICATING THIS SCENARIO...WITH A SOLID LINE OF STORMS
DEVELOPING LATER TODAY AS WELL. WITH PW VALUES RUNNING AROUND 1.50
INCHES...TORRENTIAL RAINFALL ALWAYS A CONCERN. HOWEVER...STORMS
SHOULD BE MOVING A DECENT CLIP (25 MPH)...AND NOT EXPECTING ANY BACK
BUILDING STORMS.

UPDATED ZONES ALREADY SET OUT TO ENHANCE THE WORDING OF THE
THUNDERSTORMS.

SF

.PREVIOUS DISCUSSION...
THE 00Z UPPER AIR PLOTS SHOWED A 110KT UPPER LEVEL JET NOSING INTO
THE PACIFIC NORTHWEST AT THE BASE OF AN UPPER LOW OVER THE GULF OF
ALASKA....WITH ANOTHER UPPER LOW OVER CENTRAL CANADA AND A RIDGE
ACROSS EASTERN NORTH AMERICA. THE CURRENT IR LOOP SHOWS A MESO SCALE
CONVECTIVE SYSTEM COVERING MUCH OF EASTERN KANSAS/WESTERN MISSOURI
ON THE NOSE OF THE LOW LEVEL JET. STRONG OUTFLOW FROM THIS SYSTEM IS
CURRENTLY PRODUCING ADDITIONAL CONVECTION OVER THE MISSOURI/ILLINOIS
BORDER. MEANWHILE...A SURFACE WARM FRONT EXTENDS FROM NORTH CENTRAL
ILLINOIS TO NORTHERN INDIANA. NOT MUCH IN THE WAY OF CONVECTION HAS
OCCURRED ACROSS LOWER MICHIGAN...JUST SOME SCT/BKN STRATO CU. TIMING
AND CHANCES OF CONVECTION AS WELL AS THE POTENTIAL FOR SEVERE
WEATHER TODAY CONTINUES TO BE THE MAIN FORECAST CONCERN THIS
PACKAGE.

AS FAR AS THE OVERALL LARGE SCALE PATTERN...THE 00Z MODEL SUITE ARE
IN OVERALL GOOD AGREEMENT. THEY GENERALLY SHOW THE UPPER LOW OVER
THE GULF OF ALASKA AND THE ONE OVER CENTRAL CANADA GRADUALLY PUSHING
EAST AND WEAKENING. THIS WILL FLATTEN THE RIDGE OVER EASTERN NORTH
AMERICA...LEADING TO A MORE ZONAL FLOW OVER THE NORTHERN CONUS BY
MONDAY...WITH THE MAIN BELT OF WESTERLIES EXTENDING FROM THE PACIFIC
NORTHWEST INTO THE GREAT LAKES. SURFACE FEATURES IN THIS PATTERN
WILL BE RATHER WEAK AND THEREFORE WILL BE INFLUENCED MORE BY SHORT
TERM MESO SCALE FEATURES. THE MODELS WILL CONTINUE TO HAVE
DIFFICULTY HANDLING THESE SYSTEMS...ESPECIALLY BEYOND 12 HOURS.
GIVEN SOME SERIOUS CONVECTIVE FEEDBACK SEEN THROUGHOUT MANY PERIODS
OF THE GFS...WILL LEAN A LITTLE MORE TOWARD THE ETA SOLUTION.

THE WARM FRONT SOUTH OF THE STATE WILL LIFT NORTHWARD THIS MORNING
WITH THE ONSET OF DIURNAL HEATING. THIS FRONT IS EXPECTED TO MOVE
ACROSS THE NORTHERN PORTIONS OF THE FORECAST AREA DURING THE
AFTERNOON. THE DEEPENING BOUNDARY LAYER WILL ALLOW SFC DEWPOINTS TO
RISE INTO THE LOWER 70S SOUTH OF THIS BOUNDARY. CURRENT THINKING IS
THAT THERE WILL BE PERIODS OF SUNSHINE THIS MORNING AND EARLY
AFTERNOON AS STRATO CU MIXES OUT. THUS EXPECT TEMPS TO REACH INTO
THE LOWER 80S WITH SOME HEATING...WHICH SHOULD ALLOW 0-1KM MIXED
LAYER CAPE TO APPROACH 2500 J/KG BY AFTERNOON. A CONVECTIVELY
INDUCED WAVE OVER IOWA IS EXPECTED TO MOVE INTO THE NORTHERN GREAT
LAKES THIS AFTERNOON. THIS WILL SEND A SURFACE TROUGH AXIS INTO THE
REGION FROM THE WEST BY 21Z...PER LATEST MESO ETA. THIS COMBINED
WITH SOME UPPER LEVEL DIVERGENCE WILL BRING A FAIRLY GOOD CHANCE OF
THUNDERSTORMS THIS AFTERNOON AND EVENING. WILL ONLY MENTION A CHANCE
OF CONVECTION SOUTH OF I-69 THIS MORNING AS SOME LOW LEVEL THETA-E
ADVECTION MOVES UP AHEAD OF THE SFC WARM FRONT. THE DAY CREW WILL
HAVE TO MONITOR WHAT THE REMNANTS OF THE UPSTREAM CONVECTION WILL DO
AS THE COMPLEX HAS DRIFTED MUCH FARTHER SOUTH THAN MODELS INDICATED.
A MORE SOUTHERLY TRACK OF SHORT WAVE ENERGY COULD LEAD TO MORE
WIDESPREAD AND STRONGER CONVECTION OVER SE MICHIGAN.

I WILL HIT THE POSSIBILITY OF SEVERE WEATHER THIS AFTERNOON AND
EVENING VERY HARD IN THE HWO GIVEN THE POTENTIAL INSTABILITY.
ALTHOUGH ETA SOUNDINGS INDICATE  0-6KM SHEAR ONLY ON THE ORDER
OF 25-30 M/S...I HAVE CONCERN THAT THE SURFACE WINDS WILL BE MORE
EAST-SOUTHEASTERLY AHEAD OF THE WARM FRONT...ESPECIALLY NEAR LAKE
HURON. THIS WOULD CERTAINLY INCREASE THE DIRECTIONAL SHEAR AS WELL
AS LOW LEVEL HELICITY. WITH THE PRESENCE OF A WARM FRONT...LIFTED
CONDENSATION LEVELS BELOW 3K FT AND 0-3KM HELICITY GREATER THAN 100
M2/S2...THERE IS THE RISK OF ISOLATED TORNADOES LATER TODAY. GIVEN
THE POTENTIAL UPDRAFT STRENGTHS...DAMAGING WINDS AND LARGE HAIL WILL
ALSO BE POSSIBLE.

THE LOW LEVEL FLOW IS EXPECTED TO STRENGTHEN TONIGHT. THE ETA MAX
THETA E CAPE INDICATES NEARLY 1500 J/KG SOUTH OF I-69 THROUGH THE
OVERNIGHT. THE ETA ALSO INDICATES THAT CONVECTION WILL REDEVELOP
OVER NORTHERN ILLINOIS/SOUTHERN WISCONSIN ALONG A LINGERING SURFACE
BOUNDARY. THINK ANY CONVECTION UPSTREAM WILL BE ABLE TO SUSTAIN
ITSELF AS IT MOVES EASTWARD ACROSS THE SOUTHERN LAKES GIVEN THE
ELEVATED INSTABILITY AXIS ACROSS THE REGION. WITH MID LEVEL WINDS
INCREASING TO 50KTS OVERNIGHT AND COOLING 500MB TEMPS INCREASING MID
LEVEL LAPSE RATES...THERE WILL BE THE POTENTIAL FOR A SECOND ROUND
OF SEVERE THUNDERSTORMS OVERNIGHT...MAINLY FOCUSSED ACROSS THE
SOUTHERN HALF OF THE FORECAST AREA. IT IS INTERESTING TO NOTE THAT
THE 00Z ETA SOLUTION DEVELOPS A SQUALL LINE OVER SOUTHERN WISCONSIN
AND BRINGS IT EAST ACROSS SOUTHERN LOWER MICHIGAN LATE TONIGHT INTO
EARLY MONDAY. AT THIS POINT...WILL JUST CARRY A CHANCE OF THUNDER
TONIGHT SINCE AFTERNOON/EVENING CONVECTION WILL INFLUENCE WHERE THE
BETTER LOW LEVEL CONVERGENCE WILL FOCUS TONIGHT.

WILL MAKE LITTLE CHANGES TO THE FORECAST BEYOND TONIGHT. ALTHOUGH
THE ETA SOLUTION SHOWS THE PRESENCE OF AN E-W FRONT OVER LOWER
MICHIGAN BOTH MONDAY AND TUESDAY WITH AMPLE INSTABILITY. THINK THAT
CONVECTION ALONG THE FRONT WILL FORCE IT FARTHER SOUTH...CAUSING THE
BETTER CHANCE FOR CONVECTION TO OCCUR SOUTH OF THE STATE. STILL
LOOKING AT A TROUGH MOVING INTO THE UPPER MIDWEST ON WEDNESDAY. ALL
THE MODELS HAVE TRENDED STRONGER WITH THE RIDGE OVER THE
SOUTHEASTERN US AND THUS ARE LESS AMPLIFIED WITH THIS TROUGH. THIS
SHOULD LEAD TO A SLOWER MOVING FRONT. FOR NOW HAVE DECIDED TO ADD
POPS TO WEDNESDAY NIGHT. HIGH PRESSURE AND COOLER TEMPS STILL LOOK
ON TARGET TO MOVE INTO THE AREA LATER IN THE WEEK.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

CONSIDINE

EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT
HTTP://WWW.CRH.NOAA.GOV/DTX  (ALL LOWER CASE)

HAZARDOUS WEATHER OUTLOOK FOR SOUTHEAST MICHIGAN
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1225 PM EDT SUN JUN 13 2004

MIZ047>049-053>055-060>063-068>070-075-076-082-083-141000-
BAY-GENESEE-HURON-LAPEER-LENAWEE-LIVINGSTON-MACOMB-MIDLAND-MONROE-
OAKLAND-SAGINAW-SANILAC-SHIAWASSEE-ST. CLAIR-TUSCOLA-WASHTENAW-WAYNE-
1225 PM EDT SUN JUN 13 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST MICHIGAN.

.DAY ONE...THIS AFTERNOON AND TONIGHT

NUMEROUS THUNDERSTORMS WILL DEVELOP THIS AFTERNOON AND CONTINUE
INTO THE EVENING HOURS. SEVERE WEATHER IS LIKELY WITH SOME OF THESE
STORMS. THE STRONGER STORMS WILL BE CAPABLE OF WIND GUSTS TO 70 MPH
AND HAIL ONE INCH OR GREATER IN DIAMETER. A FEW TORNADOES ARE ALSO
POSSIBLE...ESPECIALLY ACROSS THE TRI-CITIES AND THUMB REGION. VERY
HEAVY RAINFALL AND FREQUENT LIGHTNING WILL ALSO BE POSSIBLE WITH
THESE STORMS. THUNDERSTORMS WILL MOVE NORTHEAST AT 25 MPH. THE
CHANCE OF SEVERE WEATHER IS FROM 2 PM THIS AFTERNOON TO 10 PM
THIS EVENING. NO THUNDERSTORMS ARE EXPECTED AFTER MIDNIGHT.

A WARM FRONT WILL MOVE NORTH OF THE REGION THIS AFTERNOON. AN UPPER
LEVEL DISTURBANCE AND A SURFACE TROUGH WILL THEN MOVE ACROSS THE
REGION EARLY THIS EVENING. THIS SYSTEM WILL TRIGGER NUMEROUS
THUNDERSTORMS.

.DAY TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

THERE IS A CHANCE OF THUNDERSTORMS ON MONDAY AS AN UPPER LEVEL
DISTURBANCE MOVES THROUGH THE REGION.

THERE IS ANOTHER CHANCE OF THUNDERSTORMS TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT AS A SLOW MOVING COLD FRONT MOVES THROUGH THE
REGION. THERE IS ALSO A CHANCE OF THUNDERSTORMS ON FRIDAY AS ANOTHER
COLD FRONT MOVES THROUGH THE REGION.

.SPOTTER INFORMATION STATEMENT...

DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGER IMMEDIATELY.

SPOTTER ACTIVATION IS LIKELY THIS AFTERNOON AND EVENING.

SF