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000
FXUS63 KDTX 121717
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
117 PM EDT WED JUN 12 2013


.AVIATION...

//DISCUSSION...

THE POTENTIAL FOR THUNDERSTORMS STILL EXISTS FOR LATE THIS AFTERNOON
AND INTO THE EVENING HOURS AS A WARM FRONT SLOWLY LIFTS TOWARDS THE
MICHIGAN BORDER. THE BEST TIMEFRAME FOR CONVECTION WILL MOST LIKELY
FALL BETWEEN 22Z-04Z AT THE DETROIT TAFS AND PTK. FNT/MBS WILL MOST
LIKELY NOT SEE ANY CONVECTION TONIGHT HOWEVER RAIN SHOWERS WILL
STILL BE POSSIBLE AT THE TERMINALS. A SECONDARY ROUND OF
THUNDERSTORM DEVELOPMENT IS ALSO POSSIBLE AFTER MIDNIGHT AS A MCS
BEGINS TO DEVELOPS TO OUR WEST. CONFIDENCE IN THE LOCATION AND TRACK
OF THIS MCS AND IF IT WILL IMPACT ANY OF THE TERMINALS IS STILL
QUITE LOW AND WILL HAVE TO BE MONITORED AS DEVELOPMENT BEGINS LATER
THIS EVENING.

FOR DTW...THE GREATEST THUNDERSTORM POTENTIAL WILL BE
IN THE 23Z-02Z TIMEFRAME AND PERSIST INTO THE EVENING DUE TO A WARM
FRONT LIFTING INTO AREA AS A LOW PRESSURE SYSTEM APPROACHES FROM THE
WEST.

//DTW THRESHOLD THREATS...

* MODERATE CONFIDENCE IN THUNDERSTORM POTENTIAL BETWEEN 22Z-03Z...BUT LOW
CONFIDENCE IN COVERAGE.

* HIGH CONFIDENCE THAT CEILINGS WILL DROP BELOW 5000 FT AFTER 00Z
DUE TO RAIN SHOWERS AND LIGHT FOG DEVELOPMENT.

* LOW CONFIDENCE IN ADDITIONAL THUNDERSTORM DEVELOPMENT AFTER 04Z.

&&

.PREV DISCUSSION...ISSUED 1049 AM EDT WED JUN 12 2013

UPDATE...

THE FORECAST CONCERNS TODAY OBVIOUSLY REVOLVE AROUND THE POTENTIAL
FOR SEVERE WEATHER ACROSS THE SOUTHERN THIRD OF THE FORECAST AREA.
AS IS OFTEN THE CASE...THE SEVERE WEATHER POTENTIAL OVER SRN MI IS
NOT VERY CLEAR CUT AND CARRIES A LOT OF UNCERTAINTY.

THE OVERNIGHT CONVECTION OVER IOWA ALLOWED A MESO SCALE VORTICITY
MAX TO DEVELOP...WHICH THE LATEST SATELLITE DATA SUGGESTS IS NOW
ROLLING ACROSS SRN WI. DESPITE WARMING CLOUD TOPS THIS MID LEVEL
IMPULSE WILL COMBINE WITH GOOD LOW LEVEL MOISTURE ADVECTION TO
SUSTAIN AT LEAST SCATTERED TO NUMEROUS SHOWERS ACROSS THE SOUTHERN
HALF OF THE FORECAST AREA WELL INTO THE AFTERNOON. THE SURFACE WARM
FRONT IS STILL EXPECTED TO LIFT TOWARD THE MI BORDER THIS
AFTERNOON. 12Z RAOBS ACROSS THE MIDWEST SHOW A DEEP ELEVATED MIXED
LAYER WHICH IS NOW OVERSPREADING THE OHIO VALLEY AND SRN GREAT
LAKES. THIS WILL PROVIDE A SUBSTANTIAL CAPPING INVERSION BY EARLY
AFTERNOON. THE CAP WILL HOWEVER ALLOW MODERATE TO HIGH INSTABILITY
TO DEVELOP SOUTH OF THE WARM FRONT THIS AFTERNOON. THE LOW LEVEL
FLOW WILL BACK AND STRENGTHEN DURING THE AFTERNOON AS THE DEEPER
MID LEVEL IMPULSE ROTATES INTO THE UPPER MS VALLEY. THIS WILL
ADVECT LOW TO MODERATE ELEVATED INSTABILITY INTO SRN MI LATER THIS
AFTERNOON...NORTH OF THE SFC WARM FRONT. THE LATEST MODEL
INDICATIONS ARE THAT THE BETTER INSTABILITY /0-3KM MU CAPE OVER
1500 J/KG/ WILL EXTEND ALONG AN AXIS FROM LANSING TO DETROIT BY
00Z THIS EVENING. IF THE CLOUDS BREAK ENOUGH LATE IN THE
DAY...SOME SURFACE BASED CAPE ALONG A SECONDARY THERMAL TROUGH
AXIS MAY IGNITE CONVECTION IN THIS REGION. DEEP LAYER SHEAR UP
TO 60 KNOTS AND GOOD LOW LEVEL CYCLONIC CURVATURE IN THE HODOGRAPH
WILL BE SUPPORTIVE OF SUPER CELLS. IT APPEARS THE MOST PROBABLE
TIME PERIOD FOR THIS CONVECTION WILL NOT BE UNTIL 22Z TO 03Z.

AS LARGER SCALE DYNAMICS INCREASE LATE THIS EVENING...CONVECTION
SHOULD GROW UPSCALE AND EVOLVE INTO A FORWARD PROPAGATING LINEAR
MCS. THE DEGREE OF INSTABILITY IS SUPPORTIVE OF THE DEVELOPMENT OF
A LARGE COLD POOL WITH THIS MCS...SO RAPID FORWARD PROPAGATION AND
DAMAGING WINDS ARE A CONCERN. THE LOCATION OF INITIATION WILL BE
KEY AS TO WHETHER THIS MCS WILL IMPACT THE EXTREME SOUTHERN
SECTIONS OF SE MI OR REMAIN SOUTH OF THE MI BORDER. IF THIS SYSTEM
DEVELOPS OVER NORTHERN ILLINOIS THIS EVENING... LOCATIONS ALONG
AND SOUTH OF THE I-94 CORRIDOR STAND A CHANCE OF BEING IMPACTED BY
THE NORTHERN SECTION OF THE MCS LATE IN THE EVENING. THERE
CERTAINLY IS A CHANCE THAT THE DYNAMICS WILL FORCE DEVELOPMENT
FARTHER SOUTH...IN WHICH CASE THE SEVERE THREAT WILL REMAIN SOUTH
OF THE FORECAST AREA.

SO IN SHORT...THERE IS A SLIGHT RISK OF SEVERE WEATHER FOR
LOCATIONS ALONG AND SOUTH OF A LANSING TO DETROIT LINE THIS
EVENING. TO THE NORTH OF THIS LINE...ANY LATE DAY CLEARING COULD
LEAD TO ENOUGH INSTABILITY TO CREATE SOME ISOLATED STRONG TO
SEVERE STORMS. THE CONFIDENCE OF THIS OCCURRING IS QUITE LOW. OVER
THE NEXT HOUR...THERE WILL BE AN UPDATE TO THE FORECAST AND HWO
MAINLY TO REFINE THE MOST PROBABLE TIME OF SEVERE WEATHER AND MAKE
SOME MINOR UPDATES TO REFLECT THE LATEST FORECAST THOUGHTS.

PREV DISCUSSION...ISSUED 332 AM EDT WED JUN 12 2013

SHORT TERM...TODAY AND TONIGHT

THE CHANCE FOR THUNDERSTORMS WILL INCREASE THROUGHOUT THE DAY AS
VIGOROUS SHORTWAVE TRACKS FROM THE CENTRAL PLAINS INTO THE MIDWEST.
INITIAL ELEVATED ACTIVITY WILL ATTEMPT TO SPILL INTO THE AREA FROM
MINNESOTA/WISCONSIN AS LOW LEVEL JET VEERS TO THE WEST EARLY THIS
MORNING. WOULD EXPECT THIS ONGOING ACTIVITY TO REMAIN WEST OF THE
AREA THROUGH THE PRE-DAWN HOURS AND THEN ARC SOUTHEAST INTO BETTER
ELEVATED INSTABILITY OVER THE INDIANA/OHIO THIS MORNING. EXPECT ANY
ACTIVITY THAT INFILTRATES SOUTHEAST LOWER MICHIGAN BEFORE 18Z WILL
WEAKEN AS IT ENCOUNTERS RELATIVELY STABLE AIR AND WILL LOWER POPS
DURING THE FIRST HALF OF THE DAY.

CONDITIONS CHANGE FROM THIS AFTERNOON INTO THIS EVENING AS LOW
PRESSURE ASSOCIATED WITH THE AFOREMENTIONED SHORTWAVE TRACKS INTO
ILLINOIS AND A WARM FRONT LIFTS NORTH INTO FAR SOUTHERN MICHIGAN.
LOW LEVEL MOISTURE ALONG/SOUTH OF THIS BOUNDARY WILL INCREASE
SUBSTANTIALLY AND PRODUCE MODERATE TO STRONG INSTABILITY OVER PARTS
OF THE AREA AS MLCAPES APPROACH 2000 J/KG OVER THE SOUTHERN CWA IN
THE 20Z-00Z TIME FRAME. WITH THIS DEGREE OF INSTABILITY...COUPLED
WITH STEEPENING LAPSE RATES AND BULK SHEAR VALUES IN THE 0-6KM LAYER
PUSHING 60 KNOTS...WOULD EXPECT TO SEE SOME SUPERCELLS FORM IN THE
VICINITY OF THE WARM FRONT. WHILE DAMAGING WINDS AND LARGE HAIL WILL
MOST LIKELY BE THE MOST PREVALENT HAZARD...LOW LEVEL HELICITY VALUES
SUGGEST A TORNADO OR TWO WILL BE POSSIBLE LATE IN THE DAY. THE BEST
CHANCE OF SEVERE WEATHER WILL EXIST FROM THE M 59 CORRIDOR SOUTH
WITH HIGHEST TORNADO POTENTIAL SOUTH OF I 94 WHERE THE MOST
CONSISTENT CONVERGENCE ALONG THE WARM FRONT WILL LIKELY EXIST.

THE AFTERNOON/EARLY EVENING THUNDERSTORMS OVER THE REGION WILL BE
TRUMPED BY MAIN CONVECTIVE SYSTEM WHICH WILL DEVELOP WITH THE LOW
PRESSURE SYSTEM AS SHORTWAVE MOVES FROM NORTHERN ILLINOIS INTO THE
OHIO VALLEY OVERNIGHT. WITH CAPE READINGS MORE IN THE 3000-4000 J/KG
RANGE IN THIS REGION...WOULD EXPECT ISOLATED/SCATTERED STORMS TO
EVOLVE INTO AN IMPRESSIVE SQUALL LINE/BOW...WHICH SHOULD PROPAGATE
EAST/SOUTHEAST INTO THIS BETTER INSTABILITY...AND GRADUALLY ROB THE
INSTABILITY POOL FEEDING SOUTHERN MICHIGAN ACTIVITY AS MAIN EVENT
SETS UP OVER THE NORTHERN/CENTRAL OHIO VALLEY DURING THE COURSE OF
THE EVENING.

WILL GIVE MODELS SOME CREDIT AND MAINTAIN RATHER HIGH POPS INTO MUCH
OF THE NIGHT AS THE CONSENSUS CONTINUES TO SHOW A RATHER ACTIVE MID
LEVEL FRONTOGENETIC RESPONSE NORTH OF THE LOW PRESSURE TRACK INTO
THE NIGHTTIME HOURS. HOWEVER...EXPECT THE WIDESPREAD QPF TOTALS OF
AN INCH OR MORE FORECAST FOR THE SOUTHERN CWA ARE MOST LIKELY A BIT
HIGH AS THE DEVELOPING MCS WILL LIKELY BECOME THE MAIN FOCUS FOR
CONVERGENCE/LIFT WITH THE OVERALL SYSTEM. WOULD EXPECT THE NORTHERN
EDGE OF THIS BETTER RAINFALL TO SET UP I-69/M-59 AND SHIFT EAST
RATHER QUICKLY BY 12Z.

LONG TERM...

DRIER AND COOLER AIR WILL BE FILTERING INTO THE CENTRAL GREAT
LAKES THURSDAY...WITH CANADIAN AIRMASS FULLY ENTRENCHED ON
FRIDAY...AS RATHER AMPLIFIED UPPER LEVEL PATTERN FOR MID JUNE SETS
UP. THURSDAY COULD BE A SNEAKY WARM DAY...AS 850 MB TEMPS STILL
HOVER AROUND 10 C...BUT DEW PTS WILL BE TAKING A NOTICEABLE PLUNGE
DURING THE AFTERNOON HOURS...AS SHORTWAVE TROUGH AXIS COMING OUT OF
ONTARIO TRACKS THROUGH. IF SURFACE DEW PTS DO NOT MIX OUT FAST
ENOUGH...IT IS NOT OUT OF THE QUESTION FOR THAT MID LEVEL TROUGH TO
TOUCH OFF AN ISOLATED AFTERNOON SHOWER/THUNDERSTORM AS 500 MB TEMP
DROP GOOD 4C DEGREES 18-00Z. 00Z NAM/GFS/REGIONAL GEM CONVECTIVE
SCHEMES ALL KICK IN WITH A COUPLE HUNDREDTHS ALONG/WEST OF U.S. 23.

THE PRESSURE GRADIENT STAYING UP THURSDAY NIGHT WILL PROBABLY HOLD
MINS AT OR ABOVE 50 DEGREES...WITH FRIDAY NIGHT THE BETTER SETUP AS
THE 1020 MB HIGH WILL BE IN PLACE. LATEST GUIDANCE SUGGESTS THE BEST
RADIATING SITES SLIPPING INTO THE MID TO UPPER 40S.

UPPER LEVEL RIDGE AXIS WILL BE SLIDING THROUGH THE CENTRAL GREAT
LAKES ON SATURDAY...AND WARM FRONTAL SURGE/MOISTURE TRANSPORT COULD
SUPPORT A WEAKENING THUNDERSTORM COMPLEX MAKING IT INTO LOWER
MICHIGAN SATURDAY NIGHT...AND THUS CHANCE POPS. MODESTLY UNSTABLE
AIRMASS THEN LOOKS TO RESIDE OVER THE AREA FOR THE SECOND HALF OF
THE WEEKEND INTO EARLY NEXT WEEK...ALLOWING FOR A CONTINUED CHANCE
OF SHOWERS AND THUNDERSTORMS...AS DAMPENING SHORTWAVE TROUGH
TRAVELS THROUGH THE GREAT LAKES REGION...PER 00Z EURO. HIGHS IN
THE 70S LOOK TO BE THE RULE FOR THE EXTENDED PERIOD.

MARINE...

LOW LEVEL MOISTURE REMAINS IN PLACE OVER PORTIONS OF LAKE HURON
EARLY THIS MORNING. WHILE THE MOISTURE HAS SCOURED OUT TO SOME
EXTENT OVER THE SOUTHERN PART OF THE LAKE...WILL MAINTAIN THE FOG
ADVISORY INTO THIS MORNING. OTHERWISE...WEAK WINDS WILL PREVAIL
THROUGH THURSDAY KEEPING WAVES BELOW 2 FEET THROUGH THAT TIME.

THE OTHER MAIN CONCERN WILL BE POSSIBLE SHOWERS AND THUNDERSTORMS
LATER TODAY INTO TONIGHT. WIDESPREAD SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO DEVELOP BY THIS EVENING AND PERSIST OVERNIGHT OVER LAKE
SAINT CLAIR AND LAKE ERIE AS A SURFACE LOW MOVES THROUGH THE OHIO
VALLEY. STORMS MAY ALSO REACH INTO SOUTHERN LAKE HURON AND SAGINAW
BAY...BUT MOST OF LAKE HURON WILL REMAIN NORTH OF THE PRECIPITATION
SHIELD.

&&

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

LAKE HURON...
     DENSE FOG ADVISORY...LHZ361-LHZ362-LHZ363-LHZ421-LHZ422-LHZ441-
     LHZ442-LHZ443-LHZ462-LHZ463-LHZ464...UNTIL 6 PM WEDNESDAY.

LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.

&&

$$

AVIATION.....RK
UPDATE.......SC
SHORT TERM...DG
LONG TERM....SF
MARINE.......DG


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