550  
FXUS63 KDTX 191941 CCA  
AFDDTX  
 
AREA FORECAST DISCUSSION...CORRECTED  
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI  
341 PM EDT SUN MAY 19 2024  
   
KEY MESSAGES
 
 
- WARM AND MUGGY CONDITIONS ARE EXPECTED TODAY AND DURING THE EARLY  
PART OF THE WEEK WITH DAYTIME HIGHS IN THE 80S.  
 
- SHOWERS AND THUNDERSTORMS ARE LIKELY THIS AFTERNOON MAINLY FROM  
PORT HURON SOUTHWESTWARD TO ADRIAN INCLUDING METRO DETROIT. BRIEF  
HEAVY DOWNPOURS, GUSTY WINDS, AND SMALL HAIL ARE THE MAIN CONCERNS  
THIS AFTERNOON.  
 
- CHANCES EXIST FOR THUNDERSTORMS MONDAY AFTERNOON MAINLY NORTH OF I  
69. THERE WILL BE A POTENTIAL FOR STRONG TO SEVERE THUNDERSTORMS,  
BUT LOW CONFIDENCE EXISTS WITH EXACTLY THE STRONG TO SEVERE THREAT  
WILL OCCUR.  
 
- A MUCH LESS HUMID AIRMASS IS EXPECTED FOR THE END OF THE WEEK.  
 

 
   
DISCUSSION
 
 
A WEAK FRONTAL BOUNDARY MOVING THROUGH MICHIGAN EARLY TODAY  
SUPPORTING ISOLATED SHOWERS AND THUNDERSTORMS WITHIN THE NARROW  
THETAE PLUME MENTIONED IN THE MORNING UPDATE. A WARM AIRMASS REMAINS  
IN PLACE TODAY WITH 850 MB TEMPERATURES TO 14-15C. FORECAST  
SOUNDINGS FOR THIS AFTERNOON SUGGEST MIXING DEPTHS WELL UP THROUGH  
850 MB. THIS SUPPORTING HIGH TEMPERATURES INTO THE 80S AGAIN FOR  
INLAND AREAS. TEMPERATURES WILL BE COOLER AND MORE IN THE 70S ALONG  
THE LAKESHORE COMMUNITIES. THE HIGH MIXING DEPTHS WILL NOT HAVE ANY  
SIGNIFICANT EFFECT ON THE WINDS AS LOWER LEVEL COLUMN FLOW IS AT 15  
KNOTS OR LESS.  
 
DIFFERENTIAL HEATING AND SURFACE CONVERGENCE FOCUSED ALONG THE LAKE  
BREEZES AND REMNANT FRONTAL BOUNDARY FROM AROUND PORT HURON THROUGH  
THE DETROIT METRO REGION DOWN TO MONROE COUNTY IS EXPECTED TO  
TRIGGER ADDITIONAL CONVECTION THIS AFTERNOON. CURRENT OBSERVATIONS  
AT 1930Z FOR KONZ SHOW SSE WIND AND 76 DEGREES WHILE NEARBY KDTW IS  
AT A WSW WIND AT 88 DEGREES. STILL, FAIRLY GOOD CONSENSUS AMONGST  
THE HI-RES MODEL SUITE FOR GREATER COVERAGE OF SHOWERS AND  
THUNDERSTORMS TO DEVELOP LATER THIS AFTERNOON. THE NARROW THETAE  
PLUME HAS NOW MOVE INTO THE EASTERN CWA SHOWN WELL ON VISIBLE  
SATELLITE WITH THE AFTERNOON AGITATED CUMULUS FIELD. ACTIVITY PICKS  
UP OVER THE NEXT HOUR OR SO WITH ISOLATED CELLS CURRENTLY GETTING  
UNDERWAY ALONG THE I-69 CORRIDOR EAST OF FLINT AND ACROSS SOUTHERN  
SANILAC COUNTY. PEAK OF ACTIVITY DEVELOPS SOUTHWESTWARD BETWEEN 4 PM  
AND 9 PM. THE WARM AND MOIST AIRMASS IS SUPPORTING GOOD INSTABILITY.  
MESOANALYSIS SHOWING UPWARDS OF 2500 J/KG OF MLCAPE CENTERED ACROSS  
SOUTHEAST MICHIGAN. MID LEVEL LAPSE RATES ARE NOT TOO GREAT AT 6.5-  
7.0 C/KM WITH LOW LEVEL LAPSE RATES WHERE GREATEST CONVECTION IS  
TOWARDS 9 C/KM OR SLIGHTLY BETTER. VERY LITTLE SHEAR IN PLACE AS  
WELL AT AROUND 15 KNOTS OF BULK SHEAR. THIS BRINGS MORE PULSE TYPE  
THUNDERSTORMS ALONG THESE BOUNDARIES WITH ANY OUTFLOW BOUNDARIES  
DRIVING ADDITIONAL UPDRAFTS. HIGH MOISTURE IS IN PLACE WITH PWATS TO  
AROUND 1.25 INCH. ALL OF THIS BRINGS POTENTIAL FOR WATER LOADED  
DOWNBURST WINDS AND BRIEF HEAVY RAINFALL WITH ANY STRONGER  
THUNDERSTORM THAT CAN DEVELOP. CAPE FROM -10C TO -30C IS IN THE 500-  
700 J/KG RANGE WITH 50 DBZ 1 INCH HAIL HEIGHTS AT AROUND 27KFT TO  
30KFT BRINGING POTENTIAL FOR AT LEAST SMALL HAIL WITH THE  
STRONGER UPDRAFTS. THERE ARE SOME LIMITING FACTORS TODAY THAT  
BRING UNCERTAINTY TO THE FORECAST. THESE ARE THE RIDGING EXTENDING  
INTO THE CENTRAL GREAT LAKES, THE NOTABLE ANTICYCLONIC FLOW AT  
700 MB DIRECTLY OVERHEAD WHERE CONVECTION IS BEING ADVERTISED, AND  
POTENTIALLY SOME WEAK CAPPING AROUND 600-700 MB. ALL OF THIS  
COULD LIMIT STRONGER CONVECTION OR PERHAPS SUPPRESS WIDER SPREAD  
CONVECTION. THERE IS MODERATE CONFIDENCE THAT THUNDERSTORMS SHOULD  
HOLD LARGELY UNDER SEVERE CRITERIA.  
 
A SHORTWAVE TROUGH WILL BE LIFTING OUT OF THE CENTRAL PLAINS INTO  
WISCONSIN AND THROUGH THE NORTHERN GREAT LAKES ON MONDAY. THIS WILL  
LIFT A WARM FRONT NORTHWARD AND BRING A RENEWED SURGE OF MOIST  
ADVECTION AND A CHANCE FOR SHOWERS AND THUNDERSTORMS DURING THE  
AFTERNOON. DAYTIME INSTABILITY WILL BE SUFFICIENT AGAIN TO SUPPORT  
THUNDERSTORMS WITH 1500-2000 J/KG OF MLCAPE FORECAST BY THE RAP.  
SHEAR WILL INCREASE TO AROUND 35 KNOTS TOWARDS THE EVENING HOURS.  
UNCERTAINTY REMAINS AS TO WHAT SORT OF COVERAGE WILL LOOK LIKE  
THROUGHOUT THE DAY. A MARGINAL RISK FOR SEVERE WEATHER EXISTS ACROSS  
MOST OF SOUTHEAST MICHIGAN TOMORROW. A MORE SOUTHERLY TRACK OF THE  
VORT MAX INTO NORTHERN LOWER MICHIGAN WILL BRING BETTER STRONG TO  
SEVERE THUNDERSTORM CHANCES TO CENTRAL PORTIONS OF THE CWA WHEREAS  
THE NORTHERLY TRACKS FOCUSES BETTER SEVERE THUNDERSTORM CHANCES  
TOWARDS THE TRI-CITIES.  
 
ACTIVE WEATHER STRETCH CONTINUES ON TUESDAY AS A MORE DYNAMIC LOW  
PRESSURE SYSTEM DEVELOPS OVER THE UPPER MISSISSIPPI RIVER VALLEY.  
LONGER RANGE MODELS POINT TOWARDS PRECIPITATION POTENTIAL DOWNSTREAM  
OF THIS STRENGTHENING LOW ON TUESDAY MORNING MAYBE INTO EARLY  
AFTERNOON WITH A RELATIVELY BRIEF DRY PERIOD BEFORE ACTIVITY MOVES  
IN TUESDAY NIGHT WELL AHEAD OF THE MAIN COLD FRONT. SLOWING OF THIS  
FRONT MAINTAINS SHOWER AND THUNDERSTORM CHANCES FOR MUCH OF  
WEDNESDAY WITH A CONTINUED RISK OF SEVERE WEATHER DEPENDING ON  
AVAILABLE INSTABILITY. COLD FRONT WILL COOL THINGS DOWN OUT OF THE  
80S FOR THURSDAY WITH SURFACE HIGH PRESSURE LIKELY BRINGING DRY  
CONDITIONS DURING THE LATE WEEK PERIOD.  
 

 
   
MARINE
 
 
A WEAK COLD FRONT EASES ACROSS SOUTHERN LAKE HURON, LAKE ST. CLAIR,  
AND WESTERN LAKE ERIE THROUGH THIS EVENING WITH ISOLATED TO  
SCATTERED SHOWERS AND STORMS POSSIBLE IN THE NEARSHORE WATERS.  
SEVERE WEATHER IS NOT LIKELY BUT LOCALIZED DOWNPOURS CAN BE EXPECTED  
WHERE STORMS DO OCCUR. WINDS REMAIN LIGHT BEHIND THE FRONT, VEERING  
TO NORTH/NORTHEAST TONIGHT BEFORE CONTINUING AROUND TO  
EAST/SOUTHEAST MONDAY MORNING AT 10 KNOTS OR LESS. THE FRONT LIFTS  
BACK NORTH AS A WARM FRONT ON MONDAY AHEAD OF A LOW SET TO TRACK IN  
MONDAY NIGHT INTO TUESDAY. THIS WILL BRING AN AREA OF SHOWERS AND  
STORMS MAINLY FOCUSED ACROSS NORTHERN/CENTRAL LAKE HURON. WINDS AND  
WAVES REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA WITH THIS SYSTEM. A  
STRONGER LOW DEVELOPS OVER THE PLAINS ON TUESDAY, LIFTING INTO  
WESTERN LAKE SUPERIOR ON WEDNESDAY. THIS WILL SEND A COLD FRONT  
ACROSS THE REGION WITH STRONGER SOUTHERLY WINDS TO 20 KNOTS OR ABOVE  
PRECEDING IT. LESS HUMID AIR SETTLES IN ON A WESTERLY BREEZE  
THURSDAY AS HIGH PRESSURE BUILDS IN THROUGH THE LATE WEEK.  
 

 
   
PREV DISCUSSION
 
 
ISSUED AT 1223 PM EDT SUN MAY 19 2024  
 
AVIATION...  
 
HIGHER BASED (6-10 KFT) CLOUD BASES THIS AFTERNOON WITH LIGHT  
SOUTHWEST FLOW GIVING WAY TO WEAK AND VARIABLE WINDS/LAKE  
BREEZES/OUTFLOW BOUNDARIES. THUNDERSTORM COVERAGE REMAINS  
CHALLENGING, AS SURFACE BASED CAPES REACH AND EXCEED 2500 J/KG.  
HOWEVER, MID LEVELS REMAIN VERY DRY WITH AN UPPER LEVEL RIDGE AXIS  
IN PLACE ALSO ATTEMPTING TO HINDER ACTIVITY/COVERAGE. WILL BE  
COUNTING ON SOME LOW LEVEL CONVERGENCE FROM THE COLD FRONT AND  
MARINE INFLUENCE TO GET ADDITIONAL ACTIVITY GOING, AND STILL HAVE  
PLENTY OF MIXED SIGNALS IN HIRES SOLUTIONS, AS SUBTLE UPPER LEVEL  
WAVE CURRENTLY TRACKS NORTHEAST THROUGH SOUTHERN LAKE HURON. WILL  
CONTINUE TO MONITOR REAL TIME TRENDS AND CONTINUE TO FINE  
TUNE/ADJUST INHERITED TAFS, WHICH IS ADVERTISING THUNDERSTORMS FOR  
THE SOUTHERN TAF SITES LATE IN THE DAY. CONFIDENCE REMAINS SHAKY, AS  
MUTED RESPONSE WITH JUST ISOLATED-SCATTERED DISORGANIZED  
SHOWERS/THUNDERSTORMS IS IN PLAY AS WELL, WHICH COULD LINGERING INTO  
EARLY EVENING HOURS. ONCE DIURNAL ACTIVITY DISSIPATES, ANTICIPATING  
MOSTLY CLEAR SKIES TONIGHT, AS THE LOW LEVELS ATTEMPT TO DRY OUT  
WITH LIGHT EASTERLY WINDS. STILL COULD BE SOME RESIDUAL HIGHER  
SURFACE DEW PTS OVER THE SOUTHERN TAFS TO SUPPORT LIGHT FOG/MVFR  
VISIBILITY REDUCTION LATE TONIGHT.  
 
FOR DTW/D21 CONVECTION...CONFIDENCE IS HIGH CLOUDS BASES OUTSIDE OF  
ANY THUNDERSTORMS/SHOWERS WILL BE ABOVE 5000 FEET THIS  
AFTERNOON/EVENING, BUT STILL SEEMS LIKE THERE IS A REASONABLE CHANCE  
FOR A SLOW MOVING THUNDERSTORM/SHOWER TO IMPACT THE TERMINAL LATE  
TODAY, WITH POTENTIAL FOR A STRONG WET MICRO-BURST WIND GUST AND  
HEAVY DOWNPOURS LEADING TO IFR VISIBILITY RESTRICTION. TIMING IS  
STILL UNCERTAIN, AND COULD OCCUR ANYTIME BETWEEN 19-01Z, IF AT ALL.  
 
DTW THRESHOLD PROBABILITIES...  
 
* LOW-MODERATE FOR SCATTERED THUNDERSTORMS IN THE AIRSPACE BETWEEN  
19Z-01Z. LOW FOR THUNDERSTORMS ON MONDAY.  
 

 
   
DTX WATCHES/WARNINGS/ADVISORIES
 
 
MI...NONE.  
LAKE HURON...NONE.  
LAKE ST CLAIR...NONE.  
MICHIGAN WATERS OF LAKE ERIE...NONE.  

 
 

 
 
DISCUSSION...AA  
MARINE.......TF  
AVIATION.....SF  
 
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE  
AT WWW.WEATHER.GOV/DETROIT.  
 
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