088  
FXUS63 KDTX 020004  
AFDDTX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI  
804 PM EDT SUN MAY 1 2016  
 
   
AVIATION
 
 
THE CLOSED UPPER LEVEL CIRCULATION OVER IA/WI/IL WILL EJECT EASTWARD  
TONIGHT...RESULTING IN ANOTHER FRONTAL WAVE RESPONSE AND  
PRECIPITATION EPISODE OVER SOUTHEASTERN MICHIGAN. THE BRIEF PERIOD  
OF MVFR CONDITIONS CAME TO FRUITION HERE THIS AFTERNOON...ALTHOUGH  
THE CLOUD DECK FOR ALL AREAS HAS REMAINED OPAQUE. WARM ADVECTION AND  
MASS OF DEEPER MOISTURE WILL RESULT IN THE REDEVELOPMENT OF IFR LATE  
EVENING WITH POSSIBLE LIFR CIG HEIGHTS. THE OVERALL DURATION OF  
LIGHT TO OCCASIONALLY MODERATE RAINFALL MAY BE AROUND 6 TO 8 HOURS  
IN LENGTH ESPECIALLY FOR AREAS SOUTH OF THE I 69 CORRIDOR. ALONG THE  
NORTHERN FRINGES AT KFNT/KMBS...THERE WILL BE LESS RAIN BUT IFR/LIFR  
AND DRIZZLE IS STILL EXPECTED. THERE WILL BE A PERSISTENT OVERCAST  
ON MONDAY...BUT MODESTLY STRONGER ADVECTIONS OCCURING POST UPPER  
LEVEL LOW PRESSURE ENERGY SUPPORTS A MORE AGGRESSIVE EVOLUTION TO  
MVFR/VFR HEIGHTS DURING THE EARLY AFTERNOON.  
 
FOR DTW...THE BRIEF PERIOD OF MVFR WILL LEAD BACK INTO IFR THIS  
EVENING AS DEEP COLUMN SATURATION/WARM AIR ADVECTION INCREASES AHEAD  
OF THE UPPER LEVEL LOW. CANNOT RULE OUT LIFR GIVEN THE HIGH AMOUNT  
OF AMBIENT MOISTURE. THERE IS A STRONGER SIGNAL IN SUPPORT FOR MVFR  
CIGS BY LATE MORNING/EARLY AFTERNOON.  
 
//DTW THRESHOLD PROBABILITIES...  
 
* HIGH FOR CIG AOB 5KFT  
 
* LOW FOR CIG AOB 200 FT 6-12Z.  
 

 
   
PREV DISCUSSION
 
ISSUED 334 PM EDT SUN MAY 1 2016  
 
DISCUSSION...  
 
MOISTURE/CLOUDS TRAPPED BENEATH AN INVERSION AND NORTHEAST FLOW OFF  
THE LAKES HAVE KEPT TEMPERATURES COOL TODAY...GENERALLY IN THE UPPER  
40S TO LOW 50S THIS AFTERNOON. MAY SEE ONLY A FEW BREAKS IN CLOUDS  
THIS EVENING BEFORE CLOUD SHIELD ASSOCIATED WITH THE NEXT AREA OF  
LOW PRESSURE BEGINS TO SPILL OVER THE AREA.  
 
UPPER LOW OVER NE/IA WILL TRACK EAST TONIGHT...OPENING AS IT BEGINS  
TO PHASE WITH THE BAGGY TROUGH OVER THE GREAT LAKES AND EASTERN  
CANADA. UPPER ENERGY IS EXPECTED TO PASS THROUGH SOUTHERN MICHIGAN  
AND THE NORTHERN OHIO VALLEY TONIGHT...WITH THE SURFACE LOW CENTER  
LOOKING TO PASS TO OUR SOUTH OVER OHIO. SYSTEM WILL TRACK ALONG A  
FRONTAL BOUNDARY DRAPED OVER THE REGION...ELEVATED PORTIONS OF WHICH  
WILL REMAIN OVER SOUTHERN LOWER MICHIGAN. CONVERGENCE/ASCENT ALONG  
THE FRONT LOOKS TO INCREASE AS THE SYSTEM RIDES ALONG THE BOUNDARY  
TONIGHT...WITH FORCING ALSO GETTING A BOOST FROM LEFT EXIT REGION  
FORCING FROM A JET STREAK TO OUR SOUTH. THIS SHOULD PROMPT A NICE  
RESPONSE IN THE FORM OF RAIN TONIGHT...WITH EMBEDDED CONVECTION AS  
MID-LEVEL LAPSE RATES STEEPEN TO 7-8 C/KM. HIGHEST RAIN TOTALS WILL  
BE SITUATED ALONG/SOUTH OF THE M-59 CORRIDOR...CLOSER TO WHERE A  
WEAK LOW-LEVEL JET WILL BE FEEDING ADDITIONAL MOISTURE INTO THE  
AREA. DEFORMATION AREA AND ASSOCIATED RAIN LOOK TO PASS EAST OF THE  
AREA BY SUNRISE AS THE LOW QUICKLY SCOOTS TOWARDS THE EAST COAST.  
 
HIGH PRESSURE CENTERED OVER THE NORTHERN GREAT LAKES WILL EXPAND  
BACK INTO THE AREA MONDAY AS THE LOW DEPARTS. COOLER AIR SPILLING IN  
ALOFT BEHIND THE LOW...ENHANCED BY ANOTHER UPPER WAVE PASSING FROM  
ONTARIO INTO QUEBEC...WILL PROMOTE STEEP LAPSE RATES UP THROUGH  
ABOUT 750MB AS SURFACE HEATING COMMENCES. MODEL SOLUTIONS ARE  
INCONSISTENT WITH HOW MUCH MOISTURE WILL BE PRESENT UP THROUGH AN  
INVERSION POSITIONED JUST ABOVE THIS LEVEL...WITH NAM MUCH MORE  
MOIST THAN GFS. NAM WOULD SUPPORT DEVELOPMENT OF SCATTERED SHALLOW  
CONVECTION AND PERHAPS SOME MORNING DRIZZLE AS SOME DRYING OCCURS IN  
THE MID LEVELS. WILL HOLD OFF ON ADDING RAIN MENTION AND STICK WITH  
JUST CLOUDS BASED ON GFS/EURO...AS NAM SOMETIMES CARRIES A BIAS WITH  
TOO MUCH LOW-LEVEL MOISTURE. WARMING WILL BE TEMPERED BY SOME CLOUD  
COVER (ESPECIALLY SOUTH) AND NORTH FLOW...BUT HIGHS SHOULD BE ABLE  
TO REACH THE MID 50S TO NEAR 60.  
 
SOUTHWEST FLOW AND MIXING ON TUESDAY AHEAD OF TROUGH APPROACHING  
FROM THE NORTH SHOULD BRING NOTICEABLY WARMER TEMPERATURES...WITH  
MAX TEMPS EXPECTED TO REACH INTO THE MID OR PERHAPS EVEN UPPER 60S.  
SURFACE TROUGH AXIS AND COLD FRONT LOOK TO WORK DOWN THROUGH  
SOUTHEAST MICHIGAN LATE TUESDAY NIGHT PER LATEST MODEL CONSENSUS.  
THIS WILL BRING ANOTHER CHANCE FOR RAIN SHOWERS.  
 
CUTOFF UPPER LOW PROGGED BY GLOBAL MODELS TO DRIFT OVER SOUTHEAST  
MICHIGAN WEDNESDAY WITH LOWER HEIGHTS LINGERING INTO EARLY THURSDAY.  
RESULT WILL BE COOL AND SHOWERY WEATHER. CURRENT INDICATIONS ARE  
THAT THE LARGE RIDGE OVER THE CENTRAL US WILL EXPAND EASTWARD INTO  
THE GREAT LAKES FRIDAY AND SATURDAY...LEADING TO A SOLID WARMING AND  
DRYING TREND.  
 
MARINE...  
 
NORTHEAST WINDS CONTINUE ACROSS THE CENTRAL GREAT LAKES INTO  
TONIGHT...GENERALLY LIGHT...BUT SOME CHANNELING ACROSS SAGINAW BAY  
TO SUPPORT GUSTS ABOVE 20 KNOTS INTO THE EVENING. A WEAK PRESSURE  
GRADIENT TOMORROW WILL SUPPORT LIGHT AND VARIABLE WINDS...CONTINUING  
INTO TUESDAY. A COLD FRONT IS FORECASTED TO SWING THROUGH THE  
CENTRAL GREAT LAKES...CAUSING WINDS TO SHIFT TO THE NORTHWEST BY  
WEDNESDAY EVENING...BUT STILL 20 KNOTS OR LESS.  
 
HYDROLOGY...  
 
A COMPACT AND FAST-MOVING SYSTEM WILL MOVE THROUGH THE AREA  
TONIGHT...WITH AROUND HALF AN INCH OF RAIN EXPECTED ALONG AND SOUTH  
OF M59 CORRIDOR. THE BULK OF RAINFALL IS FORECAST TO OCCUR  
BETWEEN MIDNIGHT AND 6 AM LOCAL TIME. NO FLOODING IS EXPECTED...WITH  
JUST MODEST RISE IN STREAMS AND RIVERS...ALONG WITH PONDING/STANDING  
WATER IN NORMALLY PRONE LOW LYING AREAS.  
 

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

 
 

 
 
AVIATION.....CB  
DISCUSSION...HLO/DT  
MARINE.......SF  
HYDROLOGY....SF  
 
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE  
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).  
 
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