576  
FXUS63 KDTX 281101  
AFDDTX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI  
701 AM EDT TUE APR 28 2015  
 
   
AVIATION
 
 
THE ONSET OF DAYTIME HEATING THIS MORNING IS EXPECTED TO LEAD TO A  
RAPID DEVELOPMENT/EXPANSION OF STRATO CU. THIS CLOUD DEVELOPMENT IS  
A RESULT OF MOISTURE ADVECTION OVERNIGHT UNDERNEATH A DEEP  
INVERSION. THE PERSISTENCE OF THIS INVERSION IS LIKELY TO HOLD  
CLOUDS IN PLACE LATE INTO THE AFTERNOON OR EVENING.  
 
FOR DTW...ASIDE FROM THE DAYTIME CLOUD ENHANCEMENT...A WEAK SFC  
GRADIENT WILL SUPPORT LAKE BREEZE DEVELOPMENT IN THE 21 TO 23Z TIME  
FRAME.  
 
//DTW THRESHOLD PROBABILITIES...  
 
* LOW IN CEILINGS AT OR BELOW 5000 FT THIS MORNING. MEDIUM THIS  
AFTERNOON AND EVENING.  
 

 
   
PREV DISCUSSION
 
ISSUED 327 AM EDT TUE APR 28 2015  
 
SHORT TERM...TODAY AND TONIGHT  
 
THE DEEP CYCLONIC FLOW WHICH HAS BEEN IN PLACE ACROSS LOWER MI THE  
LAST SEVERAL DAYS WILL FINALLY LOOSEN ITS GRIP ON THE AREA TODAY AS  
THE ELONGATED MID LEVEL TROUGH AXIS PUSHES OFF THE EAST COAST. MID  
LEVEL RIDGING WILL IN TURN BUILD INTO LOWER MI FROM THE WEST. THE  
REGIONAL WATER VAPOR LOOP IS IN SUPPORT OF MODEL SOLUTIONS DEPICTION  
OF A WEAK MID LEVEL IMPULSE OVER NRN LOWER MI. THIS FEATURE WILL  
SLOW CONSIDERABLY AS IS ADVANCES INTO SRN LOWER MI THIS AFTERNOON  
DUE TO THE WEAKENING IN THE MID LEVEL FLOW. HI RES SOLUTIONS SUGGEST  
THIS FEATURE WILL SUSTAIN A WEAKNESS IN THE MID LEVEL HEIGHT FIELD  
OVER LOWER MI TODAY...WHICH WILL AID IN THE DEVELOPMENT OF A  
THERMALLY INDUCED SFC TROUGH OVER LOWER MI.  
 
REGIONAL SATELLITE DATA OVERNIGHT HAS SHOWN A CONSIDERABLE AMOUNT OF  
CLOUD COVER ACROSS LAKE HURON. ONGOING N-NE LOW LEVEL FLOW HAS  
BROUGHT SOME INCREASE IN LOW LEVEL MOISTURE INTO SE MI...ALTHOUGH THE  
CLOUDS HAVE THUS FAR HAD A DIFFICULT TIME SUSTAINING THEMSELVES. BOTH  
00Z DTX AND APX SOUNDINGS SHOWED A DEEP LOW LEVEL INVERSION. SLIGHT  
WARMING ABOVE THE INVERSION BASE TODAY SHOULD SUSTAIN THIS INVERSION  
DESPITE DAYTIME HEATING. THE LOW LEVEL FLOW WILL BACK TOWARD THE  
NORTHWEST THIS MORNING...THUS DECREASING THE FEED OF LOW LEVEL  
MOISTURE INTO SE MI. ENOUGH MOISTURE SHOULD STILL BE IN PLACE UNDER  
THE INVERSION TO ALLOW THE ONSET OF DAYTIME HEATING TO CAUSE THE  
RAPID DEVELOPMENT OF A BROKEN TO OVERCAST STRATO CU FIELD. THESE  
CLOUDS SHOULD HAVE DIFFICULTY DECREASING DURING THE LATTER HALF OF  
THE DAY CONSIDERING THE DEPTH OF THE INVERSION AND NO REAL PUSH OF  
DRIER AIR. YESTERDAYS TEMPS CERTAINLY STRUGGLED WITH THE CLOUD  
COVER. MODEL SOUNDINGS SUGGEST THE MOISTURE DEPTH WILL NOT BE AS  
HIGH AS YESTERDAY AND THERE APPEARS TO BE A BETTER POTENTIAL FOR  
SOME INTERVALS OF SUN TODAY...ESPECIALLY THIS MORNING. SO OPTIMISTIC  
AFTERNOON HIGHS AROUND 60 WILL BE MAINTAINED. THE LOSS OF DAYTIME  
HEATING WILL LEAD TO SOME EROSION OF THE CLOUDS THIS EVENING. THE  
BOUNDARY LAYER WILL RAPIDLY DECOUPLE UNDER ANY PERIOD OF CLEAR SKIES  
TONIGHT GIVEN THE WEAK GRADIENT FLOW. THIS WILL SUPPORT FCST MIN  
TEMPS DOWN INTO THE 30S TONIGHT /40S IN URBAN DETROIT/.  
 
LONG TERM...WEDNESDAY THROUGH MONDAY  
 
MID TO UPPER LEVEL RIDGING IN PLACE AT 12Z WEDNESDAY WILL BREAK DOWN  
RAPIDLY AS A ROBUST SHORTWAVE WILL DIVE SOUTHWARD THROUGH THE  
WESTERN GREAT LAKES DURING THE DAY. AN ATYPICAL SYSTEM TO DEAL WITH  
GIVEN THE LARGER WAVLENGTH OF THE SHORTWAVE ALONG WITH THE NEAR  
STRAIGHT SOUTHWARD TRAJECTORY OF THE CIRCULATION. NORTHERLY SYSTEMS  
TEND TO BE DRY ONES FOR THE AREA. MODELS PROG DRY AIR TO BEGIN THE  
DAY...WITH DEEPER SYSTEM MOISTURE NOT PIVOTING INTO THE WESTERN AND  
CENTRAL SECTIONS OF THE LOWER PENINSULA UNTIL AFTER 20Z. FORECASTED  
THERMODYNAMIC PROFILES SUGGEST DIURNAL HEATING WILL BE NEEDED TO  
GENERATE A CONVECTIVELY UNSTABLE (<100 J/KG MUCAPE) LAYER BETWEEN  
SHOWERS 5-12 KFT AGL LAYER. A GOOD CONSENSUS EXISTS THE BEST  
POTENTIAL WILL RESIDE ACROSS THE WESTERN PART OF THE STATE. DRIER  
AIR IN THE LOWER TROPOSPHERE STILL SUPPORTS TEMPERATURES REACHING  
THE LOW TO MID 60S.  
 
THE QUESTION THEN BECOMES WHAT SORT OF POTENTIAL WILL EXIST FOR  
CONTINUED SHOWERS WEDNESDAY NIGHT WITH THE LACK OF DIURNAL HEATING.  
MODELS SEEM TO BE CONVERGING ON A SIGNAL THAT HEART OF THE CYCLONIC  
CIRCULATION AND DEEPER MOISTURE WILL TUMBLE OR WOBBLE RAPIDLY DOWN  
INTO SECTIONS OF IL/IN FOR WEDNESDAY NIGHT. MODELS ARE NOW  
STRUGGLING TO KEEP SHOWERS GOING...LIKELY DUE TO THE LACK OF A  
FORCING MECHANISM. WILL KEEP A LOW CHANCE MENTION GOING OUT OF  
RESPECT FOR THE CYCLONIC FLOW. OVERALL A LOW CHANCE/LOW QPF TYPE  
FORECAST.  
 
FORECAST DETAILS AND REASONING HAS CHANGED SINCE 24 HOURS AGO  
CONCERNING THE THURSDAY FORECAST. A CONSENUS IS EMERGING THAT  
COLDEST OF MIDLEVEL AIR WILL REMAIN WEST OF MICHIGAN. IN  
FACT...MODEL DATA IS NOW SUGGESTING THAT WARMER 850MB TEMPERATURES  
WILL ADVECT FROM THE NORTHEASTERN UNITED STATES WESTWARD INTO THE  
CENTRAL GREAT LAKES. THE INBOUND AIRMASS WILL CONTAIN HIGHER THETA E  
CONTENT AS WELL. NWP SUGGESTS A POTENTIAL FOR DECENT CONVECTIVE  
DEPTHS DEVELOPING DIURNALLY AND WILL CONTINUE THE LOW CHANCE POPS  
FOR THURSDAY. THE MESSAGE IS AGAIN A LACK OF A FORCING  
MECHANISM/TRIGGER. TEMPEATURES ON THURSDAY ARE NOW EXPECTED TO REACH  
THE 60 DEGREE MARK.  
 
MARINE...  
 
FAVORABLE MARINE CONDITIONS TODAY AS SURFACE HIGH PRESSURE WILL  
RESIDE ACROSS THE CENTRAL GREAT LAKES...PROVIDING LIGHT WINDS AND  
LOW WAVES. WEAKENING HIGH PRESSURE WILL BE REPLACED BY WEAK SURFACE  
TROUGHING TONIGHT...BUT WINDS ARE STILL EXPECTED TO REMAIN BELOW 20  
KNOTS. HOWEVER...WINDS WILL BE NORTHERLY...AND THERE COULD BE  
ONSHORE COMPONENT TO SUPPORT SLIGHTLY HIGHER WAVES ALONG THE  
NEARSHORE WATERS.  
 

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

 
 

 
 
AVIATION.....SC  
SHORT TERM...SC  
LONG TERM....CB  
MARINE.......CB  
 
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE  
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).  
 
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