483  
FXUS63 KDTX 240353  
AFDDTX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI  
1153 PM EDT SAT MAY 23 2015  
 
   
AVIATION
 
 
HIGH PRESSURE TO THE EAST OF THE REGION WILL SUSTAIN LIGHT WINDS AND  
CLEAR SKIES BELOW 12K FT THROUGH DAYBREAK. SSW WINDS WILL INCREASE  
LATE IN THE MORNING AS DAYTIME HEATING DEEPENS THE MIXED LAYER. A  
WARM FRONT WILL LIFT INTO LATE SUN AFTERNOON/EVENING. THIS SYSTEM  
WILL PROVIDE A CHANCE FOR SOME LATE DAY SHOWERS...POTENTIAL DOES NOT  
LOOK HIGH ENOUGH AT THIS POINT TO INCLUDE IN THE TAFS ATTM.  
 
//DTW THRESHOLD PROBABILITIES...  
 
* NONE.  
 

 
   
PREV DISCUSSION
 
ISSUED 311 PM EDT SAT MAY 23 2015  
 
SHORT TERM...THIS AFTERNOON AND TONIGHT  
 
VERY QUIET WEATHER WILL PERSIST THROUGH TONIGHT AS A RIDGE OF  
SURFACE HIGH PRESSURE EXTENDS BACK NORTHWEST ACROSS THE ENTIRE  
REGION. LATE DAY TEMPERATURES WILL RANGE IN THE LOW TO MID 70S UNDER  
PLENTY OF SUNSHINE AND SOUTH TO SOUTHWEST WINDS OF 10 MPH OR LESS IN  
MOST CASES. THESE WINDS WILL BACK TO SOUTHEAST EARLY THIS EVENING IN  
SOME LOCATIONS DUE TO LAKE BREEZE BOUNDARIES...BUT REMAIN 10 MPH OR  
LESS.  
 
WITH THE CENTER OF THIS HIGH PRESSURE POSITIONED FURTHER SOUTHEAST  
OF THE AREA...SOUTH TO SOUTHWEST WINDS WILL REMAIN CLOSE TO 5 MPH  
TONIGHT. THIS...COMBINED WITH A GENERAL MODERATION IN THE AIRMASS  
OVER THE AREA...WILL RESULT IN MILDER TEMPERATURES TONIGHT WITH LOWS  
GENERALLY IN THE 50 TO 55 DEGREE RANGE WITH UPPER 40S LIMITED TO  
PARTS OF THE THUMB AND SPOTTY RURAL LOCATIONS ACROSS THE SAGINAW  
VALLEY AND IRISH HILLS WEST AND SOUTHWEST OF METRO DETROIT.  
 
LONG TERM...  
 
TSTORMS ARE ONGOING IN THE GREAT PLAINS IN ADVANCE OF THE LARGE  
CLOSED LOW SPINNING OVER THE GREAT BASIN. THIS THUNDERSTORM COMPLEX  
WILL ULTIMATELY DIE WITH THE LOSS OF DIURNAL HEATING. REMNANTS WILL  
BE DRAWN NORTHEAST AS THE GREAT BASIN LOW EJECTS INTO THE CENTRAL  
PLAINS DURING THE DAY SUNDAY. SOUTHWESTERLY GRADIENT FLOW INTO SEMI  
WILL PERSIST AROUND THE LARGE ANTICYCLONE ANCHORED OFF THE WEST  
COAST. HIGHS IN THE UPPER 70S WILL BE THE RULE ALONG WITH DEWPOINTS  
INCREASING INTO THE MID 50S BY SUNSET. ABUNDANT DRY AIR IN THE  
LOWEST 6KFT IS EXPECTED TO SIGNIFICANTLY LIMIT THE POTENTIAL FOR  
REMNANTS OF THE AFOREMENTIONED CONVECTION TO SURVIVE THEIR TRIP INTO  
SE MICHIGAN, EVEN WITH THE HELP OF MARGINAL ISENTROPIC ASCENT  
INCREASING BY SUNDAY NIGHT. CONVECTION-RESOLVING WRF-ARW/NMM SUPPORT  
THIS EXPECTATION.  
 
NEBULOUS SCENARIO THEN EXISTS FOR MONDAY. DEEP LAYER SOUTHWEST FLOW  
WILL PERSIST, SENDING HIGHS INTO THE UPPER 70S/LOW 80S AND DEWPOINTS  
INTO THE 60S. UPPER LOW WILL CONTINUE ITS TRANSITION TO A LOWER  
AMPLITUDE OPEN WAVE AS IT LIFTS FROM OMAHA TO THE ARROWHEAD OF  
MINNESOTA DURING THE DAY MONDAY. EXTENDED PERIOD OF MOISTURE  
TRANSPORT WITHIN GUSTY SOUTHWEST FLOW WILL ALLOW PWATS TO RISE TO  
1.7 INCHES, WHICH WOULD BE A RECORD FOR THE DATE PER LOCAL UPPER AIR  
DATABASE. LAPSE RATES WILL BE QUITE POOR AND FLOW WILL BE  
ANTICYCLONIC THROUGH THE LAYER, EVEN IF ONLY WEAKLY SO AT THE  
SURFACE. CLOUDS WILL LIMIT INSTABILITY POTENTIAL, THOUGH THERE IS  
SOME POTENTIAL FOR AN MCV ORIGINATING OUT OF ARKLATEX AREA  
CONVECTION TO LIFT TOWARD THE AREA LATE MONDAY. THIS REPRESENTS THE  
ONLY DISCERNIBLE TRIGGER MECHANISM. BLANKET POPS REMAIN WARRANTED  
FOR MONDAY, BUT DECIDEDLY PULLED BACK FROM LIKLIES. THE ECMWF  
APPEARS TO BE THE ONLY MEMBER OF THE 12Z SUITE WITH A QPF OUTPUT  
THAT CLOSELY MATCHES ITS OWN FORCING FIELDS. THE ONLY CERTAINTY FOR  
MONDAY IS THAT IT WILL BE WARM AND MUGGY.  
 
SOUTHWEST FLOW WILL PERSIST INTO MONDAY NIGHT LEADING TO ANOTHER  
HUMID NIGHT WITH LOWS RUNNING 10 TO 15 DEGREES ABOVE NORMAL.  
 
A FAIRLY ACTIVE PATTERN REMAINS FOR THE EXTENDED PERIOD AS A  
SERIES OF LOW PRESSURE SYSTEMS ARE FORECASTED TO IMPACT SOUTHEAST  
MICHIGAN. RAIN AND THUNDERSTORM CHANCES WILL REMAIN IN PLACE FROM  
TUESDAY THROUGH THE END OF THE WEEK. HAVE ONLY INCLUDED CHANCE POPS  
INTO THE FORECAST FOR NOW TO ACCOUNT FOR UNCERTAINTY IN THE TIMING  
OF THESE SYSTEMS. OTHER THAN RAIN...HIGH TEMPERATURES WILL REMAIN  
STEADY IN THE MID 70S TO LOW 80S THROUGH FRIDAY WHICH WILL BE ABOVE  
NORMAL FOR THIS TIME OF YEAR /NORMAL IS LOW 70 DEGREES/.  
 
MARINE...  
 
WINDS WILL DIMINISH THIS EVENING AS THE PRESSURE GRADIENT RELAXES  
AND WILL REMAIN LIGHT THROUGH THE WEEKEND. A MODERATE SOUTHERLY  
BREEZE WILL DEVELOP DURING THE DAY MONDAY WITH GUSTS IN EXCESS OF 25  
KNOTS POSSIBLE. SMALL CRAFT ADVISORIES FOR WIND WILL BE POSSIBLE FOR  
ALL NEARSHORE ZONES. WAVE IMPACTS WILL BE MINIMIZED DUE TO LACK OF  
ONSHORE FLOW. THUNDERSTORMS WILL BE POSSIBLE OVER NORTHERN LAKE  
HURON SUNDAY NIGHT THROUGH MONDAY. THE BEST THUNDERSTORM CHANCES FOR  
AREAS FURTHER SOUTH WILL BE MONDAY EVENING.  
 

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

 
 

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