844  
FXUS63 KDTX 272053  
AFDDTX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI  
353 PM EST TUE JAN 27 2015  
   
SHORT TERM
 
THROUGH TONIGHT  
 
QUIET STRETCH OF WEATHER TAKING US THROUGH TONIGHT AS HIGH PRESSURE  
CENTERED OVER QUEBEC AND EASTERN ONTARIO DROPS SOUTHWARD THROUGH THE  
GREAT LAKES. THE RESULTANT NORTHERLY FLOW WILL USHERS AN  
INCREASINGLY DRIER AIRMASS INTO THE STATE. NE FLOW EARLIER IN THE  
DAY UTILIZED LAKE HURON MOISTURE TO PRODUCE SOME LAKE EFFECT CLOUDS  
OVER MUCH OF THE THUMB BUT AS WINDS TURN MORE NORTHERLY...DRIER AIR  
IS ADVECTING INTO THE REGION WHICH IS ERODING THE CURRENT CLOUD  
FIELD. THIS WILL HELP EXPEDITE THE PROCESS OF CLEARING THE SKIES OUT  
THIS EVENING. WITH THE CLEARING SKIES...DRY AIRMASS AND CALM WINDS  
WITH THE SFC HIGH...WE CAN EXPECT ANOTHER NIGHT OF FAVORABLE  
RADIATIONAL COOLING. EVEN THOUGHT MID LEVEL HEIGHTS WILL BE ON THE  
RISE WITH TEMPS SLOWLY CLIMBING IN THE 900-500MB LAYER...THE BL WILL  
REMAIN DECOUPLED AND TEMPS WILL FALL INTO THE SINGLE DIGITS...SOME  
10 DEGREES BELOW NORMAL.  
 

 
   
LONG TERM
 
 
SURFACE HIGH PRESSURE LINGERING OVER THE REGION WEDNESDAY WILL  
ENSURE ONE MORE QUIET WEATHER DAY IN SE MICHIGAN. QUICKLY THICKENING  
HIGH CLOUDS DURING THE AFTERNOON WILL BE THE FIRST SIGN OF THE NEXT  
LOW PRESSURE SYSTEM SET TO MOVE INTO THE GREAT LAKES THURSDAY WHICH  
IS STILL ON TRACK TO BRING A ROUND OF SNOW TO OUR AREA BUT ALSO AT  
LEAST A SHORT PERIOD OF MIXED PRECIPITATION FROM THE OHIO BORDER UP  
THROUGH THE NORTHERN SUBURBS OF DETROIT. TOTAL ACCUMULATION IN THE 1  
TO 3 INCH RANGE REMAINS ON TARGET FOR NOW WITH THE HIGHER END OF THE  
RANGE MORE LIKELY IN THE NORTHERN THUMB AND THE LOW END TOWARD THE  
OHIO BORDER WHERE A MIX WILL BE A LIMITING FACTOR.  
 
AFTERNOON SATELLITE IMAGERY INDICATES THE UPPER WAVE OVER THE GREAT  
BASIN IS BEING PICKED UP BY THE NORTHERN STREAM AND IN GOOD POSITION  
TO LATCH ON TO THE ENTRANCE REGION OF THE UPPER JET INTO THE CENTRAL  
PLAINS WEDNESDAY. CLOSE BEHIND IS THE NORTHERN STREAM WAVE MOVING  
INLAND FROM THE PACIFIC COAST OF CANADA BOTH OF WHICH WILL GET A  
BROAD AREA OF SURFACE LOW PRESSURE DEVELOPMENT UNDERWAY OVER THE  
PLAINS. THE PRIMARY SURFACE WAVE WILL BE EMBEDDED WITHIN THE STRONG  
LOW LEVEL BAROCLINIC ZONE SET UP FROM THE DAKOTAS INTO THE TENNESSEE  
VALLEY BY WEDNESDAY AFTERNOON. ASSUMING SUFFICIENT SEPARATION IS  
MAINTAINED...A MODEST COUPLED JET STRUCTURE ALOFT WILL AID IN  
CONTINUED DEVELOPMENT OF THE LEAD WAVE AND SURFACE LOW. A CROSS  
SECTION OF THETA-E FROM THE SOUTHERN PLAINS TO GREAT LAKES ALSO  
INDICATES VERY LOW STABILITY IN THE LOW TO MID LEVELS WHICH FAVORS  
MODEL SOLUTIONS THAT OFFER A DEEPER SURFACE LOW OR ARE TRENDING  
DEEPER WITH THE LOW OVER IOWA WEDNESDAY NIGHT WITH A WEAKER SURFACE  
REFLECTION OF THE NORTHERN STREAM WAVE OVER THE NORTHERN GREAT  
LAKES. THIS SETS THE STAGE FOR A GREATER AMOUNT OF WARM AIR BEING  
DRAWN NORTHWARD FROM THE PLAINS INTO THE MID LEVELS OVER THE GREAT  
LAKES AS PRECIPITATION DEVELOPS TOWARD THURSDAY MORNING.  
 
THE 12 HR LIQUID EQUIVALENT QPF IS PUSHING 0.3 INCH IN THE GFS AND  
CANADIAN SOLUTIONS FOR THURSDAY WHICH REPRESENTS THE POTENTIAL FOR A  
STRONGER SOLUTION ON THE SYSTEM AND A GREATER INFLUENCE OF WET BULB  
COOLING ON P-TYPE AT THE ONSET. IT ALSO STILL SUPPORTS A 3 INCH  
ACCUMULATION ON THE UPPER END SINCE A SNOW RATIO CLOSER TO OR EVEN  
SUB 10:1 IS MORE LIKELY IN THE WARM THERMAL PROFILE. MODEL SOUNDINGS  
FROM THE 12Z RUNS AND 09Z SREF MEAN INDICATE ENOUGH DRY AIR IN THE  
LOW LEVELS TO LEAN TOWARD SLOWER ONSET TIMING...BUT STILL STARTING  
BEFORE SUNRISE...DURING THE MORNING DRIVE...AND IN THE FORM OF SNOW.  
A STRONG SOUTHERLY LOW LEVEL JET AVERAGING 45 KNOTS IN THE 900-850  
MB LAYER THEN SHOWS POTENTIAL TO QUICKLY DRIVE ENOUGH WARM AIR  
NORTHWARD TO OVERWHELM WET BULB EFFECTS AND CHANGE TYPE OVER TO  
FREEZING RAIN UP TO ABOUT THE M-59 CORRIDOR. THE AVAILABILITY OF  
WARM AIR LOOKS MORE THAN SOLID IN OBSERVATIONS TODAY OVER THE  
SOUTHERN PLAINS IN SUPPORT OF A STRONG SURFACE WARM FRONT IN MODEL  
DEPICTIONS. AT THE SAME TIME...SUB FREEZING SURFACE AIR WILL BE  
ENTRENCHED NORTH OF THE FRONT OVER SE MICHIGAN...SCOURED OUT BRIEFLY  
AROUND NOON...AND THEN WARMER AIR WILL BE SWEPT EASTWARD AS THE  
SYSTEM OCCLUDES DURING THE AFTERNOON. THIS WILL CHANGE REMAINING  
PRECIP BACK OVER TO SNOW BEFORE ENDING THURSDAY EVENING.  
 
DEPARTING TROUGH WILL BE REPLACED BY SLIGHT UPPER LEVEL RIDGING  
FRIDAY INTO THE START OF THE WEEKEND. THE NEW MONTH WILL START OUT  
WITH BELOW NORMAL TEMPERATURES...ALONG WITH PERIODS OF ACTIVE  
WEATHER. THINGS WILL THEN CHANGE AS ANOTHER TROUGH DIGS DOWN ACROSS  
THE GREAT LAKES COME SUNDAY AS AN AREA OF LOW PRESSURE DEVELOPS  
ACROSS THE SOUTH AND MOVES NORTHEAST TOWARDS THE AREA. THIS SYSTEM  
HAS THE POTENTIAL TO BRING SNOW TO THE SOUTHEAST MICHIGAN DEPENDING  
ON THE OVERALL TRACK.  
 

 
   
MARINE
 
 
HIGH PRESSURE WILL GRADUALLY SHIFT ACROSS THE GREAT LAKES TONIGHT  
THROUGH WEDNESDAY MORNING GIVING WAY TO THE NEXT WAVE OF LOW  
PRESSURE ARRIVING OVER THE MIDWEST BY WEDNESDAY NIGHT. LAKE HURON  
AND LOWER MICHIGAN WILL BE IN BETWEEN THE TWO SYSTEMS WHICH WILL  
PRODUCE AN UPTICK IN SOUTHERLY WINDS, BUT GUSTINESS WILL BE LIMITED  
TO LESS THAN 30 KNOTS DUE TO WARM STABLE AIR MOVING IN FROM THE  
SOUTH. THIS WILL CHANGE BY THURSDAY NIGHT AS COLD AND STRONG  
NORTHWEST WIND WILL DEVELOP AS THE LOW EXITS THE GREAT LAKES. A GALE  
WATCH IS NOW IN EFFECT FOR POTENTIAL 40 KNOT GUSTS THROUGH FRIDAY  
MORNING. LOWER WIND SPEED IS EXPECTED HEADING INTO THE WEEKEND BUT A  
RENEWED STRETCH OF ACTIVE MARINE WEATHER IS ANTICIPATED INTO NEXT  
WEEK AS MULTIPLE BOUTS OF ARCTIC AIR TRAVERSE THE WATERS.  
 

 
   
AVIATION
 
ISSUED 1234 PM EST TUE JAN 27 2015  
 
PRIMARILY VFR CONDITIONS THROUGH THE TAF CYCLE AS AN AREA OF HIGH  
PRESSURE SLIDES THROUGH THE REGION. THE ONE CONCERN FOR THIS  
AFTERNOON IS MOISTURE ADVECTING INLAND OFF LAKE HURON LEADING TO  
POCKETS OF MVFR LAKE EFFECT STRATO-CU. THE DRY AIR HAS MADE IT  
DIFFICULT TO SUSTAIN THE CLOUDS TOO FAR INLAND BUT DID INCLUDE A  
MVFR TEMPO GROUP FOR MBS AND FNT FOR A FEW HOURS TO ACCOUNT FOR  
THICKER CLOUD COVER IN THAT AREA. AFTERNOON WINDS WILL DECREASE THIS  
EVENING...BECOME LIGHT AND VARIABLE OVERNIGHT.  
 
//DTW THRESHOLD PROBABILITIES...  
 
* LOW FOR CEILING BELOW 5000 FT TODAY.  
 

 
   
DTX WATCHES/WARNINGS/ADVISORIES
 
 
MI...NONE.  
LAKE HURON...GALE WATCH FROM THURSDAY EVENING THROUGH FRIDAY MORNING FOR  
LHZ361>363-462>464.  
 
LAKE ST CLAIR...NONE.  
MICHIGAN WATERS OF LAKE ERIE...NONE.  

 
 

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