Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000 FXUS63 KDTX 271940 AFDDTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 340 PM EDT FRI MAR 27 2015 .SHORT TERM...TONIGHT GOOD SUBSIDENCE AND DRYING OCCURRING BEHIND UPPER LEVEL TROUGH AXIS MOVING THROUGH THE CENTRAL GREAT LAKES THIS AFTERNOON...WITH SURFACE DEW PTS PLUNGING TO AROUND ZERO OVER CENTRAL SECTIONS OF THE STATE...UNDER MOSTLY CLEAR SKIES. CLOUDS HAVE THINNED OUT OVER SOUTHEAST MICHIGAN...BUT COLD (NEGATIVE UPPER TEENS AT 850 MB) NORTHERLY FLOW OFF LAKE HURON IS MAINTAINING JUST ENOUGH MOISTURE TO MAINTAIN MOSTLY CLOUDY SKIES AND EMBEDDED SNOW SHOWERS. THE ACTIVITY IS VERY DISORGANIZED...BUT STEEP LOW LEVEL LAPSE RATES HAVE PRODUCED VERY SMALL INTENSE CELLS...DROPPING VSYBS BRIEFLY BELOW 1 MILE IN ISOLATED SPOTS. WITH HIGH PRESSURE BUILDING OVER THE WESTERN GREAT LAKES TONIGHT...THE DRIER AIR/CLEAR SKIES SHOULD CONTINUE TO BLEED INTO SOUTHEAST MICHIGAN...BUT PROBABLY STRUGGLE TO ADVANCE MUCH PAST U.S. 23. LONG FETCHED NORTHERLY FLOW AND LOW LEVEL CONVERGENCE FORECASTED BY 12Z NAM OVER THUMB REGION THIS EVENING SHOULD MAINTAIN...OR ALLOW FOR REDEVELOPMENT OF ACTIVITY. STILL...THE OVERALL DRY ENVIRONMENT AND LOW INVERSION HEIGHTS WILL TEMPER ACTIVITY...AND EXPECTING A VERY NARROW BAND WITH SOME MOVEMENT...AND THUS ANTICIPATING ACCUMULATIONS BELOW 1 INCH. WITH TEMPERATURES STILL HOLDING THE 20S THIS AFTERNOON...MINS IN THE LOW TO MID TEENS SHOULD BE NO PROBLEM...WITH THE POTENTIAL FOR SINGLE NUMBERS IF THAT CLEARING LINE ADVANCES EAST OVERNIGHT. RECORD LOWS FOR MARCH 28TH ARE GENERALLY IN THE LOWER SINGLE NUMBERS AND ARE LIKELY OUT OF REACH AS WINDS WILL PROBABLY NOT GO CALM EVEN IF WE DO TOTALLY CLEAR OUT. && .LONG TERM... LONGWAVE TROUGH CURRENTLY CENTERED NEAR MICHIGAN AND INDIANA WILL COMPACT AND MOVE EASTWARD...LEADING TO A 500MB HEIGHT RECOVERY SUNDAY THROUGH THE EXTENDED PERIOD. SATURDAY WILL CONTINUE TO BE WELL BELOW NORMAL AS THE H85 TEMP FIELD REMAINS IN THE NEGATIVE TEENS C. EXPECTING MAXES IN THE MID 30S. DESPITE THESE LOW VALUES...ANTICYCLONE DIRECTLY OVERHEAD WILL PROVIDE A LIGHT WIND FIELD AND FULL SUN. ADDING LATE MARCH INSOLATION...CONDITIONS MAY NOT FEEL TOO BAD. ONCE THE SURFACE HIGH MOVES SOUTHEAST OF THE CWA ON SUNDAY...SOUTHWEST WINDS OF 40-50KT AT H85 WILL QUICKLY USHER IN WARMER TEMPERATURES. THIS LLJ WILL ALSO ACT TO INCREASE MOISTURE CONTENT (3-4G/KG) TO AN APPROACHING COLD FRONT. THE WAVE ORIGINATES WITH PACIFIC MOISTURE AND TRANSLATES ACROSS A CONTINENTAL AIRMASS BEFORE BEING REINFORCED WITH GOM MOISTURE ON SUNDAY. TOUGH CALL ON PRECIP TYPE WITH THIS SYSTEM AS TOP-DOWN IT FAVORS A COLD CANADIAN TEMP PROFILE. SURFACE TO H7 HOWEVER...IT SEEMS THE WAA IS TAKING OVER AND SURFACE TEMPS SHOULD BE AROUND +1C. WHILE THERE IS A CHANCE THAT RAIN/SNOW MIX OR A 35F SNOW COULD OCCUR...FAVORING THE WARMER SIDE OF GUIDANCE THAT INDICATES ABOVE FREEZING TEMPS IN THE BOUNDARY LAYER (FIRST 1500+ FEET). FORECAST THEREFORE CALLING FOR A COLD 0.2 INCH RAIN EVENT SUNDAY AFTERNOON-EVENING. BRIEF RIDGING ON MONDAY WILL ALLOW FOR DRY CONDITIONS TO PERSIST ACROSS SOUTHEAST MICHIGAN FOR THE BEGINNING OF NEXT WEEK. ACTIVE WEATHER QUICKLY RETURNS THOUGH ON MONDAY NIGHT AS A CLIPPER SYSTEM ROLLS THROUGH THE REGION. TEMPERATURES LOOK TO BE COLD ENOUGH AT THIS TIME TO SUPPORT ALL SNOW...WHICH COULD RESULT IN A HALF INCH OF SNOW AT THE VERY LEAST...MAINLY NORTH OF THE M-59 CORRIDOR. THERE IS STILL SOME DISAGREEMENT IN THE TRACK OF THIS SYSTEM THOUGH...SO PRECIP TYPE AND AMOUNT IS NOT COMPLETELY CERTAIN. WARMER TEMPERATURES AND DRY CONDITIONS RETURN ON WEDNESDAY AND LAST INTO THURSDAY...WHEN THE NEXT POTENTIAL RAIN MAKER ARRIVES. && .MARINE... NORTH WINDS WILL BE SLOW TO RELAX OVER LAKE HURON TONIGHT AS ISOBARS SPREAD OUT SOME DUE TO INCOMING HIGH PRESSURE. THE LAKE REMAINS ACTIVE WITH UPPER LEVEL TEMPS STILL VERY COLD (H85 AT -13C)...WHICH ADDS TO THE HIGHER WINDS OVER THE WATER. LOOK FOR HIGH WAVES ESPECIALLY NEAR THE THUMB REGION AS THE NORTH FETCH IS FAVORABLE FOR AMPLIFICATION. WINDS RAMP BACK UP SUNDAY WITH SOME GUSTS TO GALES AS 990MB LOW MOVES JUST NORTH OF THE REGION. SOUTHWEST WINDS WILL USHER IN WARMER AIR...SO NOT EXPECTING LAKES TO BECOME UNSTABLE. && .AVIATION...ISSUED 1226 PM EDT FRI MAR 27 2015 CLEARING TREND WILL ATTEMPT TO WORK IN FROM THE WEST/NORTHWEST AS SUBSIDENCE OCCURS THIS AFTERNOON BEHIND UPPER LEVEL TROUGH AXIS. DO THINK MBS WILL SCATTER OR CLEAR OUT. HOWEVER...COLD NORTHERLY FLOW OFF LAKE HURON WILL TEND TO MAINTAIN LAKE CLOUDS AND EMBEDDED SNOW SHOWERS FARTHER EAST. FORTUNATELY...CLOUD BASES AND VSBYS SHOULD BE PREDOMINATELY OF THE LOW VFR VARIETY THROUGH TONIGHT...EVEN IF CLOUDS DO IN FACT HOLD...WITH JUST LOCALIZED MVFR SNOW SHOWERS/CEILINGS. SURFACE HIGH PRESSURE BUILDING INTO LOWER MICHIGAN WILL ALLOW WINDS TO BACK A BIT TO THE NORTHWEST LATE TONIGHT...WHICH SHOULD SET UP THE TAF SITES FOR MOSTLY CLEAR SKIES TOMORROW. FOR DTW...LOW VFR CLOUDS AND BRIEF MVFR SNOW SHOWERS WILL DIMINISH THIS AFTERNOON...WITH CONFIDENCE IN CLOUDS/CEILINGS HOLDING THEN DIMINISHING THIS EVENING AND TONIGHT...AS DRIER AIR AND HIGH PRESSURE ATTEMPTS TO BUILD IN FROM THE WEST. //DTW THRESHOLD PROBABILITIES... * HIGH CONFIDENCE IN CEILINGS AOB 5000 FT THIS AFTERNOON...MEDIUM CONFIDENCE THIS EVENING...LOW CONFIDENCE AFTER MIDNIGHT. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR LHZ421-441-442. LAKE ST CLAIR...NONE. MICHIGAN WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...SF LONG TERM....MM/RK MARINE.......MM AVIATION.....SF YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

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