Issued by NWS Detroit/Pontiac, MI
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000 FXUS63 KDTX 150502 AFDDTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 102 AM EDT FRI MAY 15 2009 .AVIATION... AVIATION CONDITIONS WILL REMAIN IN THE VFR CATEGORY TODAY AND THIS EVENING, PUNCTUATED BY LIGHT WIND AS HIGH PRESSURE SLIDES THROUGH THE REGION. THERE WILL BE AN INCREASE IN HIGH CLOUDS DURING THE EARLY MORNING HOURS THAT WILL LAST THROUGH THE DAY, BUT IT WILL BE DRY THROUGH SUNSET. RAIN SHOWER POTENTIAL WILL THEN BE ON THE INCREASE THIS EVENING AS WARMER AND MORE HUMID AIR MAKES A MOVE INTO SE MICHIGAN. && .PREV DISCUSSION...ISSUED 337 PM EDT THU MAY 14 2009 SHORT TERM...TONIGHT WILL BE A QUIET NIGHT FOR WEATHER AS STRONG GUSTY WEST WINDS THIS AFTERNOON DECREASE QUICKLY THIS EVENING WITH THE LOST OF DIURNAL MIXING AND AS THE SURFACE GRADIENT RELAXES. ATMOSPHERE HAS DRIED OUT TREMENDOUSLY AS PWS WENT FROM 1.0 AT 12Z TO .29 AT 15Z ACCORDING TO DTX SOUNDINGS, THUS, THE LACK OF ANY CU THIS AFTERNOON. HIGH PRESSURE WILL SLIDE ACROSS THE STATE TONIGHT BRINGING CLEAR SKIES AND LIGHT AND VARIABLE WINDS. TEMPERATURES WILL MAINLY BE IN THE 40S WITH SOME 30S POSSIBLE ACROSS THE INTERIOR THUMB REGION. LONG TERM...FRIDAY THROUGH THURSDAY ONLY ONE MAIN WEATHER SYSTEM TO DEAL WITH IN THE EXTENDED FORECAST AND THAT COMES RIGHT AWAY LATE FRIDAY INTO FRIDAY NIGHT IN THE FORM OF A POWERFUL SHORTWAVE...THAT IS NOW TRACKING THROUGH THE PACIFIC NORTHWEST. THIS SYSTEM WILL DEEPEN ACROSS THE NORTHERN CONUS AND SOUTHERN CANADA FRIDAY/FRIDAY NIGHT AS IT TRACKS INTO THE NORTHERN GREAT LAKES. WILL ADJUST THE FORECAST SLIGHTLY TO ACCOUNT FOR THE POTENTIAL OF SCATTERED THUNDERSTORMS BY LATE FRIDAY AFTERNOON ALONG A DEVELOPING WARM FRONTAL FEATURE THROUGH SOUTHERN LOWER MICHIGAN WHICH TAKES SHAPE IN ADVANCE OF THE MAIN FORCING. FRIDAY NIGHT STILL LOOKS TO BE PRIME TIME FOR WIDESPREAD CONVECTION AS THE STORM SYSTEM WRAPS UP TO THE NORTH AND FORCES A COLD FRONT THROUGH THE REGION. WILL NOT HAVE TO ADJUST THIS PORTION OF THE FORECAST MUCH AT ALL. IN BEHIND THIS SYSTEM...COLDER AIR WILL FILTER INTO THE REGION AS A LARGE HIGH PRESSURE SYSTEM BUILDS FROM THE PLAINS INTO THE MIDWEST AND OHIO VALLEY. SO...AFTER SEVERAL DAYS WITH HIGHS AOA 70 FOR HIGH TEMPERATURES...60S WILL BE MORE COMMON...WITH 50S EVEN PREVALENT BY SUNDAY. DURING THIS TIMEFRAME...EARLY SUNDAY INTO EARLY MONDAY...THE LOWS WILL BE RATHER CHILLY AGAIN...WITH UPPER 30S/LOWER 40S COMMON. THE NEXT SIGNIFICANT SHORTWAVE ACROSS NOAM REMAINS WELL NORTH OF THE AREA WITH THE 12Z RUNS...DIGGING FROM THE ARCTIC CIRCLE TO HUDSON BAY DURING THE FIRST PART OF NEXT WEEK. AT THE SAME TIME...A LARGE UPPER RIDGE WILL BEGIN EXPANDING OVER HE EASTERN HALF OF THE CONUS AS THE NEXT BATCH OF NORTHERN PACIFIC ENERGY CARVES OUT A WESTERN CONUS TROUGH. THIS RIDGE WILL ACT TO STALL A COLD FRONT THAT THIS FAR NORTHERN SYSTEM DRIVES TOWARDS THE REGION...AND TRENDS IN THE MODEL RUNS TODAY SUGGEST THE COLD FRONT MAY STALL TO THE NORTH OF THE CWA. THE FORECAST IS ACTUALLY COMPLICATED TO SOME DEGREE BY A TROPICAL-LIKE LOW PRESSURE THAT THE MODELS ARE TRYING TO FORM OVER OR NEAR THE FLORIDA PENINSULA. IF THIS COMES TO FRUITION...WOULD EXPECT THE UPPER RIDGE TO BUILDS MORE STRONGLY INTO THE NORTHEAST CONUS AND ENSURE THAT THIS FRONT DOES NOT MAKE IT HERE. WILL NOT PULL THE CHANCE FOR SHOWERS/THUNDERSTORMS COMPLETELY OUT OF THE FORECAST FOR THE MIDDLE OF NEXT WEEK JUST YET...BUT ATTM EXPECT ACTIVITY TO BE DISORGANIZED AND VERY SCATTERED IN NATURE AS UPPER RIDGING HOLDS TOUGH...AND THE MAIN ENERGY REMAINS ANCHORED TO OUR WEST. WITH THE BUILDING RIDGE...TEMPERATURES WILL WARM HEADING THROUGH NEXT WEEK WITH A STRETCH OF DAYS WITH HIGHS SOLIDLY INTO THE 70S WITH LOWS IN THE 50S BY AND LARGE. MARINE... STRONG AND GUSTY WESTERLY FLOW FROM TIGHT GRADIENT AND DIURNAL MIXING IS CAUSING THE WIND GUSTS INTO THE 30 KNOT RANGE AT TIMES ACROSS MOST OF THE WATERS. THIS WILL DIE DOWN RAPIDLY THIS EVENING AND WINDS WILL GO LIGHT OVERNIGHT AS HIGH PRESSURE MOVES QUICKLY ACROSS THE STATE. THE NEXT CHANCE FOR ADVISORIES WILL COME LATE SATURDAY AND SATURDAY NIGHT AS ANOTHER STRONG COLD FRONT BLASTS THROUGH THE GREAT LAKES REGION. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....BT SHORT TERM...DRC LONG TERM....DG MARINE.......DRC YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
