Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000 FXUS63 KDTX 030359 AFDDTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1159 PM EDT TUE SEP 2 2014 .AVIATION... //DISCUSSION... AREA OF HIGH PRESSURE SETTLES OVER THE REGION THROUGH WEDNESDAY. THERE REMAINS A VERY LOW PROBABILITY FOR FOG TO DEVELOP UNDER LIGHT/CALM WINDS EARLY THIS MORNING...BUT THE DEGREE OF LOW LEVEL DRYING APPEARS SUFFICIENT ENOUGH TO REFRAIN FROM ANY INCLUSION AT THIS TIME. THIS ENVIRONMENT WILL ENSURE A CLEAR SKY HOLDS BELOW 5000 FT THROUGH THE TAF PERIOD. A LIMITED FIELD OF DIURNAL CU IS EXPECTED ABOVE THIS LEVEL WEDNESDAY AFTERNOON. //DTW THRESHOLD THREATS... * NONE && .PREV DISCUSSION...ISSUED 315 PM EDT TUE SEP 2 2014 SHORT TERM...THROUGH TONIGHT CURRENT OBSERVATIONS STILL HAVE THE SURFACE COLD FRONT SITUATED ROUGHLY ALONG A LINE FROM PORT HURON DOWN THROUGH ANN ARBOR. THIS HAS BEEN THE FOCUS FOR RAIN AND THUNDERSTORMS TODAY AND WILL CONTINUE TO BE THE CASE THROUGH THE EARLY EVENING. LATEST SATELLITE AND RADAR AS OF 3PM SHOW SHOWERS FINALLY DIMINISHING. AREAS NORTH OF THE BOUNDARY HAVE AND WILL REMAIN DRY THROUGH THE OVERNIGHT HOURS. ONCE THE FRONT SETTLES OFF TO THE EAST...RAIN/THUNDERSTORM CHANCES OVER THE SOUTHERN CWA WILL END. VERY FEW CHANGES WERE MADE TO THE GOING FORECAST WITH THE ONLY CHANGE BEING TO UP POPS SLIGHTLY ACROSS THE SOUTH THROUGH 21Z. HIGH PRESSURE WILL SLOWLY TAKE OVER THIS EVENING AND EXTEND THROUGH THE OVERNIGHT HOURS. DRIER AIR HAS ALREADY BEGUN FILTERING INTO THE NORTHERN HALF OF THE CWA WHERE DEWPOINTS ARE IN THE MIDDLE TO UPPER 50S. THIS TREND IS EXPECTED TO CONTINUE WHILE SLOWLY SCOURING OUT ANY LOW LEVEL LINGERING CLOUDS OVERNIGHT. A WAS DISCUSSED IN THE PREVIOUS DISCUSSION...A FEW AREAS OF SHALLOW GROUND FOG MAY BE POSSIBLE ACROSS NORTHERN AREAS EARLY WEDNESDAY MORNING A LITTLE MOISTURE REMAINS IN THE BOUNDARY LAYER. LOWS OVERNIGHT WILL BE COOLER THAN THE PREVIOUS NIGHT WITH LOWS RANGING FROM THE LOWER 60S OVER THE DETROIT METRO AREA TO THE UPPER 50S TO THE NORTH. LONG TERM... DRY WEATHER AND INCREASING TEMPS ARE ON TAP FOR WEDNESDAY THROUGH THURSDAY AS HEIGHTS BUILD AND SWLY FLOW INCREASES AHEAD OF THE WAVE DIGGING INTO THE PACNW THIS AFTERNOON. THIS WAVE WILL SHEAR ACROSS SOUTHERN CANADA, REACHING JAMES BAY BY FRIDAY. AS IT DOES SO, A RESPECTABLE LOW-LEVEL JET RESPONSE IS FORECAST TO EMERGE UPSTREAM SUPPORTING EPISODES OF CONVECTION OVER THE UPPER MS VALLEY. FLOW WILL ONLY SLOWLY BACK TO SOUTHERLY ON WEDNESDAY WITH LITTLE AIRMASS CHANGE COMPARED TO TODAY. HOWEVER, WITH GREATER INSOLATION EXPECTED AS TODAY`S COLD FRONT PROGRESSES EAST, TEMPERATURES SHOULD MODERATE A FEW DEGREES TO AROUND 80F. WARM ADVECTION THROUGH THE COLUMN WILL TAKE HOLD ON THURSDAY AS DEEP LAYER SWLY FLOW INCREASES AHEAD OF THE RAPIDLY APPROACHING PAC NW WAVE. CONVECTION WILL REMAIN TIED TO THE UPSTREAM THETA-E AXIS/LOW-LEVEL JET. WHILE IT IS NOT OUT OF THE QUESTION THAT NOCTURNAL REMNANT ACTIVITY APPROACHES THE AREA LATE WED NIGHT OR THURSDAY MORNING, MUCH PREFER TO LET THE COARSE RESOLUTION MODELS HANDLE THE SYNOPTIC SCALE AND WILL DEFER TO HIGH RES ARW/WRF FOR SPECIFICS. AS EXPECTED, THE HIGH RES GUIDANCE DOES NOT ALLOW ANY SUCH REMNANTS TO REACH THE CWA AND KEEPS CONVECTION TIED TO UPSTREAM FORECING. AS SUCH, PREFER TO SEE THE WHITE`S OF ITS EYES SO TO SPEAK BEFORE CLUTTERING THE GRIDS WITH POPS. THE FORECAST IS THEREFORE DRY THROUGH THURSDAY. INSTEAD, THURSDAY WILL LIKELY BE CHARACTERIZED BY A FAIR AMOUNT OF CONVECTIVE DEBRIS EARLY, INCREASING DEWPOINTS, AND H85 TEMPERATURES RISING INTO THE UPPER TEENS. PER EXPECTATION FOR NO/MINIMAL PRECIP, MAINTAINED FORECAST HIGHS ON THE WARMER SIDE OF GUIDANCE. TSTORM CHANCES WILL INCREASE LATE THURSDAY NIGHT AS VEERING LLJ AXIS MIGRATES TOWARD THE AREA. SHOWERS AND THUNDERSTORMS REMAIN LIKELY FRIDAY AS A COLD FRONT MOVES THROUGH THE REGION WITH MOIST AND UNSTABLE AIR PRECEDING THE FRONT. THERE REMAINS A DECENT DENSITY GRADIENT IN PLACE AND ISOLATED SEVERE WIND GUSTS REMAIN POSSIBLE. COOL HIGH PRESSURE WILL FILL IN BEHIND THE FRONT FOR SEVERAL DAYS AS TEMPERATURES TREND SEVERAL DEGREES COOLER THAN NORMAL. MARINE... LIGHT WINDS WILL GIVE WAY TO A MODERATE SOUTHERLY BREEZE THURSDAY INTO FRIDAY AS A COLD FRONT APPROACHES THE AREA. STABLE WARM SOUTHERLY FLOW WILL KEEP WIND GUSTS TO A MINIMUM. THERE IS A LOW CHANCE FOR THUNDERSTORMS ACROSS NORTHERN LAKE HURON ON THURSDAY...WITH INCREASING CHANCES FOR ALL THE WATERS THURSDAY NIGHT THROUGH FRIDAY NIGHT. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....MR SHORT TERM...SS LONG TERM....JVC/MM MARINE.......JVC YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

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