Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000 FXUS63 KDTX 031944 AFDDTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 344 PM EDT MON AUG 3 2015 .SHORT TERM...THIS EVENING THROUGH TONIGHT A SECONDARY COLD FRONTAL TROUGH SWINGING THROUGH LOWER MI TODAY PRODUCED ISOLATED TO SCATTERED COVERAGE OF SHOWERS AND THUNDERSTORMS...WHICH WILL WANE INTO THE EVENING HOURS. THE PRE- FRONTAL AIRMASS WAS ABLE TO REACH INTO THE UPPER 70S/LOW 80S WITH LOW 60 DEWPOINTS...COMBINED WITH FAVORABLE LOW/MID LEVEL LAPSE RATES AIDED BY CAA ALOFT AND THE FRONTAL FORCING WAS ABLE TO PRODUCE SOME WEAK THUNDERSTORMS. THE SFC FRONT IS NOW EXTENDING ALONG A LINE FROM BAX TO JACKSON AND WILL CONTINUE EASTWARD...EXITING SE MI THIS EVENING...LEAVING A DRIER FORECAST IN ITS WAKE. CLOUD TRENDS THIS EVENING AND OVERNIGHT ARE LOOKING A BIT TRICKIER. MUCH DRIER DEWPOINTS IN THE LOW 50S...EVEN A FEW 40S NOTED IN MID MI...BEHIND THE FRONT WILL TRY TO DRY THE COLUMN OUT QUICKLY...BUT VISIBLE SATELLITE SHOWS A ROBUST CLOUD FIELD WITHIN THE DEEP CYCLONIC FLOW WHICH WILL DROP SOUTH AND EAST AND SHOULD IMPACT LOCATIONS NORTH OF I69 THROUGH MOST OF THE NIGHT. SO WE WILL LIKELY HAVE A GRADIENT OF CLEAR TO MOSTLY CLOUDS SET UP ACROSS OUT CWA AND HAVE HEDGED THE FORECAST ACCORDINGLY. && .LONG TERM... ANOTHER VIGOROUS SPOKE OF SHORTWAVE ENERGY IS DUE INTO THE AREA ON TUESDAY AS STRONG UPPER LOW PRESSURE REMAINS CENTERED NEAR JAMES BAY FOR ANOTHER DAY. MUCH LIKE TODAY...EXPECT AN EXPANDING AREA OF SCATTERED SHOWERS AND A FEW EMBEDDED THUNDERSTORMS AS ENHANCED LIFT FROM THIS WAVE COINCIDES WITH DAYTIME INSTABILITY MAXIMUM. WITH THE OVERALL UPPER TROUGH AXIS SLOWLY EDGING EASTWARD DURING THIS TIME FRAME...EXPECT THE BEST CONCENTRATION OF THIS CONVECTION TO OCCUR OVER LAKE HURON/THUMB REGION WITH A STEADILY DIMINISHING CHANCE OF RAINFALL SOUTHWEST FROM THERE. WITH NEUTRAL TO WEAK WARM AIR ADVECTION BACK INTO AREA IN ADVANCE OF THIS WAVE...TEMPERATURES WILL REMAIN MILD WITH UPPER 70S TO LOWER 80S COMMON FOR HIGH TEMPERATURES DURING THE AFTERNOON. A SLIGHTLY DOWNSLOPING FLOW INTO METRO DETROIT WILL MOST LIKELY GARNER A TEMPERATURE AROUND 83F. SHOWER ACTIVITY WILL WANE QUICKLY IN THE EARLY EVENING AS LIFT FROM THE SHORTWAVE SHIFTS EAST AND DAYTIME INSTABILITY IS LOST. WITH THE COOLER AIRMASS SETTLING INTO THE AREA...EXPECT COOL READINGS TUESDAY NIGHT WITH LOW TEMPERATURES DOWN INTO THE 50S IN MOST LOCATIONS AND PROBABLY RIGHT AROUND 50F IN SOME LOCATIONS ALONG THE NORTH OF ABOUT THE I-69 CORRIDOR. THESE COOL TEMPERATURES WILL PERSIST INTO THE MIDDLE OF THE WEEK AS CANADIAN HIGH PRESSURE BUILDS INTO AREA WITHIN NORTHWEST FLOW REGIME. HIGHS WEDNESDAY WILL HOLD IN THE LOWER/MID 70S WITH LOWS BACK INTO THE 50S WEDNESDAY NIGHT. WITH THIS HIGH IN PLACE...DRY WEATHER IS EXPECTED TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. THURSDAY THROUGH MONDAY. MODELS APPEAR TO BE IN HIGH DISAGREEMENT WITH THURSDAY`S WEATHER SCENARIO...WHICH LENDS LOW CONFIDENCE TO PRETTY MUCH ALL OF THE EXTENDED PERIOD. WEDNESDAY IS STILL FAVORING HIGH PRESSURE AND DRY CONDITIONS...SO WILL CONTINUE TO FOLLOW YESTERDAY`S THINKING AND HOLD OVER DRY CONDITIONS FOR MOST OF SOUTHEAST MICHIGAN ON THURSDAY MORNING. THE EXCEPTION WILL REMAIN THE SOUTHERN MOST COUNTIES WHERE SCATTERED SHOWERS WILL BEGIN EDGING INTO THE CWA PRIOR TO 8AM. WILL ALSO KEEP SHOWERS EXPANDING INTO THE CWA THROUGH THE AFTERNOON AND EVENING. AT LEAST A SLIGHT CHANCE OF SHOWERS IS FAVORED THROUGH THE WEEKEND. MID 70 DEGREE HIGHS ANTICIPATED THROUGH SATURDAY WITH HIGH TEMPS NUDGING INTO THE UPPER 70S BY SUNDAY. && .MARINE... WHILE HEADLINES ARE NOT EXPECTED OVER THE NEXT FEW DAYS OVER LAKE HURON...A RATHER STRONG UPPER LOW FOR THIS TIME OF YEAR WILL REMAIN DISPLACED SOUTH OF HUDSON BAY ALLOWING SEVERAL SHOTS OF COOLER AIR WITH ACCOMPANYING GUSTY NORTH TO NORTHWEST WINDS IN THE WAKE OF THE PASSING COLD FRONTS. THESE SYSTEMS WILL ALSO BRING SCATTERED SHOWERS AND A FEW THUNDERSTORMS TO MAINLY LAKE HURON TODAY AND AGAIN TUESDAY AFTERNOON AND EVENING. THE FIRST SUCH FRONT WILL BRING GUSTS OVER PARTS OF THE LAKE HURON OPEN WATERS TO 20 KNOTS OR A BIT MORE THIS EVENING...WITH A SECOND FRONT BRINGING SLIGHTLY STRONGER WINDS OVERNIGHT TUESDAY NIGHT WITH GUSTS IN THE 25 KNOT AREA. WHILE THIS SYSTEM MAY BRING CONDITIONS APPROACHING SMALL CRAFT ADVISORIES...THE NORTHWEST TRAJECTORY WILL WINDS WILL THEN SLOWLY DECREASE ON WEDNESDAY AS A HIGH PRESSURE SYSTEM APPROACHES WITH A LIGHT AND VARIABLE WIND FIELD ON THURSDAY AS THIS HIGH BUILDS OVER THE REGION. && .AVIATION...ISSUED 142 PM EDT MON AUG 3 2015 PRIMARILY VFR CONDITIONS THROUGH THE FORECAST AS DRIER AIR STARTS MOVING INTO THE STATE. THE CAVEAT IS THE FIRST FEW HOURS OF THE FORECAST THIS AFTERNOON AS A SYSTEM SLIDES THROUGH NORTHERN MI WITH A TROUGH EXTENDING DOWN INTO SE MI. A NARROW CORRIDOR OF ISOLATED SHOWERS HAS DEVELOPED AND WILL TRACK EASTWARD THROUGH THE AFTERNOON. COVERAGE IS ISOLATED TO SCATTERED SO JUST INCLUDED TEMPOS FOR FNT AND PTK. SOUTHERN FLANK IS NOT HOLDING TOGETHER PER VISIBLE SATELLITE SO ELECTED NOT TO INCLUDE IN THE DETROIT TAFS. WESTERLY WINDS WILL TOP OUT NEAR 20 KNOTS DURING THE AFTERNOON. FOR DTW...THERE IS A CHANCE THAT THE ISOLATED SHOWERS COULD IMPACT THE TERMINAL BETWEEN 20-23Z THIS AFTERNOON BUT ELECTED TO HOLD OFF ON ANY MENTION DUE TO THE ISOLATED COVERAGE AND DRIER AIR TO THE WEST. CURRENT SHOWERS TRACKING TOWARD PTK SHOULD STAY NORTH OF THE TERMINAL. //DTW THRESHOLD PROBABILITIES... * LOW FOR CIGS BELOW 5000 FT AGL TUESDAY. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MICHIGAN WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...DRK LONG TERM....DG/DE MARINE.......DG AVIATION.....DRK YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

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