Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000 FXUS63 KDTX 260352 AFDDTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1152 PM EDT MON MAY 25 2015 .AVIATION... UPSTREAM OBSERVATIONS ACROSS THE OHIO VALLEY SHOW SOME SEMBLANCE OF LOW STRATUS LIFTING NORTHWARD. AREA OBSERVATIONS DO HOWEVER SUGGEST MODEL SOLUTIONS MAY BE A LITTLE OVERZEALOUS WITH THE DEGREE OF LOW LEVEL MOISTURE UPSTREAM. THIS WILL SUPPORT JUST A TEMPO FOR SOME PERIODIC LOW CLOUDS TOWARD DAYBREAK TUES. FOR DTW...THE ARRIVAL OF LOW CLOUDS /IF ANY/ SHOULD HOLD OFF UNTIL 11 OR 12Z. THE CHANCE FOR THUNDERSTORMS WILL INCREASE LATE TUES AFTERNOON INTO TUES EVENING WITH THE APPROACH OF AN UPPER SHORT WAVE. //DTW THRESHOLD PROBABILITIES... * MEDIUM IN CIGS BELOW 5000 FT LATE TONIGHT AND TUESDAY MORNING. * MEDIUM IN THUNDERSTORMS LATE TUESDAY AFTERNOON AND EVENING. && .PREV DISCUSSION...ISSUED 847 PM EDT MON MAY 25 2015 UPDATE... MID LEVEL SUBSIDENCE HAS BEEN BUILDING ACROSS SE MI THIS EVENING AND IS INHIBITING ADDITIONAL SHOWER DEVELOPMENT. THIS SUBSIDENCE WILL PERSIST THROUGH THE NIGHT AND WILL SUPPORT THE CURRENT DRY FORECAST OVERNIGHT. A CONSIDERABLE AMOUNT OF HIGH CLOUDS ACROSS LOWER MI AND THE POTENTIAL FOR SOME LOW STRATUS TO DEVELOP OVER/ADVECT INTO SE MI WILL SUPPORT AN INCREASE IN CLOUD COVERAGE AND A SLIGHT UPWARD ADJUSTMENT TO FORECAST MIN TEMPS TONIGHT. PREV DISCUSSION...ISSUED 348 PM EDT MON MAY 25 2015 SHORT TERM...THIS AFTERNOON AND TONIGHT VEERED LOW-LEVEL JET SITUATED OVERHEAD AS A WEAK SHORTWAVE LIFTS ACROSS THE WESTERN GREAT LAKES THIS AFTERNOON. H7-H5 THETA-E GRADIENT IS PRESENTLY SUPPORTING AN ARC OF SHOWERS THAT HAVE PROVEN EFFICIENT IN MIXING DOWN ENVIRONMENTAL WINDS OF 50MPH WITH A LONE REPORT OF 60MPH. LARGE SCALE SUPPORT FOR THIS PARTICULAR ROUND OF SHOWERS WILL EXIT NORTHEAST BY 21Z. DRY SLOT INTRUSION HAS ERODED THE MAJORITY OF LOW CLOUDS, PROVIDING A WINDOW WITHIN WHICH MODEST RECOVERY MAY TAKE PLACE OVER THE NEXT COUPLE OF HOURS. STILL QUESTION THE POTENTIAL FOR THUNDER, WITH NO CTG STRIKES OBSERVED VIA NLDN YET TODAY, BUT THE POTENTIAL FOR UPDRAFTS OF EQUAL STRENGTH TO THOSE ALREADY OBSERVED WILL EXIST AS DYNAMIC SHORTWAVE FORCING RACES THROUGH THE AREA 20-00Z. THUS, THE FORECAST PROCEEDS WITH A HIGHER CHC POP FOR A PARTIAL COVERAGE OF SHOWERS THROUGH 00Z WITH CONTINUED POTENTIAL FOR 50 MPH WIND GUSTS OR PERHAPS AN ISOLATED 60 MPH. VIGOROUS SHORTWAVE TRIGGERING TODAY`S SEVERE CONVECTIVE EPISODE IN TEXAS/OKLAHOMA WILL LIFT NORTH THROUGH TONIGHT FORCING DOWNSTREAM RIDGING. RESULTING SUBSIDENCE WILL FAVOR MOSTLY CLEAR SKIES THROUGH THE NIGHT SAVE FOR PASSING CIRRUS DEBRIS. SOUTHERLY GRADIENT AT THE SURFACE WILL ADVECT LOW-LEVEL MOISTURE AND ASSOCIATED CLOUDS FROM THE OHIO VALLEY INTO THE SOUTHERN CWA BY SUNRISE. SOUTH WINDS WILL HOVER AROUND 10 KTS THROUGH THE NIGHT WITH LOWS BOTTOMING OUT IN THE MID 60S. LONG TERM... THE WARM AND MOIST AIRMASS NOW IN PLACE OVER THE AREA WILL PERSIST INTO TUESDAY AND WEDNESDAY AS SOUTHWEST FLOW CONTINUES AROUND THE WEST EDGE OF A PERSISTENT UPPER RIDGE CENTERED OVER THE SOUTHEAST CONUS AND SOUTHWEST ATLANTIC OCEAN. THIS WILL MAINTAIN AFTERNOON TEMPERATURES IN THE UPPER 70S TO LOWER 80S BOTH DAYS. THE MINIMUM TEMPERATURES WILL REMAIN VERY MILD TUESDAY NIGHT WITH LOWS IN THE MIDDLE 60S...BUT COOL SOME BY WEDNESDAY NIGHT AS A WEAK COLD FRONT MOVES INTO THE AREA AS SHORTWAVE ENERGY EJECTING FROM A WESTERN AND CENTRAL CONUS UPPER TROUGH BREAKS DOWN THE NORTH AND NORTHWEST PART OF THE AFOREMENTIONED RIDGE AND ALLOWS FOR SLIGHTLY COOLER READINGS OVER THE AREA. SHOWER AND THUNDERSTORM CHANCES WILL ALSO INCREASE TUESDAY AND TUESDAY NIGHT AS THE UPPER HEIGHTS LOWER IN RESPONSE SHORTWAVE ENERGY LIFTING INTO THE REGION. WHILE THE SEVERE WEATHER POTENTIAL IS NOT HIGH...A FEW STRONG STORMS WILL GUSTY WINDS WILL BE POSSIBLE GIVEN THE INCREASINGLY UNSTABLE ENVIRONMENT. LINGER CONVECTIVE ACTIVITY WILL ALSO AFFECT THE AREA WEDNESDAY AS THE COLD FRONT SHIFTS THROUGH THE LOWER GREAT LAKES...WITH ACTIVITY THEN FADING WEDNESDAY NIGHT AS COOLER...DRIER AIR BEGINS TO WORK INTO THE AREA. DRY WEATHER WILL START OFF THE EXTENDED PERIOD AS HIGH PRESSURE BUILDS SOUTH INTO THE REGION ON THURSDAY. DRY CONDITIONS WILL CONTINUE THROUGH THURSDAY NIGHT BEFORE THE NEXT ROUND OF WET WEATHER MOVES INTO THE AREA ON FRIDAY. RAIN SHOWER AND THUNDERSTORM CHANCES WILL STICK AROUND THROUGH SATURDAY NIGHT AS A SERIES OF LOW PRESSURE AND FRONTAL SYSTEMS TRACK ACROSS THE GREAT LAKES. HIGH PRESSURE RETURNS ON SUNDAY AND WILL REMAIN FIRMLY IN PLACE ACROSS THE NORTHERN GREAT LAKES WITH A WARM FRONT OVER THE OHIO VALLEY REGION. THIS SET UP WILL MAKE FORECASTING PRECIPITATION CHANCES ON SUNDAY A BIT DIFFICULT AS ANY SLIGHT SHIFT NORTH OR SOUTH WILL CAUSE EITHER A WETTER OR DRIER FORECAST ACROSS SOUTHEAST MICHIGAN. CURRENT MODEL RUNS ARE SHOWING SOME INDICATION THAT THERE WILL BE A BETTER CHANCE FOR RAIN IN THE SOUTHERN CWA WITH THE NORTHERN CWA /NORTH OF M-59/ STAYING RELATIVELY DRY. HAVE ADDED SLIGHT CHANCE POPS TO THE NORTH AND CHANCE POPS IN THE SOUTH TO ACCOUNT FOR THIS TREND...HOWEVER...THIS WILL HAVE TO BE FINE TUNED AS THE WEEK PROGRESSES. MARINE... SMALL CRAFT ADVISORIES WILL REMAIN IN PLACE INTO THIS EVENING AS SOUTHWEST WINDS CONTINUE TO GUST TO 25 KNOTS (OR MORE NEAR THE SCATTERED SHOWERS AND/OR THUNDERSTORMS OVER THE AREA). OFFSHORE WINDS WILL LIMIT THE POTENTIAL FOR WAVE GROWTH IN THE NEARSHORE ZONES WITH SIGNIFICANT WAVE HEIGHTS EXPECTED TO MAX OUT AROUND 2 TO LOCALLY 3 FEET. MAXIMUM WAVE HEIGHTS WILL REACH 4 TO POSSIBLY 5 FEET...MAINLY FURTHER AWAY FROM SHORE. WINDS WILL SUBSIDE SOMEWHAT OVERNIGHT AND REMAIN MORE IN THE 10 TO 15 KNOT RANGE WITH GUSTS TO 20 KNOTS TUESDAY INTO WEDNESDAY. THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL INCREASE FROM TUESDAY INTO TUESDAY NIGHT AND LINGER INTO WEDNESDAY AS A FRONTAL BOUNDARY EDGES INTO THE AREA AS HIGH PRESSURE RIDGE SETTLES SLIGHTLY TO THE SOUTH AND EAST OVER THE NEXT FEW DAYS. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MICHIGAN WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....SC UPDATE.......SC SHORT TERM...JVC LONG TERM....DG/RK MARINE.......DG YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

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