Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000 FXUS63 KDTX 301103 AFDDTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 703 AM EDT SAT APR 30 2016 .AVIATION... AREAWIDE VFR THROUGH THE DAYLIGHT HOURS TODAY. WIND WILL HOLD FIRMLY OUT OF THE EAST INTO THIS EVENING BEFORE BACKING TO THE NE UPON PASSAGE OF THE LOW TO THE SOUTH TONIGHT. PLENTY OF MOISTURE ASSOCIATED WITH THIS SYSTEM WILL SUPPORT AT LEAST MODERATE RAIN RATES 00-06Z...PARTICULARLY IN THE DETROIT AREA...ALONG WITH RAPID DETERIORATION OF CIGS TO LOW MVFR. LINGERING LOW-LEVEL MOISTURE IN ITS WAKE WILL SUPPORT IFR BY LATE TONIGHT INTO EARLY SUNDAY MORNING. FOR DTW...BEST ESTIMATE FOR START TIME TO PRECIP IS 21Z. CIGS WILL INITIALLY REMAIN ELEVATED DUE TO ANTECEDANT DRY AIR BUT WILL RAPIDLY DETERIORATE BY 00Z AS HEAVIER RAIN MOVES IN. STOUT FLOW OUT OF THE EASTERLY QUADRANT WILL PERSIST THROUGH THE FORECAST PERIOD. //DTW THRESHOLD PROBABILITIES... * HIGH FOR CIGS AOB 5KFT BY 00Z. && .PREV DISCUSSION...ISSUED 352 AM EDT SAT APR 30 2016 DISCUSSION... TODAY...INCREASINGLY FAVORABLE ENVIRONMENT FOR A SOLID RAINFALL EVENT LOCALLY HEADING INTO TONIGHT CURRENTLY IN THE EARLY STAGES OF DEVELOPMENT JUST UPSTREAM. WATER VAPOR DISPLAYING A CLEAR SIGNAL OF DEEP LAYER NORTHWARD MOISTURE TRANSPORT LODGED WITHIN THE ATTENDANT STRENGTHENING MID LEVEL SOUTHWESTERLIES IMMEDIATELY DOWNSTREAM OF THE CLOSED LOW/HEIGHT FALLS NOW LIFTING INTO THE CENTRAL PLAINS. A CLASSIC APPEARING SETUP AT THE FRONT END...PRECEDED BY A PERIOD OF BRIEF SHORTWAVE RIDGING THAT WILL SWEEP ACROSS SE MICHIGAN TODAY. RAPID ADVANCEMENT OF HIGH CLOUD COMBINED WITH PESKY LINGERING STRATUS WILL LEAVE A SHRINKING WINDOW FOR CLEAR SKY EARLY TODAY. MODEST RECOVERY TO THE LOW LEVEL THERMAL PROFILE GIVEN THE GENERAL UPWARD INCREASE IN MEAN THICKNESSES AND SOME ADDED INSOLATION POTENTIAL /PARTICULARLY NORTH/. CONTINUED LOW LEVEL EASTERLY FLOW WILL MAINTAIN A NEUTRAL ADVECTIVE COMPONENT...NETTING A SOMEWHAT LIMITED OVERALL RESPONSE. WITH THAT...STILL LOOKING FOR HIGHS UPPER 50S/AROUND 60 MOST LOCALES. TONIGHT...WELL DEFINED MOISTURE AXIS LOCKED ALONG AN EMERGING STRONG WING OF MID LEVEL ISENTROPIC ASCENT/WAA EXPECTED TO RAPIDLY ADVANCE INTO SE MICHIGAN AFTER 20Z. AN ADDITIONAL CONTRIBUTION OF DCVA AND CONVERGENCE AS SHORTWAVE ENERGY AND LOW LEVEL JET FORCING IMPINGE ON THE REGION WILL CONTRIBUTE TO AN EXPANSIVE REGION OF RAINFALL LIFTING ACROSS ALL LOCALES THIS EVENING/TONIGHT. 00Z NAM/ARR/NMM MODEL SUITE POINT TOWARD A POTENTIALLY MORE DYNAMIC RESPONSE OVERNIGHT INTO EARLY SUNDAY...PORTIONS OF SE MICHIGAN BECOMING FAVORABLY POSITIONED BENEATH A STRENGTHENING 850-700 MB FRONTAL ZONE AND DEFORMATION AXIS. DIMINISHED STABILITY THROUGH THIS LAYER WILL ADD A CONVECTIVE ELEMENT AND THE POTENTIAL FOR A PERIOD OF MODERATE TO LOCALLY HEAVY RAINFALL. INSTABILITY NOT ENOUGH TO INCLUDE A THUNDER MENTION...BUT RAINFALL AMOUNTS IN EXCESS OF HALF AN INCH CERTAINLY IN PLAY. SUNDAY AND SUNDAY NIGHT...MID LEVEL FORCING/DEFORMATION MAY BE SLOW TO VACATE THE REGION EARLY SUNDAY...PARTICULARLY OVER NORTHERN/EASTERN SECTIONS AS THE PARENT SURFACE AND MID LEVEL CIRCULATIONS SLOWLY EXIT INTO ONTARIO. THIS WILL MAINTAIN THE CHANCE FOR SHOWERS TO LINGER THROUGH THE FIRST HALF OF THE DAY. SUBSTANTIAL RESIDUAL MOIST LOW LEVEL ENVIRONMENT WILL ENSURE CONSIDERABLE CLOUDINESS HOLDS ALL LOCALES...WITH POST-SYSTEM NORTHWEST FLOW AGAIN RESULTING IN BELOW NORMAL TEMPERATURES. AFTERNOON READINGS REACHING INTO THE 50S REMAIN ON TARGET. GREATER FORECAST UNCERTAINTY YET IN THE SUNDAY NIGHT PERIOD...MODEL GUIDANCE PROVIDING A MIXED SIGNAL ON THE EVENTUAL TRACK OF THE AFOREMENTIONED CENTRAL PLAINS CLOSED LOW EJECTING THROUGH THE OHIO VALLEY/SOUTHERN MICHIGAN DURING THIS TIME WINDOW. POTENTIAL FOR STRONGER DCVA WITHIN THE NORTHERN PERIPHERY OF THIS WAVE TO PROVIDE AT LEAST A CHANCE FOR ADDITIONAL SHOWER DEVELOPMENT...POSITIONING YIELDING A GREATER POSSIBILITY SOUTH OF THE M-59 CORRIDOR. EARLY NEXT WEEK...BROADER LONGWAVE TROUGHING LEFT IN THE WAKE OF THE ACTIVE WEEKEND PATTERN. INCREASING DRY AIR ADVECTION INTO MONDAY WILL FAVOR A STEADY CLEARING TREND...THE ADDED INSOLATION POTENTIAL BOOSTING HIGHS BACK TOWARD THE LOWER 60S. MODERATING TREND CONTINUES INTO TUESDAY UNDER GENERAL SUBSIDENCE AND WEAK RIDGING. TEMPERATURES BACK IN THE VICINITY OF NORMAL FOR EARLY MAY /MID 60S/. MARINE... MODERATE NORTHEASTERLY ONSHORE FLOW WILL BECOME FRESH AT TIMES LATE TONIGHT THROUGH SUNDAY AS LOW PRESSURE PASSES SOUTH OF THE AREA. WINDS WILL GUST TO SMALL CRAFT ADVISORY CRITERIA DURING THIS TIME WHILE PERSISTENT ONSHORE FLOW ALLOWS SIGNIFICANT WAVE HEIGHTS TO BECOME ELEVATED IN THE NEARSHORE ZONES OF LAKE HURON. A SMALL CRAFT ADVISORY HAS BEEN ISSUED ACCORDINGLY. MODERATE NORTHWEST WIND WILL FILL IN IN THE WAKE OF THE LOW EARLY NEXT WEEK. HYDROLOGY... LOW PRESSURE LIFTING THROUGH THE OHIO VALLEY WILL PRODUCE WIDESPREAD RAIN TONIGHT. WIDESPREAD AMOUNTS OF AROUND ONE HALF OF AN INCH ARE ANTICIPATED WITH LOCATIONS SOUTH OF THE I-69 CORRIDOR SEEING UP TO THREE QUARTERS OF AN INCH. THE FAVORED TIME PERIOD FOR THE HEAVIEST RAIN IS BETWEEN 10 PM AND 5 AM LOCAL TIME. IT SHOULD BE NOTED THAT,DEPENDING ON HOW LONG DEFORMATION FORCING LINGERS INTO EARLY SUNDAY, THERE MAY BE AN OPPORTUNITY FOR AN ADDITIONAL FEW TENTHS OF AN INCH THROUGH LATE SUN MORNING. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR MIZ060>063-068>070. LAKE HURON...SMALL CRAFT ADVISORY FROM 5 AM TO 8 PM EDT SUNDAY FOR LHZ421-422- 441>443. LAKE ST CLAIR...NONE. MICHIGAN WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....JVC DISCUSSION...MR MARINE.......JVC HYDROLOGY....JVC YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

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