Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000 FXUS63 KDTX 220353 AFDDTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1153 PM EDT SUN SEP 21 2014 .AVIATION... //DISCUSSION... A DEEP LOW LEVEL INVERSION /SHOWN IN THE 00Z APX SOUNDING/ WILL MAINTAIN STRATUS ACROSS SE MI THROUGH DAYBREAK. THE CEILINGS LOOK TO HOVER AROUND THE 3000 FT THRESHOLD MUCH OF THE NIGHT. ONGOING LOW LEVEL DRY AIR ADVECTION MAY ACTUALLY LIFT BASES JUST A BIT BY DAYBREAK. A CLEARING TREND IS EXPECTED BY EARLY MON AFTERNOON AS THE DRY AIR MIXES INTO THE CLOUD LAYER. //DTW THRESHOLD THREATS... * HIGH CONFIDENCE IN CIGS BELOW 5KFT TONIGHT...MEDIUM CONFIDENCE MONDAY MORNING. && .PREV DISCUSSION...ISSUED 336 PM EDT SUN SEP 21 2014 SHORT TERM...TONIGHT UPPER LEVEL LOW/CIRCULATION PIVOTING THROUGH THE CENTRAL GREAT LAKES THIS AFTERNOON...SUPPORTING PLENTY OF SHOWERS (CATEGORICAL) WORKING THEIR WAY THROUGH SOUTHEAST MICHIGAN. SURFACE COLD FRONT NOW STARTING TO SURGE SOUTHWARD THROUGH SOUTHERN LOWER MICHIGAN...AND SHOULD MOSTLY BE OUT OF THE CWA AROUND 00Z...WITH JUST A LOW/SLIGHT CHANCE OF SOME LEFTOVER LIGHT SHOWERS ACROSS THE FAR EASTERN SECTION OF THE CWA FOR A COUPLE HOURS POST 00Z. THE ADDED CONVERGENCE ALONG THE FRONT IS ENHANCING THE SHOWERS PRESENTLY...WITH EVEN A FEW LIGHTENING STRIKES NOTED EARLIER TOWARD SAGINAW BAY. WITH ONLY ABOUT 500 J/KG OF SURFACE BASED CAPE TO WORK WITH...EXPECTING THUNDER ACTIVITY TO REMAIN ISOLATED. THE 12Z NAM IS ADAMANT LOW LEVEL MOISTURE WILL REMAIN TRAPPED UNDERNEATH THE DEVELOPING SUBSIDENCE INVERSION BEHIND THE UPPER LEVEL TROUGH AXIS OVERNIGHT...WITH CLOUDS LOCKED IN THE 2000-3000 FOOT LEVEL. THE 12Z GFS/EURO ARE DRIER...BUT STILL ENOUGH EVIDENCE IN THE 925-850 MB LAYER TO GO WITH MORE PESSIMISTIC SKY FORECAST TONIGHT...AS CLOUDS ARE STILL LOCKED IN NORTH OF THE GREAT LAKES IN ONTARIO. WOULD REFER MORE NORTHERLY FLOW (VS NORTHWEST) OFF LAKE HURON AS 850 MB TEMPS DROP TO ZERO OR SLIGHTLY COLDER TO BE 100 PERCENT CONFIDENT IN THE CLOUDS...BUT NONE-THE-LESS...HAVE AVERAGE TO ABOVE CONFIDENCE IN MOSTLY CLOUDY SKIES PREVAILING THROUGH THE NIGHT...WHICH SHOULD KEEP MINS ON THE PLUS SIDE OF 40 DEGREES...ABOUT 20 DEGREES COLDER COMPARED TO THIS MORNINGS LOWS. LONG TERM...MONDAY THROUGH SUNDAY SPRAWLING HIGH PRESSURE SYSTEM WILL BUILD INTO THE AREA MONDAY AND BRING CLEARING SKIES. THE CANADIAN ORIGIN OF THIS HIGH WILL RESULT IN COOL CONDTIONS WITH HIGHS IN THE LOWER 60S FOR THE MOST PART. BY MONDAY NIGHT...RETURN SOUTHWEST FLOW IS ALREADY SETTING UP AROUND THIS HIGH AS THE CENTER BECOMES ESTABLISHED OVER THE OHIO VALLEY. THIS WILL HOLD LOW TEMPERATURES CLOSE TO SEASONAL AVERAGES IN THE MIDDLE 40S. TEMPERATURES WILL CONTINUE TO MODERATE INTO TUESDAY AS HIGH PRESSURE MOVES EAST AND COMBINES WITH ANOTHER HIGH PRESSURE CENTER DROPPING SOUTHEAST THROUGH QUEBEC. TEMPERATURES ARE EXPECTED TO CLIMB TO AROUND 70 ON TUESDAY UNDER MOSTLY SUNNY SKIES AND FALL INTO THE UPPER 40S/LOWER 50S TUESDAY NIGHT AS THE QUIET CONDITIONS PREVAIL FROM THE STRONG HIGH PRESSURE THAT EVOLVES OVER UPSTATE NEW YORK AND THE NEW ENGLAND STATES. FOR THE EXTENDED...SPRAWLING HIGH PRESSURE WILL EXTEND FROM THE WESTERN ATLANTIC OCEAN TO THE OHIO VALLEY AND GREAT LAKES REGION. SE MI WILL REMAIN UNDER THE INFLUENCE OF THIS HIGH FOR SEVERAL DAYS AS THE UPPER LEVEL PATTERN BECOMES STAGNANT UNDER AN OMEGA BLOCKING HIGH PATTERN. TEMPERATURES WILL BE ON THE INCREASE THROUGH THE WEEK WITH ABOVE NORMAL VALUES EXPECTED. MARINE... SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL END AS LOW PRESSURE SHIFTS QUICKLY EAST OVERNIGHT. NORTHERLY FLOW IN THE WAKE OF THIS SYSTEM WILL REMAIN GUSTY INTO TONIGHT...BEFORE SLOWLY EASING LATE TONIGHT INTO MONDAY. EVEN AS THE FLOW SUBSIDES...WAVE ACTION WILL BE SLOWER TO FALL SO SMALL CRAFT ADVISORIES WILL REMAIN IN EFFECT OVER PORTIONS OF THE LAKE HURON NEARSHORE ZONES INTO MONDAY AFTERNOON. FAVORABLE MARINE CONDITIONS THEN SET UP FOR THE REMAINDER OF THE WEEK AS HIGH PRESSURE BECOMES ESTABLISHED OVER MUCH OF THE NORTHEASTERN UNITED STATES. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON... SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS FROM PORT AUSTIN TO HARBOR BEACH...UNTIL 10 AM MONDAY. SMALL CRAFT ADVISORY...INNER SAGINAW BAY...UNTIL 8 AM MONDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM HARBOR BEACH TO PORT HURON...UNTIL 4 PM MONDAY. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....SC SHORT TERM...SF LONG TERM....DG/MM MARINE.......DG YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

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