Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000 FXUS63 KDTX 251104 AFDDTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 704 AM EDT SAT OCT 25 2014 .AVIATION...
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//DISCUSSION... MVFR/LOW VFR CLOUDS THIS MORNING AS COLD FRONT WORKS THROUGH SOUTHEAST MICHIGAN. CLEARING WILL THEN TAKE PLACE THIS AFTERNOON...AS WESTERLY WINDS ALSO RAMP UP...WITH GUSTS LIKELY REACHING AND EXCEEDING 20 KNOTS. ONCE SKIES CLEAR OUT BY LATE IN THE DAY...SHOULD SEE CLEAR SKIES PERSIST TONIGHT. HOWEVER...COLD NORTHWEST FLOW WILL ATTEMPT TO SEND SOME LAKE INDUCED CLOUDS TOWARD THE AREA...MAINLY UP TOWARD MBS. WITH THE DRY AIR FILTERING IN AND WESTERLY WINDS HOLDING UP AROUND 10 KNOTS...NO FOG CONCERNS TONIGHT. //DTW THRESHOLD THREATS... * HIGH CONFIDENCE IN CEILINGS BELOW 5000 FEET THIS MORNING. * LOW CONFIDENCE WIND GUSTS WILL EXCEED CROSSWIND THRESHOLDS THIS AFTERNOON.
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&& .PREV DISCUSSION...
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ISSUED 349 AM EDT SAT OCT 25 2014 SHORT TERM... TODAY AND TONIGHT WITH THE MOSTLY CLEAR SKIES WHICH DEVELOPED BY MIDNIGHT...THE GOOD RADIATORS ACROSS SOUTHEAST MICHIGAN HAVE FALLEN TO AROUND 40 DEGREES...WITH MINS IN THE LOW TO MID 40S ACROSS MOST OF THE CWA. THERE IS SOME FOG AROUND...LOCALLY DENSE IN SPOTS...BUT CONDITATIONS SHOULD ACTUALLY IMPROVE SLIGHTLY TOWARD SUNRISE AS CLOUDS SPREAD IN FROM THE WEST WITH THE APPROACHING COLD FRONT. BASED ON THE 295K ISENTROPIC ASCENT AND UPSTREAM LIGHT RADAR RETURNS...COULD SEE A FEW SPRINKLES THIS MORNING AS THE FRONT CROSSES THE AREA. HOWEVER...THE PRONOUNCED DRY SLOT PUNCHING IN THIS AFTERNOON WILL QUICKLY SCOUR OUT ANY REMNANT LOW LEVEL MOISTURE...WITH BREEZY WESTERLY WINDS DEVELOPING AS THE BOUNDARY LAYER DEPTH EASILY EXCEEDS 925 MB. BASED ON FORECASTED 925 MB TEMPS IN THE LOWER TEENS THIS AFTERNOON...LOOKING AS MAXES IN THE 60S...WITH THE STANDARD NORTHWEST TO SOUTHEAST GRADIENT UNDER THE WEST-NORTHWEST FLOW. SPEAKING OF GRADIENTS...THERE LOOKS TO BE SHARP 850 MB RH GRADIENT WITH THE COLD NORTHWEST FLOW TONIGHT...BUT OUTSIDE OF THE NORTHERN THUMB REGION...THERE LOOKS TO BE LITTLE SUPPORT FOR CLOUDS...PER 12Z NAM. HOWEVER..WITH WESTERLY WINDS PERSISTING THROUGH THE NIGHT...CLOSE TO 10 KNOTS...SHOULD SEE BIT MORE UNIFORM MINS...WITH CONTINUED COLD ADVECTION THROUGH THE NIGHT ALLOWING MINS TO DIP TO AROUND 40 DEGREES. LONG TERM...SUNDAY THROUGH FRIDAY RIDGING WILL BRING DRY WEATHER AND ABUNDANT SUNSHINE TO SOUTHEAST MICHIGAN ON SUNDAY. HOWEVER COLD AIR WILL BE IN PLACE BEHIND THE DEPARTING COLD FRONT AS 850 MB TEMPERATURES FALL TO 3 TO 5 CELSIUS. DESPITE SUNNY SKIES THE COOLER AIRMASS WILL MEAN HIGHS WILL GENERALLY BE LIMITED TO THE MIDDLE TO UPPER 50S SUNDAY AFTERNOON. THE RIDGE WILL TRACK EAST SUNDAY NIGHT...ALLOWING FOR WARM AIR ADVECTION TO COMMENCE IN EARNEST ACROSS THE CENTRAL GREAT LAKES ON MONDAY AS 850 MB TEMPERATURES RISE TO 12 TO 14 CELSIUS. A WARM FRONT WILL LIFT NORTH THROUGH THE SOUTHERN GREAT LAKES ON MONDAY...ACTING AS A TRIGGER FOR SHOWERS AND A FEW THUNDERSTORMS...MAINLY ACROSS THE NORTH WHERE THE FRONT WILL SETTLE DURING THE AFTERNOON HOURS. A SHORTWAVE TRACKING THROUGH THE SOUTHERN GREAT LAKES WILL ASSIST IN PRECIPITATION DEVELOPMENT ON MONDAY...WITH WARM MOIST AIR AND INCREASED INSTABILITY BRINGING THE CHANCE FOR THUNDERSTORMS EMBEDDED WITHIN THE SHOWER ACTIVITY. DESPITE THE PASSAGE OF THE WARM FRONT...HIGHS WILL VARY GREATLY ON MONDAY...WITH HIGHS AROUND 60 ACROSS THE THUMB GIVEN A SOUTHEASTERLY SURFACE WIND OFF LAKE HURON...WITH HIGHS AROUND 70 NEAR THE OHIO BORDER AWAY FROM THE MAIN PRECIPITATION AND DEEPER INTO THE WARM SECTOR. THE PARENT LOW ASSOCIATED WITH THE AFOREMENTIONED WARM FRONT WILL DEVELOP OVER THE WESTERN GREAT LAKES MONDAY NIGHT...THEN TRACK EAST THROUGH THE NORTHERN GREAT LAKES TUESDAY...DRAGGING A COLD FRONT THROUGH THE CENTRAL GREAT LAKES ON TUESDAY. MODELS HAVE COME IN BETTER AGREEMENT THIS RUN...MAINLY THE ECMWF WHICH HAS COME IN FASTER THIS RUN...MORE IN LINE WITH THE GFS IN CLEARING THE FRONT THROUGH BY TUESDAY. ALTHOUGH IT IS NOT LOCK STEP WITH THE FASTER GFS SOLUTION...IT IS IN THE SAME BALL PARK TO ALLOW FOR LIKELY POPS ON TUESDAY GIVEN THE HIGHER DEGREE OF CONFIDENCE IN FROPA SOMETIME ON TUESDAY RATHER THAN A POSSIBLE FROPA SOLUTION THAT IS A WHOLE 12 HOURS APART PER THE PREVIOUS RUNS. CONTINUED INSTABILITY WILL KEEP THUNDERSTORMS IN THE FORECAST DURING THIS TIME PERIOD UNTIL THE COLD FRONT CLEARS THE AREA. WITH THE BETTER MODEL AGREEMENT...IT APPEARS RAIN CHANCES WILL BE OFF TO THE WEST BY TUESDAY NIGHT GIVEN THE SUBSIDENCE BEHIND THE DEPARTING FRONT. THEREFORE WILL DRY OUT THE FORECAST ON TUESDAY NIGHT...WITH RIDGING EXPECTED TO KEEP THE WEATHER DRY INTO WEDNESDAY AS A SHOT OF COOL DRY AIR SENDS AFTERNOON HIGHS BACK DOWN INTO THE LOWER TO MIDDLE 50S ON WEDNESDAY. A WEAK LOW PRESSURE SYSTEM IS THEN ON TRACK TO AFFECT THE CENTRAL GREAT LAKES DURING THE LATER PART OF THE WORK WEEK. GIVEN THE WEAK NATURE OF THIS LOW PRESSURE SYSTEM IT IS NOT SURPRISING THAT THE MODELS ARE HAVING A HARD TIME RESOLVING THE TIMING AND IMPACT OF THIS LOW PRESSURE SYSTEM. THERE ARE HINTS THAT THIS SYSTEM COULD BRING THE FIRST TASTE OF WINTER TO SOUTHEAST MICHIGAN LATE IN THE WEEK...WITH SOME SNOW FLAKES POSSIBLE ACROSS THE AREA. HOWEVER THE AFOREMENTIONED ISSUES WITH THE EXACT TIMING AND STRENGTH OF THIS SYSTEM DOES NOT LEND ITSELF TO A GREAT DEGREE OF CONFIDENCE THIS FAR OUT...BUT IT DOES BEAR WATCHING WITH THE UPCOMING HALLOWEEN HOLIDAY AT THE VERY END OF THE EXTENDED FORECAST. MARINE... STRONG UPPER LEVEL WAVE OF LOW PRESSURE WILL DIVE INTO THE GREAT LAKES REGION TODAY. THE DYNAMIC SYSTEM WILL LEAD TO A TIGHT PRESSURE GRADIENT OVER THE NORTHERN GREAT LAKES WITH COLD AIR POSSIBLY BUILDING INTO THE NORTHERN 1/2RD OF LAKE HURON. IT IS BEHIND THIS DEVELOPING FRONTAL BOUNDARY THAT CONDITIONS WILL BECOME QUITE UNSTABLE. THESE UNSTABLE CONDITIONS WILL LEAD TO GALE FORCE NORTHWESTERLY WINDS ACROSS THE NORTHERN 1/2 OF LAKE HURON TONIGHT. FURTHER SOUTH...ALTHOUGH WINDS ARE NOT EXPECTED TO REACH GALE FORCE...WAVES ARE EXPECTED TO BUILD UP OVER SOUTHERN LAKE HURON TONIGHT...THEN SLOWLY SUBSIDE ON SUNDAY AS HIGH PRESSURE BUILDS IN FROM THE WEST AND THE PRESSURE GRADIENT SLOWLY LOOSENS. ELEVATED WAVE HEIGHTS WILL NECESSITATE THE ISSUANCE OF A SMALL CRAFT ADVISORY FOR OUTER SAGINAW BAY AS WELL AS THE LAKE HURON NEARSHORE WATERS FROM PORT AUSTIN TO PORT SANILAC. THE EXTREME SOUTHERN ZONE FROM PORT SANILAC TO PORT HURON WILL NEED TO BE MONITORED CLOSELY AS IT IS FORECAST TO REACH SMALL CRAFT ADVISORY CRITERIA FOR A BRIEF TIME ON SUNDAY. HOWEVER GIVEN THE BREVITY...UNCERTAINTY...AND THE FACT THAT CONDITIONS WILL NOT BE MET UNTIL SUNDAY WILL HOLD OFF ON HEADLINES WITH THIS ISSUANCE.
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&& .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON... SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS FROM PORT AUSTIN TO HARBOR BEACH...FROM 8 PM SATURDAY TO 4 PM SUNDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM HARBOR BEACH TO PORT SANILAC...FROM MIDNIGHT SUNDAY TO 4 PM SUNDAY. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....SF SHORT TERM...SF LONG TERM....KURIMSKI MARINE.......KURIMSKI YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

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