Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS63 KDTX 280745 AFDDTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 345 AM EDT MON JUL 28 2014 .SHORT TERM... TODAY AND TONIGHT EARLY MORNING SATELLITE IMAGERY SHOWS THE UPPER LOW SPINNING AWAY FROM SE MICHIGAN BUT STILL ABLE TO SUPPORT A PATTERN OF SHOWERS AROUND THE NORTHWEST FLANK OF THE SYSTEM. MODEL ANALYSIS FIELDS INDICATE THIS IS ASSOCIATED WITH A WELL-DEFINED DEFORMATION AXIS WRAPPING AROUND THE SYSTEM WHICH WILL EFFICIENTLY WRING OUT REMAINING MOISTURE FOR A FEW MORE HOURS. RADAR TRENDS SUPPORT MODEL DEPICTIONS OF THE PATTERN LEAVING THE TRI CITIES DRY AT PRESS TIME AND THEN SLIDING SOUTHWARD AND SHRINKING EASTWARD ON A PACE TO EXIT THE REST OF THE AREA AROUND 8 AM. THE CONTINUED EASTWARD DEPARTURE OF THE LOW WILL BOLSTER NORTHERLY SURFACE WIND AND COLD ADVECTION THAT IS ALREADY IN PROGRESS ACROSS LOWER MICHIGAN. THE 00Z MODEL SOLUTIONS ARE CONSISTENT WITH THE LAST SEVERAL RUNS SHOWING A POCKET OF 850 MB AIR AT ABOUT 5C RECOVERING TO ABOUT 7C DURING THE AFTERNOON. SOUNDING ANALYSIS TRANSLATES THAT INTO HIGHS MOSTLY IN THE UPPER 60S WITH A BOUNDARY LAYER MIXING TO 800 MB. THIS IS ABOUT 15 DEGREES BELOW NORMAL HIGHS THAT ARE STILL IN THE LOWER 80S DURING THE LAST WEEK OF JULY...BUT ONLY APPROACHING THE RECORD LOWEST MAX TEMP AT DTW WHICH IS 68/1926 WHILE FNT AND MBS ARE IN THE LOWER TO MID 60S. HIGH CLOUDS STRIPPING AWAY REVEAL SOME BREAKS IN THE STRATUS OVER LOWER MICHIGAN DURING THE EARLY MORNING. THERE COULD BE SOME EXPANSION OF OPEN SKY FOR A FEW HOURS POST SUNRISE BUT THESE WILL QUICKLY FILL IN AS SURFACE HEATING RAMPS UP BY LATE MORNING. MODEL SOUNDINGS INDICATE ENOUGH MOISTURE FOR A GENEROUS CU RESPONSE BUT WITH ENOUGH MID LEVEL SUBSIDENCE TO PREVENT SHOWERS. EXPECT THE AFTERNOON CLOUD PATTERN TO LINGER LONG ENOUGH INTO THE EVENING TO BLEND IN WITH MID AND HIGH CLOUDS ARRIVING WITH THE NEXT UPPER LEVEL HEIGHT FALL CENTER IN NORTHERLY FLOW ALOFT. THE APPROACH OF THE UPPER WAVE WILL ALSO SHARPEN SURFACE PRESSURE GRADIENT ENOUGH TO MAINTAIN A 5-10 KNOT WIND THROUGH THE NIGHT. THE COMBINATION OF CLOUDS AND WIND WILL THEN PREVENT TEMPERATURES FROM REACHING FULL RADIATIONAL COOLING POTENTIAL AND KEEP MIN TEMPS IN THE 50S WITH THE EXCEPTION OF THE USUAL COOL SPOTS THAT COULD TOUCH THE UPPER 40S BY SUNRISE TUESDAY. && .LONG TERM...TUESDAY THROUGH SUNDAY COOL CYCLONIC FLOW WILL PERSIST OVER THE CENTRAL GREAT LAKES FROM TUESDAY INTO FRIDAY AS THE UPPER LOW REMAINS OVER ONTARIO AND QUEBEC. WEAK UPPER SHORTWAVES PIVOTING AROUND THE LOW WILL OCCASIONALLY BRUSH ACROSS THE AREA...BRINGING QUICK SHOTS OF MOISTURE. DAYTIME HEATING WILL HELP US DESTABILIZE EACH DAY WITH SURFACE HEATING COMBINING WITH COOL AIR ALOFT (H850 TEMPS RUNNING JUST BELOW 10C THROUGH THIS PERIOD) TO STEEPEN LAPSE RATES. TEMPERATURES WILL ALSO RUN A BIT BELOW NORMAL...WITH HIGHS ONLY IN THE 70S (COMPARED TO AVERAGE HIGHS IN THE LOW 80S). FOR TUESDAY...MODELS HAVE BEEN CONSISTENT WITH DROPPING A VERY WEAK UPPER WAVE DOWN FROM CANADA...BRINGING A SURGE OF LOW/MID LEVEL MOISTURE WITH IT. THE SHORTWAVE AND ASSOCIATED SURFACE TROUGH ARE PROGGED TO WORK ACROSS THE AREA DURING PEAK HEATING. MODEL FORECAST SOUNDINGS LACK A CAP AND SHOW LAPSE RATES FROM THE SURFACE TO 500MB RANGING BETWEEN 7 AND 9 C/KM. THIS SHOULD PROVIDE SCATTERED TO NUMEROUS SHOWERS ACROSS THE AREA...WITH A LITTLE BETTER COVERAGE EXPECTED NORTH OF M-59...CLOSER TO THE UPPER WAVE AND COOLER AIR ALOFT. FREEZING LEVELS ARE EXPECTED TO RUN AROUND 9000 FEET WITH THE COOLER AIRMASS OVERHEAD. WHILE THE POTENTIAL FOR THUNDERSTORMS WILL BE LOW...THUNDERSTORMS OR EVEN MORE VERTICALLY DEVELOPED SHOWERS THAT DEVELOP WILL BE CAPABLE OF SMALL HAIL. CANADIAN UPPER LOW WILL LIFT NORTH FOR THE WEEKEND...BUT MEDIUM RANGE MODELS ARE STILL IN STRONG AGREEMENT WITH KEEPING SOME TROUGHING THROUGH THE GREAT LAKES. WHILE SHOWERS AND THUNDERSTORMS WILL STILL BE POSSIBLE...WE SHOULD SEE SOME MODERATION IN TEMPERATURES INTO THE UPPER 70S OR NEAR 80 FOR HIGHS. && .MARINE... GUSTY WINDS WILL PERSIST TODAY BEHIND A COLD FRONT...AND AS THE CENTRAL GREAT LAKES BECOMES SITUATED BETWEEN LOW PRESSURE TRACKING THROUGH THE EASTERN GREAT LAKES AND HIGH PRESSURE BUILDING OVER THE PLAINS AND UPPER MIDWEST. GUSTS UP TO 30 KNOTS WILL BE POSSIBLE OVER THE SOUTHERN HALF OF LAKE HURON TODAY...IN ADDITION TO LARGE WAVES. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR THE NEARSHORE WATERS OF LAKE HURON....INCLUDING ALL OF SAGINAW BAY. FURTHER SOUTH OVER LAKE ST CLAIR AND LAKE ERIE...GUSTS SHOULD STAY MOSTLY BETWEEN 18 AND 23 KNOTS...HOWEVER A FEW GUSTS TO 25 KNOTS CAN BE EXPECTED. WIND SPEEDS WILL DECREASE TONIGHT AS LOW PRESSURE OVER THE EASTERN GREAT LAKES STARTS TO LIFT NORTH AND ALLOWS THE SURFACE PRESSURE GRADIENT OVER MICHIGAN TO RELAX. THE CENTRAL GREAT LAKES WILL THEN REMAIN IN COOL CYCLONIC FLOW THROUGH THE MID-WEEK PERIOD. THIS WILL PROVIDE CHANCES FOR SHOWERS AND A FEW THUNDERSTORMS...BUT WINDS SHOULD BECOME FAIRLY LIGHT (UNDER 15 KNOTS) AS ONLY WEAK TROUGHING REMAINS OVER THE AREA. && .AVIATION...ISSUED 1153 PM EDT SUN JUL 27 2014 //DISCUSSION... DEFORMATION SHRAS WILL WRAP SOUTH/SOUTHEAST THROUGH THE AREA EARLY IN THE FORECAST AS POTENT SHORTWAVE GRADUALLY SHIFTS TO THE EAST OVERNIGHT. NORTH/NORTHWEST LOW LEVEL FLOW IN THE WAKE OF THIS WAVE WILL USHER IN MVFR/LOWER VFR STRATUS...WHICH WILL PERSIST INTO THE DAY MONDAY. AS THE BOUNDARY LAYER BECOMES WELL MIXED...WINDS WILL GUST TO 20 KNOTS OR MORE WITHIN TIGHT PRESSURE GRADIENT. THIS WILL HELP TO ERODE/LIFT STRATUS WITH TIME AND SCT VFR CONDITIONS ARE EXPECTED BY LATE AFTERNOON/EARLY EVENING. FOR DTW...SHRAS WILL PERSIST OFF/ON THROUGH 08Z/09Z BEFORE EXITING SHORTWAVE PULLS DEFORMATION SHRAS EAST WITH IT. CIGS WILL FALL BELOW 5000 FEET OVERNIGHT AND REMAIN AT LEAST BKN INTO MIDDAY MONDAY. //DTW THRESHOLD THREATS... * HIGH CONFIDENCE IN CEILINGS AOB 5000 FEET OVERNIGHT...WITH LOWER CONFIDENCE ON SUNDAY. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...BEACH HAZARDS STATEMENT...MIZ048-MIZ049...UNTIL 10 PM MONDAY. BEACH HAZARDS STATEMENT...MIZ055-MIZ063...FROM 8 AM MONDAY TO 10 PM MONDAY. LAKE HURON... SMALL CRAFT ADVISORY...SAGINAW BAY AND THE NEARSHORE WATERS FROM PORT AUSTIN TO HARBOR BEACH...UNTIL MIDNIGHT TUESDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM HARBOR BEACH TO PORT HURON...FROM 8 AM MONDAY TO MIDNIGHT TUESDAY. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...BT LONG TERM....HLO MARINE.......HLO AVIATION.....DG YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.