Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000 FXUS63 KDTX 261752 AFDDTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1252 PM EST MON JAN 26 2015 .AVIATION... WEAK SURFACE HIGH PRESSURE WILL BE THE PRIMARY INFLUENCE ON AVIATION CONDITIONS OVER SE MICHIGAN FOR THE REST OF TODAY THROUGH TONIGHT AND TUESDAY. THIS WILL SUPPORT DRY AND MOSTLY VFR CONDITIONS BETWEEN A WEAK LOW PRESSURE SYSTEM THAT WILL DISSIPATE OVER THE MIDWEST AND THE STRONG WINTER STORM UNFOLDING ALONG THE EAST COAST. THE GREATEST UNCERTAINTY IN THE FORECAST CONCERNS HOW MUCH WESTWARD REACH MVFR STRATOCU WILL HAVE FROM LAKE HURON TODAY AND FROM THE EASTERN GREAT LAKES AS THE EAST COAST STORM INTENSIFIES TONIGHT. THERE IS ALSO SOME POTENTIAL FOR ADDITIONAL CLOUD CONTRIBUTIONS FROM LAKE HURON... LAKE ERIE...AND LAKE ONTARIO GIVEN THE EASTERLY LOW LEVEL FLOW. EXPECT A FEW POCKETS OF MVFR CEILING TO POSSIBLY REACH FNT AND MBS DURING THE AFTERNOON BUT IT WILL TAKE UNTIL AFTER MIDNIGHT FOR ANYTHING TO ARRIVE OVER THE REST OF THE AREA AS THE LATEST OBSERVATIONS OVER SOUTHERN ONTARIO ARE CLEAR. EXPECT COVERAGE WILL DEVELOP AND EXPAND WESTWARD AFTER SUNSET WITHIN A FAVORABLE NOCTURNAL INVERSION AND THEN BE SUBJECT TO IMPROVEMENT AS LOW LEVEL WIND BACKS TOWARD THE NORTH WITH TIME DURING TUESDAY. //DTW THRESHOLD PROBABILITIES... * MODERATE FOR CEILING BELOW 5000 FT TONIGHT INTO TUESDAY MORNING. && .PREV DISCUSSION...ISSUED 302 AM EST MON JAN 26 2015 SHORT TERM...TODAY AND TONIGHT COLD TEMPERATURES WILL PERSIST TODAY AND TONIGHT AS NORTHEAST FLOW CONTINUES TO FEED INTO AREA FROM LARGE HIGH PRESSURE SYSTEM CENTERED JUST TO THE NORTH OF THE AREA. HIGHS THIS AFTERNOON WILL CLIMB TO AROUND 20 DEGREES WITH LOWS TONIGHT FALLING BACK INTO THE SINGLE DIGITS TO LOWER TEENS. THIS TEMPERATURE FORECAST...ESPECIALLY FOR TONIGHT...IS COMPLICATED BY A TRICKY CLOUD FORECAST AS VARIOUS SOURCES OF CLOUDS WILL EXIST THROUGHOUT THE NEXT 24 HOURS. INITIAL MID LEVEL CLOUDS ASSOCIATED WITH SHORTWAVE PHASING INTO MAJOR EAST COAST STORM WILL EXIT THE AREA EARLY THIS MORNING...LEAVE A FAIR AMOUNT OF THE CWA PARTLY TO MOSTLY SUNNY FOR A TIME. MEANWHILE...LOWER STRATUS ASSOCIATED WITH COLD EAST TO NORTHEAST FLOW FROM LAKE HURON WILL LINGER OVER THE NORTHERN THUMB AND SAGINAW VALLEY THIS MORNING BEFORE ERODING AND SHIFTING NORTH AS THE LOW LEVEL FLOW GRADUALLY VEERS TO A MORE EASTERLY DIRECTION. DURING THE WHOLE TIME...ADDITIONAL HIGH MID TO UPPER LEVEL CLOUDS WILL SPILL BACK INTO AREA AS ADDITIONAL JET ENERGY DIGS SHARPLY INTO DEVELOPING UPPER TROUGH/STORM OVER THE NORTHEAST CONUS. BETWEEN THESE UPPER LEVEL CLOUDS...WHICH WILL PERSIST INTO TONIGHT AND LOWER CLOUDS PIVOTING BACK INTO OR NEAR PARTS OF AREA FROM THIS EVENING INTO THE OVERNIGHT AS THE EAST COAST SYSTEM BOMBS OUT...EXPECT MOSTLY CLOUDY SKIES FOR MUCH OF THE AREA. PARTS OF THE THUMB MAY BE THE EXCEPTION AS DRIER LOW FROM THE AFOREMENTIONED HIGH WILL WEDGE IN BETWEEN THESE OTHER TWO MOISTURE SOURCES. GIVEN THIS EXPECT THE LOWEST TEMPERATURES OVER THIS PART OF THE CWA...NOT AN UNCOMMON OCCURRENCE BY ANY MEANS. LONG TERM... WATER VAPOR IMAGERY REVEALS BROAD RIDGING IN PLACE ACROSS THE WESTERN UNITED STATES AND FAR EAST PACIFIC. TO THE EAST, A CLIPPER HAS BEGUN THE EARLY STAGES OF A RAPID DEVELOPMENT SEQUENCE INTO A CLASSIC COASTAL CYCLONE. UPPER-LEVEL FLOW OVER THE GREAT LAKES WILL REMAIN NORTHWESTERLY AS IT WILL BE POSITIONED BETWEEN THESE TWO PRIMARY PLAYERS IN THE LONGWAVE CONFIGURATION. THE UPSTREAM RIDGE WILL, HOWEVER, BEGIN TO FEEL THE PINCH OF EAST PAC TROUGH IN RELATIVELY SHORT ORDER AS IT ABSORBS THE BAJA LOW AND CAUSES RAPID LONGWAVE DEAMPLIFICATION ACROSS THE WEST ON TUESDAY AS THE ENERGY RACES EAST. THIS WILL IN TURN SHUNT A STOUT SHORTWAVE RIDGE ACROSS THE CWA ON TUES, ENSURING THE OVERALL FLOW REMAINS PROGRESSIVE DESPITE LARGE CYCLONE TO THE EAST. TUESDAY THROUGH TUESDAY NIGHT WILL THUS BE DOMINATED BY SURFACE HIGH PRESSURE BENEATH A STOUT MID-LEVEL DRY LAYER. SOME UNCERTAINTY WITH REGARD TO DIURNAL CLOUD POTENTIAL, BUT THERE HAS BEEN SOME TENDENCY IN THE NAM TO OVERESTIMATE BOUNDARY LAYER MOISTURE OVER THE LAST FEW DAYS. A SLIGHTLY LESS AGGRESSIVE DAYTIME CLOUD FORECAST FAVORS HIGHS IN THE MID 20S...A FEW DEGREES WARMER THAN TODAY. LOWS TUESDAY NIGHT WILL BE SENSITIVE TO CLOUD COVER STREAMING ACROSS THE RIDGE AXIS WITHIN QUICK-MOVING NW FLOW. INHERITED FORECAST IN THE UPPER SINGLE DIGITS PLAYS A REASONABLE MIDDLE-GROUND. HIGH PRESSURE WILL TRANSLATE EAST ON WEDNESDAY AND RETURN FLOW WILL TAKE SHAPE AS AFOREMENTIONED PAC ENERGY SUPPORTS DEVELOPING LOW PRESSURE OVER THE MIDWEST. WARM ADVECTION WILL PUSH HIGHS CLOSE TO 30 DEGREES WEDNESDAY. A CLIPPER IS FORECAST BY THE SUITE OF GUIDANCE TO SWEEP ACROSS THE AREA LATE WEDNESDAY NIGHT INTO THURSDAY. GENERAL CONSENSUS IS AT LEAST 1-3" WITH RESPECTABLE DYNAMICS AND MOISTURE, BUT HURT BY A WARM THERMODYNAMIC PROFILE. DIFFERENCES IN THE MODELS AT THIS JUNCTURE ARISE PRIMARILY WITH RESPECT TO THE STRENGTH OF A LEAD SHORTWAVE WITH ORIGINS IN TODAY`S BAJA LOW. TOO EARLY TO SLICE AND DICE DETAILS MUCH, BUT THE ECMWF HAS TRENDED TOWARD A MORE DOMINANT NORTHERN WAVE WHICH WILL SUPPORT BOTH A DEEPER AND MORE PROGRESSIVE SOLUTION. GFS/GEM ALLOW THE SURFACE LOW TO REMAIN TIED TO THE LEAD SHORTWAVE WHICH ALLOWS FOR A WEAKER, BUT MORE MATURE, CIRCULATION CAPABLE OF PRODUCING A MORE RESPECTABLE LOW/MID-LEVEL FGEN RESPONSE AND HIGHER SNOW TOTALS. GOT THE BALL ROLLING BY INTRODUCING A GENERAL 1-2" FOR WED NIGHT/THURS. MARINE... LIGHT TO MODERATE WINDS WILL PERSIST THROUGH THURSDAY AS THE GRADIENT RELAXES DUE TO RESIDENT HIGH PRESSURE. AN APPROACHING WEAK LOW PRESSURE WEDNESDAY NIGHT THROUGH THURSDAY WILL CAUSE AN UPTICK IN SOUTHERLY WINDS, BUT GUSTINESS WILL BE LIMITED DUE TO WARM STABLE FLOW FROM THE SOUTH. COLD AIR MOVING INTO THE GREAT LAKES IN THE WAKE OF THIS SYSTEM WILL MARK THE BEGINNING OF A RENEWED STRETCH OF ACTIVE MARINE WEATHER THURSDAY NIGHT INTO NEXT WEEK AS MULTIPLE BOUTS OF ARCTIC AIR TRAVERSE THE WATERS. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MICHIGAN WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....BT SHORT TERM...DG LONG TERM....JVC MARINE.......JVC YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

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