Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000 FXUS63 KDTX 262243 AFDDTX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 543 PM EST THU FEB 26 2015 .AVIATION... DRY NORTHERLY FLOW AND THE LOSS OF DIURNAL SUPPORT WILL BRING A STEADY CLEARING TREND TO THE LINGERING LOW VFR STRATUS EARLY THIS EVENING. EXISTING ARCTIC HIGH PRESSURE WILL SUSTAIN A DRY/STABLE ENVIRONMENT INTO FRIDAY. THERE WILL BE A LIMITED COVERAGE OF DIURNAL STRATOCUMULUS DEVELOPMENT DURING THE DAYLIGHT HOURS...CEILINGS AT LOWER VFR PER RECENT MODEL SOUNDING DATA. A BACKING WIND FIELD WITH TIME...SETTLING INTO A SOUTHWEST DIRECTION BY AFTERNOON AS THE HIGH SLIPS TO THE EAST. //DTW THRESHOLD PROBABILITIES... * MEDIUM FOR CEILINGS AT LEAST INTERMITTENLY BELOW 5000 FT THROUGH 01Z. && .PREV DISCUSSION...ISSUED 335 PM EST THU FEB 26 2015 SHORT TERM... THROUGH TONIGHT ANY LINGERING SNOW SHOWERS OVER SOUTHEASTERN PORTIONS OF THE CWA WILL CONTINUE TO DIMINISH THIS AFTERNOON AS THE ASSOCIATED WAVE PROGRESSES EAST. RIDGING OVER THE NORTHERN GREAT LAKES THEN SLIDES SOUTH OVER THE AREA ALLOWING FOR DRIER NORTHERLY AIR TO TAKE OVER THIS EVENING INTO THE OVERNIGHT HOURS. WITH CAA MOVING INTO THE AREA...A CLEARING TREND WILL BE SEEN LATER TONIGHT AS IS ALREADY EVIDENT BY CURRENT SATELLITE UPSTREAM. AS THE PRESSURE GRADIENT WEAKENS...WINDS SLACKEN OVERNIGHT BECOMING LIGHT TO CALM OVER MUCH OF THE AREA. WITH CLEARING SKIES AND LIGHT WINDS...EXPECTING A GOOD RADIATIONAL COOLING EVENT INTO EARLY FRIDAY MORNING. THIS WILL BE THE MAIN CONCERN IN THE SHORT TERM WITH THE CONTINUED COLD AND POSSIBLY RECORD BREAKING LOWS GOING INTO FRIDAY MORNING. GIVEN LIGHT TO CALM WINDS EXPECTED OVERNIGHT...WILL NOT ISSUE A WIND CHILL ADVISORY HOWEVER WIND CHILLS MAY TOUCH ADVISORY CRITERIA FOR A COUPLE OF HOURS ESPECIALLY IN THE THUMB AREA. RECORD LOWS FOR FEB 27 DETROIT AREA: -4 (1934) FLINT AREA: -14 (1994) SAGINAW: -8 (1934) LONG TERM... EXPANSIVE HIGH PRESSURE (1040+ MB) OVER CENTRAL CANADA EXTENDING SOUTH INTO THE PLAINS THIS AFTERNOON...WITH THE CENTER OF THE HIGH SLIDING THROUGH THE OHIO VALLEY VALLEY FRIDAY NIGHT. AIRMASS LOOKS TO BE REMAINING VERY DRY (PW VALUES UNDER A TENTH)...WITH SURFACE DEW PTS BELOW ZERO...PROVIDING FOR FAVORABLE RADIATING NIGHT (NOT IDEAL DUE TO MODEST WINDS). MIN TEMPS SHOULD BE LOWEST TOWARD THE OHIO BORDER...WHERE THE WEAKEST GRADIENT WILL RESIDE. INHERITED GRIDS (ZERO TO -8 BELOW) REFLECT THIS...AND NOT PLANNING ON MAKING ANY CHANGES. WITH FAVORABLE VERY LIGHT SOUTHWEST DRAINAGE WIND FOR DTW...GOOD CHANCE FOR LOW TO REACH OR EXCEED THE RECORD VALUE FOR FEBRUARY 28TH (-1 SET IN 1994). YESTERDAY AND TODAY THE LATE FEBRUARY SUNSHINE HAS BEEN REVEALING ITS STRENGTH...WITH TEMPS CRUISING PAST OUR FORECASTED MAXES...AS THE OLD/DIRTY SNOWPACK HAS A REDUCED ALBEDO. WITH THAT IN MIND...WILL BE RAISING TEMPS ON FRIDAY...AS THESE DRY AIRMASSES ARE CONDUCIVE TO INCREASED DIURNAL SWINGS. THERE IS A LIGHT LOW LEVEL WESTERLY FLOW DEVELOPING TOMORROW...WHICH COULD SUPPORT A MODEST CU UP...BUT WILL CARRY MAXES UP AROUND 20 DEGREES NONE-THE-LESS. LIGHT SOUTHWEST RETURN FLOW CONTINUING ON SATURDAY WILL SUPPORT A FURTHER WARM UP...LOW/MID 20S...BASED ON 925 MB TEMPS OF -10 TO -12 C AND FULL INSOLATION. INCREASING CLOUDS AND WARM ADVECTION PATTERN EVENING SHOULD HOLD MAXES IN SINGLE NUMBERS AND THEN CAUSE A RISE...WITH GOOD CHANCE OF LIGHT SNOW DEVELOPING SATURDAY NIGHT WITH 140 KNOT JET CORE LIFTING OVERHEAD...WITH WHAT LOOKS TO BE SUFFICIENT MOISTURE SURGE ARRIVING TOWARD 12Z SUNDAY...WITH SPECIFIC HUMIDITIES CLIMBING AROUND 2 G/KG AT 700 MB (PER 12Z GFS/NAM)...OR SLIGHTLY HIGHER IF ONE IS TO BELIEVE THE 12Z EURO. BLEND OF MODEL QPFS SUGGEST 1 TO 3 INCH SNOWFALL FORECAST...HIGHEST TOTALS SOUTH...WITH THE EURO STILL ADVERTISING A BIT MORE...AND THE CANADIAN MUCH LESS. THE EXACT SNOW TO LIQUID RATIOS WILL PROBABLY HOLD THE KEY...AS AIRMASS MAY WARM UP ENOUGH SUPPORT MORE CLIMO NORM VALUES OF 12:1 VS THE HIGHER 15-17:1 VALUES ADVERTISED. LINGERING LOW PRESSURE FROM THE WEEKEND WILL ALLOW FOR SNOW TO CONTINUE MONDAY MORNING INTO EARLY MONDAY AFTERNOON. NEXT SYSTEM MOVES IN FOR TUESDAY WITH SCATTERED SNOW SHOWERS TUESDAY MORNING AND INCREASING CHANCES OF PRECIPITATION THROUGH DAY INTO WEDNESDAY MORNING. TEMPERATURES ARE EXPECTED TO WARM TUESDAY AFTERNOON WHICH COULD MEAN RAIN AND SNOW MIXED OVER THE NORTHERN HALF OF THE CWA AND RAIN OVER THE SOUTHERN HALF. TEMPS LOOK TO DROP BELOW FREEZING OVERNIGHT TUESDAY INTO EARLY WEDNESDAY MORNING WHICH LIKELY MEANS PRECIPITATION CHANGING OVER TO ALL SNOW LATE TUESDAY NIGHT. BY WEDNESDAY AFTERNOON THE TEMPS REBOUND BACK INTO THE 30`S BRINGING A REPEAT OF TUESDAY AFTERNOONS WEATHER. IT SHOULD BE NOTED THAT POPS DROP WEDNESDAY SO ANY PRECIPITATION IS EXPECTED BE SCATTERED. MARINE... HIGH PRESSURE WILL BE BUILDING INTO THE OHIO VALLEY TOMORROW AND TOMORROW NIGHT...WITH MODEST SOUTHWEST RETURN FLOW DEVELOPING AROUND THE HIGH OVER THE CENTRAL GREAT LAKES. CENTRAL SECTIONS OF LAKE HURON WILL PROBABLY SEE WINDS INCREASE INTO THE 15 TO 20 KNOT RANGE ..OTHERWISE WINDS REMAIN ON THE LIGHTER SIDE....WITH GRADUALLY WEAKENING SOUTHWEST GRADIENT INTO THE WEEKEND...AS ANOTHER COLD FRONT SLIDES THROUGH SUNDAY NIGHT. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MICHIGAN WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....99 SHORT TERM...SS LONG TERM....SF/DE MARINE.......SF YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

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