992
FXUS63 KDTX 161055
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
655 AM EDT FRI MAY 16 2008
AVIATION
WEAK HIGH PRESSURE RIDGING WILL SLOWLY SHIFT EAST TODAY...WITH A
COLD FRONT DROPPING THROUGH BY LATE TONIGHT. MOISTURE WILL BE
LACKING IN THE LOWEST LEVELS...KEEPING CEILINGS IN VFR THROUGH
THE TAF PERIOD. COLD FRONT MAY BRING A FEW LIGHT SHOWERS OVERNIGHT...
BUT WILL HAVE LITTLE IMPACT FOR AVIATION INTERESTS. WINDS WILL SHIFT
TOWARD THE SOUTHWEST BY THIS AFTERNOON...INCREASING TONIGHT AS THE
PRESSURE GRADIENT TIGHTENS AHEAD OF THE COLD FRONT.
PREV DISCUSSION
ISSUED 336 AM EDT FRI MAY 16 2008
SHORT TERM...TODAY
ELONGATED NARROW SFC RIDGE AXIS STRETCHING FROM THE SOUTHERN PLAINS
TO WESTERN QUEBEC WILL MAINTAIN CONTROL ACROSS THE CENTRAL GREAT
LAKES TODAY. BASED ON LATEST SATELLITE TRENDS...THE BKN/OVC HIGH
CLOUD DECK WILL LIFT EAST OF THE REGION AROUND DAYBREAK...LEAVING A
FAIR AMOUNT OF SUNSHINE FOR TODAY. THE ONSET OF WEAK WARM AIR
ADVECTION AS THE LOW LEVEL GRADIENT TAKES MORE OF A WESTERLY
COMPONENT...COMBINED WITH THE STRONG INSOLATION...WILL PUSH HIGHS
TOWARD THE UPPER 60S/AROUND 70. GFS INDICATING THE POTENTIAL FOR A
FEW LIGHT SHOWERS PRIOR TO 00Z ACROSS THE THUMB...DRIVEN BY WEAK
SHORTWAVE ENERGY AND ISENTROPIC ACCENT. HOWEVER...FORCING LOOKS TOO
MEAGER TO OVERCOME THE DRY LOWER LEVELS...AND WILL LEAN TOWARD THE
DRIER NAM WITH JUST AN INCREASE IN MID LEVEL CLOUDINESS INTO THE
EARLY EVENING.
LONG TERM...
UNUSUALLY STRONG UPPER LEVEL RIDGE (FOR MAY) CENTERED ALONG THE
COAST OF OREGON...(595 DAM AT 500 MB)...SHATTERING
RECORD HIGH TEMPERATURES ACROSS NORTHERN CALIFORNIA YESTERDAY.
UNFORTUNATELY...WE WILL BE EXPERIENCING THE OPPOSITE END OF THE
SPECTRUM WITH DEEP VORTEX DEVELOPING OVER THE GREAT LAKES REGION
THIS WEEKEND.
COLD MID TROPOSPHERIC TEMPS OF -26 TO -28 C (AT 500 MB) WILL LEAD TO
STEEP MID LEVEL LAPSE RATES (GREATER THAN 7 C/KM). FORECAST
SOUNDINGS SUGGESTING EQL LEVELS ABOVE -20 C...AND HAVE ADDED A
SLIGHT CHANCE OF THUNDERSTORMS ON SATURDAY WITH MIXED LAYER LI'S
GOING TOWARD ZERO OR SLIGHTLY NEGATIVE...WITH NAM ALSO INDICATING K
INDICES NEAR 30...WHICH IS LIKELY OVERDONE WITH LESS POST FRONTAL
LOW LEVEL MOISTURE EXPECTED.
USED MAV GUIDANCE FOR MAX/MINS...EXCEPT USED THE NAM ON
SATURDAY...AS LOWER 70S SEEMED A BIT WARM FOR DETROIT WITH SURFACE
COLD FRONT SLIDING THROUGH BY 15Z. ALTHOUGH...THE BOUNDARY LAYER
DEPTH SHOULD BE DEEP (NEAR 775 MB) WITH STRONG WESTERLIES.
00Z GFS/CANADIAN GLOBAL INDICATING SHORTWAVE RIDGING ON MONDAY AHEAD
OF THE NEXT SYSTEM AND DECIDED TO TAKE A CHANCE AND GO WITH A DRY
FORECAST SINCE THE ENTIRE REST OF THE FORECAST HAS CHANCE POPS. THE
00Z EUROPEAN ALSO SUGGEST A DRY FORECAST ON MONDAY...BUT IS LESS
PRONOUNCED WITH THE RIDGING.
NO CHANGES MADE BEYOND MONDAY.
MARINE...
HIGH PRESSURE RIDGING WILL REMAIN IN PLACE TODAY...MAINTAINING
FAVORABLE MARINE CONDITIONS UNDER A DEVELOPING SOUTHWEST WIND.
WINDS WILL INCREASE TONIGHT AS THE PRESSURE GRADIENT TIGHTENS IN
ADVANCE OF THE NEXT COLD FRONT. NORTHWEST WINDS WILL INCREASE
FURTHER IN THE WAKE OF THIS FRONT EARLY SATURDAY...LEADING TO GUSTS
OF 25-30 KNOTS OVER ALL NEARSHORE WATERS SATURDAY. THE POTENTIAL
FOR WIND GUSTS TO APPROACH GALE FORCE WILL EXIST FROM SATURDAY
AFTERNOON THROUGH THE OVERNIGHT HOURS OVER THE NORTHERN LAKE HURON
OPEN WATERS. WINDS WILL REMAIN GUSTY THROUGH THE REMAINDER OF THE
WEEKEND AS A SEASONABLY COLD AIRMASS FILTERS ACROSS THE LAKES. THIS
WILL LEAD TO A LONGER DURATION OF SMALL CRAFT ADVISORY CONDITIONS...
WITH HIGHER WAVES LINGERING INTO MONDAY ALONG THE LAKE HURON
NEARSHORE.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
HURON INCLUDING SAGINAW BAY...FROM 4 AM SATURDAY TO 8 AM
MONDAY.
GALE WATCH...LHZ361-LHZ362...FROM NOON SATURDAY TO 8 AM SUNDAY.
GALE WATCH...LHZ363...FROM 8 PM SATURDAY TO 8 AM SUNDAY.
LAKE ST CLAIR...
SMALL CRAFT ADVISORY...FROM 8 AM SATURDAY TO 8 PM SUNDAY.
MI WATERS OF LAKE ERIE...
SMALL CRAFT ADVISORY...FROM 8 AM SATURDAY TO 8 PM SUNDAY.
AVIATION.....MR
SHORT TERM...MR
LONG TERM....SF
MARINE.......MR
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
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