Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 011710
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
110 PM EDT SAT AUG 1 2015


.AVIATION...

PASSING WEAK SHORTWAVE WILL AID DIURNAL CUMULUS FIELD AND BRING SCT
TO BKN LOWER VFR DECK IN THE 5-7KT FOOT RANGE. SCT SHRAS WILL REMAIN
EAST OF THE TERMINALS BY AND LARGE. WEST WINDS WILL GUSTS TO 20 KTS
CAN BE EXPECTED INTO 00Z-01Z TIME FRAME. GUSTY SW FLOW WILL SET UP
BY MIDDAY SUNDAY AS GRADIENT TIGHTENS IN ADVANCE OF APPROACHING COLD
FRONT. GUSTS MAY REACH/TOP 25 KNOTS AT TIMES BY AFTERNOON.

FOR DTW...SCT-BKN CUMULUS FIELD AT 5KFT MAY TEND TO LIFT TO 6-7KFT
AS AFTERNOON PROCEEDS. OTHERWISE...WINDS FROM 270-280 DEGREES WILL
GUST TO NEAR 20 KNOTS TODAY WITH 210-220 DEGREE WINDS GUSTING TO 25
KTS OR MORE BY MIDDAY SUNDAY.

//DTW THRESHOLD PROBABILITIES...

* NONE.

&&

.PREV DISCUSSION...ISSUED 318 AM EDT SAT AUG 1 2015

SHORT TERM...TODAY AND TONIGHT

MODIFIED PERSISTENCE FORECAST TODAY AS A WEAK H4 PV ANOMALY EMBEDDED
WITHIN CYCLONIC NW FLOW ROTATES THROUGH THE AREA DURING PEAK
HEATING. LOWER MOISTURE QUALITY COMPARED TO YESTERDAY WILL LIMIT
PROSPECTS FOR SHOWER COVERAGE, BUT ONCE AGAIN EXPECT BEST FORCING
AND LAPSE RATES ACROSS THE THUMB. ISOLATED SHOWERS, PERHAPS A CLAP
OR TWO OF THUNDER, ALONG WITH ANOTHER AFTERNOON CU UP ARE IN STORE
WITH GREATEST COVERAGE OF CLOUDS ACROSS THE NORTH. SLIGHTLY COOLER
COLUMN NOTED AS COOLING TAKES PLACE IN THE WAKE OF YESTERDAY`S
SHORTWAVE. H85 TEMPS AROUND 11-12C AT 12Z THIS MORNING WILL SUPPORT
HIGHS TOPPING OUT NEAR 80 DEGREES. DIMINISHED GRADIENT WILL SUPPORT
WLY AFTN GUSTS TOPPING OUT AT ONLY 15-20 KTS. LIMITED COOLING
POTENTIAL ONCE AGAIN TONIGHT AS HEIGHTS REBOUND WITH THE PASSAGE OF
EMBEDDED SHORTWAVE RIDGE AND LIGHT WARM ADVECTION PERSISTS THROUGH
THE OVERNIGHT PERIOD. CIRRUS DEBRIS FROM ANY CONVECTION THAT
DEVELOPS UPSTREAM THIS EVENING WILL SPREAD INTO THE AREA BY SUNRISE.
NO COMPLAINTS WITH 00Z GUIDANCE OFFERING LOWS AROUND 60.

LONG TERM...

THE FORECAST FOR THE SECOND HALF OF THE WEEKEND WILL BE INFLUENCED
BY THE UPPER LEVEL ENERGY/WAVE COMING OUT OF THE PACIFIC
NORTHWEST...WHICH TRACKS THROUGH THE MIDWEST TONIGHT AND THROUGH THE
OHIO VALLEY DURING SUNDAY. HOW MUCH MOISTURE WILL THIS WAVE
TAKE/DISPLACE TO OUR SOUTH AND EAST? AND HOW MUCH POST WAVE
SUBSIDENCE WILL LINGER...AS NORTHERN STREAM UPPER LEVEL TROUGH DIGS
SOUTHEAST FROM CENTRAL CANADA AND MAIN COLD FRONT MOVES THROUGH
EARLY MONDAY MORNING. GOOD DYNAMICS SUNDAY EVENING/NIGHT...ALONG
WITH FAVORABLE LOW LEVEL FGEN/CONVERGENCE SHOULD SUPPORT SHOWERS AND
THUNDERSTORMS...EVEN IF THAT LEAD WAVE ROBS MUCH OF THE
MOISTURE...AND STILL OK FORECASTING LIKELY POPS FOR SUNDAY
EVENING/NIGHT. 00Z NAM INDICATING SURFACE DEW PTS APPROACHING 70
DEGREES...WHICH IS PROBABLY A BIT OF A STRETCH...BUT MID/UPPER 60S
WOULD STILL YIELD CAPES AROUND 1500 J/KG...WHICH COULD SUPPORT A FEW
SEVERE STORMS WITH THE STRONG WIND FIELDS AND STEEP MID LEVEL LAPSE
RATES ADVERTISED (7+ C/KM BETWEEN 700-500 MB). DAY 2 OUT OF SPC
INDICATING A SLIGHT CHANCE FOR THE MAJORITY OF SOUTHEAST MICHIGAN.

VERY LARGE UPPER LEVEL LOW CENTERED OVER NORTHERN ONTARIO EARLY NEXT
WEEK...ALLOWING FOR COOLER TEMPERATURES OVER THE GREAT LAKES REGION
AS 850 MB TEMPS FALL INTO THE UPPER SINGLE NUMBERS BY WEDNESDAY.
SPOKES OF ENERGY/UPPER LEVEL DISTURBANCES ROTATING AROUND THE
PERIPHERY COULD TRIGGER ISOLATED/SCATTERED CONVECTION...BUT
UNCERTAINTY ON TIMING AND EXACT POSITION OF THESE FEATURES.

MARINE...

WESTERLY WINDS TODAY ARE EXPECTED TO BE A BIT LIGHTER COMPARED TO
YESTERDAY...WITH STRONGER WINDS FORECASTED TO PEAK OUT AROUND 20
KNOTS. AN APPROACHING COLD FRONT WILL STRENGTHEN THE SOUTHWEST
GRADIENT ON SUNDAY HOWEVER...WITH GUSTS AROUND 25 KNOTS LIKELY OVER
THE NEARSHORE WATERS. THE COLD FRONT WILL LIKELY TRIGGER STRONG TO
SEVERE THUNDERSTORMS SUNDAY EVENING AND NIGHT BEFORE SLIPPING SOUTH
THROUGH THE CENTRAL GREAT LAKES MONDAY MORNING. POST FRONTAL
NORTHWEST FLOW OVER NORTHERN LAKE HURON LOOKS TO BE IN THE 20 TO 25
KNOT RANGE MONDAY AFTERNOON AND MONDAY NIGHT BEFORE DECREASING
SLIGHTLY AS WE HEAD INTO TUESDAY.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
&&

$$

AVIATION.....DG
SHORT TERM...JVC
LONG TERM....SF
MARINE.......SF


YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).


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