Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 310649
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
249 AM EDT FRI JUL 31 2015

.SHORT TERM...TODAY AND TONIGHT

JET MAX EMBEDDED WITHIN SW PERIPHERY OF THE HUDSON BAY CLOSED LOW
WILL PROPAGATE SOUTH AND EAST TODAY IN SUPPORT OF THE COMPACT
CIRCULATION POSITIONED OVER NORTHWEST ONTARIO AT PRESS TIME. DCVA
WITHIN STEEP LAPSE RATE ENVIRONMENT HAS CONTRIBUTED TO A GENEROUS
COVERAGE OF NOCTURNAL CONVECTION FROM NW ONTARIO ACROSS LAKE
SUPERIOR. THIS FAVORABLE ENVIRONMENT WILL REMAIN LARGELY NORTH OF
THE AREA THROUGH TODAY, WITH BETTER LAPSE RATES MODELED TO JUST
GRAZE THE THUMB. MODEST MOISTURE RETURN EVIDENT ON GOES 7.4U CHANNEL
SUGGESTS SLIGHTLY BETTER MID-LEVEL MOISTURE QUALITY TODAY WHICH
SHOULD, AT THE LEAST, CONTRIBUTE TO A BETTER COVERAGE OF CU COMPARED
TO YESTERDAY. DIURNAL DESTABILIZATION TO THE TUNE OF A FEW HUNDRED
J/KG MLCAPE WILL BE SUPPORTIVE OF A FEW SHOWERS ALONG THE MOISTURE
GRADIENT, MAINLY ACROSS THE NORTH WHERE FORCING/LAPSE RATES WILL BE
MAXIMIZED. ATTM, PROBABILITY SOUTH OF I-69 REMAINS TOO LOW GIVEN THE
DRY COLUMN AND SHALLOW LAYER OF MOISTURE TO INCLUDE A WX MENTION, SO
WILL TOE THE LINE WITH JUST A CHC POP ACROSS THE NORTH. GIVEN THE
POTENTIAL FOR DIABATIC COOLING WITHIN THE WELL-MIXED BOUNDARY LAYER,
AN ISOLATED GUST TO 50 MPH WILL BE POSSIBLE, BUT EXPECTING LARGELY
BENIGN CONVECTION ON THE WHOLE GIVEN LACK OF APPRECIABLE INSTABILITY.

COOLER 850MB TEMPS WILL ONCE AGAIN CONTRIBUTE TO SIGNIFICANT
BOUNDARY LAYER GROWTH IN THE AFTERNOON SUPPORTING HIGHS SIMILAR TO
YESTERDAY. LIKEWISE, DECENT WIND FIELD THROUGH THE DEPTH OF THE
COLUMN WILL AGAIN CONTRIBUTE TO WIND GUSTS TOPPING OUT AROUND 25KTS
DURING PEAK HEATING. GRADIENT WILL REMAIN SUFFICIENTLY STRONG TO
MAINTAIN A MIXED COMPONENT NEAR THE SURFACE THROUGH TONIGHT, LEADING
TO OVERNIGHT LOWS SIMILAR TO BOTH THIS MORNING AND THURSDAY
MORNING...LOW TO MID 60S.

&&

.LONG TERM...

LARGE UPPER LEVEL LOW OVER HUDSON BAY WILL DRIFT SOUTHWARD OVER THE
WEEKEND...TAKING RESIDENCE OVER NORTHERN ONTARIO BY EARLY NEXT WEEK.
THIS CIRCULATION WILL DIRECT SEVERAL FAST MOVING UPPER LEVEL
DISTURBANCES THROUGH THE GREAT LAKES REGION AS THEY COME OVER THE
TOP OF THE UPPER LEVEL RIDGE EXTENDING NORTH INTO WESTERN CANADA.
ONE SUCH UPPER LEVEL DISTURBANCE COMES THROUGH SATURDAY...BUT THE
MID LEVEL COLD POOL OF -18 C AT 500 MB TRACKS THROUGH NORTHERN LAKE
HURON...WITH WARMING MID LEVEL TEMPS AS ONE HEADS SOUTH...WHICH WILL
LIMIT INSTABILITY (MUCAPES LESS THAN 1000 J/KG). MID LEVEL LAPSE
RATES ALSO LOOK VERY WEAK...AROUND 5 C FROM 700-500 MB...AND
PLANNING ON CARRYING SLIGHT CHANCE POPS NORTH OF M-59...AS LI`S
ACTUALLY LOOK TO REMAIN POSITIVE SOUTH OF M-59. THIS IS GOOD NEWS AS
STRONG 500 MB JETS (60 KNOTS) NOSES INTO SOUTHERN LOWER MICHIGAN
DURING SATURDAY. LAKE HURON WATER TEMPS IN THE 60S (LOWER 70S
SAGINAW BAY) AND BEING CLOSER TO THE COLD CORE WILL CONTRIBUTE TO
INSTABILITY AND SERVE AS SLIGHTLY BETTER CHANCE FOR SHOWERS AND
THUNDERSTORMS ACROSS NORTHERN THUMB REGION.

WINDS BACKING TO A MORE WEST-SOUTHWEST DIRECTION SATURDAY NIGHT INTO
SUNDAY WILL ALLOW FOR GOOD MOISTURE TRANSPORT AND SHORTWAVE TO SNEAK
IN FROM THE MIDWEST. THE 00Z CANADIAN IS ONE OF THE MORE AGGRESSIVE
SOLUTIONS...BUT EVEN GFS/NAM INDICATING POTENTIAL FOR SHOWERS AND
THUNDERSTORMS DURING SUNDAY. WITH INCREASING HEIGHT FALLS AND MAIN
TROUGH AXIS ARRIVING MONDAY...AN EVEN BETTER CHANCE OF STORMS WILL
EXIST SUNDAY NIGHT AS COLD FRONT APPROACHES...PER 00Z EURO.
TEMPERATURES ARE EXPECTED TO HOVER RIGHT AROUND NORMAL FRIDAY-
SUNDAY...WITH COOLER TEMPS ARRIVING NEXT WEEK.

&&

.MARINE...

WESTERLY WINDS WILL PICK UP AGAIN TODAY OVER LAND AREAS AS MIXING
DEPTHS INCREASE...WITH GUSTS APPROACHING 25 KNOTS OVER THE NEARSHORE
WATERS...ULTIMATELY SHORT LIVED AND COMING UP SHORT OF SMALL CRAFT
CONDITIONS. THERE LOOKS TO BE A LOW CHANCE OF SHOWERS AND ISOLATED
THUNDERSTORMS OVER LAKE HURON AS AN UPPER LEVEL DISTURBANCE PASSES
THROUGH TODAY. THE CYCLE LOOKS TO REPEAT ITSELF AGAIN ON SATURDAY.
THE CHANCE FOR SHOWERS AND THUNDERSTORMS WILL INCREASE ON
SUNDAY...WITH GOOD CHANCE FOR ACTIVITY SUNDAY NIGHT INTO MONDAY AS A
COLD FRONT SLIPS THROUGH THE CENTRAL GREAT LAKES...USHERING IN 15 TO
25 KNOT NORTHWEST WINDS FOR EARLY NEXT WEEK.

&&

.AVIATION...ISSUED 1151 PM EDT THU JUL 30 2015

CLEAR SKIES HAVE ALLOWED WINDS TO DIMINISH. THEY WILL REMAIN LIGHT
THROUGH DAYBREAK. A LITTLE COOLER AIR ALOFT SHOULD DEEPEN THE MIXED
LAYER MORE QUICKLY IN COMPARISON TO THURSDAY. THIS WILL OFFER THE
POTENTIAL FOR WSW WINDS TO INCREASE EARLIER IN THE AFTERNOON. A WEAK
COLD FRONT WILL TRAVERSE SE MI LATE FRI AFTERNOON. THE CHANCE FOR
THUNDERSTORMS AHEAD OF THIS FRONT WILL BE LIMITED BY WEAK
INSTABILITY AND A POTENTIAL CAPPING INVERSION.

//DTW THRESHOLD PROBABILITIES...

* LOW IN THUNDERSTORM POTENTIAL FRIDAY AFTERNOON AND EVENING.

&&

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

$$

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


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