Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 050715
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
315 AM EDT SUN JUL 5 2015

.SHORT TERM...TODAY AND TONIGHT

UPPER LEVEL RIDGE AND CORRESPONDING DRY AIRMASS IN PLACE OVER THE
WESTERN/CENTRAL GREAT LAKES REGION...ESPECIALLY IN THE MID
LEVELS...AS 00Z RAOBS FROM DTX...APX...GRB INDICATED 700 MB DEW PT
DEPRESSIONS IN THE RANGE OF 30 TO 41 C. AS SUCH...LITTLE IN THE WAY
OF CU DEVELOPMENT YESTERDAY...WITH HIGHS TOPPING OUT IN THE LOWER
80S/AROUND 80 DEGREES ACROSS SOUTHEAST MICHIGAN. MODIFICATION OF THE
AIRMASS SHOULD CONTINUE TODAY...AS MODEST RISE IN HEIGHTS TAKES
PLACE...AND HIGHS ARE EXPECTED TO TOP OUT IN THE MID 80S UNDER
MOSTLY SUNNY SKIES AND BASED ON 850 MB TEMPS UP TO 15 C BY DAY`S
END.  QUIET WEATHER TO CONTINUE TONIGHT AS RIDGE HOLDS ON AND 1000
TO 500 MB MEAN RH REMAINS LOW...40 PERCENT OR SLIGHTLY LESS. RETURN
FLOW IN THE LOW LEVELS WILL JUST BEGIN TO GET GOING...AND LIKELY
HOLD MINS IN THE LOWER 60S...IN LINE WITH THE INCREASE IN DEW PTS.

&&

.LONG TERM...

A SEASONALLY DEEP UPPER LOW OVER NRN MANITOBA WILL LIFT INTO HUDSON
BAY ON MONDAY. THE 00Z MODEL SUITE SHOWS AMPLIFICATION OF THE SHORT
WAVE IMPULSE NOW OVER BRITISH COLUMBIA AS IT ROTATES ACROSS THE
US/CANADIAN BORDER WITHIN THE BASE OF THIS UPPER LOW. THE ASSOCIATED
MID LEVEL HEIGHT FALLS OVERSPREADING THE NRN PLAINS ON MONDAY WILL
DRIVE A SFC COLD FRONT FROM THE UPPER MS VALLEY INTO THE WRN GREAT
LAKES. LOW LEVEL S-SW FLOW WILL STRENGTHEN ACROSS LOWER MI ON MONDAY
IN RESPONSE TO THIS...ALLOWING 850MB TEMPS TO RISE INTO THE UPPER
TEENS BY EVENING. MODEL SOUNDINGS AND MOS GUIDANCE CONTINUE TO
SUPPORT AFTERNOON HIGHS IN THE MID TO UPPER 80S ON MON. MODEL
SOLUTIONS TEND TO UNDERESTIMATE MIXING DEPTHS IN THESE
CIRCUMSTANCES...WHICH SUGGEST SOME LOCALS MAY BREAK THE 90 DEGREE
MARK. STRONG MID LEVEL CAPPING MON INTO MON EVENING WILL INHIBIT
CONVECTION.

THE BETTER MID LEVEL HEIGHT FALLS AND UPPER JET SUPPORT ASSOCIATED
WITH THE TROUGH AXIS ARE FORECAST TO ROTATE INTO NRN ONTARIO MON
NIGHT INTO TUESDAY. THIS WILL CAUSE THE DEEP LAYER FRONTAL DYNAMICS
TO WEAKEN A BIT AS THIS SYSTEM ADVANCES ACROSS LOWER MI. SUBSTANTIAL
MID LEVEL HEIGHT FALLS AND SFC CYCLOGENESIS TO THE NORTH OF THE STATE
WILL STILL FORCE THE SFC FRONT ACROSS LOWER MI LATE MON NIGHT
THROUGH TUESDAY. STRONG PREFRONTAL SW FLOW IS FORECAST TO SUSTAIN
GOOD MOISTURE TRANSPORT INTO THE FRONTAL CIRCULATION. MODEL
SOLUTIONS GENERALLY SUPPORT AN AXIS OF DEEP LAYER MOISTURE /PWATS
AROUND 2 IN/ ALONG THE FRONT. THIS COUPLED WITH AT LEAST WEAK
ELEVATED INSTABILITY WILL SUPPORT A GOOD CHANCE OF CONVECTION ALONG
THIS FRONT. OVERALL CONSENSUS OF THE 00Z MODEL SUITE BRING THE AXIS
OF DEEP LAYER MOISTURE INTO AT LEAST THE WRN HALF OF THE FORECAST
AREA PRIOR TO DAYBREAK TUES...WITH THE SFC FRONT EXITING TO THE EAST
TUES AFTERNOON. GIVEN THE DEEP LAYER MOISTURE...MID LEVEL LAPSE
RATES ARE NOT FCST TO BE VERY STEEP. THIS WILL CERTAINLY LIMIT
SEVERE POTENTIAL. IF THE FRONTAL SYSTEM SLOWS A BIT...DIURNAL
DESTABILIZATION WOULD BE ABLE TO GENERATE A LITTLE BETTER
INSTABILITY...THUS INCREASING THE RISK OF STRONG TO SEVERE
CONVECTION TUESDAY.

THE PASSAGE OF THIS SYSTEM WILL DRIVE COOLER AND DRIER AIR INTO THE
GREAT LAKES BY MID WEEK. TEMPS ON WED MAY AVERAGE A GOOD TEN DEGREES
BELOW NORMAL. BROAD MID LEVEL TROUGHING ACROSS THE NRN TIER OF THE
US WILL SLOWLY WEAKEN DURING THE LAST FEW DAYS OF THE FORECAST
PERIOD. THIS WILL SUPPORT A GRADUAL WARMING TREND HEADING INTO NEXT
WEEKEND.

&&

.MARINE...

HIGH PRESSURE ACROSS THE REGION WILL SUSTAIN TRANQUIL CONDITIONS ON
THE LAKES TODAY THROUGH THIS EVENING. SOUTHERLY WINDS WILL GRADUALLY
INCREASE ON MONDAY AHEAD OF A COLD FRONT APPROACHING THE WESTERN
GREAT LAKES. STRONG OVER LAKE STABILITY WILL HOLD GUSTS BELOW 20
KNOTS. THE FRONT IS FORECAST TO TRAVERSE NORTHERN LAKE HURON LATE
MONDAY NIGHT AND SOUTHERN LAKE HURON BY LATE TUESDAY MORNING OR
EARLY AFTERNOON. THERE IS A GOOD CHANCE OF THUNDERSTORMS ALONG THIS
FRONTAL BOUNDARY LATE MONDAY NIGHT INTO TUESDAY. THE PASSAGE OF THE
FRONT WILL BE MARKED BY A VEERING OF THE WINDS TO THE NORTHWEST.
WIND SPEEDS WILL DECREASE BY WEDNESDAY AS HIGH PRESSURE EXPANDS
ACROSS THE GREAT LAKES.

&&

.AVIATION...ISSUED 1157 PM EDT SAT JUL 4 2015

CLEARING SKY WITH LIGHT AND VARIABLE WIND MAKES MBS THE BEST AREA
FOR MEANINGFUL FOG TOWARD SUNRISE. THIS IS WHERE LOW LEVEL MOISTURE
IS POOLED A LITTLE MORE DEEPLY WITHIN THE REMAINS OF THE SURFACE
FRONT. ELSEWHERE...THE DISSIPATION OF THE FRONT WILL ALLOW THE
RESTORATION OF HIGH PRESSURE OVER THE REGION WHICH WILL PROMOTE VFR
CLEAR CONDITIONS AND LIGHT WIND THROUGH THE DAY AND INTO SUNDAY
EVENING.

FOR DTW... A SHALLOW SURFACE MOISTURE PROFILE APPEARS MOST SUITABLE
FOR GROUND FOG AS OPPOSED TO A RESTRICTION BASED ON TEMPERATURE AND
DEWPOINT TRENDS SO FAR TONIGHT.

//DTW THRESHOLD PROBABILITIES...

* NONE.

&&

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

$$

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


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



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