-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KDTX 162303
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
703 PM EDT THU MAY 16 2013

.AVIATION...

-- Changed Discussion --
//DISCUSSION...

THE LAKE BREEZE/BACKDOOR COLD FRONT HYBRID MADE STEADY PROGRESS
THROUGH SE MICHIGAN DURING THE LATE AFTERNOON AND WILL BRING A
NORTHEAST WIND SHIFT TO ALL TERMINAL SITES WITH ITS PASSAGE EARLY IN
THE EVENING. THIS SURFACE FEATURE WILL OPEN THE DOOR ON THE
INFLUENCE OF CANADIAN HIGH PRESSURE CENTERED OVER NORTHERN ONTARIO
THAT WILL SUPPLY A LIGHT EASTERLY WIND THROUGH FRIDAY. OTHERWISE,
HIGH CLOUDS WILL GRADUALLY SPREAD IN FROM THE UPPER MIDWEST AND
THICKEN THROUGH THE PERIOD.

//DTW THRESHOLD THREATS...

* NONE.
-- End Changed Discussion --

&&

.PREV DISCUSSION...
-- Changed Discussion --
ISSUED 334 PM EDT THU MAY 16 2013

SHORT TERM...TODAY AND TONIGHT

THE SOUTHERN LOBE OF CANADIAN SURFACE HIGH PRESSURE IS NUDGING INTO
THE GREAT LAKES REGION...SEEKING OUT THE LARGE GREAT LAKES
AGGREGATE. ANALYSIS OF SURFACE OBSERVATIONS AND LOW LEVEL THETA E
PROGS SHOW A WEAK SYNOPTIC FRONTAL BOUNDARY DELINEATING THE LEAD
EDGE OF THE STABLE HIGH PRESSURE DOME. THIS IS A BACKDOOR TYPE COLD
FRONT THAT WILL EXHIBIT SOME PNEUMONIA FRONT TYPE CHARACTERISTICS
BACK ACROSS WISCONSIN. THE FRONT LOCALLY...IS MORE OF A BACK
DOOR/STATIONARY FRONT HYBRID WITH A CONTRAST OF SFC OBSERVATIONS
DEPENDENT UPON FRONTAL POSITIONING. WARM MID MAY INSOLATION HAS
ALLOWED CENTRAL LOWER MICHIGAN TO PUSH EASILY ABOVE 80 DEGREES WHILE
THE LAKE HURON SHORELINE AND THUMB IS MIRED IN THE 50S TO LOWER 60S.
FOR THE REST OF THE EVENING...EXPECT THE DIURNAL LAKE SCALE RIDGING
COMPONENT TO KICK OFF AN AGGRESSIVE LAKE BREEZE PUSH OFF OF LAKES
HURON/ST CLAIR/ERIE. AN EXPECTED TIMING THROUGH THE CITY OF DETROIT
IS 23Z...THROUGH FAR WESTERN WASHTENAW COUNTY BY 03Z. THIS NOCTURNAL
RELEASE WILL ACT IN BUILDING THE SURFACE HIGH IN TOTAL. THE EAST
BREEZE LATER THIS EVENING WILL CARRY A CHILL...EXPECT APPARENT
TEMPERATURES IN THE LOW TO MID 50S BY 11 PM...40S IN THE THUMB BY 9
PM EDT.

EASTERLY FLOW WILL REMAIN IN PLACE OVER THE FORECAST AREA FOR THE
DURATION OF THE OVERNIGHT. QUIET WEATHER IS EXPECTED WITH
TEMPERATURES BOTTOMING OUT IN THE 40S AREAWIDE.

LONG TERM...FRIDAY THROUGH WEDNESDAY

SURFACE HIGH PRESSURE IS STEADILY INTENSIFYING OVER WESTERN ONTARIO
THIS AFTERNOON AS LONGWAVE RIDGE AMPLIFICATION TAKES PLACE IN
RESPONSE TO THE TROUGH DIGGING INTO THE SOUTHWEST. THIS HIGH
WILL FURTHER STRENGTHEN AS IT TRANSLATES TOWARD THE CANADIAN
MARITIMES THROUGH SUNDAY. THIS, IN CONCERT WITH LAKE ENHANCEMENT OF
SURFACE HIGH PRESSURE, WILL SUPPORT LARGELY DRY AND STABLE
CONDITIONS THROUGH THE WEEKEND WITH NOTHING MORE THAN AN OUTSIDE
CHANCE AT A SHOWER. SURFACE WINDS, INITIALLY OUT OF THE ENE ALONG
THE SOUTHERN PERIPHERY OF THE HIGH, WILL PUSH NOTABLY COOLER AIR
INTO THE CWA FOR FRIDAY, WITH MOST LOCATIONS STRUGGLING INTO THE LOW
70S UNDER PASSING MID/HIGH CLOUD COVER. TEMPERATURES WILL THEN WARM
SATURDAY INTO SUNDAY AS THE SURFACE HIGH SHIFTS EAST AND FORCES
WINDS TO VEER TOWARD A MORE SOUTHERLY DIRECTION. HIGHS WILL APPROACH
80 BY SUNDAY.

SAID JET ENERGY IS STILL PROGGED BY THE 12Z GUIDANCE TO CLOSE OFF
SOMEWHERE EAST OF THE ROCKIES EARLY NEXT WEEK WITH ADDITIONAL
SOUTHWARD PROPAGATION OF HIGH LATITUDE ENERGY FAVORING THE
DEVELOPMENT OF A SECOND CLOSED LOW ALONG THE WEST COAST AROUND THE
SAME TIME. HOWEVER, AS THE GUIDANCE CONTINUES TO KEY IN ON MORE
VIGOROUS PAC ENERGY, IT APPEARS THAT THE RESULTING HIGH AMPLITUDE
PATTERN WILL BE FORCED ALONG IN RATHER QUICK ORDER AS OPPOSED TO THE
PREVIOUSLY DEPICTED PROLONGED PERIOD OF BLOCKED FLOW. AS A RESULT,
IT IS BECOMING INCREASINGLY LIKELY THAT ORGANIZED
SHOWER/THUNDERSTORM ACTIVITY WILL BE MAINLY CONFINED TO THE
MONDAY-WEDNESDAY PERIOD.

A WARMER AND MUCH MORE HUMID AIRMASS CHARACTERIZED BY DEWPOINTS IN
THE 60S WILL MAKE AN ORGANIZED PUSH INTO LOWER PENINSULA ON MONDAY
AS THE SOUTHERLY GRADIENT INCREASES AHEAD OF DEVELOPING LOW PRESSURE
OVER THE CENTRAL CONUS. THE INCREASE IN LOW-LEVEL MOISTURE IS
PROGGED TO OCCUR COINCIDENT WITH THE APPROACH OF LOW AMPLITUDE
ENERGY EMANATING FROM THE LARGE CUTOFF LOW UPSTREAM, WHICH WILL SET
THE STAGE FOR DIURNALLY ENHANCED TSTORM DEVELOPMENT BY MONDAY
AFTERNOON. THE LARGE SCALE ENVIRONMENT IS BEGINNING TO LOOK LIKE IT
WILL FEATURE A DECENT DIRECTIONALLY SHEARED WIND PROFILE ALONG WITH
MODERATE CAPE VALUES OF AROUND 1000 J/KG PER 16.00 ECMWF, WHICH IS
MORE THAN SUFFICIENT TO SUPPORT ORGANIZED UPDRAFTS CAPABLE OF
CARRYING A LOW-END SEVERE THREAT. SHOWER AND THUNDERSTORM
PROBABILITIES WILL PERSIST OR INCREASE MONDAY NIGHT INTO TUESDAY
NIGHT AS A DEVELOPING LOW-LEVEL JET TAKES AIM ON THE AREA.

MARINE...

WINDS WILL VEER NORTHEASTERLY TONIGHT IN ADVANCE OF STRONG HIGH
PRESSURE BUILDING INTO THE WESTERN GREAT LAKES.  FAVORABLE MARINE
CONDITIONS WILL EXIST ON FRIDAY AS THIS HIGH SLOWLY WORKS THROUGH
THE REGION.  EXTENDED PERIOD OF LIGHTER EASTERLY FLOW WILL EXIST
THROUGH THE WEEKEND.
-- End Changed Discussion --

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.

&&

$$

AVIATION.....BT
SHORT TERM...CB
LONG TERM....JVC
MARINE.......CB


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