Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 281641
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1241 PM EDT SUN JUN 28 2015

.AVIATION...

DECENT VFR CU FIELD THIS AFTERNOON ACROSS SOUTHEAST MICHIGAN...WITH
GUSTY NORTHWEST WINDS AT OR SLIGHTLY ABOVE 20 KNOTS. WINDS WILL
DIMINISH BY EARLY EVENING...BUT CONFIDENCE IN CLOUDS TOTALLY
DISSIPATING IS NOT AS HIGH...BUT NOT EXPECTING MUCH MORE THAN FEW-
SCT COVERAGE POST SUNSET. THERE IS AN OUTSIDE CHANCE OF LIGHT FOG
TONIGHT...BUT FELT ENOUGH DRYING WILL TAKE PLACE THIS AFTERNOON TO
NOT INCLUDE IN TAF. THERE IS A SLIGHT CHANCE A SHOWER COULD GO UP
NEAR MBS LATE TODAY. FOCUS TOMORROW WILL BE ON THE SYSTEM LIFTING
NORTH INTO THE STATE...PRODUCING HEAVY RAIN SHOWERS AND POSSIBLE
THUNDERSTORMS...LIKELY ARRIVING ACROSS SOUTHERN TAF SITES BY EARLY
AFTERNOON.

FOR DTW...BORDERLINE SCT-BKN COVERAGE OF CU FIELD AROUND 5000 FOOT
LEVEL THIS AFTERNOON...WITH SOME CLOUDS POTENTIALLY LINGERING
TONIGHT. RAIN SHOWERS AND POSSIBLE THUNDERSTORMS EXPECTED TO
OVERSPREAD BY EARLY TOMORROW AFTERNOON.

//DTW THRESHOLD PROBABILITIES...

* LOW IN CEILINGS BELOW 5000 FEET THROUGH 15Z MONDAY...HIGH
  THEREAFTER.

* LOW TO MEDIUM CONFIDENCE IN THUNDERSTORMS TOMORROW AFTERNOON.

&&

.PREV DISCUSSION...ISSUED 1059 AM EDT SUN JUN 28 2015

UPDATE...

WITH THE GOOD DEAL OF SUNSHINE THIS MORNING...EXPECTING MOST
LOCATIONS TO TOP OUT IN THE MID 70S (EXCEPTION THUMB REGION)...WITH
UPPER 70S POSSIBLE TOWARD TRI-CITIES REGION AS 850 MB TEMPS RISE
TO AROUND 11 C. RESIDUAL LOW LEVEL MOISTURE AND STUBBORN CYCLONIC
FLOW STILL EXPECTING A DECENT CU UP. WITH THE LACK OF MID LEVEL
RIDING/WARMING TAKING PLACE...THERE IS CONCERN ENOUGH LOCALIZED
CONVERGENCE AND SLIVER THIN CAPE IN THE 5-15 KFT LAYER MAY BE
SUFFICIENT TO GENERATE A FEW SHOWERS TOWARD TRI-CITIES REGION...AS
SEVERAL HIGH RESOLUTION MODELS SUGGEST. HOWEVER...SURFACE DEW PTS
ARE IN THE UPPER 40S ACROSS NORTHERN LOWER MICHIGAN...BELOW WHAT
THE 12Z NAM IS SUGGESTING...AND WILL CONTINUE TO EVALUATE/MONITOR
TRENDS BEFORE ADDING SHOWER MENTION.

PREV DISCUSSION...ISSUED 404 AM EDT SUN JUN 28 2015

SHORT TERM...TODAY AND TONIGHT

DEFORMATION AXIS CONTINUES TO PIVOT THROUGH FAR EASTERN MICHIGAN
THIS MORNING AS IT LINGERS BEHIND AN EXITING AREA OF LOW PRESSURE.
EXPECT THIS TO IMPACT THE AREA THROUGH THE LATE MORNING HOURS...WITH
SHOWERS AND AREAS OF DRIZZLE GRADUALLY DECREASING IN COVERAGE.
PRECIPITATION IS NOT EXPECTED TO BE HEAVY.

WEAK SURFACE RIDGING WILL BUILD IN BEHIND THE DEPARTING LOW TO
PROVIDE MUCH DRIER WEATHER THIS AFTERNOON AND TONIGHT. MODELS ARE
HINTING AT A FEW SHOWERS DEVELOPING LATE THIS AFTERNOON OVER WESTERN
AND NORTHERN LOWER MICHIGAN. FORECAST MODEL SOUNDINGS FROM WESTERN
MICHIGAN INDICATE A WEAKER MID-LEVEL INVERSION WILL BE PRESENT OVER
THESE PARTS OF THE STATE LATER TODAY...AS THIS AREA RESIDES CLOSER
TO COOLER AIR ALOFT ASSOCIATED WITH A STRONG SHORTWAVE DROPPING
THROUGH THE MIDWEST/WESTERN GREAT LAKES. GFS/NAM SOUNDINGS FOR MBS
LOOK PRETTY STABLE...AND WILL LEAVE MENTION OF PRECIP OUT OF THE
FORECAST AFTER ABOUT 1PM TODAY. ALTHOUGH CLOUDS TRAILING THE
DEPARTING LOW WILL GRADUALLY SLIDE EAST TODAY...AMPLE MOISTURE LOOKS
TO REMAIN AND EXPECT ADDITIONAL CU DEVELOPMENT TODAY AS HEATING
COMMENCES. THIS SHOULD MAINTAIN A SCT-BKN CLOUD DECK UNTIL DRIER AIR
ARRIVES DURING THE EARLY EVENING. GUSTY NORTH WINDS WILL ALSO
DIMINISH THROUGH THE DAY AS SURFACE RIDGING BUILDS INTO MICHIGAN AND
SURFACE GRADIENT RELAXES. TEMPERATURES SHOULD REBOUND BY QUITE A BIT
TODAY...BUT STILL REMAIN SHY OF NORMAL RANGING FROM THE UPPER 60S TO
MID 70S (COOLEST OVER THE THUMB...WARMEST OVER THE SAGINAW VALLEY).

MOSTLY CLEAR SKIES AND LIGHT WINDS OVERNIGHT MAY PROMOTE SOME FOG
DEVELOPMENT GIVEN SATURATED SOILS...WHICH SHOULD HELP DEWPOINTS STAY
UP IN THE 50S. ADDED ONLY A PATCHY MENTION OF FOG FOR NOW...TAKING
STRONGLY INTO ACCOUNT THE SHORT DURATION OF DARKNESS THIS CLOSE TO
THE SUMMER SOLSTICE. SOME HIGHER CLOUDS WILL ALSO START TO WORK INTO
SOUTHERN LOWER MICHIGAN LATE AS LOW PRESSURE BEGINS TO TRACK THROUGH
ILLINOIS.

LONG TERM...MONDAY THROUGH SATURDAY

THE PARADE OF SHORTWAVES DIGGING AROUND THE PERSISTENT EASTERN NOAM
TROUGH WILL CONTINUE TO IMPACT THE MIDWEST AND GREAT LAKES REGIONS
THROUGH THE MIDDLE OF THE WORK WEEK. EXPECTATIONS ARE FOR WET AND
UNSETTLED WEATHER WITH DAYTIME TEMPERATURES MON-FRI RUNNING 5 TO 10
DEGREES BELOW SEASONAL AVERAGES.

THE NEXT SHORTWAVE WILL CASCADE DOWN THE WESTERN EXTENSION OF THE
TROUGH AND SETTLE INTO PORTIONS OF NORTHERN IL/IN BY 12Z MONDAY.
WHILE ABSOLUTE VORTICITY CHARTS PROG A DAMPENING WAVE...A DEVELOPED
MIDLEVEL CYCLONIC CIRCULATION WILL END UP SUPPORTING A WEAK SURFACE
REFLECTION AT THE WESTERN LAKE ERIE SHORELINE BY 06Z TUESDAY. LACK
OF LARGE SCALE FORCING WITH VIRTUALLY NO JET STREAK ALOFT POINTS TO
AN EVENT THAT WILL BE DRIVEN PURELY FROM THETA E/WARM AIR
ADVECTION/MOISTURE TRANSPORT PROCESSES. A BAND OF NUMEROUS TO
CATEGORICAL COVERAGE OF SHOWERS WILL LIFT INTO THE SOUTHERN SECTIONS
OF THE CWA AFTER 15Z MONDAY...THEN PROGRESS SLUGGISHLY NORTHWARD
DURING THE COURSE OF THE AFTERNOON. INSTABILITY WITH THIS ACTIVITY
WILL BE LACKING AT LESS THAN 500 J/KG WITH POOR NEAR SURFACE THETA E
AND POOR MIDLEVEL LAPSE RATES. THE ONE ITEM TO HIGHLIGHT WILL BE
SOME POTENTIAL FOR REINVIGORATION OF DEEP MOIST CONVECTION NEAR THE
FAR SE SECTIONS OF THE CWA (MONROE/LENAWEE/WAYNE/LAKE ERIE) AS THE
LEFT QUADRANT NOSE OF AN 850MB JETLET WILL ROTATE TO OUR IMMEDIATE
SOUTH. IT IS PLAUSIBLE THAT ACCOMPANYING LOW TO MIDLEVEL CONVERGENCE
WILL BE ENOUGH TO CAUSE AN UPTICK IN FORCED ASCENT. PWATS ARE
FORECASTED TO CLIMB TO THE 1.75 INCH RANGE BY EVENING...WHICH BRINGS
THE POSSIBILITY FOR HEAVY RAINFALL. ATTM...THE PLAN IS TO ADDRESS
THIS IN THE HWO. HIGHS MONDAY WILL ONLY REACH 70 DEGREES ACROSS THE
FAR SOUTH UNDER OPAQUE CLOUD...MIDDLE 70S ACROSS THE NORTHERN CWA
WHERE DRY CONDITIONS ARE ANTICIPATED FOR MUCH OF THE DAY.

MONDAY NIGHT AND TUESDAY MORNING...THE SETUP LOOKS PRIME FOR VERY
LOW CEILING HEIGHTS AND A POTENTIAL FOR FOG. MODELS ARE SHOWING A
DOWNRIGHT LACK OF ANY ORGANIZED DRY AIR ADVECTION. EXPECT ALOT OF
CLOUDS GOING INTO TUESDAY. WITH THE TIMEFRAME BETWEEN WAVES...TIMED
A DRY PERIOD FOR THE LATTER HALF OF MONDAY NIGHT AND THROUGH MIDDAY
TUESDAY.

A FAIR AMOUNT OF UNCERTAINTY EXISTS WITH REGARDS TO THE SYSTEM THAT
HAS BEEN ADVERTISED FOR TUESDAY AFTERNOON AND NIGHT. THE 28.00Z
ECMWF ARRIVED SUGGESTING A GREATER DETACHMENT OF LOOSELY ORGANIZED
SHORTWAVE ENERGY FROM FAVORABLE JET DYNAMICS ALOFT. IN FACT...THE
CURRENT FORECAST SUGGESTS THE SHORTWAVE WILL BE POSITIONED IN AN
AREA THAT SHOULD BE UNDERGOING SOME BROAD SUBSIDENCE. A COUPLE OF
CURRENT THOUGHTS ON THIS TUESDAY SYSTEM. 1. THERE IS A WELL
DEVELOPED TROUGH AXIS THAT IS FORECASTED TO TRACK THROUGH DURING THE
LATE AFTERNOON AND EVENING SO FUTURE ADJUSTMENTS TO THE FORECAST ARE
ANTICIPATED. 2. GIVEN THE BROAD WAVELENGTH OF THE MID-UPPER TROUGH
AND THE TIMING OF THE ENERGY DIRECTLY WITHIN IT...THE POTENTIAL IS
PERCEIVED LOW FOR ANY GREAT DEAL OF WARM AIR ADVECTION ON THE
FORWARD FLANK. FOR THIS SECOND REASON...LOWERED POPS TO THE CHANCE
CATEGORY.

MARINE...

SEASONABLY STRONG SURFACE LOW PRESSURE NEAR CLEVELAND WILL LIFT
NORTHWARD TO UPSTATE NEW YORK TODAY. THE STRONG NORTHERLY WIND FIELD
WILL SUBSIDE SLOWLY OVER THE FAR SOUTHERN LAKE HURON BASIN...LAKE ST
CLAIR...AND LAKE ERIE. TRENDS IN SURFACE OBSERVATIONS SUPPORT AN
EXPIRATION OF THE GALE WARNING THAT HAD BEEN IN EFFECT. NORTH WINDS
OF 20 TO 25 KNOTS WITH SIGNIFICANT WAVE HEIGHTS RANGING 3 TO 5 FEET
SUPPORT SMALL CRAFT ADVISORY HEADLINES THROUGH THE EARLY AFTERNOON
HOURS. DECREASING WINDS WILL CONTINUE THIS EVENING...WITH WINDS 10
KNOTS OR LESS TONIGHT AS A WEAK SURFACE RIDGE ARRIVES. THE NEXT LOW
PRESSURE SYSTEM LOOKS TO BE TRACKING THROUGH SOUTHERN LOWER MICHIGAN
MONDAY NIGHT...BRINGING ANOTHER ROUND OF SHOWERS AND POSSIBLE
THUNDERSTORMS. DEPENDING ON THE STRENGTH OF THE LOW...SOUTHWEST
WINDS SOUTH OF THE LOW OVER LAKE ST CLAIR AND LAKE ERIE COULD GUST
TO 25 KNOTS...WITH POSSIBLE NORTHWEST GUSTS TO AROUND 25 KNOTS
BEHIND THE LOW OVER LAKE HURON ON TUESDAY.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT UNTIL 10 PM EDT THIS EVENING FOR MIZ049-055-
     063-083.

LAKE HURON...SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR LHZ441>443.

LAKE ST CLAIR...SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR LCZ460.

MICHIGAN WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR LEZ444.

&&

$$

AVIATION.....SF
UPDATE.......SF
SHORT TERM...HLO
LONG TERM....CB
MARINE.......CB


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



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