Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 290353
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1153 PM EDT THU MAY 28 2015

.AVIATION...

A FEW STREAKS OF CIRRUS WILL CONSTITUTE VFR CONDITIONS AT ALL
TERMINAL SITES DURING THE EARLY MORNING. THERE COULD ALSO BE SOME
BRIEF MVFR FOG AROUND SUNRISE BUT COVERAGE AND DENSITY WILL BE
LIMITED AS SOUTH WIND STRUGGLES TO INCREASE DURING THE NIGHT. THERE
WILL ALSO BE SOME HIGHER BASED CU/AC CLOUDS ARRIVING FROM THE SOUTH
AND WEST TOWARD SUNRISE AND THROUGH THE MORNING. THESE CLOUDS WILL
BE THE FIRST SIGN OF DEEPENING MOISTURE AND INCREASING HUMIDITY
EXPECTED TO PROGRESS NORTHWARD FROM THE OHIO VALLEY ACROSS SE
MICHIGAN THROUGH THE DAY. THE INCREASED HUMIDITY WILL SUPPORT THE
POTENTIAL FOR THUNDERSTORM DEVELOPMENT BUT STILL MAINLY INTO FRIDAY
EVENING. THERE IS GREATER CONFIDENCE IN TIMING AND COVERAGE AT MBS
AND FNT BY MID EVENING.

FOR DTW... THE WIND STARTING OUT SLIGHTLY SOUTH OF EAST DURING THE
NIGHT WILL BRING A LITTLE EXTRA MOISTURE INTO THE TERMINAL FROM LAKE
ERIE. THIS ADDS SOME CONFIDENCE TO MVFR FOG RESTRICTION BUT WILL
HOLD OFF ON IFR IN THE FORECAST AND MONITOR OBSERVATIONAL TRENDS.
INCREASING WIND SPEED AND HIGH CLOUDS MAY ALSO LIMIT IFR RESTRICTION
THROUGH MID MORNING.

//DTW THRESHOLD PROBABILITIES...

* LOW POTENTIAL FOR CEILING AT 5000 FEET OR LESS TODAY AND FRIDAY
  TONIGHT.

* LOW POTENTIAL FOR THUNDERSTORMS FRIDAY NIGHT.

&&

.PREV DISCUSSION...ISSUED 335 PM EDT THU MAY 28 2015

SHORT TERM...THROUGH TONIGHT

A CONSIDERABLY DRIER LOW LEVEL ANTICYCLONIC FLOW TUCKED BENEATH A
GENERAL INCREASE IN UPPER HEIGHTS LARGELY SUSTAINING A STABLE
PROFILE THIS AFTERNOON...WITH LIMITED DIURNAL CU DEVELOPMENT.
EXCEPTION ACROSS THE TRI-CITIES...WITH THIS CORRIDOR WITHIN THE
FRINGE OF SOME WEAK UPWARD ASCENT AND ACCOMPANYING AGITATED
CU FIELD NOW EMERGING OFF THE LEE OF LAKE MICHIGAN.  THERE DOES
REMAIN THE POSSIBILITY FOR A FEW ISOLATED CELLS TO EMERGE UPSTREAM
ALONG THIS FEATURE PRIOR TO SUNSET.  THIS WILL CONTRIBUTE TO A VERY
LOW PROBABILITY FOR A SHOWER/THUNDERSTORM TO PERHAPS DRIFT INTO THE
TRI-CITIES BEFORE THE THERMODYNAMIC ENVIRONMENT QUICKLY DETERIORATES
WITH SUNSET.

OTHERWISE...LOOKING AT A TRANQUIL EVENING/NIGHT UNDER A CLEAR SKY
AND LIGHT SOUTHEAST FLOW.  A DRYING NEAR SURFACE CONDITION WILL KEEP
ANY FOG FORMATION LIMITED IN COVERAGE AND VERY SHALLOW.  LOWS
TONIGHT SETTLING WITHIN A RANGE FROM MID 50S TO LOWER 60S.

LONG TERM...

UPPER LEVEL RIDGE AXIS SLIDING TO THE EAST TOMORROW WILL ALLOW A
WEAK WARM FRONT TO LIFT NORTH THROUGH SOUTHEAST MICHIGAN...WITH BEST
DEFINITION/HEIGHT FALLS TOWARD SAGINAW BAY. GFS/NAM SUGGESTING
THE BULK OF THE GULF OF MEXICO RETURN MOISTURE WILL WORK INTO THE
WESTERN AND EASTERN GREAT LAKES...WITH SOUTHEAST MICHIGAN MORE IN A
WEAK 850-700 MB THETA-E MINIMUM DURING THE AFTERNOON HOURS.
STILL...WITH THE MOISTURE ADVECTION AND BLCAPES OF 500-1000 J/KG AND
POSSIBLE LAKE BREEZE INTERACTION/WARM FRONT WORTHY OF CHANCE POPS.
THE CAPE VALUE IS A BLEND OF GFS/NAM...AS THE 12Z NAM SURFACE DEW
PTS CLIMBING TO 70 DEGREES APPEARS TO BE OVERLY AGGRESSIVE...WITH
THE AIRMASS SOUTH OF ST LOUIS AND OVER KENTUCKY INDICATING DEW PTS
IN THE MID TO UPPER 60S THIS AFTERNOON. LOOKING FOR HIGHS IN THE MID
80S TOMORROW BASED ON 850 MB TEMPS AROUND 15 C. WITH THE GENERALLY
LOW CAPE AND BORDERLINE 0-6 KM BULK SHEAR AROUND 25 KNOTS...WILL
PROBABLY BE HARD PRESSED TO SEE ANY SEVERE STORMS.

DEEP/COLD (-34 C AT 500 MB) UPPER LEVEL LOW WORKING INTO ONTARIO
DURING SATURDAY...WITH UPPER LEVEL PV/ENERGY OVER THE
CENTRAL/NORTHERN ROCKIES SHEARING OFF TO THE NORTHEAST OUT AHEAD OF
THIS SYSTEM. ABUNDANT MOISTURE STREAMING INTO SOUTHEAST
MICHIGAN THROUGH SATURDAY  (850 MB DEW PTS PROGGED TO RISE TO 13
C...WITH PW VALUES APPROACHING 1.75 INCHES)...COUPLED WITH LOW LEVEL
FRONTAL FORCING DURING SATURDAY SHOULD BE SUFFICIENT TO GENERATE
SHOWERS AND THUNDERSTORMS. HOWEVER...RIGHT ENTRANCE FORCING OF THE
STRONG UPPER LEVEL JET (130+ KNOTS AT 250 MB) LOOKS TO BE DISPLACED
TO OUR NORTH AT THIS TIME. WITH EARLY DAY ACTIVITY
DEVELOPING...SBCAPES WOULD LIKELY REMAIN BELOW 1000 J/KG (GFS)...BUT
NAM SUGGESTS MORE LIKE 1500 J/KG. THIS WILL BE IMPORTANT AS 0-6 KM
WILL BE FORMIDABLE...WELL INTO THE 40S (KNOTS). 6 HOUR FLASH FLOOD
GUIDANCE IS ABOVE 2 INCHES ACROSS SOUTHEAST MICHIGAN...SO WE CAN
ABSORB A HEFTY RAINFALL WITH THE PREVIOUSLY MENTIONED EXTREME
MOISTURE PARAMETERS FOR LATE MAY STANDARDS.

THERE IS A DISCREPANCY ON STRENGTH AND TIMING OF SECOND WAVE OF LOW
PRESSURE RIDING ALONG THE FRONT...WHICH WOULD PROLONG HEAVY
RAINFALL...BUT 12Z EURO SUGGEST THIS WAVE WILL TRACK THROUGH THE
OHIO VALLEY SATURDAY EVENING/NIGHT...WHILE CANADIAN RIDES A WEAKER
LOW CLOSER TO THE SOUTHERN MICHIGAN BORDER LATE SATURDAY.

STRONG SURFACE HIGH PRESSURE BUILDS INTO THE REGION ON SUNDAY
RESULTING IN DRY WEATHER ACROSS THE ENTIRE CWA. THIS HIGH IS
EXPECTED TO SLOWLY DRIFT EASTWARD THROUGH NEXT THURSDAY...KEEPING
CONDITIONS DRY AND CALM THROUGH THIS TIMEFRAME. THE NEXT CHANCE OF
RAIN ARRIVES ON THURSDAY NIGHT. UNCERTAINTY REMAINS IN THIS SYSTEM
AS IT IS NEARLY A WEEK AWAY. THEREFORE...HAVE ONLY INCLUDED LOW
CHANCE POPS /30 PERCENT/ IN THE FORECAST FOR THURSDAY NIGHT AND INTO
NEXT FRIDAY. AS FAR AS TEMPERATURES GO...HIGH TEMPERATURES WILL BE
ON A GRADUAL WARMING TREND...STARTING OFF ON SUNDAY IN THE LOW
60S...AND WARMING UP INTO THE MID 80S BY THURSDAY. A SIMILAR TREND
WILL BE IN PLACE WITH THE LOW TEMPERATURES...STARTING OFF IN THE MID
40S SUNDAY NIGHT...WARMING INTO THE LOW 60S BY THURSDAY NIGHT.

MARINE...

LIGHT SOUTHERLY WINDS TOMORROW WILL BRING IN MOIST AND WARMER AIR
TO THE REGION...WITH SHOWERS AND THUNDERSTORMS DEVELOPING FRIDAY
NIGHT INTO SATURDAY AS COLD FRONT SLIDES THROUGH THE CENTRAL GREAT
LAKES. NORTHERLY WINDS BEHIND THE FRONT SATURDAY EVENING AND NIGHT
LOOK TO GUST ABOVE 20 KNOTS...ALLOWING FOR A MODERATE WAVE BUILD UP
OVER THE SOUTHERN HALF OF LAKE HURON...WHICH MAY REQUIRE SMALL CRAFT
ADVISORIES INTO SUNDAY MORNING. DRY WEATHER WILL RETURN FOR SUNDAY
HOWEVER.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

AVIATION.....BT
SHORT TERM...MR
LONG TERM....SF/RK
MARINE.......SF


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