Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 242301
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
701 PM EDT SUN MAY 24 2015


.AVIATION...

ONGOING SHOWERS WILL MAINLY BE FOCUSED NORTH OF FNT DURING THE
REMAINDER OF THE EVENING AS THE REGION OF LIGHT RAIN CONTINUES ON A
NORTH-NORTHEASTWARD TRAJECTORY. ENOUGH LOW LEVEL DRY AIR LOOKS TO
REMAIN IN PLACE ACROSS SE MI TO KEEP CLOUDS BASES ABOVE 5K FT WITH
THIS REGION OF RAIN. THE RAIN IS LIFTING NORTHWARD AHEAD OF A WARM
FRONT THAT WILL LIFT NORTH ACROSS SE MI OVERNIGHT. THE PASSAGE OF
THE FRONT WILL BE MARKED BY A VEERING OF THE WIND TOWARD THE SOUTH.
A STRONG SOUTHERLY GRADIENT WILL THEN LEAD TO INCREASING SOUTHERLY
WINDS /EVEN PRIOR TO DAYBREAK/...WITH GUST LIKELY TOPPING 25 KNOTS
BY EARLY MON AFTERNOON.

FOR DTW...THE WARM FRONTAL PASSAGE AND ASSOCIATED SHIFT IN THE WIND
DIRECTION IS EXPECTED IN THE 05Z TO 06Z TIME FRAME.

//DTW THRESHOLD PROBABILITIES...

* LOW IN THUNDERSTORMS MONDAY AFTERNOON.

&&

.PREV DISCUSSION...ISSUED 310 PM EDT SUN MAY 24 2015

SHORT TERM...THIS AFTERNOON AND TONIGHT

RAIN SHOWERS WILL BECOME MORE NUMEROUS OVER THE SAGINAW VALLEY LATE
TODAY INTO THIS EVENING AS LOW PRESSURE LIFTS NORTH THROUGH THE MID
MISSISSIPPI VALLEY AND A WARM FRONT EXTENDING EAST FROM THIS LOW
BECOMES BETTER DEFINED WITH TIME. WITH PERSISTENT LIFT AND MOISTURE
POOLING WITH THIS FEATURES...DRY LOW LEVELS AOB 8KFT WILL EVENTUALLY
SATURATE WITH THE WIDESPREAD VIRGA OF TODAY REACHING THE SURFACE
BEFORE THE FRONT SHIFTS NORTH OVERNIGHT.

THE CHANCE FOR MEASURABLE RAIN WILL ALSO INCREASE SLIGHTLY SOUTH
INTO THE I-69/M-59 CORRIDOR...BUT REMAIN RELATIVELY LOW DURING THE
SAME TIME FRAME LATE THIS AFTERNOON AND EARLY THIS EVENING. IN
GENERAL...REALLY ONLY EXPECT SCATTERED SPRINKLES SOUTH OF I-69 AS
BOTH DRY AIR AND EXTRA CAPPING FROM UPPER LEVEL RIDGE CONTINUE TO
INHIBIT SHOWER COVERAGE/INTENSITY. WHEN ALL IS SAID AND DOWN...DO
EXPECT LIKELY TO CATEGORICAL POPS OVER THE SAGINAW VALLEY...WITH A
TIGHT GRADIENT SOUTHWARD...TAPERING TO LITTLE/NO CHANCE OF
MEASURABLE RAINFALL FROM AROUND I-94 OR SO SOUTH TO THE MICHIGAN
AND OHIO STATE LINE.

VERY MILD TEMPERATURES IN THE 70S TO AROUND 80 WILL ONLY EDGE BACK
INTO THE LOWER TO MID 60S OVERNIGHT AS WARM SECTOR SOUTH OF THE WARM
FRONT EXPANDS NORTH THROUGH THE AREA AND DEW POINTS STEADILY RISE
THIS EVENING INTO TONIGHT.

LONG TERM...

SHORTWAVES WILL CONTINUE TO EJECT ACROSS THE MIDDLE MS VALLEY AND
ACROSS THE WESTERN GREAT LAKES AS DEEP LAYER SW FLOW PERSISTS AROUND
LARGE SCALE ANTICYCLONE OVER THE EAST COAST AND MEAN TROUGHING IN
THE SOUTHWEST.

NEXT TWO SHORTWAVES TO IMPACT THE AREA ARE EVIDENT ON WV IMAGERY
OVER CENTRAL TEXAS AND SOUTHWEST NEW MEXICO. THE FORMER WILL LIFT
NORTH WITHIN PREVAILING SW FLOW TONIGHT, BRINGING WITH IT THE
REMNANTS OF THIS AFTERNOON`S ARKLATEX REGION CONVECTION. WITHOUT
RESPECTABLE LARGE SCALE SUPPORT, REMNANTS WILL STRUGGLE TO PENETRATE
THE DOME OF DRY AIR OVER SOUTHEAST MICHIGAN. THIS IS WELL-DEPICTED
BY THE 12Z WRF-ARW/NMM AND 4KM NAM. GIVEN THE RATHER NEBULOUS
FORCING SITUATION AS THE PRIMARY SHORTWAVE DYNAMICS REMAIN DISPLACED
TO THE WEST, PREFERRED TO MOVE FORWARD WITH A CONSERVATIVE FORECAST.
IT APPEARS THAT THE BEST CHANCE FOR SHOWERS OR TSTORMS WILL BE
DURING A BRIEF WINDOW 19-21Z WHEN THE H7-H5 MOISTURE AXIS SWINGS
THROUGH THE CWA DURING PEAK HEATING. A PARTIAL COVERAGE OF SHOWERS
DOES APPEAR LIKELY, BUT EXPECTATION FOR LOWER COVERAGE PRECLUDES A
HIGHER POP MENTION. LAPSE RATES WILL BE MEAGER AT BEST, SO CAPE OF
PERHAPS 400-500 J/KG WILL BE SPREAD THIN AND THUNDER WILL HARD TO
COME BY, MUCH LESS ANY KIND OF SEVERE THREAT. MOST NOTEWORTHY
SENSIBLE WX FEATURE FOR MONDAY WILL BE DEWPOINTS RISING WELL INTO
THE 60S AND WINDS GUSTING TO 25 KNOTS AS THE BOUNDARY LAYER GROWS TO
900MB PER 4KM NAM AND MIXES DOWN STRONGER WINDS ALOFT.

CONTINUED SOUTHWEST FLOW WILL SUSTAIN WARM AND MUGGY CONDITIONS
MONDAY NIGHT AS THE SECOND SHORTWAVE SUPPORTS ANOTHER CONVECTIVE
EPISODE OVER THE ARKLATEX. THIS WAVE WILL LIFT NORTH IN SIMILAR
FASHION, AND IS DEPICTED TO BE ONLY SLIGHTLY STRONGER THAN ITS
PREDECESSOR. THERE MAY BE A WINDOW FOR A HIGHER PROBABILITY OF
SHOWERS BY WEDNESDAY NIGHT AS THIS WAVE ACTUALLY TURNS THE MEAN FLOW
CYCLONIC FOR A BRIEF TIME, BUT IT`S HARD TO ARGUE FOR ANYTHING
HIGHER THAN A 40 POP ATTM.

A FAIRLY ACTIVE PATTERN REMAINS FOR THE EXTENDED PERIOD AS A
SERIES OF LOW PRESSURE SYSTEMS ARE FORECASTED TO IMPACT SOUTHEAST
MICHIGAN. RAIN AND THUNDERSTORM CHANCES WILL BEGIN WEDNESDAY
MORNING. THE ONLY DRY DAY COULD BE ON THURSDAY WHEN HIGH PRESSURE
TRIES TO NUDGE ITS WAY INTO SOUTHEAST MICHIGAN. RAIN SHOWERS RETURN
ON FRIDAY AND SATURDAY. HAVE ONLY INCLUDED CHANCE POPS INTO THE
FORECAST FOR NOW TO ACCOUNT FOR UNCERTAINTY IN THE TIMING OF THESE
SYSTEMS. HIGH TEMPERATURES WILL REMAIN IN THE UPPER 70S TO LOW 80S
THROUGH THURSDAY WITH FRIDAY HIGHS APPROACHING THE MID 80S IN SOME
LOCATIONS.

MARINE...

SMALL CRAFT ADVISORIES ARE IN EFFECT FOR ALL NEARSHORE WATERS AND
LAKE SAINT CLAIR FOR MEMORIAL DAY. SOUTHWEST WIND WILL BECOME
MODERATE TO FRESH OVER ALL AREA WATERS BY LATE IN THE MORNING. WIND
GUSTS ARE FORECAST TO FREQUENTLY REACH 22 TO 26 KNOTS. OFFSHORE
WINDS WILL LIMIT THE POTENTIAL FOR WAVE GROWTH IN THE NEARSHORE
ZONES WITH SIGNIFICANT WAVE HEIGHTS EXPECTED TO MAX OUT AROUND 2 TO
LOCALLY 3 FEET. MAXIMUM WAVE HEIGHTS WILL REACH 4 TO POSSIBLY 5
FEET...MAINLY FURTHER AWAY FROM SHORE. THUNDERSTORM POTENTIAL IS LOW
WITH ONLY A SLIGHT CHANCE DURING THE AFTERNOON.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...SMALL CRAFT ADVISORY FROM 2 PM TO 10 PM EDT MONDAY FOR LHZ421-422-
     441>443.

LAKE ST CLAIR...SMALL CRAFT ADVISORY FROM 10 AM TO 10 PM EDT MONDAY FOR LCZ460.

MICHIGAN WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY FROM 10 AM TO 10 PM EDT MONDAY FOR LEZ444.

&&

$$

AVIATION.....SC
SHORT TERM...DG
LONG TERM....JVC/RK
MARINE.......JVC


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



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