Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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481
FXUS63 KDTX 280728
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
328 AM EDT THU APR 28 2016

.DISCUSSION...

RAIN SHOWERS TOOK THEIR TIME GETTING INTO SOUTHEAST MICHIGAN TONIGHT
LOWER LEVELS WERE RATHER DRY PER THE OOZ DTX SOUNDING LAST NIGHT.
SHOWERS WILL CONTINUE TO MOVE NORTHEAST ACROSS THE AREA EARLY THIS
MORNING AS THE CENTER OF THE LOW PASSES JUST TO THE SOUTH OF THE
AREA.  RAIN CHANCES WILL INCREASE DURING THE DAY TODAY AS THE
FRONTAL BOUNDARY LINGERS OVER THE AREA. LOW WILL THEN WEAKEN AND
BECOME AN OPEN WAVE AS IT PASSES ACROSS THE GREAT LAKES REGION LATER
THURSDAY NIGHT INTO FRIDAY.  MODEST MID LEVEL LAPSE RATES OVER THE
SOUTHERN THIRD OF THE CWA WILL SUPPORT THE CONTINUED CHANCES FOR
ELEVATED THUNDERSTORMS DURING THE DAY. WHILE MOISTURE WILL BE
MAINTAINED THROUGH THE DAY SUPPORTING PRECIP...DRIER LOW LEVELS AND
BETTER FORCING TO THE SOUTH WILL KEEP THINGS SOMEWHAT SUBDUED.
LATEST NAM IS SHOWING LESS OF A CHANCE FOR WIDESPREAD PRECIP WITH
OTHER MODELS SHOWING THE BULK OF THE PRECIP TO COME THROUGH THE
MORNING AND EARLY AFTERNOON HOURS.  LATEST HRRR IS ALSO JUST
ADVERTISING SCATTERED PRECIP WITH SOME EMBEDDED CONVECTION.  BY
FRIDAY AFTERNOON...THINGS START TO DRY OUT AS RIDING TAKES OVER.
THIS RIDING WILL HOLD THROUGH FRIDAY INTO EARLY SATURDAY BEFORE THE
NEXT WAVE APPROACHES FROM THE CENTRAL PLAIN.  TODAY WILL BE THE
COLDEST DAY IN THE EXTENDED FORECAST PERIOD AS EASTERLY FLOW AND
CLOUDS KEEP TEMPS CONFINED IN THE UPPER 40S. TEMPS DO START TO
MODERATE SLIGHTLY THIS WEEKEND INTO NEXT WEEK WITH HIGHS GETTING BACK
INTO THE 60S ALTHOUGH STILL ON THE COOL SIDE.

&&

.MARINE...

STEADY NORTHEAST FLOW BETWEEN HIGH PRESSURE OVER ONTARIO AND LOW
PRESSURE TRACKING INTO THE OHIO VALLEY WILL LEAD TO BUILDING WAVES
OVER LAKE HURON TODAY.  SMALL CRAFT ADVISORIES REMAIN IN EFFECT AS
WAVES BUILD INTO THE 3 TO 5 FOOT RANGE AT TIMES OVER MUCH OF THE
NEARSHORE WATERS OF LAKE HURON. THIS LOW WILL ALSO BRING A CHANCE
FOR A FEW THUNDERSTORMS TO LAKE ST CLAIR AND WESTERN LAKE ERIE.

HIGH PRESSURE WILL EXPAND BACK INTO THE CENTRAL GREAT LAKES TONIGHT
AND REMAIN POISED OVER THE AREA INTO SATURDAY...ALLOWING WINDS AND
WAVE HEIGHTS TO DECREASE. ANOTHER LOW PRESSURE SYSTEM WILL THEN LIFT
INTO THE OHIO VALLEY OR SOUTHERN GREAT LAKES SATURDAY NIGHT INTO
SUNDAY...BRINGING ANOTHER PERIOD OF STEADY ONSHORE FLOW LATE IN THE
WEEKEND. SMALL CRAFT ADVISORIES MAY BE NEEDED ONCE AGAIN. ALTHOUGH
WAVE CONDITIONS APPEAR TO BE MARGINAL AT THIS TIME...MUCH LIKE THE
EVENT TODAY.

&&

.HYDROLOGY...

AN AREA OF RAINFALL WILL LIFT NORTHWARD THROUGH SOUTHEAST MICHIGAN
TODAY AS LOW PRESSURE TRACKS ACROSS THE OHIO VALLEY. WHILE DRY LOW
LEVEL CONDITIONS WILL INITIALLY LIMIT RAINFALL POTENTIAL...SOME
LOCATIONS...GENERALLY SOUTH OF I-69...MAY RECEIVE UP TO ONE QUARTER
OF AN INCH OF RAIN BY LATE THIS AFTERNOON.

ANOTHER LOW PRESSURE SYSTEM WILL BRING THE NEXT CHANCE OF WIDESPREAD
RAIN LATE SATURDAY INTO SATURDAY NIGHT. AT THIS TIME...IT APPEARS
THAT ONE QUARTER TO ONE HALF AN INCH OF RAINFALL WILL BE POSSIBLE
WITH THIS SYSTEM. THE BEST CHANCE FOR STEADY RAINFALL WILL ONCE
AGAIN FOCUS SOUTH OF THE I-69 CORRIDOR.

&&

.AVIATION...ISSUED 1234 AM EDT THU APR 28 2016

NO CHANGES IN TIMING WERE NEEDED FROM THE EARLIER TAF FORECASTS WITH
RESPECT TO PRECIPITATION ONSET. RADAR TRENDS SUPPORT NOTHING MORE
THAN VIRGA KNOCKING ON THE DOORSTEP OF SOUTHEASTERN MICHGIAN AT
LEAST THROUGH THE FIRST 3 HOURS. LATEST HRRR ITERATIONS HAVE FALLEN
IN LINE WITH THE CONSENSUS FOR PRECIPITATION TO BEGIN REACHING THE
GROUND FOR DETROIT SHORTLY AROUND/AFTER 10Z. LIGHT RAIN WILL LIFT
FROM SOUTH TO NORTH DURING THE COURSE OF THE MORNING WITH THE RAIN
LOOKING TO MOVE OUT OF THE DETROIT TERMINALS BY 16Z. PRECIPIATION
END TIMES ARE LESS CERTAIN ACROSS THE CENTRAL PORTIONS OF THE CWA AS
THE AXIS OF DEEPER MIDLEVEL MOISTURE STALLS OVERHEAD WITHIN A
BROADER CORRIDOR OF STRETCHING DEFORMATION. LATEST MODEL DATA
SUPPORTS VERY POOR MOITURE QUALITY/DEEP SATURATION ISSUES THROUHGOUT
MUCH OF THE DAY. ATTM...CONFIDENCE IS SKEWED HIGHER THAT CIG HEIGHTS
WILL REMAIN VFR WITH SOME POCKETS OF MVFR VSBYS IN RAIN ACTIVITY.
CONFIDENCE IS ALSO RELATIVELY HIGH THAT CIGS OF AROUND 4-5 KFT AGL
WILL HOLD OVER A GREATER PORTION OF SOUTHEASTERN MICHIGAN AS THE
MIDLEVEL LOW PRESSURE CENTER WILL ONLY BE APPROACHING THE AREA FROM
THE WEST...THUS RESULTING IN A CONTINUED FAVORABLE LOCATION FOR WARM
AIR ADVECTION PROCESSES.

FOR DTW...RAIN AND MVFR VISIBILITIES ARE EXPECTED TO START IMPACTING
THE TERMINAL AFTER 10Z...WITH SHOWER EXPECTED TO LIFT NORTH BY THE
START OF THE AFTERNOON AS DRIER AIR MOVES IN AT THE MID LEVELS.
EASTERLY WINDS WILL CONTINUE THROUGH THE TAF PERIOD.

//DTW THRESHOLD PROBABILITIES...

* HIGH WITH CEILINGS FALLING BELOW 5000 FEET THURSDAY MORNING AND
  REMAINING THERE THROUGH 00Z.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 10 PM EDT THIS
     EVENING FOR LHZ421-422-441-442.

LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LEZ444.

&&

$$

DISCUSSION...SS
MARINE.......DG
HYDROLOGY....DG
AVIATION.....DG


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



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