Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 011105
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
705 AM EDT FRI MAY 1 2015

.AVIATION...

VFR WILL BE FIRMLY IN PLACE OVER THE TERMINAL CORRIDOR TODAY THROUGH
TONIGHT THANKS TO HIGH PRESSURE BUILDING OVER THE REGION. NORTH WIND
AT 10 KNOTS OR LESS DURING THE MORNING WILL BECOME INFLUENCED BY
LAKE BREEZE INTERACTION DURING THE AFTERNOON INTO THIS EVENING.
CLOUDS WILL BE LIMITED TO SHALLOW FAIR WEATHER CUMULUS DURING THE
AFTERNOON WHICH WILL DISSIPATE AROUND SUNSET. MID TO HIGH CLOUDS
BEGIN TO MOVE INTO THE REGION AROUND SUNRISE SATURDAY.

//DTW THRESHOLD PROBABILITIES...

* NONE.

&&

.PREV DISCUSSION...ISSUED 407 AM EDT FRI MAY 1 2015

SHORT TERM... TODAY AND TONIGHT

WEATHER CONDITIONS WILL PROVIDE AN IDEAL START TO THE MONTH OF MAY
AS HIGH PRESSURE TAKES CONTROL TO KICK OFF THE WEEKEND. THE DAY WILL
START WITH SUNNY SKY HELPING TEMPERATURES REBOUND FROM THE 40S MOST
LOCATIONS. AFTERNOON HIGHS IN THE UPPER 60S TO LOWER 70S...5-10
DEGREES ABOVE NORMAL...WILL BE REACHABLE OUTSIDE OF THE SHORELINE
AREAS WHICH WILL BE SUBJECTED TO COOLER LAKE BREEZE CONDITIONS.

THE SURFACE RIDGE WILL START OUT OVER THE WESTERN GREAT LAKES AND
MIDWEST DURING THE MORNING WITH ADDITIONAL LARGE SCALE SUBSIDENCE
PROVIDED BY THE UPPER LEVEL RIDGE AXIS. BOTH WILL PROGRESS EASTWARD
AND BECOME CENTERED OVER LOWER MICHIGAN BY LATE AFTERNOON. SURFACE
HEATING WILL THEN HELP THE BOUNDARY LAYER BUILD TO NEAR 800 MB AND
LEAD TO SCATTERED COVERAGE OF SHALLOW CUMULUS. THE NAM IS MOST
BULLISH ON COVERAGE BOTH IN LOW LEVEL RH DEPICTIONS AND MODEL
SOUNDINGS. THIS APPEARS TIED TO LOW LEVEL CONVERGENCE INDUCED BY
LOCALIZED SURFACE PRESSURE FALLS DUE TO DIFFERENTIAL HEATING BETWEEN
THE LAND AND LAKES.

THE DIURNALLY DEPENDENT CUMULUS WILL FADE QUICKLY WITH SUNSET THIS
EVENING. CLEAR SKY AND LIGHT WIND FOR THE BULK OF THE NIGHT WILL
ALLOW TEMPS TO DROP BACK INTO THE 40S FOR LOWS BEFORE SOME MID TO
HIGH CLOUDS DRIFT IN FROM THE WEST TOWARD SUNRISE SATURDAY.

LONG TERM...

MID AND HIGH CLOUDS SATURDAY MORNING WILL BE ASSOCIATED WITH THE
REMNANTS OF THE FRONTAL SYSTEM OVER THE PLAINS AND MIDWEST TODAY.
THE FRONT WILL WASH OUT BY TONIGHT BUT THE LEADING THETA-E RIDGE AND
WEAK UPPER TROUGH WILL MAINTAIN JUST ENOUGH INTEGRITY TO SUPPORT
CLOUDS AS THESE FEATURES DRIFT OVER THE AREA DURING SATURDAY.
COVERAGE WILL BE MOSTLY SCATTERED TO BROKEN AND WON`T LAST ALL DAY
JUDGING BY TRENDS IN BOTH THE EVOLUTION OF MODEL MID LEVEL THETA-E
FEATURES AND RH FIELDS. TEMPERATURE GUIDANCE IS A COUPLE DEGREES
WARMER THAN TODAY WHICH SEEMS REASONABLE CONSIDERING THE LATE BOOST
IN SURFACE HEATING THAT IS LIKELY. THERE WILL ALSO BE A STRONGER
WESTERLY WIND COMPONENT THAT WILL HELP RESIST INLAND LAKE BREEZE
PENETRATION FOR THE SHORELINE AREAS.

MORE OF THE SAME SUNDAY IN TERMS OF MID TO HIGH CLOUDS AS SOUTHWEST
FLOW STRENGTHENS MODESTLY AHEAD OF THE NEXT FRONTAL SYSTEM MOVING
THROUGH CENTRAL CANADA AND THE PLAINS. THE WIND FIELD WILL HELP
BOOST TEMPS INTO THE FINAL STAGE OF THE WEEKEND WARMING TREND. HIGHS
IN THE MID 70S ARE ON TARGET WITH A BOOST OF SURFACE HEATING
WITHIN THE CLOUD PATTERN.

LOW TO MID LEVEL MOISTURE TRANSPORT BUILDING IN THE PLAINS SUNDAY
WILL SPREAD INTO LOWER MICHIGAN SUNDAY NIGHT. THIS WILL THICKEN
CLOUDS DURING THE NIGHT AND CARRY A LATE CHANCE OF SHOWERS INTO THE
SAGINAW VALLEY AND NORTHERN THUMB. SHOWERS AND THUNDERSTORMS ARE
THEN LIKELY MONDAY OVER ALL AREAS AS THE FRONT AND DEEP THETA-E
RIDGE SLIDE THROUGH THE REGION. DYNAMIC SUPPORT WILL BE LIMITED ON
THE SOUTH FLANK OF THE BROAD UPPER TROUGH BUT THE STRUCTURE OF THE
FRONT WILL BE SOLID ENOUGH TO MAINTAIN THE PRECIPITATION PATTERN
WITHIN THE MOISTURE AXIS. TIMING WILL ALSO BE COINCIDENT WITH
MAXIMUM DIURNAL HEATING PRODUCING JUST ENOUGH INSTABILITY
INDICATED IN MODEL DATA TO MAINTAIN THUNDER CHANCES.

GLOBAL MODEL SOLUTIONS ARE IN GOOD AGREEMENT WITH LARGE SCALE HEIGHT
FALLS OVER THE FOUR CORNERS AND PACIFIC NORTHWEST HEADING INTO THE
MID WEEK PERIOD. THE CORRESPONDING DOWNSTREAM RIDGE WILL SET UP FROM
THE MIDWEST TO THE MID ATLANTIC COAST. THIS WILL BE FAVORABLE FOR
REMNANTS OF THE MONDAY FRONT TO STALL NEAR THE OHIO BORDER TUESDAY
INTO WEDNESDAY AND LEAVE UNSETTLED CONDITIONS OVER SE MICHIGAN UNTIL
THE FRONT WASHES OUT BY THURSDAY.

MARINE...

NORTH TO NORTHEAST FLOW WILL REMAIN IN THE 10 TO 15 KNOT RANGE
FOR THE MOST PART OVER LAKE HURON AND LIMIT WAVE GROWTH DESPITE
THE PERSIST LONG FETCH OVER THE LAKE. THIS FLOW WILL BECOME LIGHT
AND VARIABLE BY TONIGHT AS A SMALL AREA OF SURFACE HIGH PRESSURE
BUILDS INTO THE AREA. QUIET WEATHER WILL PERSIST INTO THE WEEKEND
AS LIGHT SOUTHERLY FLOW DEVELOPS ONCE THIS HIGH MOVES TO THE EAST
AND SOUTHEAST. A FRONTAL BOUNDARY WILL SAG SOUTH INTO THE AREA
LATE SUNDAY NIGHT INTO MONDAY AND STALL THROUGH MID WEEK. THIS
WILL PROVIDE A BETTER CHANCE OF SHOWERS AND PERHAPS THUNDERSTORMS
EARLY NEXT WEEK...ESPECIALLY FROM SOUTHERN LAKE HURON SOUTH INTO
LAKE ERIE BY THE MONDAY AND TUESDAY TIME FRAME.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

AVIATION.....BT
SHORT TERM...BT
LONG TERM....BT
MARINE.......DG


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