Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 251726
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
126 PM EDT MON APR 25 2016


.AVIATION...

CLOUDS ARE THICKENING AND CIGS ARE LOWERING THROUGH THE AFTERNOON AS
MOISTURE CONTINUES TO STREAM INTO THE REGION BEHIND A WARM FRONT AND
AHEAD OF THE APPROACHING LOW PRESSURE SYSTEM. THE INITIAL SURGE OF
MOISTURE WILL OCCUR BETWEEN 20Z-00Z WHICH MAY IGNITE A FEW SHOWERS
BUT MODELS HAVE CONTINUED TO SUGGEST COVERAGE/CONFIDENCE OF THESE
SHOWERS IS LOW ENOUGH TO EXCLUDE FROM THE TAFS. BETTER CHANCE OF
SHOWERS AND THUNDERSTORMS WILL COME AFTER 02Z WHEN THE COLD FRONT
BEGINS TO SWING THROUGH LOWER MICHIGAN. WILL CONTINUE TO HIGHLIGHT
THE 02Z-07Z WITH THE BEST CHANCE OF SEEING THUNDERSTORMS. IN THE
WAKE OF THE SYSTEM...CIGS AND VSBYS WILL DROP TO MVFR AND POSSIBLY
IFR FOR A PERIOD. MAY SEE SOME DRIZZLE EARLY TUESDAY BEFORE DRIER
AIR WORKS BACK INTO THE AREA.

FOR DTW...WARM FRONT SLOWLY APPROACHING FROM THE SOUTHWEST WHICH HAS
KEPT SOUTHEASTERLY FLOW AND DRIER AIR IN PLACE. THIS HAS KEPT CIGS
ABOVE 5KFT THUS FAR TODAY AND WILL CONTINUE FOR THE NEXT SEVERAL
HOURS. WINDS WILL SHIFT TO SOUTHWESTERLY ONCE THE FRONT LIFTS NORTH
AROUND 19Z-20Z. FORCING ALONG THE WARM FRONT MAY BE ENOUGH TO SPARK
A COUPLE SHOWERS BUT CHANCES ARE TOO LOW TO INCLUDE IN THE TAF AT
THIS TIME. BEST CHANCE WILL COME BETWEEN 03Z-07Z AS THE TRAILING
COLD FRONT SWEEPS THROUGH.

//DTW THRESHOLD PROBABILITIES...

* LOW IN THUNDERSTORMS AFFECTING TERMINAL THIS EVENING.

* MEDIUM IN CEILINGS BELOW 5000 FEET AFTER 06Z TUESDAY.

&&

.PREV DISCUSSION...ISSUED 336 AM EDT MON APR 25 2016

DISCUSSION...

SURFACE AND UPPER LEVEL LOWS CURRENTLY OUT OVER SOUTHERN SD/MN WILL
CONTINUE TO PUSH EAST TODAY BRINGING UNSETTLED WEATHER TO THE GREAT
LAKES REGION.  A BOUNDARY ASSOCIATED WITH THIS LOW HAS BEEN SITUATED
OVER CENTRAL LOWER MICHIGAN AND WILL CONTINUE TO HOLD OVER THE AREA
TODAY.  WHILE SOUTHERLY WINDS OVER THE SOUTHERN TWO THIRDS OF THE
CWA WILL BRING IN WARMER AIR...LOCATIONS ALONG THE LAKE HURON
SHORELINE WILL REMAIN EASTERLY NORTH OF THE BOUNDARY KEEPING TEMPS
ON THE COOLER SIDE.  SHOWER ACTIVITY WILL REMAIN CONFINED TO THE
THUMB REGION THIS MORNING WHILE THE REST OF THE AREA REMAINS DRY
UNTIL LATER THIS AFTERNOON.  LATEST MODEL RUNS HAVE SLOWED THE
ARRIVAL OF THE LOW WITH THE MAIN WINDOW FOR THUNDERSTORM ACTIVITY
CURRENTLY LOOKING TO BE CONFINED TO THE OVERNIGHT PERIOD.  SOME
MODELS ARE ALSO SHOWING THE POTENTIAL FOR SOME DEVELOPMENT OUT AHEAD
OF THE MAIN ACTIVITY BETWEEN 21Z AND OOZ FOLLOWED BY A SHORT BREAK
BEFORE THE POTENTIAL FOR MORE THUNDERSTORM ACTIVITY KICKS IN AROUND
06Z-09Z.  MOST OF THE DAY LOOKS TO STAY FAIRLY CAPPED BEFORE THE
BETTER INSTABILITY AND FORCING TRIES TO WORK IN.  THE LOW WILL MOVE
EAST AND IS EXPECTED TO WEAKEN AS IT MOVES ACROSS LOWER MICHIGAN
RIDING ALONG THE BOUNDARY THAT HAS BEEN IN PLACE.  MODEST MID LEVEL
LAPSE RATES AND INSTABILITY ALONG WITH THE WIND FIELD WILL AID IN
THE DEVELOPMENT OF THUNDERSTORMS OVERNIGHT. SPC DAY 1 OUTLOOK
CONTINUES TO HAVE LOCATIONS SOUTH OF I-69 IN MARGINAL RISK FOR
DAMAGING WINDS AND HAIL. CONCERN WITH SEVERE POTENTIAL LAYS IN THE
TIMING OF THE FORCING AND INSTABILITY ESPECIALLY WITH THE SLOWER
ONSET WITH THE LATEST MODELS. LOW TEMPS TONIGHT SHOULD STAY RATHER
MILD WITH THE SOUTHERLY FLOW AND LATER ONSET OF THE COLD FRONT.

LINGERING SHOWERS WILL HANG AROUND EARLY TUESDAY AS THE LOW EXITS
THE REGION TO THE EAST.  UPPER LEVEL RIDGING AND SURFACE HIGH
PRESSURE BUILDING IN FROM THE NORTH TAKE OVER LATER TUESDAY HOLDING
THROUGH AT LEAST WEDNESDAY NIGHT.  THIS WILL BRING A SHORT PERIOD OF
DRIER CONDTIONS TO SE MI BEFORE ANOTHER LOW LOOKS TO ENCROACH ON THE
AREA FOR THURSDAY.  BY THE END OF THE WEEK...DRIER WEATHER IS
EXPECTED ONCE AGAIN BEFORE THE END OF THE WEEKEND BECOMES ACTIVE
AGAIN.

MARINE...

A FRONT WILL SETTLE SOUTHWARD ACROSS LAKE HURON TODAY...LEADING TO
FRESH EAST TO NORTHEAST WINDS OVER THE NORTHERN BASIN AND MODERATE
SOUTHEAST WINDS TO THE SOUTH. SHOWERS WILL BE PREVALENT IN THE
VICINITY OF THIS BOUNDARY WITH A CHANCE OF THUNDERSTORMS LATER IN
THE DAY.

FRESH NORTHEAST FLOW WILL THEN SETTLE IN ACROSS ALL AREA WATERS
THIS EVENING INTO TUESDAY. SMALL CRAFT ADVISORIES WILL REMAIN IN
PLACE FOR THE NEARSHORE WATERS OF LAKE HURON AS THE PERSISTENT
ONSHORE FLOW LEADS TO BUILDING WAVES LATE TODAY WHICH WILL PERSIST
INTO TUESDAY. THERE IS A SMALL CHANCE THAT WIND GUSTS TONIGHT INTO
TUESDAY MORNING MAY APPROACH GALE FORCE. HOWEVER...THE MARGINAL
NATURE OF THIS EVENT PRECLUDES A GALE WARNING. HIGH PRESSURE WILL
THEN BRING DIMINISHING WINDS THROUGH MIDWEEK.

HYDROLOGY...

LOW PRESSURE AND AN ATTENDING COLD FRONT WILL MOVE THROUGH SOUTHEAST
MICHIGAN LATE TODAY INTO TONIGHT WITH NUMEROUS SHOWERS AND EMBEDDED
THUNDERSTORMS BECOMING INCREASINGLY LIKELY FROM LATE AFTERNOON INTO
THE EVENING HOURS. WHILE WIDESPREAD BASIN AVERAGE RAINFALL WILL
HOVER AROUND ONE QUARTER OF AN INCH...LOCALIZED RAINFALL AMOUNTS OF
ONE HALF TO THREE QUARTERS OF AN INCH WILL BE POSSIBLE FROM LATE
TODAY INTO EARLY TUESDAY MORNING. THE BULK OF THE RAIN IS FORECAST
BETWEEN 00-06Z TONIGHT WHEN THUNDERSTORMS WILL BE MOST LIKELY.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 10 PM EDT TUESDAY
     FOR LHZ421-441>443.

     SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 10 PM EDT TUESDAY
     FOR LHZ422.

LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
&&

$$

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


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



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