Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 241915
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
315 PM EDT SUN APR 24 2016

.DISCUSSION...

A STRONGLY CONFLUENT MID LEVEL FLOW IS IN PLACE ACROSS THE GREAT
LAKES REGION TO THE SOUTH OF A HUDSON BAY POLAR LOW. MEANWHILE...
SATELLITE DATA INDICATES AN INFLUX OF LOW-MID LEVEL MOISTURE INTO
THE UPPER MS VALLEY/WRN GREAT LAKES IN ADVANCE OF A CLOSED MID LEVEL
LOW NOW OVER THE NRN HIGH PLAINS. THE ASSOC SFC LOW OVER SD HAS A
QUASI STATIONARY FRONT EXTENDING INTO NRN LOWER MI. THERE IS A
NOTABLE THERMAL GRADIENT ALONG THIS FRONT AS SOUTHERLY FLOW ADVECTS
VERY MILD AIR ACROSS THE WARM SECTOR...WHILE THE CIRCULATION AROUND
THE CENTRAL CANADA SFC HIGH IS MAINTAINING COLD CONDITIONS TO THE
NORTH. THE INFLUX OF HIGHER THETA E AIR INTO THE WESTERN GREAT LAKES
HAS RESULTED IN SOME SHOWERS MOVING INTO CNTL MI THIS AFTERNOON.
THE UPPER LOW ACROSS THE PLAINS WILL BE FORCED EASTWARD TONIGHT.
THERE IS ALSO ONGOING STRENGTHENING OF AN UPPER JET MAX TO THE
NORTHEAST OF LOWER MI. THESE TWO FACTORS WILL SUPPORT INCREASING
FRONTOGENESIS IN THE MID LEVELS ALONG/NORTH OF THE SFC FRONT THIS
EVENING INTO THE OVERNIGHT. THE FORCING WILL LARGELY REMAIN FOCUSED
ACROSS NRN LOWER MI. CONTINUED MID LEVEL THETA E ADVECTION DURING
THE COURSE OF THE NIGHT AND THE CLOSER PROXIMITY TO THE MID LEVEL
FGEN CONTINUES TO SUPPORT A GOOD CHANCE OF SHOWERS ACROSS THE
SAGINAW VALLEY/THUMB THIS EVENING AND TONIGHT. FARTHER
SOUTH...INCREASING MID LEVEL CLOUDS WITH ISOLATED LIGHT
SHOWERS/SPRINKLES IS ALL THAT IS EXPECTED.

CONTINUED AGREEMENT IS SHOWN AMONG THE MID LEVEL MODEL SUITE THAT
THE CLOSED MID LEVEL LOW NOW OVER THE PLAINS WILL RAPIDLY
DAMPEN/SHEAR APART AS IT ENTERS THE CONFLUENCE ACROSS THE GREAT
LAKES. THE REMNANT WAVE IS FORECAST TO TRAVERSE LOWER MI LATE MON
NIGHT/TUES MORNING...WITH THE ASSOCIATED SURFACE LOW TRACKING ALONG
THE QUASI STATIONARY FRONT OVER SRN LOWER MI LATE MON NIGHT.
THERE IS STILL SOME DISAGREEMENT AMONG MODEL SOLUTIONS AS TO
PLACEMENT OF THE SFC FRONT ON MONDAY. THE EASTWARD ADVANCEMENT OF
THE UPSTREAM UPPER LOW IS SHOWN TO INVOKE SOME SHORT WAVE RIDGING
DOWNSTREAM ACROSS LOWER MI LATE TONIGHT INTO EARLY MON AFTERNOON.
MODEL SOUNDINGS SUGGEST THIS WILL DEVELOP A MID LEVEL CAPPING
INVERSION AND SUPPRESS PRECIP THROUGH THE FIRST HALF OF THE DAY.
THIS WILL SUPPORT A WELL MIXED FLOW IN THE WARM SECTOR AND WILL
LIKELY HOLD THE FRONT UP NEAR LAKE HURON THROUGH EARLY MON
AFTERNOON. WELL MIXED CONDITIONS SOUTH OF THE FRONT WITH 925MB TEMPS
FORECAST TO PUSH +19C WILL SUPPORT HIGHS WELL INTO THE 70S. TEMPS ON
THE COLD SIDE OF THE FRONT /WHERE THE AIR WILL HAVE LAKE HURON
MODIFICATION/ WILL BE IN THE 40S AND 50S. THIS FRONT IS FORECAST TO
NUDGE SOUTHWARD ACROSS THE SAGINAW VALLEY/THUMB LATE MONDAY...WHICH
WOULD RESULT IN A SUBSTANTIAL LATE DAY DROP IN TEMPS IN THESE
LOCALS.

MODEL SOUNDINGS CONTINUE TO SUGGEST MODEST DAYTIME DESTABILIZATION
WILL LEAD TO SB CAPE APPROACHING 1K J/KG. SOME SEMBLANCE OF A CAP
SHOULD HOLD OFF ON CONVECTIVE INITIATION UNTIL LATE IN THE DAY WHEN
MID LEVEL HEIGHT FALLS BEGIN TO OVERSPREAD THE REGION FROM THE WEST.
THE APPROACH OF THE UPPER WAVE AND ENHANCED LOW LEVEL CONVERGENCE
ASSOCIATED WITH THE SFC LOW WILL SUPPORT BETTER CHANCES FOR
CONVECTION MON NIGHT. ADVECTION OF HIGHER LOW LEVEL MOISTURE MON
NIGHT WITH RELATIVELY STEEP MID LEVEL LAPSE RATES WILL SUSTAIN A
GOOD DEAL OF ELEVATED INSTABILITY /SHOWALTER OF -2 TO -4 C/ MON
NIGHT. THIS INSTABILITY COMBINED WITH 0-6KM SHEAR ON THE ORDER OF 25
TO 40 KNOTS SUGGESTS A CHANCE OF SOME STRONG TO SEVERE CONVECTION
LATE MON THROUGH MON NIGHT. THE PASSAGE OF THE SFC LOW TO THE EAST
TUESDAY MORNING WILL DRIVE THE COLD FRONT SOUTH OF THE STATE BY TUES
AFTERNOON. LINGERING LOW LEVEL MOISTURE UNDER A DEEPENING LOW LEVEL
INVERSION WILL LIKELY SUSTAIN AN ABUNDANCE OF LOW CLOUDS TUES WHILE
PERSISTENT NORTHEAST WINDS OFF LAKE HURON AID IN HOLDING SFC TEMPS
DOWN. THIS WILL SUPPORT FAIRLY COLD TEMPS TUES AFTERNOON/TUES NIGHT.
THE DEGREE OF LOW LEVEL MOISTURE...WITH DRYING ATOP THE MOIST LAYER
AND GOOD SHEAR WITHIN THE INVERSION ALSO SUGGESTS SOME POTENTIAL FOR
DRIZZLE DURING THE DAY TUESDAY.

HIGH PRESSURE WILL REMAIN OVER THE GREAT LAKES REGION ON WEDNESDAY
KEEPING CONDITIONS DRY AND COOL. CLOUDS BUILD INTO THE REGION ON
WEDNESDAY AFTERNOON AS THE NEXT LOW PRESSURE SYSTEM APPROACHES FROM
THE WEST. WHILE THE CENTER OF THIS LOW WILL REMAIN SOUTH OF THE OHIO
BORDER...RAIN SHOWERS ARE EXPECTED ACROSS SOUTHEAST MICHIGAN ON
THURSDAY. AN ISOLATED THUNDERSTORM IS ALSO POSSIBLE ACROSS THE
SOUTHERN CWA ON THURSDAY AFTERNOON AS BETTER INSTABILITY WORKS INTO
THE AREA. STRONG HIGH PRESSURE BUILDS SOUTHWARD OUT OF NORTHERN
CANADA ON FRIDAY AND REMAINS SITUATED OVER THE REGION FOR THE FIRST
HALF OF NEXT WEEKEND.

&&

.MARINE...

A FRONT WILL SETTLE OVER LAKE HURON ON MONDAY LEADING TO FRESH EAST
NORTHEAST WINDS OVER THE NORTHERN BASIN AND MODERATE SOUTHEAST WINDS
TO THE SOUTH IN ADDITION TO A WIDESPREAD CHANCE OF THUNDERSTORMS.
FRESH NE WIND WILL THEN FILL IN ACROSS ALL AREA WATERS LATE MONDAY
AFTERNOON INTO TUESDAY. SMALL CRAFT ADVISORIES MAY BE NEEDED FOR THE
NEARSHORE WATERS OF LAKE HURON FOR WINDS AS WELL AS WAVES DUE TO
PERSISTENT ONSHORE FLOW DURING THIS TIME. THERE IS A SMALL CHANCE
THAT WIND GUSTS MONDAY NIGHT INTO TUESDAY MORNING MAY REACH GALE
FORCE. CONFIDENCE THAT TIMING OF ANY GALES WILL REACH THREE HOURS IS
LOW...SO A GALE WATCH WILL NOT BE ISSUED ATTM. HIGH PRESSURE WILL
BRING DIMINISHING WINDS THROUGH MIDWEEK.

&&

.HYDROLOGY...

LOW PRESSURE AND ATTENDANT COLD FRONT WILL MOVE THROUGH SOUTHEAST
MICHIGAN MONDAY THROUGH MONDAY NIGHT. SHOWERS AND EMBEDDED
THUNDERSTORMS ARE CURRENTLY FORECAST TO PRODUCE AROUND ONE HALF TO
THREE QUARTERS OF AN INCH OF RAIN MONDAY THROUGH TUESDAY MORNING.
THE BULK OF THE RAIN IS FORECAST BETWEEN 00-06Z MONDAY NIGHT.
THUNDERSTORMS WILL POTENTIALLY PRODUCE LOCALLY HIGHER AMOUNTS.

&&

.AVIATION...ISSUED 1208 PM EDT SUN APR 24 2016

DRY AIR WILL SUPPORT PRECIPITATION-FREE AND VFR CONDITIONS THROUGH
MOST OR ALL OF THE TAF PERIOD. THE LONE EXCEPTION WILL BE KMBS WHICH
WILL RESIDE ON THE SOUTHERN FRINGE OF BETTER FORCING BY LATE
TONIGHT. LIGHT SE WIND WILL BACK TO EASTERLY OVERNIGHT BUT A WEAK
PRESSURE GRADIENT MAY ALLOW FOR VARIABLE WIND AT TIMES.

FOR DTW...A STRAY SHOWER OR TWO COULD MOVE THROUGH THE AREA AFTER
ABOUT 21Z MONDAY BUT SUSPECT CAPPING WILL LIMIT BOTH COVERAGE AND
INTENSITY UNTIL LATER MONDAY EVENING OR MONDAY NIGHT.

//DTW THRESHOLD PROBABILITIES...

* LOW THAT T-STORMS WILL IMPACT KDTW AIRSPACE MONDAY AFTN.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
&&

$$

DISCUSSION...SC/RK
MARINE.......JVC
HYDROLOGY....JVC
AVIATION.....JVC


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



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