Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 010400
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1200 AM EDT WED APR 1 2015


.AVIATION...

AREA OF MID CLOUD /5 TO 8K FT/ ASSOCIATED WITH WEAK LOW PRESSURE
WILL TRANSLATE ACROSS SOUTHEAST MICHIGAN EARLY THIS MORNING.  THIS
MOISTURE MAY GENERATE A FEW FLURRIES AT MBS/FNT/PTK...BUT NO
ACCUMULATION IS EXPECTED.   THIS CLOUD COVER AND CONTINUED LIGHT
SOUTHWEST TO WEST WIND WILL LIMIT THE POTENTIAL FOR VISIBILITY
RESTRICTIONS IN SHALLOW FOG.  A LIMITED COVERAGE OF LOWER VFR
STRATOCUMULUS FOR WEDNESDAY AS AN INCREASINGLY DRY/STABLE
ENVIRONMENT TAKES HOLD UNDER BUILDING HIGH PRESSURE.

FOR DTW...TERMINAL WILL RESIDE WITHIN THE SOUTHERN PERIPHERY OF THE
INBOUND CLOUD DECK EARLY THIS MORNING.  A BRIEF PERIOD OF CEILING IN
THE VICINITY OF 5000 FT WILL BE POSSIBLE.

//DTW THRESHOLD PROBABILITIES...

* LOW FOR CEILING AOB 5000 FEET THROUGH WEDNESDAY MORNING.

&&

.PREV DISCUSSION...ISSUED 323 PM EDT TUE MAR 31 2015

SHORT TERM... THROUGH TONIGHT

REMAINING RAIN AND SNOW FROM THIS MORNING HAS SINCE PUSHED OFF TO
THE EAST LEAVING BEHIND PERSISTENT CLOUD COVER OVER THE ENTIRE CWA.
THESE PERSISTENT CLOUDS HAVE JUST FINALLY BEGUN TO DIMINISH THIS
AFTERNOON WITH NORTHERN AREAS SEEING THE DIMINISHING TREND ALREADY.
AN AREA OF VORTICITY WILL BE IN THE PROCESS OF SHEARING OUT AND
MOVING OFF TO THE EAST BY THE TIME THE NEXT WEAK WAVE APPROACHES THE
NORTHERN CWA OVERNIGHT.  THIS WAVE IS MUCH LIKE THE WAVE THIS
MORNING THAT BROUGHT SNOW TO PARTS OF THE CWA...HOWEVER ONE BIG
DIFFERENCE IS THE AMOUNT OF MOISTURE.  THE LACK OF MOISTURE WITH THE
OVERNIGHT WAVE WILL ALLOW FOR THE CONTINUATION OF LOW CHANCE POPS
ALREADY OUTLINED IN THE GRIDS.  THE ONLY CHANGE WILL BE TO TIGHTEN
UP THE WINDOW OF TIME THAT ANY PRECIP WILL MOST LIKELY FALL.  12Z
MODEL RUNS HAVE COME IN SLIGHTLY DRIER...ESPECIALLY THE NAM IN
REGARDS TO PRECIP ACROSS THE NORTHERN HALF OF THE CWA.  WITH THE
SAGINAW VALLEY AND THUMB AREAS NOT WARMING UP AS MUCH AS SOUTHERN
AREAS OF SOUTHEAST MICHIGAN...ANY PRECIP IS EXPECTED TO STAY ALL
SNOW AS TEMPS DROP INTO THE MIDDLE 20S FOR THOSE AREAS.  AREAS
CLOSER TO THE OHIO BORDER ARE LOOKING AT HOVERING AROUND THE
FREEZING MARK FOR OVERNIGHT LOWS.  CLOUDS WILL LINGER AROUND THROUGH
THE OVERNIGHT HOURS AS THE NEXT ROUND CLOUDS STREAM IN FROM THE NEXT
WAVE CURRENTLY MOVING ACROSS THE NORTHERN GREAT LAKES.  ONCE THIS
WEAK AREA OF LOW PRESSURE MOVES OFF TO THE EAST WEDNESDAY
MORNING...CLOUDS FINALLY START TO SCATTER OUT AS UPPER LEVEL RIDGING
APPROACHES THE AREA.

LONG TERM...

ADVANCING STRONG MID-LEVEL RIDGE AXIS WILL STRENGTHEN SURFACE HIGH
PRESSURE OVER THE OHIO VALLEY ON WEDNESDAY, EVENTUALLY FORCING ITS
TRANSLATION TO THE EASTERN SEABOARD OVERNIGHT. RISING HEIGHTS
THROUGH THE DAY SIGNAL A REBOUNDING OF THE THERMAL FIELD
CHARACTERIZED BY H85 TEMPS REACHING 2-4C BY LATE WEDNESDAY EVENING.
DEEP LAYER SUBSIDENCE WILL FAVOR MOSTLY SUNNY SKIES ASIDE FROM
PASSING HIGH CLOUDS AND A PARTIAL COVERAGE OF DIURNAL STRATOCU.
RESPECTABLE INSOLATION WILL, HOWEVER, BE OFFSET BY AN AUGMENTATION OF
THE SURFACE PRESSURE FIELD BY THE GREAT LAKES THAT WILL HELP SUSTAIN
AN EASTERLY COMPONENT TO THE FLOW THROUGH THE DAY. EXPECT THE
GRADIENT IN HIGH TEMPERATURES TO RANGE FROM MID 40S IN THE THUMB AND
LAKE SHADOWED AREAS TO MID 50S ELSEWHERE...PERHAPS EVEN APPROACHING
60 IN WASHTENAW/LENAWEE COUNTIES.

DEEP LAYER SOUTHERLY FLOW WILL ORGANIZE AND STRENGTHEN THROUGH
WEDNESDAY NIGHT AS HEIGHT FALLS ASSOCIATED WITH THE UPPER LOW
CURRENTLY OFF THE PACNW COAST SPREAD ACROSS THE FRONT RANGE.
TEMPERATURES OFF THE DECK WILL CONTINUE TO RISE OVERNIGHT AS H85
TEMPERATURES RISE TO 10C BY THURSDAY MORNING. VEERING LOW-LEVEL FLOW
FROM SE TO SOUTH WILL ALLOW TEMPERATURES TO RISE ACROSS AT LEAST THE
WESTERN CWA DURING THE LATTER HALF OF THE NIGHT. HOWEVER, CONTINUED
LAKE SHADOWING WILL SUPPRESS WARMING IN THE DETROIT METRO AREA AND
THE THUMB. ONCE AGAIN EXPECTING A NOTICEABLE GRADIENT RANGING FROM
LOWS AROUND 45 CLOSER TO CENTRAL LOWER MICHIGAN AND UPPER 30S EAST.

FURTHERMORE, THE LOCAL STRENGTHENING OF THE INVERSION AND LIGHT
MOISTURE TRANSPORT OFF OF THE LAKES INTRODUCE THE PROSPECT FOR LOW
CLOUDS TO SPREAD INTO THE EASTERN CWA WEDNESDAY EVENING INTO
WEDNESDAY NIGHT.

STRENGTHENING WARM FRONT IS FORECAST TO BE POSITIONED OVER CENTRAL
ONTARIO BY THURSDAY MORNING, PLACING SOUTHEAST MICHIGAN FIRMLY IN
THE WARM SECTOR WITH A FULL DAY OF WARM ADVECTION AND DEEP SW FLOW
EXPECTED. CONVECTIVE REMNANTS/DEBRIS ASSOCIATED WITH THE PREVIOUS
UPSTREAM CONVECTIVE CYCLE SIGNIFICANTLY INCREASE UNCERTAINTY WITH
REGARD TO FORECASTING THE EXACT NATURE OF THE THERMODYNAMIC PROFILE
ON THURSDAY. HOWEVER, WAA SHOULD BE SUFFICIENT TO FORCE HIGHS INTO
AT LEAST THE MID/UPPER 60S WHILE A RELATIVELY WELL-MIXED SCENARIO
TRANSPORT THE GRADUALLY INCREASING ELEVATED WIND FIELD TO THE
SURFACE, WHICH SUPPORTS THE INHERITED FORECAST FOR GUSTS OF 25 TO 30
KNOTS THURSDAY. THE NATURE OF PREFRONTAL CONVECTION THURS AFTERNOON
IS NOT EASILY DIAGNOSED AT THIS LEAD TIME. HOWEVER, INCREASING
HEIGHT FALLS AND MID-LEVEL FORCING WILL BE SUPERIMPOSED ON AN
ENVIRONMENT THAT WILL FEATURE STEEPENING LAPSE RATES THROUGH THE
DAY. A ROUND OF SCATTERED SHOWERS OR THUNDERSTORMS IS CERTAINLY IN
THE OFFING FOR THURSDAY AFTERNOON BEFORE COLD FROPA USHERS IN COOLER
AIR OVERNIGHT.

THE EXTENDED PERIOD LOOKS TO START OFF ACTIVE AS A LOW PRESSURE
SYSTEM MOVES NORTHWARD INTO THE GREAT LAKES REGION. THE BEST CHANCE
FOR PRECIP ON FRIDAY WILL BE IN THE SOUTHERN PART OF THE CWA WITH A
BETTER CHANCE OF RAIN IN THE NORTH ON FRIDAY NIGHT. TEMPERATURES ARE
EXPECTED TO DROP INTO THE MID 30S ON FRIDAY NIGHT WHICH COULD ALLOW
SOME WET SNOWFLAKES TO MIX IN WITH THE RAIN. UNCERTAINTY IN THE
TIMING AND TRACK OF THIS SYSTEM IS QUITE LOW AND THEREFORE...HAVE
ONLY INCLUDED CHANCE POPS IN THE FORECAST FOR NOW. DRY CONDITIONS
ARE FORECASTED FOR SATURDAY AS HIGH PRESSURE TRIES TO NUDGE ITS WAY
INTO THE GREAT LAKES REGION. PRECIP RETURNS ON SUNDAY AS THE NEXT
SYSTEM TRACKS ACROSS THE AREA. AGAIN MODELS ARE IN DISAGREEMENT AND
PRECIP TYPE AND TIMING IS UNCERTAIN. HAVE PUT IN A RAIN SNOW MIX FOR
EARLY SUNDAY MORNING BEFORE CHANGING INTO ALL RAIN FOR SUNDAY
AFTERNOON BEFORE CHANGING BACK TO A RAIN AND SNOW MIX FOR SUNDAY
NIGHT AND MONDAY.

MARINE...

HIGH PRESSURE IN PLACE TONIGHT AND WEDNESDAY WILL PROVIDE LIGHT
WINDS AND LOW WAVES. SOUTHERLY WINDS WILL INCREASE WEDNESDAY NIGHT
AHEAD OF A COLD FRONT...WHICH IS EXPECTED TO MOVE THROUGH LATE
THURSDAY. WARM SOUTHERLY FLOW WILL INCREASE TO 20 TO 25 KNOTS DURING
THE DAY THURSDAY BUT STABILITY WILL LIMIT WIND GUST POTENTIAL.

&&

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

$$

AVIATION.....MR
SHORT TERM...SS
LONG TERM....JVC/RK
MARINE.......JVC


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AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).


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