Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 241103 CCA
AFDDTX

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
703 AM EDT TUE MAR 24 2015


.AVIATION...

HIGH PRESSURE WILL REMAIN ANCHORED ACROSS THE EASTERN GREAT LAKES
TODAY AND WILL SUSTAIN MAINLY CLEAR SKIES AND LIGHT WINDS THROUGH
THIS EVENING. A FAST MOVING LOW PRESSURE SYSTEM WILL THEN MOVE INTO
REGION OVERNIGHT. THIS SYSTEM WILL BRING A BRIEF PERIOD OF FREEZING
RAIN AT THE ONSET BEFORE SFC TEMPS WARM ABOVE FREEZING AND PRECIP
TRANSITIONS TOWARD ALL RAIN.

FOR DTW...BASED ON THE LATEST MODEL PROJECTIONS...THE START TIME OF
PRECIP LOOKS TO BE BETWEEN 08Z AND 10Z WED MORNING. SFC TEMPS ARE
FORECAST TO HOVER BETWEEN 30 AND 32 DEGREES BEFORE WARMING ABOVE
FREEZING IN THE 10 TO 12Z TIME FRAME.

//DTW THRESHOLD PROBABILITIES...

* HIGH FOR CEILING BELOW 5000 FEET LATE TONIGHT.

* MEDIUM FOR RAIN MIXED WITH FREEZING RAIN LATE TONIGHT.

&&

.PREV DISCUSSION...ISSUED 337 AM EDT TUE MAR 24 2015

SHORT TERM...TODAY AND TONIGHT

A MID LEVEL RIDGE NOW LOCATED ACROSS THE UPPER MIDWEST WILL
TRAVERSE LOWER MI THIS AFTERNOON AND EVENING WITHIN AN OVERALL
PROGRESSIVE LARGE SCALE PATTERN. THIS WILL CAUSE THE SURFACE HIGH
NOW EXTENDING FROM LOWER MI TO SRN QUEBEC TO SLOWLY RETREAT TO
THE EAST DURING THE DAY. THE PLACEMENT OF THE SFC RIDGE WILL
MAINTAIN A LIGHT EASTERLY FLOW ACROSS THE FORECAST AREA TODAY INTO
TONIGHT. STRONG MID LEVEL SUBSIDENCE TODAY COMBINED WITH THE
EASTERLY FLOW OFF THE GREAT LAKES WILL LIMIT MIXING POTENTIAL.
LATE MARCH SUN DOES HOWEVER WARRANT FORECAST MAX TEMPS ON THE
HIGH END OF GUIDANCE TODAY /NEAR 40 INLAND TO 30S ALONG THE
LAKESHORES/.

MID LEVEL SHORT WAVE ENERGY NOW SEEN ADVANCING ACROSS THE COLORADO
ROCKIES IS FORECAST TO AMPLIFY AS IT RACES ACROSS THE CNTL PLAINS
TODAY AND TAKE ON A NEGATIVE TILT AS IT TRACK INTO SRN LOWER MI
TOWARD DAYBREAK WED. THIS WILL RESULT IN DEEPENING SFC LOW PRESSURE
TRACKING FROM THE MID MS VALLEY THIS EVENING INTO SRN LAKE MI LATE
TONIGHT. THE WATER VAPOR LOOP ALREADY SHOWS A PLUME OF DEEP MOISTURE
LIFTING INTO THE CNTL PLAINS AHEAD OF THE MID LEVEL WAVE.
STRENGTHENING LOW LEVEL SW FLOW /50-60 KTS/...WILL TRANSPORT THIS
MOISTURE INTO SE MI OVERNIGHT. MODEL SOUNDINGS SHOW PRECIP WATER
RISING TOWARD 0.9 INCH LATE TONIGHT...WITH 850MB DEWPOINTS RISING
TOWARD +5C. THE MOISTURE WILL BE TRANSPORTED NORTHWARD UNDER
STRONGLY FORCED ISENTROPIC ASCENT TIED TO SOME RATHER GOOD UPPER
DIVERGENCE WITHIN THE LEFT EXIT REGION OF AN UPPER JET MAX. A PUSH
OF GOOD DCVA/MID LEVEL HEIGHT FALLS ASSOCIATED WITH THE UPPER WAVE
ITSELF WILL ALSO AID LARGE SCALE ASCENT. THESE FACTORS WILL LEAD TO
WIDESPREAD PRECIPITATION ADVANCING INTO SE MI AFTER 06Z AND
PERSISTING THROUGH 12Z. THE RAPID DEEPENING OF THE ELEVATED WARM
LAYER SUGGESTS PRECIP WILL MAINLY BE IN LIQUID FORM.

THERE WILL BE SOME OPPORTUNITY FOR RADIATIONAL COOLING TO DROP TEMPS
INTO THE 20S LATE THIS EVENING. EAST-SOUTHEAST FLOW AT THE SURFACE
WILL SUSTAIN SOME DEGREE OF SHALLOW LOW LEVEL DRY AIR. THUS...
SURFACE WET BULB TEMPS ARE LIKELY TO BE SEVERAL DEGREES BELOW
FREEZING AT THE ONSET OF PRECIP. TEMPERATURES WILL THEN WARM TOWARD
DAYBREAK AS THE SURFACE WARM FRONT QUICKLY LIFTS NORTH ACROSS THE
FORECAST AREA. THIS SHOULD RESULT IN JUST A BRIEF PERIOD /A COUPLE
HOURS/ OF FREEZING RAIN...BUT POSSIBLY ENOUGH TO LEAD TO A LIGHT
GLAZING OF ICE. WHILE TOTAL QPF PRIOR TO DAYBREAK SHOULD BE A
QUARTER INCH OR LESS...THERE WILL BE A CONVECTIVE COMPONENT AS STEEP
MID LEVEL LAPSE RATES ARE ADVECTED NORTHWARD. THIS MAY LEAD TO SOME
BRIEFLY HIGHER INTENSITY PRECIP RATES. LATER SHIFTS WILL HAVE TO
MONITOR LATEST OBSERVATIONAL AND MODEL TRENDS AS A FREEZING RAIN
ADVISORY AND THE ADDITION OF THUNDER MAY HAVE TO BE CONSIDERED.

LONG TERM...WEDNESDAY THROUGH MONDAY

LOOKS LIKE THE ROLLER COASTER THAT IS TYPICAL FOR MARCH WEATHER HAS
FINALLY ARRIVED...AT LEAST FOR A FEW DAYS. A COMPLEX MID/UPPER LEVEL
TROUGH DIGGING INTO THE GREAT LAKES FOR THE LATTER HALF OF THE WEEK
WILL CAUSE HIGHS TO FALL FROM NEAR 60 WED...TO AROUND 30 ON
FRI...AND BACK TO NEAR NORMAL BY THE START OF NEXT WEEK AS RIDGING
RETURNS. THIS MEANS PTYPE IN THE FORM OF SNOW WILL BE MENTIONED AT
TIMES AS WELL...BUT NOTHING SIGNIFICANT RIGHT NOW AS TEMPERATURE
FLUCTUATIONS LEND TO SHORT DURATIONS OF ANY LIGHT SNOW OR RAIN/SNOW
MIX.

THE START OF THE LONG TERM FEATURES THE AFOREMENTIONED MID/UPPER
LEVEL TROUGH WITH SEVERAL FEATURES OF NOTE INCLUDING PAIR OF SFC
LOWS...WARM FRONT...MID LEVEL SHORTWAVE...AND COLD FRONT. OVERALL
THE PATTERN HAS BEEN BEEN HANDLED FAIRLY WELL BY MODELS WITH A GOOD
DEGREE OF CONSISTENCY BETWEEN THEM FOR SEVERAL RUNS. MOST
ADJUSTMENTS WITH THIS PACKAGE DEAL WITH TIMING OF PRECIP AND
POTENTIAL FOR WARMING AND ELEVATED WINDS IN THE WARM SECTOR ON
WEDNESDAY...AS WELL AS COVERAGE OF PRECIP TIED TO A SECONDARY WAVE
ON THURSDAY AND TRAILING SHORTWAVE TROUGH ON FRIDAY.

FIRST OFF WE HAVE THE WARM FRONT SURGING NORTHWARD ON WEDNESDAY
LEADING TO AN IMPRESSIVE DRY SLOT PUNCHING INTO THE AREA PUTTING AN
ABRUPT END TO PRECIP IN THE AFTERNOON HOURS...LIKELY IN THE 18-21Z
TIMEFRAME. THE WELL ADVERTISED LL JET ASSOCIATED WITH THIS SYSTEM
HAS TRENDED DOWN A BIT THE LAST 2 MODEL RUNS BUT WILL STILL PRODUCE
A FAIRLY GUSTY DAY. THE NAM SUGGESTS THE STRONGEST POCKET OF WIND
WILL PASS OVERHEAD WEDNESDAY MORNING DURING THE TIME A STOUT
INVERSION WILL BE SETUP. WAA WILL BE STRONG IN THE 750-950MB LAYER
BUT WILL BE DISJOINTED FROM THE SFC DUE TO THE COLD EASTERLY FLOW
STEEPENING THE INVERSION. ONCE THE WARM SECTOR AND DEEPER MIXING
MOVE IN THE STRONG NOCTURNALLY ENHANCED JET WILL BE TO OUR NE. WE
MAY STILL SEE A GOOD POP OF WINDS AT THE ONSET OF THE DEEPER MIXED
LAYER WITH GUSTS OF 30-35 MPH...POSSIBLY UP TO 40MPH BEFORE STEADILY
DECREASING. TEMPERATURES IN THE WARM SECTOR HAVE ALSO COME DOWN A
FEW DEGREES TOPPING OFF IN THE UPPER 50S. MODEL CONSENSUS NOW HAS
THE DEEP LAYER FLOW BEHIND THE WARM FRONT MORE WESTERLY THAN SWERLY
WHICH WILL REDUCE THE DEGREE OF WAA INTO THE AREA. 850/925MB TEMPS
LOOK TO TOP OFF AROUND 6C INSTEAD OF 8C AS PREVIOUSLY ADVERTISED.

AFTER A BRIEF DRY PERIOD WITH THE DRY SLOT WEDNESDAY
AFTERNOON/EVENING...AN ADDITIONAL WAVE WILL LIFT NE TOWARD LAKE ERIE
ALONG THE COLD FRONT WORKING ACROSS THE STATE WEDNESDAY NIGHT. LOOKS
LIKE WE COULD SEE SOME ADDITIONAL RAIN ACROSS FAR SE LOWER MI BUT
THE SAGINAW VALLEY LOOKS TO STAY DRY AT THIS TIME AS THE PRECIP
SHIELD WILL NOT EXTEND THAT FAR NORTH. THIS FRONT WILL USHER IN SOME
VERY COLD AIR ALOFT WITH 850MB TEMPS AROUND -15C ON FRIDAY.
NORTHERLY FLOW AND CAA WILL HOLD TEMPS AROUND 30 FRO A HIGH. THE
COLD AIR WILL BE LOCKED OVER THE REGION TIL SUNDAY WHEN THE NEXT
RIDGE STARTS BUILDING BACK INTO THE AREA. WE WILL HOVER NEAR THE
MAIN BAROCLINIC ZONE EARLY IN THE WEEK WHICH COULD FAVOR WARMER
TEMPS...BUT ADDITIONAL COLD FRONTAL PASSAGES LOOK LIKE THEY COULD
KEEP COOLER AIR AROUND A WHILE LONGER. MORAL OF THAT
STORY...FUTURE ADJUSTMENTS APPEAR LIKELY FOR EARLY NEXT WEEK.

MARINE...

HIGH PRESSURE REMAINS OVER THE AREA TODAY WHICH WILL RESULT IN LIGHT
WINDS CONTINUING THROUGH THIS EVENING. SOUTHEASTERLY WINDS WILL
INCREASE AHEAD OF A WARM FRONT LATE TUESDAY NIGHT BUT WILL THEN
BECOME STRONG OUT OF THE SOUTHWEST ONCE THE WARM FRONT LIFTS THROUGH
THE AREA EARLY WEDNESDAY AFTERNOON. THE WARM AIR WILL ADD A DEGREE
OF STABILITY WHICH WILL LIMIT GUST POTENTIAL OVER THE COLD WATERS
BUT GUSTS TO NEAR GALE LOOK LIKELY. WINDS WILL STAY ELEVATED
..BUT BELOW 20 KNOTS...THROUGH THE END OF THE WEEK AS THEY TURN
NORTHERLY BEHIND A COLD FRONT.

PREV DISCUSSION...ISSUED 321 PM EDT MON MAR 23 2015

LEAD UPPER WAVE TRACKING THOUGH THE NORTHERN OHIO VALLEY THIS
AFTERNOON...WITH SECOND...LARGER AND COLDER (500 MB TEMP OF -29 C)
WAVE/CIRCULATION OVER NORTHERN MINNESOTA. THE LEAD WAVE WILL BE
TAKING MUCH OF THE MOISTURE AND ANY SNOW ALONG THE SOUTHERN MICHIGAN
BORDER WITH IT...AS SURFACE HIGH OVER LAKE HURON AND SUBSIDENCE
FUNNELS DRIER AIR INTO SOUTHEAST MICHIGAN...WITH 12Z NAM PROJECTING
925 MB DEW PT DEPRESSIONS INCREASING TO AROUND 25 C OVER SOUTHEAST
MICHIGAN TONIGHT. SURFACE DEW PTS HAVE ALREADY FALLEN INTO THE MID
SINGLE NUMBERS TO LOWER TEENS ACROSS THE THUMB REGION...SETTING US
UP FOR A GOOD RADIATING NIGHT IF WE CAN LOSE THE MID/HIGH CLOUDS.
THE COLD CORE CENTER OF THE SECOND UPPER WAVE WILL MOVE OVERHEAD
BETWEEN 9-11Z TUESDAY...SO LOOKS LIKE WE CLEAR OUT JUST BEFORE
SUNRISE...ENOUGH FOR GOOD SUNRISE DIP. OBVIOUSLY...THE FORECAST WILL
BE SENSITIVE TO TIMING THIS CLEARING...BUT EXPECTATIONS ARE FOR
UPPER SINGLE NUMBERS TO LOWER TEENS FOR MINS ACROSS MOST
LOCATIONS...WITH MID TO UPPER TEENS ACROSS THE FAR SOUTH WITH THE
MARGINAL REMNANT LOW LEVEL MOISTURE AND LATER CLEARING.

LONG TERM...

SURFACE HIGH PRESSURE CENTERED OVER THE NORTHER GREAT LAKES AND
MOISTURE RETURN WITHIN A LEE TROUGH IS SUSTAINING A WELL-DEFINED
BAROCLINIC ZONE OVER THE CENTRAL UNITED STATES THIS AFTERNOON. THE
ASSOCIATED TEMPERATURE GRADIENT IS IMPRESSIVE, WITH UPPER 60S TO THE
SOUTH AND 30S IMMEDIATELY NORTH.

THE AIRMASS WILL REMAIN RATHER STEADY STATE THROUGH TOMORROW AS A
STRONG SHORTWAVE RIDGE REINFORCES DOWNSTREAM HIGH PRESSURE.
INCREASING SUBSIDENCE WILL ELIMINATE CLOUD COVER CONCERNS WHILE COOL
EASTERLY FLOW PREVAILS AT THE SURFACE. A WELL-MIXED THERMAL PROFILE
AND FULL SUN FAVORS OVERACHIEVING POTENTIAL. THE OFFICIAL FORECAST
IS WARMER THAN MOST GUIDANCE AND CALLS FOR 40-45 AREA WIDE...WARMEST
ACROSS THE INTERIOR. THE EXCEPTION WILL BE WITHIN HURON/SAINT
CLAIR/ERIE LAKE SHADOWS WHERE TEMPERATURES ARE LIKELY TO REMAIN IN
THE 30S.

EASTWARD PROGRESSION OF THE RIDGE WILL GIVE WAY TO INCREASING HEIGHT
FALLS AS THE AFOREMENTIONED SURFACE FRONT LIFTS TOWARD LOWER
MICHIGAN. NOCTURNAL ENHANCEMENT OF WARM ADVECTION ABOVE THE BOUNDARY
LAYER WILL RESULT IN A STOUT INVERSION AND CONSIDERABLE WARMING
ABOVE THE SURFACE FOR THE BALANCE OF THE NIGHT. DEEP LAYER
ISENTROPIC ASCENT WILL QUICKLY RAMP UP AROUND 09Z ALLOWING A BAND
OF PRECIP TO LIFT INTO SEMI FROM THE SOUTHWEST. THE INVERSION
COMBINED WITH INITIALLY DRY CONDITIONS WILL CREATE THE POTENTIAL
FOR WET-BULBING AND A VERY BRIEF PERIOD OF SNOW-IP-FZRA BEFORE THE
TRANSITION TO ALL RAIN AS SURFACE WARMING PLAYS CATCH UP. A PERIOD
OF MODERATE RAIN RATES WILL BE POSSIBLE AS ISENTROPIC AND LARGE
SCALE ASCENT LIFT THROUGH THE AREA 9-15Z, ESPECIALLY OVER THE
SAGINAW VALLEY WHERE FORCING WILL BE GREATEST, BUT OVERALL
EXPECTING NOTHING MORE THAN A FEW HOURS OF EARLY MORNING SHOWERS.

THE UPPER-LEVEL FEATURE OF INTEREST IS MODELED TO TAKE THE PATH OF
LEAST RESISTANCE AS IT WRAPS NORTH IN RESPONSE TO DEVELOPING
UPSTREAM HEIGHT FALLS. THE OCCLUSION WILL LIFT THROUGH CENTRAL
MICHIGAN WITH COOL AIR FILLING IN BEHIND, BUT COLD ADVECTION WILL
NOT BE TERRIBLY IMPRESSIVE GIVEN THE SYSTEM`S LACK OF ACCESS TO THE
UPSTREAM COLD RESERVOIR. EVEN SO, LOSS OF THE LOW-LEVEL INVERSION AS
THE THETA-E RIDGE FOLDS EAST ALONG WITH DEVELOPING LIGHT COLD
ADVECTION WILL PROMOTE A WELL-MIXED ENVIRONMENT WITHIN WHICH
WESTERLY FLOW WILL HAVE THE POTENTIAL TO GUST TO AT LEAST 30
MPH...PERHAPS 40MPH AS AN UPPER LIMIT. RATHER LACKING ISENTROPIC
DESCENT WITHIN COLD ADVECTION AND THE LACK OF VIRTUALLY ANY SYSTEM
RELATIVE ISALLOBARIC COMPONENT REALLY LIMIT THE PROSPECTS FOR
HEADLINE CRITERIA WIND GUSTS. HAVE THEREFORE ELECTED TO FORGO A
MENTION OF POTENTIAL IN TODAY`S HWO. HIGHS WITHIN THE WELL-MIXED
POST FRONTAL ENVIRONMENT WILL ACTUALLY RISE WELL INTO THE
50S...PERHAPS TOUCHING 60 AS SUGGESTED BY A MAV/MET BLEND.

THE REGION WILL CONTINUE TO BE IN A LONGWAVE TROUGH THROUGH AT
LEAST THE BEGINNING OF THE WEEKEND.  THIS WILL ALLOW FOR PERSISTENT
BELOW NORMAL TEMPS ALONG WITH CHANCES FOR PRECIPITATION AS NORTHWEST
FLOW PREVAILS.  BETTER PRECIPITATION CHANCES IN THE EXTENDED WILL BE
ASSOCIATED WITH A RATHER WEAK WAVE MOVING UP FROM THE SOUTH AND
ACROSS THE OHIO RIVER VALLEY EARLY THURSDAY MORNING.  SOUTHERN
LOCATIONS WILL STAND THE BEST CHANCE AT SEEING PRECIP FROM THIS WAVE
BEFORE IT MOVES OFF TOWARDS THE EAST COAST LATER IN THE DAY ON
THURSDAY.  COLD AIR ADVECTION ASSUMES CONTROL OVER THE AREA ONCE
AGAIN BEHIND THE DEPARTING WAVE.  MODELS ARE SHOWING BRIEF RIDGING
BUILDING IN SUNDAY...HOWEVER ANOTHER TROUGH LOOKS TO QUICKLY REPLACE
THE RIDGE AS YET ANOTHER WAVE DROPS DOWN FROM THE NORTH SUNDAY
EVENING.

MARINE...

LIGHT WINDS WILL PERSIST THROUGH TUESDAY AS HIGH PRESSURE OVER THE
GREAT LAKES HOLDS FIRM. A FRESH TO STRONG SOUTHEAST BREEZE WILL
DEVELOP LATE TUESDAY NIGHT INTO WEDNESDAY MORNING BEFORE WINDS SHIFT
TO THE SOUTHWEST BEHIND A WEAK COLD FRONT. STRONG SUSTAINED WINDS
ARE EXPECTED OUT OF THE SOUTHWEST BUT LACK OF SIGNIFICANT COLD AIR
WILL REDUCE THE RISK OF GUSTS REACHING GALES ON WEDNESDAY AFTERNOON.
AT THIS TIME...THE FORECAST CALLS FOR GUSTS TOPPING OUT AT NEAR-
GALES.

PREV DISCUSSION...ISSUED 311 PM EDT MON MAR 23 2015

&&

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

$$

AVIATION.....SC
SHORT TERM...SC
LONG TERM....DRK
MARINE.......DRK


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



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