Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 231921
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
321 PM EDT MON MAR 23 2015

.SHORT TERM...TONIGHT

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 INVERION 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 RESISTENCE 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. HEIGHS 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.
&&

$$

SHORT TERM...SF
LONG TERM....JVC/SS
MARINE.......JVC


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



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