Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 032308
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
608 PM EST WED FEB 3 2016


.AVIATION...

LOWER CIGS WILL FILTER INTO TERMINALS...ALREADY MADE IT TO MBS...AS
SURFACE FRONT MOVES ESE THROUGH THE AREA THIS EVENING. A SEVERAL
HOUR PERIOD OF SHSNS WILL ALSO OCCUR ALONG THIS BOUNDARY...WITH
PERIODIC VSBYS OF 2-4SM POSSIBLE DURING THAT WINDOW. GUSTY SW WINDS
WILL EASE AFTER FROPA AND VEER TO WNW. MVFR TO LOWER VFR CONDITIONS
WILL THEN PERSIST INTO MUCH OF THURSDAY AS UNSETTLED...AND COLDER
WESTERLY FLOW REMAINS. ANY BREAKS IN THIS STRATUS DECK SHOULD BE
MINIMAL...AT LEAST UNTIL 00Z THURSDAY EVENING OR SO AS DIURNAL CYCLE
WANES AND LOW LEVEL FLOW BECOMES LIGHT/SSW AS SURFACE RIDING BUILDS
INTO AREA WITH PASSAGE OF MAIN UPPER LEVEL TROUGH AXIS AT THE END OF
THE FORECAST PERIOD.

FOR DTW...SURFACE FRONT WILL BRING WIND SHIFT TO AREA 03Z-04Z WITH
230 FLOW BECOME 270 OR SO. BORDERLINE MVFR/VFR CONDITIONS WILL TREND
TO SOLID MVFR AS THIS VEERING LOW LEVEL FLOW FUNNELS STRATUS DECK
EASTWARD OVER TERMINAL DURING THE EVENING INTO THE OVERNIGHT HOURS.
ANY GUSTS APPROACHING 25 KNOTS EARLY IN THE FORECAST WILL EASE
WITHIN A FEW HOURS THIS EVENING. CIGS...MORE BKN THAN OVC...CAN THEN
BE EXPECTED LATE TONIGHT INTO THURSDAY WITH MVFR MIXING TO LOWER
VFR AT TIMES.

//DTW THRESHOLD PROBABILITIES...

* HIGH IN CEILINGS BELOW 5000 FT THROUGH 21Z THURSDAY...MEDIUM 21Z
  TO 01Z.

&&

.PREV DISCUSSION...ISSUED 309 PM EST WED FEB 3 2016

DISCUSSION...

WEAK DEEP COLUMN COOLING UNDERWAY LOCALLY...SE MICHIGAN STILL
HOLDING WITHIN A WELL MIXED SOUTHWESTERLY GRADIENT JUST DOWNSTREAM
OF THE MAIN HEIGHT FALL GRADIENT NOW LIFTING OUT OF LAKE MICHIGAN.
SOLID GUST COMPONENT PEAKING MID AFTERNOON ALONG THE LEAD
EDGE OF THE INBOUND DEEPER MOISTURE PLUME...WINDOW FOR GUST
POTENTIAL WITHIN THE 40 TO 45 MPH RANGE ALONG FAR EASTERN SECTIONS
/PORT HURON TO MONROE/ CLOSING QUICKLY OVER THE NEXT 1-2 HOURS AS A
THICKENING STRATUS DECK CUTS INTO THE MIXING QUALITY.  OTHERWISE...
STRONG CVA TIED TO THIS MID LEVEL FEATURE WILL TEND TO SHEAR
NORTHEAST OF THE AREA...BUT WILL PROVIDE A MORE CONSOLIDATED BUT
BRIEF PERIOD OF COLD AIR ADVECTION WITH THE PASSAGE OF AN ATTENDANT
LOW LEVEL FRONT BY THIS EVENING.  OVERLAKE THERMODYNAMIC PROFILE
WILL REMAIN MODEST /CONVECTIVE DEPTH HOLDING BELOW 7K FT/...
SUGGESTING THE OVERALL DOWNSTREAM RESPONSE WILL REMAIN SOMEWHAT
MUTED.  WITH THAT SAID...IMPROVING SYNOPTIC MOISTURE DEPTH
CORRELATING WITH RENEWED/STRENGTHENING COLD AIR ADVECTION WITHIN THE
ENCROACHING MEAN TROUGH AND FRONTAL PASSAGE EARLY TONIGHT MAY SUPPORT
A PERIOD OF LIGHT SNOW SHOWER ACTIVITY.  A LOWER END PRECIPITATION
MENTION WITH LITTLE TO NO ACCUMULATION REMAINS APPROPRIATE FOR
TONIGHT.

EXTENSIVE LOW CLOUD IN PLACE THROUGH THURSDAY WITH LOW LEVEL THERMAL
TROUGHING FIRMLY ENTRENCHED.  THE COOLER RESIDENT AIR MASS STILL
ARRIVES IN THE VICINITY OF EARLY FEBRUARY NORMS...READINGS WITHIN
THE LOWER AND MIDDLE 30S RANGE.  THE COMBINATION OF A STEEPENING
LAPSE RATE ENVIRONMENT AND A PORTION OF THE LINGERING SUFFICIENTLY
DEEP MOIST LAYER AT/BELOW THE -12C ISOTHERM WILL ALLOW FOR SOME
FLURRIES.  RAPID REDUCTION IN INVERSION HEIGHTS AND CORRESPONDING
MOISTURE DEPTH TOWARD EVENING AS WEAK WARM AIR ADVECTION ENSUES
UNDER BACKING LOW LEVEL FLOW.  THIS PROCESS WILL WORK TOWARD
REDUCING THE COVERAGE OF STRATUS INTO THE OVERNIGHT PERIOD.  THIS
WILL LEAD IN A RELATIVELY BENIGN PERIOD ON FRIDAY...MARKED BY WEAK
LOW-MID LEVEL RIDGING WITHIN THE EXISTING WEST-SOUTHWEST FLOW.
GRADUAL/MODEST WARMING THROUGH THE LOWEST 5 KFT UNDER A GENERAL
INCREASE IN UPPER HEIGHTS WILL NUDGE DAYTIME TEMPERATURES UP SEVERAL
DEGREES FROM READINGS NOTED THURSDAY...HIGHS MID-UPPER 30S.

A RIDGE OF HIGH PRESSURE WILL DOMINATE THE SOUTHERN GREAT LAKES
WHILE A WEAK LOW PRESSURE TRACKS ACROSS THE NORTHERN GREAT LAKES ON
SATURDAY...BRINGING SOME SNOW SHOWERS TO THE NORTHERN THUMB AND
SAGINAW VALLEY REGIONS. LITTLE TO NO ACCUMULATION IS EXPECTED AT
THIS TIME. HIGH PRESSURE BUILDS BACK INTO THE REGION FOR SUNDAY
BEFORE THE NEXT LOW PRESSURE SYSTEM MOVES IN ON SUNDAY NIGHT.
THIS SYSTEM WILL TRACK SOUTHEASTWARD OUT OF THE NORTHERN PLAINS AND
SETTLE OVER THE GREAT LAKES BY MONDAY. CURRENT MODEL RUNS ARE
INDICATING THIS SYSTEM REMAINING FAIRLY STATIONARY OVER THE GREAT
LAKES RESULTING IN A ROUND OF SNOW SHOWERS ACROSS SOUTHEAST MICHIGAN
FROM MONDAY THROUGH TUESDAY. ACCUMULATIONS ARE HINTING AT ONLY A FEW
TENTHS...BUT IT IS TOO EARLY TO DETERMINE EXACT AMOUNTS AT THIS
TIME.

MARINE...

STRONG WINDS WILL CONTINUE TO SPREAD ACROSS THE CENTRAL GREAT LAKES
LATE THIS AFTERNOON AND EVENING AS COLDER AIR SPILLS INTO THE AREA
BEHIND A COLD FRONT. GALE FORCE WIND GUSTS DEVELOPED OVER WESTERN
LAKE ERIE AND LAKE ST CLAIR THIS AFTERNOON...PROMPTING THE ISSUANCE
OF A GALE WARNING FOR THOSE AREAS. STRONG SOUTWEST WINDS WILL
CONTINUE TO GUST TO 35 TO 40 KNOTS THROUGH THE LATE AFTERNOON AND
EARLY EVENING BEFORE SUBSIDING.

THE STRONG WINDS WILL SPREAD NORTHWARD OVER THE NEXT SEVERAL HOURS
AS LOW PRESSURE NORTH OF GEORGIAN BAY TRACKS INTO QUEBEC. THE BEST
POTENTIAL FOR LONG-DURATION GALES STILL REMAINS OVER THE CENTRAL
PORTION OF LAKE HURON...INCLUDING OUTER SAGINAW BAY...WHERE A SHORT
PERIOD OF GALE FORCE WIND GUSTS ARE EXPECTED FROM THE SOUTHWEST AND
THEN WEST LATE THIS AFTERNOON THROUGH THIS EVENING. THE SOUTHERN
PORTION OF THE LAKE AND INNER SAGINAW BAY MAY SEE A FEW GUSTS NEAR
35 KNOTS...HOWEVER GIVEN THAT THE DURATION IS ONLY EXPECTED TO LAST
A FEW HOURS AND SINCE MOST OF SAGINAW BAY IS ICE COVERED...THE GALE
WARNING WILL NOT BE EXPANDED. SURFACE LOW PRESSURE NORTH OF GEORGIAN
BAY WILL LIFT NORTHEAST INTO EASTERN QUEBEC OVERNIGHT. THIS WILL
ALLOW THE SURFACE PRESSURE GRADIENT TO WEAKEN AND END THE THREAT FOR
GALE FORCE WINDS.

ALTHROUGH A FEW SMALL RIPPLES OF LOW PRESSURE WILL WORK ACROSS THE
REGION OVER THE NEXT FEW DAYS...HIGH PRESSURE WILL REMAIN THE
DOMINANT INFLUENCE OVER THE GREAT LAKES THURSDAY AND FRIDAY.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LHZ362-363-421-462.

LAKE ST CLAIR...GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LCZ460.

MICHIGAN WATERS OF LAKE ERIE...GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LEZ444.

&&

$$

AVIATION.....DG
DISCUSSION...MR/RK
MARINE.......HLO


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