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000
FXUS63 KDTX 280501
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1201 AM EST THU NOV 28 2013

.AVIATION...

//DISCUSSION...

AN AREA OF LOW PRESSURE WILL TRACK ACROSS THE LOWER MICHIGAN ON
THURSDAY.  DEEPER MOISTURE ACCOMPANYING THIS SYSTEM WILL SUPPORT AN
AREA OF LIGHT SNOWFALL ACROSS ALL TERMINALS DURING THE DAYLIGHT
PERIOD.  UPSTREAM OBSERVATIONS AND LATEST MODEL GUIDANCE INDICATE
SNOWFALL WILL ARRIVE 13Z-14Z...WITH SOME INCREASE IN INTENSITY AND
COVERAGE EXPECTED 14-18Z.  THIS WILL RESULT IN A PERIOD OF LOW
MVFR/IFR RESTRICTIONS.  LIGHT SHOWERS MAY TEND TO PERSIST INTO THE
EVENING HOURS WITHIN COLD/MOIST CYCLONIC FLOW.

FOR DTW...LIGHT SNOWFALL WILL BRING AN ACCUMULATION OF UP TO HALF AN
INCH...CENTERED ON THE 14Z-17Z TIME WINDOW.

//DTW THRESHOLD THREATS...

* HIGH CONFIDENCE IN CEILING FALLING BELOW 5000 FT LATE THURSDAY
MORNING.

* HIGH CONFIDENCE IN SNOW AS PRECIPITATION TYPE ON THURSDAY.

&&

.PREV DISCUSSION...ISSUED 356 PM EST WED NOV 27 2013

SHORT TERM...THIS AFTERNOON AND TONIGHT

THE EXETER RADAR...VISIBLE SATELLITE AND WEB CAMS ACROSS THE EXTREME
NORTHEASTERN PORTION OF HURON COUNTY NEAR LAKE HURON SHOW THE LAKE
EFFECT SNOW BAND HAS PUSHED WELL OFFSHORE...CONTRADICTORY TO THE
LOCAL HI-RES RUNS. WITH WINDS NOT EXPECTED TO TURN MORE TO THE NORTH
WILL CANCEL THE LAKE EFFECT SNOW ADVISORY ACROSS EXTREME
NORTHEASTERN HURON COUNTY FOR THE OVERNIGHT HOURS.

ACROSS THE REST OF THE CWA MOSLY CLOUDY SKIES...SCATTERED FLURRIES
AND WINDY CONDITIONS WILL EVENTUALLY GIVE WAY TO MOSTLY CLEAR SKIES
AND LIGHTER WINDS WITH THE COMBINATION OF LOSING DAYTIME HEATING AND
THE AFOREMENTIONED RIDGE EDGING EASTWARD. THE CLEARING SKIES AND
LIGHT WINDS WILL LEAD TO RAPIDLY FALLING OVERNIGHT TEMPERATURES AS
LOWS GET INTO THE MIDDLE TO UPPER TEENS. THE MAIN FACTOR PREVENTING
TEMPERATURES FROM FALLING FURTHER IS THE LACK OF SNOW COVER AND
INCREASING CLOUDS AFTER MIDNIGHT AHEAD OF AN APPROACHING LOW
PRESSURE SYSTEM.

LONG TERM...THURSDAY THROUGH NEXT WEDNESDAY

UPPER LEVEL WAVE NOW DROPPING THROUGH MANITOBA WILL CLIP ACROSS THE
GREAT LAKES TOMORROW AND TOMORROW EVENING. THIS WILL PUSH AN AREA OF
SURFACE LOW PRESSURE ACROSS CENTRAL/NORTHERN LOWER MICHIGAN AND
BRING LIGHT SNOW ACCUMULATIONS TO THE AREA FOR THE THANKSGIVING
HOLIDAY.

AS THE LOW APPROACHES...IT WILL SEND AN ELEVATED WARM FRONT
NORTHEASTWARD INTO SOUTHEAST MICHIGAN. MOISTURE LOOKS TO REMAIN
CONFINED BELOW 700MB...BUT THIS WILL BE WHERE STEEP LAPSE
RATES...FORCING...AND THE DENDRITIC GROWTH ZONE ALL RESIDE. MODELS
SHOW A COMBINATION OF ISENTROPIC ASCENT (280K) AND FGEN PROVIDING
LIFT ALONG THE FRONT TOMORROW...WHICH SHOULD BE STRONG ENOUGH TO
KICK OUT BETWEEN 0.1 AND 0.10 INCHES OF RAIN EQUIVALENT (HIGHER
AMOUNTS AS YOU GO NORTHWARD). SNOW RATIOS WILL BE FAIRLY HEALTHY
HOWEVER...AVERAGING 19 TO 1. SO ALTHOUGH WE ARE EXPECTING A HIGH
POP/LOW QPF EVENT...GOOD RATIOS WILL BRING ACCUMULATIONS OF BETWEEN
1.0 AND 1.5 INCHES ALONG AND NORTH OF THE I-69 CORRIDOR. SOUTH OF
THERE...AMOUNTS WILL GRADUALLY TAPER TOWARDS THE OHIO BORDER WITH
ONLY A TENTH OR TWO EXPECTED THERE. SNOWFALL WILL END IN THE
AFTERNOON AND EVENING FROM SOUTHWEST TO NORTH-NORTHEAST AS THE LOW
AND ELEVATED FRONT MOVE EAST. KEPT SOME LOW POPS IN OVERNIGHT TO
COVER THE PASSAGE OF A WEAK COLD FRONT BEHIND THE LOW BUT ASCENT
LOOKS WEAK TO NONE AND THE THREAT FOR ADDITIONAL ACCUMULATIONS AFTER
10PM LOOKS LOW. MOISTURE TRAILING THE LOW AND STREAMING OFF LAKE
MICHIGAN IN NORTHWEST FLOW LOOKS TO INITIALLY BECOME TRAPPED UNDER
AN INVERSION...KEEPING CLOUD COVER AROUND THROUGH THE FIRST HALF OF
THURSDAY NIGHT. COMBINATION OF DRY AIR ADVECTION AND A NORTHERLY
SHIFT TO THE WINDS MAY THEN ALLOW FOR SOME CLEARING OVERNIGHT.

SURFACE HIGH PRESSURE IS FORECAST TO BUILD OVERHEAD ON FRIDAY AS THE
NEXT IN OUR SERIES OF CLIPPERS REMAINS OVER SASKATCHEWAN AND
MANITOBA. NORTH TO NORTHEAST FLOW OFF LAKE HURON SHOULD ALLOW SOME
CLOUDS TO FILL IN AS DIURNAL HEATING ENSUES...ESPECIALLY ACROSS THE
THUMB. AT THIS TIME...AIRMASS LOOKS DRY ENOUGH TO END LAKE EFFECT
PROCESSES...BUT WILL WATCH TO SEE IF WE CAN GET SOME LIGHT SHOWERS
OR FLURRIES. CURRENT FORECAST FOR FRIDAY REMAINS DRY.

TEMPERATURES WILL REMAIN SEASONABLY COLD...WITH MAX TEMPS STILL MORE
THAN 10 DEGREES BELOW NORMAL IN THE MID 20S TO LOW 30S THURSDAY AND
FRIDAY.

A WEAK AND MOISTURE-STARVED CLIPPER SYSTEM LOOKS TO DROP INTO THE
NORTHERN GREAT LAKES ON SATURDAY. A SHALLOW FRONTAL ZONE AND
MID-LEVEL DRY AIR WILL PRECLUDE MOST AREAS FROM RECEIVING
SIGNIFICANT SNOWFALL...BUT ANY SOUTHERN PUSH TO THE OMEGA FIELD
WOULD ALLOW FOR MEASURABLE AMOUNTS MOST AREAS NORTH OF I-69.
OUTSIDE OF THE CLIPPER SYSTEM, THE EXTENDED FORECAST CALLS FOR NORTH
TO NORTHEAST WINDS WHICH WILL ALLOW FOR LAKE EFFECT SNOW TO REACH
THE FAVORED LAKESHORE AREAS. THE TYPICAL BKN-OVC CEILINGS OF LATE
FALL WILL BE EXPECTED, AND TEMPERATURES TREND HIGHER, BUT STILL
BELOW NORMS.

MARINE...

GALE WARNINGS REMAIN IN EFFECT FOR MOST OF LAKE HURON THROUGH LATE
THIS EVENING. GUSTS TO 35 KNOT GALES ARE EXPECTED TO CONTINUE THERE
AS A STRONG LOW PRESSURE SYSTEM LIFTS UP THE COAST OF NEW ENGLAND.
SMALL CRAFT ADVISORIES ALSO REMAIN IN EFFECT FOR INNER SAGINAW BAY
AND FOR LAKE ST CLAIR...WHERE WINDS WILL CONTINUE TO GUST TO 30
KNOTS. WINDS WILL DIMINISH TONIGHT AND EARLY TOMORROW AS HIGH
PRESSURE BRIEFLY BUILDS INTO THE SOUTHERN AND CENTRAL GREAT LAKES.
THERE IS POTENTIAL THAT ADDITIONAL SMALL CRAFT ADVISORIES MAY BE
NEEDED FOR OUTER SAGINAW BAY AND FOR THE NEARSHORE WATERS OFF THE
TIP OF THE THUMB INTO LATE TOMORROW MORNING AS WAVE HEIGHTS CONTINUE
TO SUBSIDE. A LOW PRESSURE SYSTEM WILL QUICKLY CLIP ACROSS MICHIGAN
THURSDAY AND THURSDAY EVENING...BUT IS NOT EXPECTED TO BRING
SIGNIFICANT WINDS.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.

LAKE HURON...
     SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
     HURON INCLUDING OUTER SAGINAW BAY...UNTIL 10 AM THURSDAY.

LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.

&&

$$

AVIATION.....MR
SHORT TERM...KURIMSKI
LONG TERM....HLO/MM
MARINE.......HLO

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