Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 101202
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
702 AM EST WED FEB 10 2016

.AVIATION...

A PASSING UPPER LEVEL WAVE IS SUPPORTING EASTWARD EXTENSION OF SNOW
BANDS FROM LAKE MICHIGAN DURING THE EARLY MORNING. THIS WILL RESULT
IN WIDELY VARYING FLIGHT CATEGORY UNTIL SOME IMPROVEMENT AS THE
UPPER WAVE EXITS THE REGION BY LATE MORNING. A RELATIVE BREAK IN
ACTIVITY WILL LAST INTO EARLY AFTERNOON BEFORE DIURNAL ENHANCEMENT
BEGINS AN INCREASE IN SNOW SHOWER COVERAGE AGAIN. CONTINUED NW WIND
WILL LIKELY PRODUCE GREATER COVERAGE SOUTH OF FNT WHERE POCKETS OF
IFR RESTRICTION WILL BE POSSIBLE. THIS AREA WILL BE MONITORED FOR
BETTER OBSERVATIONAL EVIDENCE BEFORE ADDING RESTRICTION TO THE
FORECAST. SNOW SHOWERS WILL LINGER INTO EARLY EVENING BEFORE ANOTHER
DISSIPATING TREND BEGINS. THERE IS ALSO A GOOD CHANCE OF A
DECREASING CLOUD TREND AS WELL THAT WILL LAST THROUGH SUNRISE
THURSDAY.

FOR DTW... WEST TO NORTHWEST WIND WILL GUST MOSTLY AT 20 KNOTS OR
LESS AND STAY UNDER CROSS WIND THRESHOLD. THE WIND WILL SUPPORT
BANDS OF LAKE EFFECT SNOW SETTLING SOUTHWARD TOWARD DTW THROUGH MID
MORNING. WIDELY VARYING FLIGHT CATEGORY WILL THEN BECOME MORE
PREVAILING VFR UNTIL EARLY TO MID AFTERNOON WHEN SNOW SHOWERS WILL
INCREASE AGAIN. COVERAGE IS ANTICIPATED TO BE GREATER IN THE DTW
AREA BUT COULD ALSO SLIDE JUST SOUTH. PLAN TO LET OBSERVATIONS GUIDE
UPDATES.

//DTW THRESHOLD PROBABILITIES...

* HIGH FOR CEILING AOB 5KFT TODAY.

* HIGH FOR SNOW AS PRECIPITATION TYPE.

* LOW FOR EXCEEDING WESTERLY CROSSWIND THRESHOLD TODAY.

&&

.PREV DISCUSSION...ISSUED 358 AM EST WED FEB 10 2016

DISCUSSION...

THE GREAT LAKES ARE ACTIVE AND WIDESPREAD SNOW SHOWERS LINGER ACROSS
THE AREA AS BROAD MOIST CYCLONIC FLOW IN THE WAKE OF YESTERDAY`S
WINTER STORM PERSISTS. 850MB TEMPERATURES AROUND -15C AT PRESENT
WILL PROBABLY BE AS GOOD AS IT GETS UNTIL MONDAY CONSIDERING THE
BAFFIN ISLAND SPECIAL WILL NOT ARRIVE UNTIL LATE FRIDAY INTO
SATURDAY WHEN H85 TEMPS WILL FALL TO -25C TO -29C AND HIGHS INTO THE
SINGLE DIGITS SATURDAY.

IN THE NEAR TERM...THROUGH LATE MORNING, THE FEATURE OF INTEREST IS
THE BAND OF LIGHT RETURNS STRETCHING FROM CHICAGO TO NORTHERN LOWER
OVER TOP OF EXISTING LES ACTIVITY. THIS IS DRIVEN BY APPROACHING
CONVERGENCE ALONG THE BACK EDGE OF THE UPPER TROUGH AND IS EASILY
IDENTIFIABLE ON WATER VAPOR IMAGERY. EXPECTING AN AREAWIDE HALF INCH
AT BEST AS IT TRANSITS THE AREA THROUGH ABOUT 15Z. COLD ADVECTION IN
ITS WAKE WILL INCREASE CONVECTIVE DEPTHS BY AN APPRECIABLE MARGIN TO
AROUND 7KFT. IN ADDITION, OVERLAKE 0-1KM THETA-E LAPSE RATES WILL
FALL TO A MODERATE -4 TO -6C/KM. TOGETHER, THESE SHOULD CONTRIBUTE
TO A BOOST IN UPSTREAM LES. PERSISTENT CYCLONIC NW FLOW WILL THEN
HAVE THE POTENTIAL TO GUIDE A BAND OR TWO INTO THE AREA DURING THE
DAY IF THE LAST COUPLE DAYS OF HIGH RES SOLUTIONS ARE TO BE
BELIEVED. RECENT RADAR TRENDS SUGGEST A LAKE CONNECTION MAY ALREADY
BE IN PLAY IN SHIAWASSEE/GENESEE/OAKLAND COUNTIES EARLY THIS
MORNING. IF THAT IS THE CASE, SOME PERSISTENCE AND A LATE MORNING
BOOST IN INTENSITY WILL BE A POSSIBILITY. THE LIMITING FACTOR FOR A
HEALTHY LES BAND OF THE SUPERIOR-MICHIGAN VARIETY EXTENDING INTO THE
CWA WILL BE A LACK OF SYNOPTIC SCALE MOISTURE, THE BULK OF WHICH
WILL DEPART WITH THE UPPER TROUGH AXIS. IN FACT, THE LACK OF
MOISTURE IS REFLECTED WELL IN THE AFOREMENTIONED THETA-E LAPSE RATES
WHICH ARE ONLY MODERATE IN SPITE OF THE SO-CALLED "DELTA-T" METHOD
WHICH WOULD SUGGEST GREATER POTENTIAL. NONETHELESS, RADAR TRENDS
WILL WARRANT MONITORING THROUGH THE DAY.

COLD ADVECTION WILL CONTINUE TONIGHT, THE AIRMASS SUPPORTIVE OF VERY
COLD LOW TEMPERATURES. HOWEVER, A STOUT GRADIENT AND CLOUD COVER
WILL LIKELY PUT A FLOOR ON LOW TEMP POTENTIAL. THE RAW NAM/ARW ARE
USUALLY SUPERIOR IN THESE CASES AND BOTH ARE RATHER WARM, BUT FRESH
SNOWCOVER GIVES REASON FOR PAUSE. LOWS AROUND 10 DEGREES REPRESENT A
COMPROMISE BETWEEN THE WARM/COLD GUIDANCE.

RESIDENT AIRMASS WILL STAGNATE ON THURSDAY WITH HIGH TEMPERATURES
JUST A TOUCH COLDER THAN TODAY AS BACKING ANTICYCLONIC FLOW AROUND
HIGH PRESSURE OVER THE OHIO VALLEY WILL INTRODUCE THE PROSPECTS FOR
AT LEAST PARTIAL SUN IF NOT BETTER.

ISENTROPIC ASCENT AND MODEST MID-LEVEL THETA-E ADVECTION WILL
INCREASE AS THE MOTHERLODE OF COLD AIR APPROACHES THE GREAT LAKES
AND NEW ENGLAND. FELT A BLANKED LOW CHC POP WAS WARRANTED GIVEN
SLIGHTLY IMPROVING MOISTURE AND RAMPING UP OF BACKGROUND LARGE SCALE
ASCENT. THE COLD FRONT ITSELF WILL SWING THROUGH LATE FRIDAY, BUT
LARGE SCALE FORCING WILL DIRECT SURFACE LOW PRESSURE OVER GEORGIAN
BAY DUE EAST. AS A RESULT, LOW-LEVEL CONVERGENCE WILL RAPIDLY FOLLOW
SUIT AND THE BEST PROSPECTS FOR FRONTAL PRECIP WILL THEREFORE RESIDE
OVER EASTERN AND NORTHEASTERN PORTIONS OF THE CWA. LOWS WILL FALL TO
AROUND 0 FRIDAY NIGHT IN SPITE OF GUSTY WINDS. HIGHS SATURDAY WILL
RANGE FROM 5 TO 10. THE PEAK WIND PERIOD IN THE WAKE OF THE FRONT IS
APPEARING TO CARRY AN INCREASING LIKELIHOOD OF WARRANTING A WIND
CHILL ADVISORY LATE FRIDAY NIGHT THROUGH SATURDAY MORNING FOR PART
OR ALL OF THE AREA. WILL MAKE AN INTRODUCTORY MENTION IN THE HWO.

MARINE...

LOW PRESSURE OVER LAKE ONTARIO DURING THE MORNING WILL CONTINUE TO
MOVE INTO THE NEW ENGLAND STATES TODAY. THIS WILL LEAVE STRONG NW
WIND OVER ALL MARINE AREAS TODAY THROUGH TONIGHT. A GALE WARNING IS
NOW IN EFFECT THIS AFTERNOON AND TONIGHT FOR THE OPEN WATERS OF
CENTRAL AND SOUTHERN LAKE HURON. SMALL CRAFT ADVISORIES REMAIN IN
EFFECT FOR THE NEARSHORE WATERS OF SOUTHERN LAKE HURON THROUGH
THURSDAY DUE TO THE RESULTING HIGH WAVE ACTION AND WIND GUSTS AROUND
30 KNOTS. FREEZING SPRAY REMAINS A CONCERN AS ARCTIC AIR SURGES
SOUTHWARD OVER THE REGION TODAY THROUGH TONIGHT. A WARNING FOR HEAVY
FREEZING SPRAY IS IN EFFECT TONIGHT WHEN THE BEST COMBINATION OF
FREQUENT GALE FORCE WIND GUSTS AND COLD AIR OCCURS. LAKE EFFECT SNOW
SQUALLS WILL HAVE GREATEST COVERAGE AROUND MID LAKE IN THIS WIND
CONFIGURATION THROUGH THE PERIOD.

ALL OF THESE HARSH MARINE CONDITIONS WILL EASE GRADUALLY DURING
THURSDAY AS THE WIND BACKS AND DECREASES BY LATE IN THE DAY...BUT
THE BREAK WILL BE SHORT LIVED AS ANOTHER ARCTIC FRONT APPROACHES
THURSDAY NIGHT INTO FRIDAY. SOME OF THE COLDEST AIR OF THE SEASON
WILL BRUSH LAKE HURON AND LOWER MICHIGAN BEHIND THIS FRONT FOR THE
WEEKEND.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...NONE.

LAKE HURON...HEAVY FREEZING SPRAY WARNING FROM 7 PM THIS EVENING TO 7 AM EST
     THURSDAY FOR LHZ362-363-462>464.

     GALE WARNING FROM 1 PM THIS AFTERNOON TO 4 AM EST THURSDAY FOR
     LHZ363-462-463.

     SMALL CRAFT ADVISORY UNTIL 4 PM EST THURSDAY FOR LHZ441>443.

     GALE WARNING FROM 1 PM THIS AFTERNOON TO 10 PM EST THIS EVENING FOR
     LHZ362.

LAKE ST CLAIR...NONE.

MICHIGAN WATERS OF LAKE ERIE...NONE.

&&

$$

AVIATION.....BT
DISCUSSION...JVC
MARINE.......BT


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