Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 081702
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1202 PM EST MON FEB 8 2016

.AVIATION...

TIMING OF LOW CLOUD (MVFR) DEVELOPMENT REMAINS THE CHALLENGE THIS
AFTERNOON...AS COLDER AIR SLOWER FILTERS EAST THROUGH LOWER
MICHIGAN...WITH MID LEVEL MOISTURE BACKING IN FROM THE EAST. WHEN
LOW CLOUDS (MVFR) ARRIVE (POSSIBLY HOLDING OFF THROUGH EARLY
EVENING)...NEXT OCCUR OF BUSINESS IS SNOW SHOWER ACTIVITY...WHICH
LOOKS TO BE MOST PREVALENT ACROSS MBS/FNT LATE
TONIGHT/TOMORROW...WHERE A LIGHT ACCUMULATION (COUPLE INCHES) CAN
BE EXPECTED. CONFIDENCE IN FLURRIES/LIGHT SNOW SHOWER ACTIVITY
INCLUDED IN THE NORTHERN TAFS FOR THIS EVENING IS LOW.
LIGHT...MOSTLY NORTHWEST WINDS THROUGH TONIGHT...WILL INCREASE A
BIT TOMORROW WITH DIURNAL BOOST/BETTER MIXING SUPPORTING GUSTS OF
20 KNOTS OR SLIGHTLY BETTER.

AT DTW...
MID LEVEL CLOUD CANOPY IN PLACE TO START THE FORECAST
PERIOD...BUT LOW CLOUDS (MVFR) WILL EVENTUALLY WORK INTO THE
TERMINAL SITE FROM THE WEST/SOUTHWEST. EXACT TIMING REMAINS
DIFFICULT...AS THERE WILL LIKELY BE SOME PATCHES INITIALLY. A
SURFACE TROUGH LOOKS TO BE TRACKING THROUGH LATE TONIGHT...WHICH
MAY HELP TRIGGER LIGHT SNOW SHOWERS...BUT BETTER ACTIVITY IS
EXPECTED LATER TUESDAY AS MID LEVEL MOISTURE SINKS SOUTH. LIGHT
ACCUMULATION OF SNOW POSSIBLE...AROUND 1 INCH. ALONG WITH THE
SNOW...NORTHWEST WINDS GUSTING UP TO AROUND 25 KNOTS DURING THE
AFTERNOON.

//DTW THRESHOLD PROBABILITIES...

* LOW CONFIDENCE FOR CEILINGS AOB 5000 FT THIS AFTERNOON...MEDIUM
  THIS EVENING...AND HIGH TONIGHT INTO TOMORROW.

* HIGH CONFIDENCE IN PRECIPITATION TYPE BEING SNOW TONIGHT/TOMORROW.

* LOW CONFIDENCE IN NORTHWEST CROSSWIND TOMORROW AFTERNOON.

&&

.PREV DISCUSSION...ISSUED 829 AM EST MON FEB 8 2016

UPDATE...

IN LIGHT OF CURRENT OBSERVATION TRENDS...AN UPDATE WILL BE ISSUED
TO DROP AFTERNOON HIGHS A COUPLE DEGREES AND INCREASE PRECIP
CHANCES AROUND PORT HURON. OVERALL THE CURRENT FORECAST REMAINS
VALID AS THE PERSISTENT DEFORMATION BAND SLOWLY PUSHES BACK TOWARD
THE EAST TODAY. ALTHOUGH PRECIP WILL GRADUALLY TRANSITION TO SNOW
THIS AFTERNOON...BOUNDARY LAYER TEMPS WILL REMAIN WARM ENOUGH TO
INHIBIT ACCUMULATIONS THROUGH LATE AFTERNOON.

PREV DISCUSSION...ISSUED 337 AM EST MON FEB 8 2016

DISCUSSION...

NWP CONTINUE TO STRUGGLE WITH ENERGETIC FLOW ACROSS NOAM AT PRESS
TIME. VERY DYNAMIC TROUGH IS CLOSING OFF OVER THE WESTERN GREAT
LAKES THIS MORNING. ITS EVOLUTION HAS LARGELY BEEN GUIDED BY A VERY
HIGH AMPLITUDE UPSTREAM RIDGE AND A POWERFUL LOW DEEPENING OFF THE
EASTERN SEABOARD IMMEDIATELY DOWNSTREAM. INTERACTION WITH A 165KT
SUBTROPICAL JET STREAKING ACROSS THE GULF COAST STATES WILL
ADDITIONALLY GUIDE THE DEEPENING LONGWAVE THROUGH TUESDAY.

THE EMBEDDED WAVE OVER SAINT LOUIS AT 06Z THIS MORNING WAS
UNIVERSALLY UNDERSIMULATED BY PRIOR MODEL CYCLES AND BETTER SAMPLING
HAS ALLOWED GUIDANCE TO CONVERGE TOWARD A MORE IMPACTFUL EVOLUTION
LOCALLY. SPECIFICALLY, AS THIS WAVE PIVOTS FROM STL TO LAKE ERIE,
WEAK SURFACE CYCLOGENESIS IS ANTICIPATED INVOF THE LAKE. DEEP MOIST
CYCLONIC UPPER FLOW WILL PROVIDE A FAVORABLE BACKGROUND WITHIN WHICH
DEFORMATION AND STRONG SURFACE CONVERGENCE WILL BECOME INCREASINGLY
ORGANIZED OVER LAKE HURON THROUGH THIS EVENING. CONFIDENCE THEN
DECREASES DRAMATICALLY AS NWP SPREAD FALLS INTO AT LEAST 3 DISTINCT
CAMPS. THE EC/ARW/NMM REPRESENT THE STRONGEST CLUSTERING THROUGH THE
INITIAL CYCLOGENESIS AND THIS PREFERRED CLUSTER IS MOST STRONGLY
REPRESENTED IN THE FORECAST. THE GFS/HRRR REMAIN THE MOST
SIGNIFICANT OUTLIERS AND CONFIDENCE IN THOSE SOLUTIONS IS FURTHER
DIMINISHED BY UNUSUALLY VOLATILE RUN-TO-RUN CONTINUITY BY THE
RAP/HRRR.

THROUGH 06Z TONIGHT, CONFIDENCE IS REASONABLY HIGH THAT THE
ORGANIZING SURFACE TROUGH WILL BEGIN TO PIVOT ONSHORE IN THE THUMB.
HAVING ORGANIZED OVER THE RELATIVELY WARM LAKE WATERS IN A MODESTLY
UNSTABLE ENVIRONMENT , THERE IS POTENTIAL FOR SUBSTANTIAL MOISTURE
POOLING AND THE FORECAST WILL HAVE TO BE MONITORED FOR A POTENTIAL
OVERACHIEVING SCENARIO. THE NMM/ARW THEN ALLOW THE SURFACE
CIRCULATION TO LATCH ON TO LAKE ERIE. ADDITIONAL DEEPENING BY A FEW
ADDITIONAL MILLIBARS OVER THE LAKE -A PERFECTLY REASONABLE SCENARIO-
THE STRENGTHENING CIRCULATION AND CONTINUED ONSHORE MOVEMENT OF THE
SURFACE TROUGH OFFER POTENTIAL FOR SEVERAL ADDITIONAL INCHES OF SNOW
AS WELL AS MORE AGGRESSIVE INLAND PENETRATION. THE MORE COARSE EC
EXPECTEDLY PEELS THE LOW AWAY FASTER, CONFINING ACCUMS TO A SMALLER
RANGE AND TO A SMALLER PORTION OF THE THUMB. CONSENSUS EC/ARW/NMM
QPF YIELDS 12-HOUR ACCUMULATIONS OF 2-4" OVER THE NEXT 24 HOURS AND
24-HOUR TOTALS OF 4-7" IN EASTERN PORTIONS OF THE THUMB. THERE
REMAINS CONSIDERABLE UNCERTAINTY IN THE EVOLUTION OF CRITICAL
SURFACE FEATURES, BUT POTENTIAL FOR A WWA-WORTHY SCENARIO IS HIGH
ENOUGH TO WARRANT TAKING AN INITIAL STAB AT A HEADLINE. WORTH NOTING
THAT 06Z NAM REMAINS A BIT OF AN OUTLIER, BUT HAS SHOWN A STRONG
ADJUSTMENT TOWARD AFOREMENTIONED PREFERRED CONSENSUS.

FOR TODAY, EXPECTING LITTLE MORE THAN OCCASIONAL LIGHT SHOWERS
ACROSS THE EASTERN CWA AS BOUNDARY LAYER TEMPERATURES LIKELY REMAIN
TOO WARM TO SUPPORT SNOW UNTIL NEAR OR SHORTLY AFTER SUNSET.

A LATE WEEK CLIPPER WILL POTENTIALLY BRING LIGHT ACCUMULATIONS ON
FRIDAY IN ADDITION TO MARKING THE LEAD EDGE OF A MUCH COLDER
AIRMASS. HIGHS WILL STRUGGLE TO REACH 20 DEGREES WITH SAT AND/OR
SUNDAY POTENTIALLY STRUGGLING TO REACH 10 DEGREES. CONSECUTIVE
MORNINGS OF SUB-ZERO LOWS WILL ALSO BE POSSIBLE AND WIND CHILL
READINGS MAY APPROACH ADVISORY CRITERIA AT TIMES.

MARINE...

A BROAD AREA OF LOW PRESSURE WILL SETTLE OVER LAKE HURON AND LOWER
MICHIGAN TODAY. THIS WILL LEAD TO LIGHT AND VARIABLE WIND OVER
MARINE AREA TODAY THROUGH TONIGHT BUT WITH AN INCREASINGLY ACTIVE
SNOW SHOWER PATTERN. THE SYSTEM WILL DRIFT TOWARD LAKE ONTARIO
DURING TUESDAY AND LEAVE NORTHERLY WIND INCREASING TO MODERATE
STRENGTH BY TUESDAY NIGHT. WHILE WIND HEADLINES ARE NOT
ANTICIPATED...MARINE CONDITIONS WILL WORSEN AS COLDER AIR MOVES IN
AND COMBINES WITH THE MODERATE WIND FIELD FOR BUILDING WAVES AND
STRONGER SNOW SQUALLS. THIS WILL LAST INTO THURSDAY AND THEN WIND
WILL DIMINISH THROUGH FRIDAY WHILE ARCTIC AIR REMAINS IN PLACE INTO
NEXT WEEKEND.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 7 PM EST TUESDAY
     FOR MIZ049-054-055-062-063.

LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
&&

$$

AVIATION.....SF
UPDATE.......SC
DISCUSSION...JVC
MARINE.......BT


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


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