Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 270459
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1159 PM EST MON JAN 26 2015

.AVIATION...

LIGHT NORTHEAST FLOW WILL CONTINUE TO FAVOR SOME DEGREE OF STRATUS
EXPANSION THROUGH THE EARLY MORNING PERIOD.  RECENT OBSERVATIONAL
AND SATELLITE TRENDS NOW PROVIDE A MIXED SIGNAL...THE LEADING EDGE
OF THIS STRATUS STRUGGLING TO MAKE BETTER INROADS WESTWARD INTO THE
VERY DRY EXISTING ENVIRONMENT DOWNSTREAM.  GREATEST POTENTIAL FOR A
PERIOD OF MVFR WILL EXIST ACROSS THE DTW/YIP CORRIDOR.  A BACKING
WIND FIELD WILL EVENTUALLY SETTLE TO NORTHERLY INTO TUESDAY.  THIS
PROCESS MAY ALLOW FOR A BRIEF PERIOD OF VFR DIURNAL STRATOCU EARLY
IN THE DAY BEFORE A DRYING NORTHERLY FLOW TAKES A GREATER FOOTHOLD.

//DTW THRESHOLD PROBABILITIES...

* MODERATE FOR CEILING BELOW 5000 FT TONIGHT INTO TUESDAY MORNING.

&&

.PREV DISCUSSION...ISSUED 946 PM EST MON JAN 26 2015

UPDATE...

PERPETUATION OF A LIGHT EAST TO NORTHEAST FLOW WORKING BENEATH AN
INCREASING NOCTURNAL INVERSION PROVIDING A FAVORABLE BACKGROUND
ENVIRONMENT FOR THE EXPANSION OF STRATUS LATE THIS EVENING.  MODEST
LAKE HURON MOISTURE FLUX EFFECTIVELY AUGMENTING THE OUTER
MOISTURE PLUME ATTENDANT TO THE EAST COAST SYSTEM. STRATUS DECK
ALREADY MAKING SOLID INROADS INTO EAST-CENTRAL PORTIONS OF THE
FORECAST AREA. OBSERVATIONS AND RADAR TRENDS WOULD ALSO SUGGEST
THE SATURATED LAYER IS FAVORABLY POSITIONED WITHIN THE THERMAL
LAYER /-12C/ FOR DENDRITE PRODUCTION DESPITE THE SHALLOW MOISTURE
DEPTH. THIS WARRANTS AN INCLUSION OF FLURRIES BENEATH THIS STRATUS
CANOPY FOR THE REMAINDER OF THE OVERNIGHT PERIOD. THIS
QUESTIONABLE MOISTURE DEPTH MAY LEAVE THIS PRECIPITATION AS MORE
OF A `SNIZZLE` AT TIMES...ALTHOUGH CONFIDENCE NOT THERE YET TO
EXPLICITLY INCLUDE A FREEZING DRIZZLE MENTION. ADDITIONAL
EXPANSION APPEARS LIKELY PER RECENT TRENDS AND LATEST HI RES
GUIDANCE...IMPACTING A GOOD PORTION OF SE MICHIGAN OUTSIDE OF
PERHAPS THE TRI-CITIES BY DAYBREAK. THESE TRENDS WILL CERTAINLY
PLACE THE LOW TEMPERATURE FORECAST IN A TENUOUS POSITION...CLOUDS
EFFECTIVELY DELINEATING LOCATIONS THAT MAKE A RUN INTO THE SINGLE
DIGITS /BAD AXE ALREADY 5 DEGREES/ VERSUS THOSE THAT HOLD IN THE
TEENS. WILL LEAN SLIGHTER WARMER NOW ACROSS ALL BUT THE TRI-
CITIES/NORTHERN THUMB AND OHIO BORDER COUNTIES.

PREV DISCUSSION...ISSUED 352 PM EST MON JAN 26 2015

SHORT TERM... AFTERNOON AND TONIGHT

SE MICHIGAN IS IN THE QUIET WEATHER AREA BETWEEN A WEAK WAVE OF LOW
PRESSURE OVER THE MIDWEST AND THE DEVELOPING EAST COAST SNOWSTORM.
THE MIDWEST WAVE WILL LEAVE SOME MID AND HIGH CLOUDS OVER OUR AREA
TONIGHT AS IT SHEARS APART AND TRANSFERS ITS UPPER LEVEL ENERGY TO
THE POWERFUL CYCLOGENESIS OCCURRING OFFSHORE OF THE NEW ENGLAND
STATES. THE REMNANT MID AND HIGH CLOUDS OVER OUR AREA WILL THEN BE
COMPLEMENTED OVERNIGHT BY CLOUDS FROM THE WESTERN FRINGE OF THE EAST
COAST SYSTEM. THE AMOUNT AND EXTENT OF THESE CLOUDS REMAIN IN
QUESTION AND WILL BE STRONGLY DEPENDENT ON A BOOST FROM LAKE ONTARIO
AND LAKE ERIE WHILE THE LOW LEVEL FLOW REMAINS EASTERLY...AND THEN
FROM LAKE HURON AS THE FLOW BACKS TOWARD THE NORTH LATER IN THE
NIGHT. AFTERNOON SATELLITE IMAGERY INDICATES THAT LAKE HURON REMAINS
ACTIVE WITH EASTERLY FLOW CARRYING MOST OF THE CLOUDS INTO NORTHERN
LOWER...AND THIS SUGGESTS LAKE ERIE AND ONTARIO SHOULD BE ABLE TO
CONTRIBUTE AS MUCH TONIGHT...ESPECIALLY ONCE THE NOCTURNAL INVERSION
SETS UP AFTER SUNSET. COVERAGE MAY NOT BE SOLID BUT ENOUGH TO MAKE A
DIFFERENCE IN THE TEMPERATURE FORECAST WHEN COMBINED WITH A LAKE
HURON COMPONENT AS THE WIND TURNS TOWARD THE NORTHEAST AFTER
MIDNIGHT. EXPECT LOWS WILL BE A FEW DEGREES WARMER AT ALL LOCATIONS
COMPARED TO THIS MORNING BUT STILL CAPABLE OF SINGLE DIGITS INTERIOR
THUMB AND SAGINAW VALLEY. CLOUD COVER SHOULD THEN RESPOND WITH A
DECREASING TREND INTO TUESDAY MORNING AS THE MEAN LOW LEVEL FLOW
TURNS MORE NORTHERLY AND SHORTENS OR ELIMINATES LAKE TRAJECTORIES
AND DRAWS IN INCREASING AMOUNTS OF DRY AIR BUILDING BEHIND THE EAST
COAST SYSTEM.

LONG TERM...

A NUMBER OF FACTORS WILL ALIGN TO PRODUCE A LOCALIZED SURFACE HIGH
PRESSURE CENTER OVER SOUTHEASTERN MICHIGAN TUESDAY THROUGH WEDNESDAY
NIGHT. THE INGREDIENTS INCLUDE...VERY STRONG SYNOPTIC SCALE
SUBSIDENCE ALONG THE PERIPHERY OF THE DEEPENING ATLANTIC COASTAL LOW
PRESSURE SYSTEM...CONFLUENCE ALOFT...AND BUILDING GEOPOTENTIAL
HEIGHTS DUE TO THE STOUT SHORTWAVE RIDGING PUSHING ACROSS THE
WESTERN GREAT LAKES. VERY LITTLE CHANGES WERE NEEDED TO THE
INHERITED FORECAST. AGREE WITH THE AFOREMENTIONED DISCUSSION ON A
LESS AGGRESSIVE CLOUD FORECAST FOR TUESDAY GIVEN OVERALL MAGNITUDE
OF THE SUBSIDENCE THAT IS EXPECTED. TYPICALLY SEE VERY DRY AIRMASSES
IN THESE WRAP AROUND SURFACE RIDGES. THE WEDNESDAY MORNING LOW
TEMPERATURE FORECAST IS AN INTERESTING ONE BECAUSE OF THE
POTENTIAL FOR FAVORABLE RADIATIVE COOLING CONDITIONS. HOWEVER...A
LACK OF A FRESH SNOWPACK LIMITS THE CERTAINTY...CURRENT FORECAST
OF UPPER SINGLE DIGITS ABOVE ZERO TO TEN DEGREES IS REASONABLE.
THE EASTWARD MIGRATION OF THE SURFACE RIDGE AXIS AND REEMERGENCE
OF WESTERLY RETURN FLOW DURING THE AFTERNOON HOURS ON
WEDNESDAY...BRINGS A GOOD LIKELIHOOD THAT TEMPERATURES COULD
MODERATE BY AS MUCH AS A CATEGORY FOR WEDNESDAY. CURRENT FORECAST
CALLS FOR TEMPERATURES IN THE UPPER 20S TO AROUND 30 DEGREES.

THURSDAY WILL START OUT ACTIVE AS ANOTHER CLIPPER SYSTEM MOVES
THROUGH THE GREAT LAKES REGION.  CENTER OF THE LOW WILL BE TRACKING
ACROSS NORTHERN ILLINOIS AND SOUTHERN LOWER MICHIGAN THROUGH THE DAY
ON THURSDAY BEFORE EXITING BY EARLY FRIDAY MORNING.  PREVIOUS
DISCUSSION MENTIONED A WARMER THERMAL PROFILE WITH A GENERAL 1 TO 3
INCHES OF SNOW OVER A 12 HOUR PERIOD STILL LOOKING ON TARGET WITH
THE LATEST MODEL RUNS.  HIGHER AMOUNTS WILL LIKELY BE SEEN OVER
NORTHERN AREAS OF THE CWA WITH AMOUNTS TAPERING OFF CLOSER TO THE
OHIO BORDER.  HIGH PRESSURE THEN BUILDS IN BEHIND THE DEPARTING
CLIPPER...BRINGING WITH IT MUCH COLDER AIR TO THE REGION THIS
UPCOMING WEEKEND.

MARINE...

LIGHT TO MODERATE WINDS WILL PERSIST THROUGH THURSDAY AS THE
GRADIENT RELAXES DUE TO RESIDENT HIGH PRESSURE. AN APPROACHING WEAK
LOW PRESSURE WEDNESDAY NIGHT THROUGH THURSDAY WILL CAUSE AN UPTICK
IN SOUTHERLY WINDS, BUT GUSTINESS WILL BE LIMITED DUE TO WARM STABLE
FLOW FROM THE SOUTH. COLD AIR MOVING INTO THE GREAT LAKES IN THE
WAKE OF THIS SYSTEM WILL MARK THE BEGINNING OF A RENEWED STRETCH OF
ACTIVE MARINE WEATHER THURSDAY NIGHT INTO NEXT WEEK AS MULTIPLE
BOUTS OF ARCTIC AIR TRAVERSE THE WATERS.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
&&

$$

AVIATION.....MR
UPDATE.......MR
SHORT TERM...BT
LONG TERM....CB/SS
MARINE.......CB


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