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000
FXUS63 KDTX 100448
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1248 AM EDT MON MAR 10 2014

.AVIATION...

//DISCUSSION...

VFR CONDITIONS WILL PREVAIL AS DRY LOW LEVEL SOUTHWESTERLY FLOW
PERSISTS. STRONG PRESSURE GRADIENT WILL ALLOW WINDS TO REMAIN MIXED
SOMEWHAT DURING THE NIGHT...WITH GUSTS TO 20 KNOTS POSSIBLE EARLY
IN THE FORECAST AND AGAIN IN BETTER MIXING LATER TODAY. ANY CIGS
APPEAR TO REMAIN AOA 10KFT OR SO...EVEN AS A WEAK SURFACE TROUGH
EDGES INTO FORECAST AREA BY MONDAY EVENING.

//DTW THRESHOLD THREATS...

* NONE.

&&

.PREV DISCUSSION...ISSUED 335 PM EDT SUN MAR 9 2014

SHORT TERM...THIS EVENING AND TONIGHT

BROAD AREA OF RETURN FLOW BETWIXT THE EXITING SURFACE RIDGE OVER THE
OHIO VALLEY AND WEAK LOW RIPPLING EAST ACROSS NORTHERN ONTARIO WILL
CONTINUE TO WASH ACROSS SOUTHERN LOWER MICHIGAN TONIGHT.  THE
STRENGTHENING SURFACE PRESSURE GRADIENT WILL SUPPORT INCREASING
WINDS THE REMAINDER OF THE AFTERNOON AND THIS WILL CONTINUE THROUGH
THE EVENING.

PLENTY OF MID/HIGH LEVEL CLOUD COVER WILL BE PRESENT THROUGHOUT THE
NEXT 18 HOURS OR SO. MEANWHILE...MOISTURE RETURN IN THE LOWER LEVELS
HAS BEEN MUCH LESS THAN ADVERTISED. NOT EXPECTING DECOUPLING TO
OCCUR TONIGHT AS THE COMBINATION OF A ROBUST PRESSURE GRADIENT
/ATTENDANT GEOSTROPHIC FLOW REMAINS IN THE 25KT RANGE/ AND LACK OF
NEGATIVE RADIATIONAL FLUX WITH THE PERSISTENT CLOUD SHIELD.
CONSEQUENTLY...NOT EXPECTING TEMPERATURES TO DRIFT DOWN TOO FAR THIS
EVENING AND SHOULD REMAIN RATHER STEADY THROUGH THE NIGHT.

A WEAK IMPULSE AND MOISTURE RESPONSE AROUND 700MB WILL ROCKET
OVERHEAD LATE TONIGHT.  THE WINDOW OF MOIST ISENTROPIC ASCENT IS
RATHER SHORT AND NOT ENOUGH TO SATURATE SURFACEWARD THROUGH
EVAPORATIVE FORCING.  SO NOT EXPECTING MUCH IN THE WAY OF
PRECIPITATION DEVELOPMENT...JUST AN ENHANCED MID-CLOUD DECK AND SOME
VIRGA.

LONG TERM...

RATHER AMPLIFIED UPPER LEVEL RIDGE OVER THE DAKOTAS...WITH THE UPPER
LEVEL WAVE OVER ALBERTA BREAKING THE TOP OF THE RIDGE DOWN AS IT
COMES OVER THE TOP AND TRACKS THROUGH THE NORTHERN GREAT LAKES ON
MONDAY. STILL...A LOT OF MILD AIR IS FORECASTED TO STREAM INTO THE
SOUTHERN GREAT LAKES...AS 925-850 MB TEMPS RISE SOLIDLY IN THE
POSITIVE SINGLE NUMBERS...WITH THE INCREASING FAVORABLE LOW LEVEL
SOUTHWEST FLOW. DO NOT SEE SUFFICIENT UPSTREAM DEW PTS TO BE
TERRIBLY CONCERNED WITH LOW CLOUDS...AND I PREFER TO SKEW THE
FORECAST WARMER...AROUND 50 DEGREES...IN LINE WITH THE EURO...AND
FACTORING IN MARCH 7TH AS A BENCHMARK (925 MB TEMP OF 4 C PER 00Z
DTX SOUNDING ON MARCH 8TH).

TUESDAY IS A CHALLENGING DAY AS THE SURFACE COLD FRONT PRETTY MUCH
WASHES OUT...WITH SUBSTANTIAL BAROCLINIC ZONE IN PLACE. DEPTH OF THE
THE COLD AIR BLEEDING INTO SOUTHERN LOWER MICHIGAN DURING THE DAY IS
IN QUESTION...AND AREAS SOUTH OF M-59 LOOK TO BE MILD AGAIN
(40S)...ALTHOUGH 700 MB FGEN/CLOUDS WILL LIKELY PREVENT MAXES FROM
REACHING 50 DEGREES AGAIN. IN FACT...INCREASING EVIDENCE VIA
UKMET/CANADIAN MODELS PRECIPITATION FROM THE MID LEVEL FGEN WILL BE
STREAKING IN BY DAY`S END. IF THIS DOES HAPPEN...WET BULBING EFFECTS
SHOULD ALLOW FOR CHANGEOVER FROM RAIN TO WET SNOW AS BOUNDARY LAYER
COOLS...ESPECIALLY AS WE HEAD INTO TUESDAY EVENING.

THE FORECAST FOR TUESDAY NIGHT AND WEDNESDAY IS THEN CONTINGENT ON
THE PHASING OF NORTHERN STREAM TROUGH/UPPER WAVE COMING OUT OF
CENTRAL CANADA AND THE TROUGH/WAVE OFF THE PACIFIC NORTHWEST COAST.
12Z MODELS ALL CONVERGING ON A RAPIDLY DEEPENING LOW TRACKING ALONG
OR CLOSE TO THE OHIO RIVER TO JUST SOUTH OF PITTSBURGH...A FAVORABLE
TRACK FOR SNOW NEAR THE MICHIGAN/OHIO BORDER. THE TEMP
GRADIENT/BAROCLINIC ZONE IS IMPRESSIVE...WITH SURGE OF ARCTIC AIR
UNDER THE LOW LEVEL NORTH-NORTHEAST FLOW DURING WEDNESDAY...AS
925/850 MB TEMPS CRASH INTO THE NEGATIVE MID TEENS. 850-700 MB
SPECIFIC HUMIDITY TUESDAY NIGHT BETWEEN 3-3.5 G/KG ALONG AND SOUTH
OF M-59 CORRIDOR...AND WITH INTENSE LIFT/DEFORMATION/FGEN FOR 6
HOURS...A SWATH OF 6 INCHES OF SNOW IS POSSIBLE NEAR THE OHIO
BORDER...BEFORE THE LOW RACES TO THE EAST COAST LATE WEDNESDAY.
ANOTHER FACTOR IS THE LEAD 500 MB LOW CURRENTLY OVER MEXICO...AND IF
AND WHEN IT BECOMES ABSORBED WITHIN THE DEVELOPING STORM SYSTEM...AS
THIS FEATURE WILL LIKELY TAKE WITH IT MUCH OF THE GULF OF MEXICO
MOISTURE. 12Z CANADIAN/UKMET BOTH SUGGEST BULK OF ACTIVITY WILL MISS
US JUST TO THE SOUTH. THE 12Z EURO CAME IN WITH A TRACK JUST SOUTH
OF THE OHIO RIVER...AND RIGHT KNOW THINKING AROUND 1 INCH BETWEEN
M-59/I-69 CORRIDORS...WITH AROUND 4 INCHES TOWARD THE OHIO BORDER.
THIS IS A SENSITIVE FORECAST DUE TO THE TIMING ISSUES WITH THE DRY
ARCTIC AIR FUNNELING INTO THE CENTRAL GREAT LAKES...AND WITH LAKE
HURON MOSTLY ICED OVER...CAN`T COUNT ON MUCH LAKE EFFECT
CONTRIBUTION/MOISTENING OF THE LOW LEVELS...AND THUS CONFIDENCE IS
AVERAGE AT BEST THIS FAR OUT.

A VERY COLD NIGHT IS IN STORE WEDNESDAY NIGHT AS THE WINTER STORM
MOVES TO THE NEW ENGLAND COAST AND A SURFACE RIDGE NOSES INTO
MICHIGAN. DETAILS SUCH AS HOW QUICKLY CLOUDS CLEAR AND EXTENT OF
DECOUPLING STILL NEED TO BE WORKED OUT...BUT CURRENT GUIDANCE
DEPICTS LOWS IN THE SINGLE DIGITS. CONTINUED COLD THURSDAY BUT LOW
LEVEL WARM AIR ADVECTION WILL ENSUE LATE THURSDAY INTO FRIDAY /850
HPA TEMPS INCREASING FROM -16C TO +2C FROM 12Z THURSDAY TO 12Z
FRIDAY/ CAUSING A NICE WARMUP FOR FRIDAY. THE WARMUP LOOKS TO BE
SHORT LIVED THOUGH AS AN EXTENSION OF THE HUDSON BAY UPPER LOW WORKS
ITS WAY INTO THE UPPER MIDWEST FOR THE WEEKEND...ACCOMPANIED BY A
RETURN TO BELOW NORMAL TEMPERATURES. PRECIPITATION CHANCES ARE SLIM
TO NONE FOR THE LATTER HALF OF THE WEEK INTO SATURDAY.

MARINE...

INCREASING SOUTHWEST WINDS WILL CONTINUE THROUGH MONDAY. SOUTHWEST
GUSTS AROUND 30 KNOTS WILL BE POSSIBLE OVER THE CENTRAL AXIS OF LAKE
HURON INCLUDING OUTER SAGINAW BAY.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

AVIATION.....DG
SHORT TERM...MANN
LONG TERM....SF/DT
MARINE.......SF


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