Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 051740
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1240 PM EST THU MAR 5 2015

.AVIATION...

A BROAD AREA OF SURFACE HIGH PRESSURE WILL EXTEND FROM THE PLAINS
OVER THE ENTIRE GREAT LAKES FOR THE REST OF TODAY THROUGH TONIGHT.
IT WILL MAINTAIN FAVORABLE AVIATION CONDITIONS WHILE SLIDING TOWARD
THE ATLANTIC AND GULF COASTS THROUGH FRIDAY. THE ONLY TROUBLE SPOT
IN THE FORECAST WILL BE WITH HOW MUCH STRATOCU CAN MAKE IT OVER FROM
LAKE MICHIGAN AS LOW LEVEL WINDS TURN TOWARD THE SOUTHWEST. MBS HAS
THE BEST CHANCE OF ANY MEANINGFUL COVERAGE OF BORDERLINE MVFR/VFR
CEILING FROM ABOUT EARLY EVENING THROUGH FRIDAY MORNING. ALL
TERMINALS WILL THEN BE IMPACTED BY INCREASED WIND SPEED BY FRIDAY
AFTERNOON AS GUSTS PUSH TOWARD 25 KNOTS UNDER THICKENING HIGH
CLOUDS.

//DTW THRESHOLD PROBABILITIES...

* NONE.

&&

.PREV DISCUSSION...ISSUED 359 AM EST THU MAR 5 2015

SHORT TERM...TODAY AND TONIGHT

ANOTHER VERY COLD AIRMASS WILL BUILD THROUGH THE AREA TODAY AS
ARCTIC HIGH PRESSURE SETTLES INTO THE MID MISSISSIPPI VALLEY WITH AN
EXTENSION OF THIS HIGH EXTENDING EAST INTO THE GREAT LAKES AND OHIO
VALLEY. TEMPERATURES WILL ONLY CLIMB INTO THE MID/UPPER TEENS WITHIN
THIS AIRMASS AS SOME UPPER LEVEL CLOUDINESS ALSO IMPEDES SOLAR
INSOLATION TO A DEGREE. THESE TEMPERATURES ARE SOME 25F BELOW
AVERAGE FOR THE FIRST WEEK OF MARCH.

AS THIS HIGH CONTINUES TO SETTLE SOUTHEASTWARD TONIGHT...EXPECT
ANOTHER VERY COLD NIGHT WITH LOWS FALLING TO AROUND ZERO...PLUS OR
MINUS A FEW DEGREES. THE ONLY THING STAVING OFF AN EVEN COLDER NIGHT
WILL BE A SOUTHWEST RETURN FLOW AROUND THIS HIGH. WHILE THIS WIND
WILL HELP KEEP THE BOUNDARY LAYER PARTIALLY MIXED...IT WILL ALSO
PRODUCE WIND CHILL READINGS BELOW ZERO OVERNIGHT. IN FACT...WIND
CHILLS WILL APPROACH 15 BELOW ZERO FROM I-69 NORTH LATE TONIGHT.
WHILE THIS IS THE CRITERION FOR AN ADVISORY...WILL ALLOW THE DAY
SHIFT TO FURTHER ELEVATE AS THESE READINGS ARE ONLY REACHED FOR A
SHORT TIME AND ARE MARGINAL FOR A HEADLINE.

LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY

THE SPRAWLING COLD DOME OF SURFACE HIGH PRESSURE WILL SETTLE SOUTH
OF THE OHIO RIVER VALLEY DURING THE DAY ON FRIDAY. THE PRESSURE
GRADIENT ON THE NORTHWEST PERIPHERY OF THE ANTICYCLONE WILL
STRENGTHEN LEADING TO CLASSIC BREEZY RETURN FLOW SETUP. THERE WILL
MOST LIKELY BE A HEAVY DIURNAL COMPONENT TO THE BREEZE...WITH
SOUTHWESTERLY WINDSPEEDS REACHING THE 20 TO 30 MPH RANGE AFTER THE
NOON HOUR. INCREASING CLOUDS DURING THE AFTERNOON HOURS IN ADDITION
TO REMNANT MIDLEVEL COLD AIR SLOW TO DISLODGE WILL KEEP TEMPERATURES
IN THE MID 20S FOR DAYTIME HIGHS.

A PAIR OF FRESH NORTHERN STREAM JETLETS ARE FORECASTED TO DIG
SOUTHEASTWARD INTO THE GREAT LAKES REGION EARLY SATURDAY. THE
RESPONSE IN FRONT OF THESE JETLETS WILL BE FOR A SHORTWAVE RIDGE AND
ASSOCIATED THETA E RIDGE TO FLASH ACROSS THE STATE. THERE REMAINS
UNCERTAINTY WITH REGARDS TO THE EXACT TRAJECTORY OF THE INBOUND
SHORTWAVES. THERE HAS BEEN A LACK OF BOTH INTER AND INTRA MODEL
CONTINUITY. THIS IS IMPORTANT FOR A COUPLE OF REASONS...EXACTLY HOW
FAR NORTHWARD TEMPERATURES CAN MODERATE ON SATURDAY...AND ALSO WHERE
BEST FORCING FOR PRECIPITATION WILL EXIST ON PLACEMENT AND TIMING. A
DRY ARCTIC AIRMASS PRECEDING THE SHORTWAVE SUGGESTS DRY AIR WILL BE
A PROBLEM. IT REMAINS DIFFICULT TO GO WITH ANYTHING ABOVE A CHANCE
POP. THERMAL PROGS CONTINUE TO SUPPORT ALL SNOW AS A PTYPE DESPITE
TEMPERATURES THAT ARE EXPECTED TO CLIMB ABOVE THE FREEZING MARK.

A WEAK SYSTEM OVERALL...WITH ANOTHER JETLET DIVING INTO THE REGION
WILL LIMIT MUCH IF ANY COLD AIR ADVECTION IN THE WAKE OF THE
SATURDAY WAVE. TEMPERATURES SUNDAY WILL AGAIN BE RELATIVELY
MILD...IN THE MID 30S.

MARINE...

SURFACE HIGH PRESSURE WILL SETTLE OVER THE OHIO VALLEY AND SOUTHERN
GREAT LAKES TODAY AND TONIGHT...BRINGING FAIRLY LIGHT WINDS AND
QUIET WEATHER TO THE AREA. A LOW PRESSURE SYSTEM WILL THEN SLIDE
ACROSS NORTHERN ONTARIO FRIDAY...WHILE HIGH PRESSURE REMAINS OVER
THE OHIO VALLEY. THIS WILL BRING AN INCREASE IN SOUTHERLY WINDS
FRIDAY MORNING THROUGH FRIDAY EVENING. WINDS LOOK TO BE THE
STRONGEST OVER PORTIONS OF LAKE HURON...WITH GUSTS CURRENTLY LOOKING
TO REACH BETWEEN 30 AND 40 KNOTS. A GALE WATCH REMAINS IN EFFECT FOR
THE CENTRAL PORTION OF THE LAKE...INCLUDING SAGINAW BAY...FOR FRIDAY.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...NONE.

LAKE HURON...GALE WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING FOR LHZ362-
     363-421-422-441-462.

LAKE ST CLAIR...NONE.

MICHIGAN WATERS OF LAKE ERIE...NONE.

&&

$$

AVIATION.....BT
SHORT TERM...DG
LONG TERM....CB
MARINE.......CB


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