000
FXUS63 KDTX 272052
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
352 PM EST MON DEC 27 2010
.SHORT TERM...TONIGHT
HIGH PRESSURE OVER THE MID-MISSISSIPPI VALLEY WILL BUILD SOUTHEAST
OVERNIGHT. NORTHWESTERLY FLOW IN THE LOW LEVELS WILL BACK TO THE
WEST BUT REMAIN AROUND 10 MPH AS THE PRESSURE GRADIENT TIGHTENS. THE
BACKED FLOW WILL CAUSE LAKE EFFECT CLOUDS OFF LAKE MICHIGAN TO PUSH
FURTHER INLAND THIS EVENING...ALTHOUGH LIKELY STRUGGLING TO MAKE IT
ALL THE WAY TO THE EASTERN CWA. BY LATE TONIGHT THEY SHOULD RECEIVE
A BOOST BY ENHANCED TROUGHING OFF OF LAKE MICHIGAN WITH CLOUDS
THICKENING ACROSS THE SAGINAW VALLEY. MEANWHILE MID-LEVEL MOISTURE
IS EXPECTED TO DECREASE OVERNIGHT AS THE SHORTWAVE RIDGE AXIS BUILDS
OVERHEAD. THIS COMBINATION SHOULD RESULT IN FLUCTUATING SKY
CONDITIONS WITH AN INCREASE IN CLOUDS THROUGH EARLY
EVENING...FOLLOWED BY A CLEARING TREND THROUGH THE EARLY MORNING
HOURS...WITH CLOUDS INCREASING AGAIN ACROSS THE NORTH LATE. THE
COMBINATION OF CLOUDS AND WIND WILL GENERALLY LIMIT THE DROP IN
TEMPERATURES OVERNIGHT TO 5 TO 10 DEGREES. DAYTIME HIGHS HAVE FALLEN
SHORT OF FORECAST HIGHS AND WILL KEEP THIS IN CONSIDERATION FOR MINS
TONIGHT...WITH MOST SITES BOTTOMING OUT IN MID AND UPPER TEENS.
CLEAR SKIES AND COOLER MINS OVER THE UPPER OHIO VALLEY WILL HAVE AN
EFFECT ON TEMPERATURES IN THE FAR SOUTH WHERE THE LOWEST MINS ARE
FORECAST.
&&
.LONG TERM...TUESDAY THROUGH MONDAY
FORECAST RATIONALE HAS NOT CHANGED MUCH AS A STEADY MODERATION IN
TEMPERATURES IS EXPECTED AS DEVELOPING QUASI-ZONAL FLOW CUTS OFF
ARCTIC FLOW FROM CANADA...LEADING TO THE FIRST LEG OF IMPROVING
TEMPERATURES DURING THE MIDDLE OF THE WEEK. UPPER RIDING WILL THEN
BUILD THROUGH THE AREA DURING THE LAST PART OF THE WEEK AS A STRONG
UPPER TROUGH DIGS INTO THE ROCKIES/PLAINS. THIS WILL LEAD TO HIGH
TEMPERATURES INTO THE 40S FRIDAY INTO EARLY SATURDAY AS THE STORM
OVER THE CENTRAL PLAIN STATES LIFTS INTO THE UPPER MIDWEST.
PRECIPITATION CHANCES ARE STILL EXPECTED TO STEADILY INCREASE IN THE
THURSDAY TO SATURDAY TIME FRAME AS MOISTURE GRADUALLY INCREASES IN
THE SOUTH/SOUTHWEST FLOW REGIME IN ADVANCE OF THE DEVELOPING CENTRAL
PLAINS SYSTEM. AT FIRST...THERE IS MINIMAL LIFT TO PRODUCE RAIN/SNOW
SHOWERS AS MAIN FOCUS REMAINS WELL WEST/SOUTHWEST WITH THE DIGGING
TROUGH. SO...THROUGH THURSDAY/THURSDAY NIGHT...AREA WILL RELY ON
MODEST ISENTROPIC LIFT WITHIN WARM AIR ADVECTION REGIME TO PRODUCE
GENERALLY LIGHT/SCATTERED SHOWERS. WILL MAINTAIN A MIX OF RAIN/SNOW
SHOWERS INTO THURSDAY MORNING AS LOW LEVEL COLD AIR IS SLOW TO
ERODE. HOWEVER...DO NOT EXPECT SIGNIFICANT PRECIPITATION DURING THIS
TIME FRAME ANYWAY.
THE BETTER CHANCE OF WIDESPREAD RAIN STILL HOLDS OFF UNTIL LATE
FRIDAY INTO FRIDAY NIGHT AS THE AFOREMENTIONED SYSTEM EJECTS INTO
THE UPPER MISSISSIPPI VALLEY...PRODUCING A SURGE OF MOISTURE IN
ADVANCE OF THE ATTENDING COLD FRONT.
THE WARM CONVEYOR BELT WILL COME TO A STOP SATURDAY AS THE
CULMINATING EVENT TAKES PLACE. A STRONG COLD FRONT WILL SWEEP
THROUGH MI ACCOMPANIED BY MODERATE RAIN...TRANSITIONING TO A MIX OF
RAIN AND SNOW INTO SATURDAY AFTERNOON. THERE IS ENOUGH LIFT AND
POSITIVE BUOYANT ENERGY TO ALLOW A FEW ISO RUMBLES OF THUNDER WITH
THE FROPA AS WELL. TIMING WITH THIS EVENT IS FAIRLY CONSISTENT WITH
THE GFS AND ECMWF. TEMPERATURES RETURN TO NEAR NORMAL ON SUNDAY WITH
DRY CONDITIONS EXPECTED. HIGH PRESSURE PASSES JUST SOUTH OF MI...BUT
NEED TO KEEP OUR EYE ON A TROUGH OF LOW PRESSURE AND A VORT MAX
PROGGED TO TRAVERSE THE AREA LATE SUN.
&&
.MARINE...
WAVE HEIGHTS REMAIN HIGH ENOUGH ACROSS SOUTHERN LAKE HURON TO
CONTINUE THE SMALL CRAFT ADVISORY FOR THE ICE FREE NEAR SHORE WATERS
FROM PORT AUSTIN TO PORT HURON THROUGH 10 PM. AFTER THAT TIME...THE
WINDS WILL BACK TO THE WEST WITH THE HIGHER WAVES SHIFTING TO THE
EAST SIDE OF THE LAKE.
THE PRESSURE GRADIENT WILL TIGHTEN OVERNIGHT WITH THE CENTRAL GREAT
LAKES LOCATED BETWEEN HIGH PRESSURE OVER THE OHIO VALLEY AND A LOW
PRESSURE SYSTEM OVER CENTRAL CANADA. A SWIFT WESTERLY WIND WILL
CONTINUE ACROSS THE OPEN WATERS WITH SPEEDS AROUND 20 KNOTS WITH
GUSTS TO 25 KNOTS. WIND SPEEDS ARE EXPECTED TO RELAX BY WEDNESDAY AS
THE SURFACE RIDGE BUILDS AND THE GRADIENT RELAXES. SOUTHERLY WINDS
WILL INCREASE BY LATE THIS WEEK AS A LOW PRESSURE SYSTEM MOVES
THROUGH THE WESTERN GREAT LAKES.
&&
.AVIATION...ISSUED 102 PM EST MON DEC 27 2010
MVFR STRATUS CONTINUES TO ERODE ACROSS SE MICHIGAN ALTHOUGH FNT/PTK
REMAIN ON THE FRINGES OF THE STRATUS DECK AND MAY CONTINUE TO
EXPERIENCE THESE CONDITIONS AT TIMES. OTHERWISE LAKE EFFECT CLOUDS
FROM LAKE MICHIGAN ARE EXPECTED TO PUSH FURTHER EAST ACROSS THE
STATE INTO THIS EVENING AS WINDS BACK TO THE WEST AND HAVE INCLUDED
A TEMPO GROUP...GENERALLY 22-02Z AT MOST OF THE TAF SITES. SKIES ARE
EXPECTED TO CLEAR OUT FOR MOST OF THE NIGHT WITH STRATUS RETURNING
ON TUESDAY MORNING AS A SURFACE TROUGH BRUSHES BY TO THE NORTH AND
BRINGS SOME COOLER AIR AND AN INCREASE IN MOISTURE TO THE LOW
LEVELS.
A FEW GUSTS TO AROUND 15 KNOTS ARE EXPECTED TODAY WITH WESTERLY
WINDS INCREASING ON TUESDAY AS THE PRESSURE GRADIENT TIGHTENS AND
GUSTS OF 20-25 KNOTS BECOME MORE COMMON DURING THE AFTERNOON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO HARBOR
BEACH...UNTIL 10 PM MONDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...KEC
LONG TERM....DG/MM
MARINE.......KEC
AVIATION.....KEC
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AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
