FXUS63 KDTX 121720
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1220 PM EST FRI MAR 12 2010

.AVIATION...

IFR/LIFR STRATUS AND FOG BLOSSOMED THIS MORNING OVER SOUTHEAST
MICHIGAN. WITH HIGH CLOUDS STREAMING UP FROM THE SOUTH AND LOW
LEVEL EASTERLY FLOW PERSISTING...HAVE BECOME MORE PESSIMISTIC WITH
THE TAFS THIS AFTERNOON. STILL WILL ALLOW FOR A MODEST
IMPROVEMENT...BUT ANY MVFR CONDITIONS (DETROIT TAFS) WILL GIVE
WAY TO A RETURN TO SOLID IFR CONDITIONS TONIGHT...AS MID LEVEL
MOISTURE AND SHOWERS RETURN TO THE AREA LATE TONIGHT...CONTINUING
INTO TOMORROW. THE LOW LEVEL EASTERLY FLOW REALLY RAMPS UP
TONIGHT...WHICH IS EXPECTED TO CAUSE ENOUGH MIXING AT THE SURFACE
TO HOLD CEILINGS/VSBYS AT THE LIFR/IFR THRESHOLD. BEST CHANCE FOR
LIFR CONDITIONS WILL BE AT MBS WITH THE EAST-NORTHEAST FLOW OFF
THE FROZEN BAY.

&&

.PREV DISCUSSION...ISSUED 338 AM EST FRI MAR 12 2010

SHORT TERM...TODAY

WIDESPREAD AREA OF RAINFALL QUICKLY TAPERING OFF FROM SOUTH TO NORTH
EARLY THIS MORNING AS AN AXIS OF HIGHER MID LEVEL THETA-E SHIFTS OUT
OF THE REGION. THIS WILL LEAVE THE AREA WITHIN A RELATIVE LULL FOR
TODAY UNDER DIMINISHING MOISTURE DEPTH AND LARGER SCALE ASCENT AS
THE PREDOMINANT MID LEVEL CIRCULATION BEGINS TO DROP SOUTHEAST OUT
OF THE MID MISSISSIPPI VALLEY. LINGERING LOW LEVEL CONVERGENCE
WITHIN THE PERSISTENT/DEEP EASTERLY FLOW AND ALONG THE NORTHEAST
FLANK OF THE BROADER CIRCULATION MAY PROVE SUFFICIENT TO GENERATE
A FEW SHOWERS THROUGH THE DAY...BUT WITH POPS OF 20/30% AT MOST.
LATEST SATELLITE TRENDS SUPPORT MODEL SOUNDINGS/RH FIELDS WITH
SOME PEAKS OF SUN THIS AFTERNOON. THE ADDED INSOLATION WILL HELP
COUNTER A SLIGHT DECREASE IN THE LOW LEVEL THERMAL FIELD. THIS
TRANSLATES INTO HIGHS RANGING FROM MID 50S NORTHEAST TO AROUND 60
SOUTHWEST.

LONG TERM...TONIGHT THROUGH NEXT THURSDAY

AN UPPER LEVEL PHASING EVENT WILL BE ONGOING AT THE START OF THE
PERIOD WHICH WILL ALLOW FOR THE DEVELOPMENT OF A LARGE BREADTH PV
ANOMALY ACROSS THE EASTERN ONE HALF OF THE UNITED STATES. MODEL
GUIDANCE IS TOTALLY ONBOARD WITH ENOUGH LINKAGE TO THE CONTINUED
AMAZINGLY STRONG SUBTROPICAL JET. THIS WILL ALLOW THE SYSTEM TO
REMAIN RELATIVELY PROGRESSIVE WITH ITS INFLUENCE EAST OF THE AREA BY
SUNDAY.

RESIDUAL EFFECTS OF MIDLEVEL DRYING WILL KEEP A LOW PRECIPITATION
COVERAGE ACROSS SOUTHEASTERN MICHIGAN FOR MOST OF THE NIGHT. MODEL
SOUNDINGS ALL AGREE WITH THE DRY WEDGE AT/ABOVE 8KFT SLOWLY
SATURATING LATE. THIS INCREASE IN MID TO UPPER LEVEL MOISTURE IS A
RESULT OF INCREASING DEFORMATION FORCING ACROSS ALL OF THE CWA WITH
FLOW SHARPLY ORGANIZING DUE TO INCREASED CYCLOGENESIS OVER THE
CAROLINAS. ANY LIGHT RAIN THROUGH 9Z WILL REMAIN SCATTERED. AS THE
DEFORMATION RAMPS UP ACROSS THE FAR SOUTH LATE TONIGHT AND REST OF
THE AREA SATURDAY...PRECIPITATION WILL TRACK INTO THE AREA FROM THE
EAST. A VERY WELL ESTABLISHED ATLANTIC MOISTURE FEED WILL ALLOW FOR
DEEP COLUMN SATURATION AND CATEGORICAL COVERAGE OF RAIN GOING INTO
SATURDAY. STEEP LAPSE RATES AND ENHANCED OMEGA IN THE 800-600 MB
LAYER SUGGESTS THAT .3 TO .5 INCHES OF QPF IS REASONABLE FOR SATURDAY.
WITH THE BRISK EASTERLIES AND THICK CLOUDS...TEMPERATURES WILL
FEEL A LITTLE RAW AS HIGHS STRUGGLE IN THE 40S BOTH SATURDAY AND
SUNDAY.

UPPER LEVEL RIDGING WILL TAKE OVER FOR THE END OF THE WEEKEND AND
BEGINNING OF NEXT WEEK. THIS WILL ALLOW SURFACE RIDGING TO TAKE OVER
ACROSS ALL OF SOUTHEASTERN MICHIGAN WITH THE ANTICYCLONE CENTER
STILL BACK ACROSS THE GREAT PLAINS. THUS...EASTERLY WINDS WILL
HOLD THROUGH THE BEGINNING OF NEXT WEEK WHICH SHOULD TEMPER
THE TEMPERATURE RESPONSE. DID MANAGE TO GO ABOVE 50 FOR BOTH
MONDAY AND TUESDAY...IN HOPES THAT SOME SUNSHINE WILL ALLOW US TO
OVERACHIEVE.

MARINE...

A PERSISTENT AREA OF LOW PRESSURE SETTLING ACROSS THE TENNESSEE
VALLEY WILL MAINTAIN AN EASTERLY FLOW ACROSS THE GREAT LAKES INTO
THE WEEKEND. A RELATIVELY STABLE MARINE ENVIRONMENT WILL HINDER
STRONGER WIND GUSTS ABOVE THE STABLE LAYER FROM MIXING DOWN. THIS
WILL LARGELY KEEP GUSTS BELOW ADVISORY CONDITIONS OVER NEARSHORE
WATERS OF LAKE HURON DURING THE WEEKEND...BUT WILL CONTINUE TO
MONITOR THIS POTENTIAL.

&&

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

&&

$$

AVIATION.....SF
SHORT TERM...MR
LONG TERM....CB
MARINE.......MR


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