Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 232043
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
343 PM EST FRI JAN 23 2015

.SHORT TERM...THROUGH TONIGHT

VERY DRY AIR ABOVE 1600 FEET SAMPLED BY THE DTX RAOB ENTRAINED INTO
THE LOWER PARTS OF THE ATMOSPHERE TODAY CAUSING STRATUS TO MIX OUT
OVER MOST OF SOUTHEAST MICHIGAN. THIS OCCURRED PRIMARILY NORTH OF THE
I-94 CORRIDOR...FURTHER AWAY FROM THE SURFACE RIDGE CENTER TO OUR
SOUTH AND NEARER TO A WEAK TROUGH DROPPING INTO THE UPPER MIDWEST
WHICH IMPROVED MIXING AS YOU WENT NORTHWARD THROUGH LOWER MICHIGAN.
MODEL FORECAST SOUNDINGS KEEP THE INVERSION THAT ALLOWED THE STRATUS
DECK TO FILL IN EARLY THIS MORNING INTACT OVERNIGHT...EVEN
STRENGTHENING IT AS COLDER AIR ALOFT ARRIVES WITH AN UPPER WAVE.
WHILE THERE IS CERTAINLY SOME DEGREE OF UNCERTAINTY WITH CLOUD COVER
THIS EVENING...THE THOUGHT IS THAT STRATUS HOLDING BARELY TO OUR
WEST AND NEAR THE OHIO BORDER WILL EXPAND BACK NORTH AND EAST
TONIGHT AS WEST TO SOUTHWEST FLOW CONTINUES AND THE DEPTH OF THE
BOUNDARY LAYER DECREASES AND WE STOP MIXING INTO THE DRIER AIR
ALOFT.

UPPER TROUGH WILL CONTINUE TO DROP FROM THE UPPER MIDWEST ACROSS
LOWER MICHIGAN TONIGHT. THIS SYSTEM IS SHEARING OUT AND LACKS UPPER
SUPPORT...AND SHOULD DO LITTLE TO BOOST LIFT FROM THE REMNANT COLD
FRONT THAT WILL DROP THROUGH WITH THIS SYSTEM. DO EXPECT TO SEE AN
INCREASE IN MID/HIGH CLOUDS TONIGHT...MAINLY NORTH OF THE I-69
CORRIDOR. THIS IS WHERE LOW POPS WERE MAINTAINED FOR THE OVERNIGHT
PERIOD...MAINLY AFTER MIDNIGHT. FURTHER SOUTH...IT LOOKS AS IF
ENOUGH DRY AIR WILL REMAIN BELOW THE LAYER OF WEAK FORCING PER
LATEST CROSS-SECTIONS TO MITIGATE LIGHT SNOW THREAT.

&&

.LONG TERM...SATURDAY THROUGH THURSDAY

THIS WEEKEND ENTAILS A CHANCE FOR DRIZZLE/SNOW SHOWERS SATURDAY
BEFORE A CLIPPER SYSTEM MOVES THROUGH ON SUNDAY.  FIRST ISSUE TO
DEAL WITH IS THE POTENTIAL FOR PRECIP ASSOCIATED WITH A COLD FRONT
THAT WILL PUSHING THROUGH ACROSS THE CWA SATURDAY MORNING.
UNCERTAINTY LIES IN THE AMOUNT OF MOISTURE PRESENT WITH THE FRONTAL
PASSAGE SOME OF THE LATEST MODEL RUNS SHOWING A LITTLE MORE MOISTURE
AS COMPARED TO OTHERS.  MODEL SOUNDINGS DO SHOW SATURATION IN LOWER
LEVELS BUT OUTSIDE THE DGZ LAYER MEANING SOME LOCATIONS MAY SEE
DRIZZLE DURING THE DAY ON SATURDAY AS TEMPS WARM INTO THE MIDDLE
30S.  EXPECTING VERY LITTLE IN THE WAY OF SNOW ACCUMULATIONS ON
SATURDAY...A TRACE TO A TENTH IF THERE ARE.  THE UPPER LEVEL TROUGH
THEN SWINGS THROUGH DURING THE AFTERNOON WITH TEMPS SLOWING FALLING
BACK INTO THE 20S.

PREVIOUS DISCUSSIONS HAVE BEEN HIGHLIGHTING THE POTENTIAL FOR SNOW
ON SUNDAY WITH A CLIPPER SYSTEM THAT WILL BE DIVING DOWN FROM THE
NORTH.  THIS CLIPPER IS STILL ON TRACK TO MOVE THROUGH ON SUNDAY
WITH A FEW ADJUSTMENTS.  LATEST MODELS HAVE CONTINUED THE TREND OF
PUSHING THE SYSTEM A LITTLE FURTHER SOUTH WITH MOST OF THE MODELS
BRINGING THE LOW ACROSS NORTHERN ILLINOIS AND DOWN THROUGH THE OHIO
RIVER VALLEY.  BEST LOCATIONS FOR ACCUMULATING SNOWFALL WILL BE
ACROSS THE SOUTHERN CWA...SOUTH OF METRO DETROIT...WHERE AMOUNTS OF
UP TO 2 INCHES WILL BE POSSIBLE OVER A 12 HOUR PERIOD.  TIMING HAS
CHANGED A TINY BIT WITH REGARDS IN THE END TIME BEING A FEW HOURS
EARLIER WITH ONSET STILL LOOKING TO BE SUNDAY MORNING.  THE CLIPPER
WILL QUICKLY EXIT THE AREA BY COLDER AIR SUNDAY NIGHT WITH LOWS
DIPPING INTO THE TEENS.

AN ACTIVE WEATHER PATTERN SETS UP FOR NEXT WEEK...AS SUNDAYS LOW
CONTINUES TO PUSH OFF TO THE EAST RESIDUAL SNOW SHOWERS ARE EXPECTED
TO PERSIST THROUGH MONDAY MORNING...ESPECIALLY OVER THE SOUTHERN
HALF OF SOUTHEAST MICHIGAN. COLD AIR IS STILL ON TRACK FOR SINGLE
DIGIT LOW TEMPS TUESDAY AND WEDNESDAY MORNING...HIGH TEMPS IN THE
20S. ON THURSDAY ANOTHER LOW PRESSURE SYSTEM DROPS SOUTH LIFTING
TEMPS BACK INTO THE 30`S AS IT ADVANCES AND GENERATING ANOTHER
CHANCE FOR SNOW. A BRIEF BREAK FRIDAY WITH COLDER TEMPS MOVING IN
BEHIND THE FRONT...THEN YET ANOTHER LOW DROPPING SOUTH TO END THE
MONTH.

&&

.MARINE...

GUSTY SOUTHWEST WINDS WILL CONTINUE OVER LAKE HURON THIS EVENING AS
A WEAK TROUGH DROPS THROUGH THE NORTHERN AND CENTRAL GREAT LAKES.
GUSTS AROUND 30 KNOTS WILL REMAIN POSSIBLE OVER THE CENTRAL PART OF
THE LAKE AND SAGINAW BAY THROUGH THE EARLY EVENING. WINDS WILL FLIP
WESTERLY LATE TONIGHT AND EARLY SATURDAY BEHIND A VERY WEAK COLD
FRONT...BUT WILL NOT INCREASE IN SPEED. A SECOND COLD FRONT WILL
DROP THROUGH THE AREA LATE SATURDAY AND SATURDAY NIGHT...WITH WIND
SPEEDS INCREASING AS ADDITIONAL COLD AIR WORKS DOWN ACROSS THE LAKE
SURFACE. THESE WINDS ARE EXPECTED TO REMAIN BELOW GALE FORCE HOWEVER.

&&

.AVIATION...ISSUED 234 PM EST FRI JAN 23 2015

MOISTURE ARRIVING FROM THE SOUTHWEST ALLOWED MVFR STRATUS TO FILL IN
UNDER AN INVERSION EARLY TODAY. SINCE LATE MORNING
HOWEVER...SUBSIDENCE AND A WELL-MIXED BOUNDARY LAYER ROUGHLY NORTH
OF THE I-69 CORRIDOR HAS ALLOWED DRIER AIR TO MIX INTO THE LOWER
PART OF THE ATMOSPHERE...RESULTING IN A CLEARING TREND THAT HAS
ALREADY IMPACTED PTK AND FNT. SATELLITE IMAGERY SHOWS THIS TREND
WILL CONTINUE TOWARDS MBS AND THE DETROIT TERMINALS THROUGH THE
EARLY AFTERNOON. THE MOISTURE SHOULD SETTLE BACK UNDERNEATH THE
INVERSION TONIGHT AS MIXING DECREASES AND FLOW REMAINS SOUTHWEST TO
WEST...OFF LAKE MICHIGAN AND FROM WHERE MORE MOISTURE EXISTS. THIS
SHOULD ALLOW FOR THE REDEVELOPMENT OF AN MVFR STRATUS DECK IN THE
EVENING FOR ALL TAF SITES. A WEAK SURFACE TROUGH WILL DROP ACROSS
THE REGION LATE TONIGHT. THIS MAY RESULT IN A FEW LIGHT SNOW SHOWERS
OR FLURRIES...BUT IS EXPECTED TO HAVE LITTLE IMPACT ON CONDITIONS.

//DTW THRESHOLD PROBABILITIES...

* LOW CONFIDENCE WITH CEILINGS BELOW 5000 FEET THROUGH 03Z. MEDIUM
  CONFIDENCE TONIGHT AND TOMORROW.

&&

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

$$

SHORT TERM...HLO
LONG TERM....SS/DE
MARINE.......SS
AVIATION.....HLO


YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).



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