Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 270705
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
305 AM EDT SAT SEP 27 2014

.SHORT TERM...TODAY AND TONIGHT

FOG TRENDS WILL CONTINUE TO BE MONITORED EARLY THIS MORNING...BUT
VISIBILITIES HAVE BEEN OSCILLATING SIGNIFICANTLY...OWING TO THE
SHALLOW NATURE...AND THE DENSE FOG IS CONFINED TO THE USUAL SUSPECTS
AND DOES NOT HAVE THE AREAL COVERAGE TO JUSTIFY AN ADVISORY AT THIS
POINT.

UPPER LEVEL LOW REMAINS OVER IOWA THIS MORNING...AND THERE WILL BE
LITTLE MOVEMENT OF THIS SYSTEM DURING THE NEXT 24 HOURS. 590 DAM
HEIGHT AT 500 MB...AS OBSERVED ON THE 00Z DTX SOUNDING...WILL SLOWLY
DECREASE TODAY AND TONIGHT AS RIDGE CENTER PUSHES TO THE EAST COAST.
STILL...LOW LEVEL PROFILES..925 MB TEMPS LOOK IN LINE WITH
YESTERDAY (17 C)...AND PLANNING ON SIMILAR MAXES...MID TO UPPER
70S...UNDER SUNNY SKIES. CALM WINDS TONIGHT WILL AGAIN ALLOW FOR
THE POSSIBILITY OF RADIATION FOG...BUT SURFACE AND BOUNDARY LAYER
PRESSURE CONDENSATION DEFICITS APPEAR TO BE HIGHER COMPARED TO
THIS MORNING. THERE IS ALSO AN EXPECTED INCREASE IN HIGH CLOUDS
OVERNIGHT FROM THE SOUTH...AND WILL HOLD ON TO JUST A PATCHY FOG
MENTION...WITH MINS IN THE MID 40S TO LOWER 50S...PER LATEST MAV
GUIDANCE.

&&

.LONG TERM...SUNDAY THROUGH FRIDAY

A BREAKDOWN OF THE UPPER RIDGE AXIS OVER THE GREAT LAKES WILL OCCUR
ON SUNDAY AS A MID LEVEL WAVE TRAVERSES CENTRAL CANADA. THIS WILL IN
TURN CAUSE THE MID LEVEL LOW WHICH HAS BEEN MEANDERING OVER IOWA TO
LIFT ACROSS THE SRN GRT LKS/OH VALLEY AS AN OPEN WAVE. THERE WILL BE
LITTLE IMPACT ON THE SFC HIGH WHICH WILL REMAIN DRAPED ACROSS THE
STATE INTO MONDAY. MODEL SOLUTIONS DO HOWEVER SUGGEST A REGION OF
HIGH MOISTURE NEAR 400MB MOVING ACROSS SE MI ON SUN ON THE NOSE OF
AN STRENGTHENING UPPER JET MAX LIFTING ACROSS THE OHIO VALLEY.
DESPITE THE GREATER AMOUNT OF HIGH CLOUDS EXPECTED...MODEL SOUNDINGS
SUGGEST DEEPER MIXING WILL STILL BOOST SUN AFTERNOON HIGHS WELL INTO
THE 70S. ENOUGH CLEARING SUN NIGHT WILL PROMOTE GOOD RADIATIONAL
COOLING...CAUSING ANOTHER COOL NIGHT WITH SOME POSSIBLE FOG. THE SFC
HIGH WILL CONTINUE TO INFLUENCE THE FORECAST AREA FOR MUCH OF MONDAY
WITH PERSISTENCE SUGGESTING HIGHS AGAIN WELL INTO THE 70S.

THE LAST SEVERAL MODEL SOLUTION HAVE SHOWN A SHORT WAVE IMPULSE
EJECTING OUT OF WRN CANADA AND ROTATING INTO NRN ONTARIO ON MONDAY.
THE 00Z ECMWF SUGGESTS THIS WAVE WILL AMPLIFY CONSIDERABLY AS IT
DROPS ACROSS LOWER MI MON AFTERNOON/NIGHT...MUCH MORE THAN THE
CANADIAN AND ESPECIALLY THE GFS. SINCE THE ECMWF HAS BEEN EXTREMELY
CONSISTENT WITH THIS SOLUTION AND CONSIDERING THE DEGREE OF
UPSTREAM SHORT WAVE RIDGE AMPLIFICATION SHOWN IN ALL MODEL
SOLUTIONS...THE FORECAST WILL LEAN HEAVILY TOWARD THE ECMWF. WHILE
MOISTURE DEPTH MAY NOT BE IDEAL...THE ECMWF DOES SUGGEST THAT A
BRIEF PERIOD OF MID LEVEL FGEN AND GOOD HEIGHT FALLS ASSOCIATED WITH
THIS IMPULSE WILL BE ENOUGH TO SUPPORT A CHANCE OF SOME LIGHT RAIN
MON NIGHT. THIS MORE AMPLIFIED SOLUTION ALSO SHOWS A BETTER PUSH OF
LOW LEVEL COLD AIR UNDER STRONGER NE WINDS...WARRANTING AN INCREASE
IN FORECAST CLOUD COVER AND LOWERING OF TEMPS ON TUES. SHORT WAVE
RIDGING WILL THEN OVERSPREAD THE GREAT LAKES WED INTO THURS...
SUPPORTING DRY CONDITIONS. THE MEDIUM RANGE MODEL SUITE ALL AGREE IN
A PROGRESSIVE LONGER WAVELENGTH TROUGH PUSHING INTO THE GREAT LAKES
BY THE END OF THE WORK WEEK...SUPPORTING THE NEXT CHANCE OF RAIN ON
FRIDAY.

&&

.MARINE...

MARINE CONDITIONS WILL REMAIN BENIGN THIS WEEKEND INTO MONDAY AS
HIGH PRESSURE REMAINS ANCHORED OVER THE REGION. THE DEVELOPMENT AND
SUBSEQUENT STRENGTHENING OF NORTHEAST WINDS IS THEN FORECAST MON
NIGHT INTO TUESDAY AS A COLD FRONT DROPS ACROSS THE REGION FROM THE
NORTH.

&&

.AVIATION...ISSUED 1203 AM EDT SAT SEP 27 2014

//DISCUSSION...

THE LATEST TREND IN OBSERVATIONS INDICATES A CONVINCING PACE OF
COOLING AND MOISTENING FOR FOG DEVELOPMENT AT THE TERMINAL SITES.
JUDGING BY SURFACE DEWPOINT DEPRESSION AND THE NEWEST MODEL
SOUNDINGS...THE GENERAL FOG PATTERN CAN BE NUDGED DOWN INTO IFR IN
THE DTW CORRIDOR...WITH THE EXCEPTION OF DET...AND LIFR AT PTK
NORTHWARD. EXPECT THE FOG WILL HAVE A RADIATIONAL CHARACTER THAT
WILL BE SHALLOW ENOUGH TO LIFT AROUND MID MORNING. PERSISTENT
SURFACE HIGH PRESSURE COVERING THE GREAT LAKES WILL THEN GOVERN AN
OTHERWISE FAVORABLE AVIATION WEATHER PATTERN AS MORNING FOG BREAKS
INTO SUNNY SKY AND LIGHT EASTERLY WIND FOR THE REST OF THE DAY
FOLLOWED BY THICKENING HIGH CLOUDS SATURDAY NIGHT.

//DTW THRESHOLD THREATS...

* NONE.

&&

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

&&

$$

SHORT TERM...SF
LONG TERM....SC
MARINE.......SC
AVIATION.....BT


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






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