Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 172305
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
705 PM EDT SUN AUG 17 2014


.AVIATION...

//DISCUSSION...

THE LOSS OF DAYTIME HEATING WILL CAUSE SKIES TO CLEAR NORTH OF PTK.
THIS WILL LEAD TO GOOD BOUNDARY LAYER COOLING AND CONTINUES TO
SUGGEST A CHANCE OF SOME MVFR TYPE VISIBILITIES IN FOG...MAINLY FOR
PTK/FNT/MBS. A SUBTLE DROP IN AFTERNOON DEWPOINTS AND A SOMEWHAT
LESS THAN IDEAL GRADIENT APPEAR TO BE LIMITING FACTORS FOR GREATER
SFC VSBY REDUCTIONS IN FOG.

FOR DTW...WHILE DAYTIME HEATING HAS LIFTED CLOUD BASES...A BAND OF
MID LEVEL MOISTURE IS EXPECTED TO PERSIST OVER METRO WELL INTO THE
NIGHT. THIS SHOULD RESULT IN OCCASIONAL CLOUDS BETWEEN 5K AND 7K FT
THROUGH THE NIGHT AND WILL GREATLY LIMIT FOG POTENTIAL.

//DTW THRESHOLD THREATS...

* LOW CONFIDENCE IN CEILINGS AT OR BELOW 5000 FT TONIGHT AND MON
MORNING.

&&

.PREV DISCUSSION...ISSUED 330 PM EDT SUN AUG 17 2014

SHORT TERM...THROUGH TONIGHT

SOUTHERN LOWER MI REMAINS IN THE TRANSITION ZONE BETWEEN A LOW
PRESSURE SYSTEM TRACKING THROUGH THE OHIO VALLEY AND HIGH PRESSURE
BUILDING SE THROUGH ONTARIO. THE TRANSITION ZONE IS ALSO THE
LOCATION OF THE COLD FRONT LAID OUT BY YESTERDAYS DEPARTING LOW
PRESSURE SYSTEM WELL TO OUR EAST NOW WHICH IS PHASING WITH A WARM
FRONT PRECEDING THE LOW OVER THE OHIO VALLEY. MOISTURE WRAPPING
AROUND THE LOW IS ACTING TO REINFORCE THE ALREADY MOIST RIBBON ALONG
THE COLD FRONT WHICH HAS RESULTED IN A SOLID CLOUD DECK THROUGH THE
AFTERNOON WITH SOME LIGHT SHOWERS NOW POPPING UP OVER SW LOWER MI.
WILL HOLD ONTO THE SLIGHT CHANCE POPS ACROSS THE FAR SOUTH AS THESE
PULSE LIGHT SHOWERS LINGER FOR A FEW HOURS. OTHERWISE DRY THROUGH
THE OVERNIGHT.

AS THE PATTERN EVOLVES THROUGH THE EVENING...PRESSURE WILL BEGIN TO
RISE AT THE SURFACE AS HEIGHTS ALOFT INCREASE WITH SHORTWAVE RIDGING
ADVANCING OVER THE AREA. OVERALL THIS WILL ACT TO DRY OUT THE COLUMN
ALOFT BUT MOISTURE REMAIN LOCKED IN THE BL. THIS WILL ONCE AGAIN
PRESENT THE OPPORTUNITY FOR SOME FOG TO DEVELOP LATE TONIGHT. THIS
WILL BE LESS LIKELY SOUTH OF ABOUT I96 AS THEY HAVE BEEN SOCKED IN
WITH CLOUDS ALL DAY WHICH MAY LINGER INTO THE OVERNIGHT SLOWING DOWN
COOLING EFFECTS. TO THE NORTH...A DIURNAL CU FIELD DEVELOPED THIS
AFTERNOON WHICH WILL FADE QUICKLY THIS EVENING ALLOWING FOR A BETTER
RADIATIONAL COOLING RESPONSE. JUDGING FROM LAST NIGHT...EXPECT A
SLIGHTLY BETTER COVERAGE OF FOG. MODELS ARE ALL HITTING ON THIS
ALTHOUGH NOT QUITE AS HARD AS THEY DID FOR LAST NIGHT.

LONG TERM...MONDAY THROUGH SUNDAY

QUIET WEATHER WILL PERSIST INTO MONDAY AND MONDAY NIGHT AS SURFACE
HIGH PRESSURE GRADUALLY BUILDS EAST FROM THE NORTHERN GREAT LAKES
AND ONTARIO INTO QUEBEC. A STRAY SHOWER IS NOT OUT OF THE QUESTION
NEAR THE MICHIGAN AND OHIO STATE LINE AS THE DRY AIR ASSOCIATED WITH
THIS AFOREMENTIONED HIGH SHIFTS SLOWLY OFF TO THE EAST...BUT MOST IF
NOT ALL LOCATIONS ARE EXPECTED TO REMAIN DRY.

AS AUGUST SLOWLY WANES...AVERAGE TEMPERATURES HAVE EDGED DOWN TO
NEAR 60 FOR LOWS AND 80 FOR HIGHS. SO...TEMPERATURES WILL BE ONLY A
DEGREE OR TWO BELOW AVERAGE.

SHOWER AND THUNDERSTORM CHANCES RETURN DURING THE COURSE OF THE DAY
TUESDAY AS AN UPPER LOW PRESSURE CURRENTLY LOCATED OVER TOP OF THE
MEAN UPPER RIDGE AXIS OVER THE CANADIAN ROCKIES SHIFTS SLOWLY INTO
THE AREA. DRY AIR ASSOCIATED WITH THE EXITING SURFACE HIGH PRESSURE
SYSTEM WILL TAKE SOME TIME TO DISLODGE...SO THE COVERAGE OF SHOWERS
AND STORMS WILL ONLY GRADUALLY INCREASE OVER THE AREA...PARTICULARLY
IN THE AFTERNOON AND EVENING.

TEMPERATURES WILL REMAIN LARGELY THE SAME AS MONDAY AS THIS UPPER
LOW REMAINS UNCONNECTED TO THE NORTHERN STREAM POLAR JET STREAM AND
ACTUALLY DROPS UNDER A DEVELOPING RIDGE WITH THIS NORTHERN FLOW AS
HEIGHTS EXPAND OVER MUCH OF EASTERN CANADA FOR ONE OF THE FEW TIMES
THIS SUMMER.

DAYS 4 THROUGH 7:

THE LOW PRESSURE SYSTEM THAT DROPS OUT OF SOUTH CENTRAL CANADA ON
TUESDAY WILL CONTINUE MOVING ACROSS THE GREAT LAKES ON WEDNESDAY
KEEPING SHOWERS AND THUNDERSTORMS IN THE FORECAST FOR THE CENTRAL
GREAT LAKES. THE UPPER LEVEL TROUGH WILL LINGER ACROSS THE GREAT
LAKES WITH A FRONTAL BOUNDARY JUST TO OUR SOUTH...MAINTAINING RAIN
CHANCES THROUGH THE END OF THE WEEK. THIS TROUGH WILL EVENTUALLY
SLIDE EAST...HOWEVER ANOTHER SYSTEM IS FAST ON ITS HEELS...SO SOME
MENTION OF SHOWERS WILL PERSIST INTO NEXT WEEKEND...AT LEAST FOR
SOUTHERN SOUTHEAST MICHIGAN.

MARINE...

WITH HIGH PRESSURE CENTERED JUST NORTH AND NORTHEAST OF THE AREA AND
FIRMLY ESTABLISHED INTO THE CENTRAL GREAT LAKES...MARINE CONDITIONS
WILL REMAIN QUITE FAVORABLE INTO TUESDAY WITH LIGHT NORTHEAST TO
EAST FLOW AND MINIMAL WAVE DEVELOPMENT. AN APPROACHING LOW PRESSURE
SYSTEM WILL EVENTUALLY BRING ANOTHER CHANCE OF SHOWERS AND STORMS BY
LATE TUESDAY AND TUESDAY NIGHT...BUT WITH VERY LITTLE BAROCLINICITY
WITH THIS SYSTEM...THE FLOW OVER THE REGION WILL REMAIN WEAK AND
WINDS AND WAVES WILL REMAIN SUBDUED.

&&

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

&&

$$

AVIATION.....SC
SHORT TERM...DRK
LONG TERM....DG/DE
MARINE.......DG


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AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).






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