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000
FXUS63 KDTX 300430
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1130 PM EST FRI NOV 29 2013


.AVIATION...

//DISCUSSION...

MID AND HIGH LEVEL CLOUDS WILL CONTINUE TO WORK INTO LOWER MICHIGAN
TONIGHT AS LOW PRESSURE TRACKS TOWARDS THE NORTHERN GREAT LAKES. VFR
CONDITIONS ARE EXPECTED TO PREVAIL AT ALL SOUTHEAST MICHIGAN
TERMINALS THROUGH THE REMAINDER OF TONIGHT AND TOMORROW. A COLD
FRONT WILL THEN BEGIN TO DROP DOWN THROUGH THE AREA SATURDAY NIGHT
AS LOW PRESSURE TRACKS NORTH OF LAKE HURON. THIS WILL BRING LOWER
CLOUDS AND A CHANCE FOR SNOW SHOWERS...WHICH MAY MIX WITH RAIN LATE.
BY 06Z...SHOWERS AHEAD OF THE FRONT ARE EXPECTED TO JUST MAKE IT
INTO THE MBS AREA.

FOR DTW...CEILINGS BELOW 5000 FEET AND RAIN/SNOW SHOWERS SHOULD HOLD
OFF UNTIL JUST BEYOND THE TAF PERIOD (AFTER 12Z SUN).

//DTW THRESHOLD THREATS...

* HIGH CONFIDENCE IN CEILINGS ABOVE 5000 FEET THROUGH SATURDAY
EVENING.

&&

.PREV DISCUSSION...ISSUED 822 PM EST FRI NOV 29 2013

UPDATE...
GOING FORECAST REMAINS IN GOOD SHAPE THIS EVENING AS STRONG HIGH
PRESSURE EXITS EAST AND MID AND HIGH LEVEL CLOUDS BEGIN TO FILL IN
AHEAD OF LOW PRESSURE STILL OVER SASKATCHEWAN AND MANITOBA.
TEMPERATURES HAVE ALREADY FALLEN INTO THE UPPER TEENS TO MID 20
ACROSS THE AREA. EXPECT TO SEE THESE TEMPS LEVEL OFF OVER THE NEXT
FEW HOURS AS CLOUDS MOVE IN AND THICKEN...AND AS THE LIGHT
SOUTHEAST WIND CONTINUES TO STRENGTHEN IN RESPONSE TO THE
TIGHTENING PRESSURE GRADIENT. DID MAKE A QUICK ADJUSTMENT TO DROP
TEMPS A FEW DEGREES BEFORE ALL THESE PROCESSES AND WARMING TAKES
PLACE.

PREV DISCUSSION...ISSUED 328 PM EST FRI NOV 29 2013

SHORT TERM...TONIGHT

A 1042MB SFC HIGH WILL MOVE FROM THE EASTERN GREAT LAKES THIS
AFTERNOON TO NEW ENGLAND BY SATURDAY MORNING IN ADVANCE OF A MID
LEVEL SHORT WAVE RIDGE. THERE IS A REGION OF MID/HIGH LEVEL CLOUDS
ALREADY ADVANCING INTO THE NORTHERN AND WESTERN PART OF THE STATE.
THESE CLOUDS ARE ASSOCIATED WITH A BROAD REGION OF LOW-MID LEVEL
WARM AIR ADVECTION EXTENDING FROM MN INTO THE WRN GREAT LAKES. THIS
REGION OF ASCENT WILL OVERSPREAD SE MI TONIGHT AND WILL LEAD TO
INCREASING MID CLOUDS DURING THE COURSE OF THE NIGHT. EXTREMELY DRY
LOW LEVEL AIR HAS BEEN LIFTING INTO SRN MI THIS AFTERNOON. THIS WILL
SUPPORT A PERIOD OF CLEAR SKIES THIS EVENING BEFORE MID/HIGH CLOUDS
THICKEN...ALLOWING TEMPS TO DROP WELL DOWN INTO THE 20S. A
STRENGTHENING S-SE GRADIENT AND CLOUD COVER DURING THE OVERNIGHT
WILL LEAD TO STEADY IF NOT SLOWLY RISING TEMPS PAST MIDNIGHT.

LONG TERM...SATURDAY THROUGH FRIDAY

MODELS IN GOOD AGREEMENT THROUGH THE REST OF THE WEEKEND INTO THE
START OF NEXT WEEK. GIVEN THE WEAK DYNAMICS WITH THE NEXT SYSTEM
THAT MOVE THROUGH THE FORECAST AREA SATURDAY NIGHT INTO EARLY SUNDAY
MORNING...LIKE THE LESS AGRESSIVE QPF AND MOISTURE PROFILE OF THE
GFS.

SATURDAY WILL BE BREEZY AS SOUTHERLY WINDS BRINGING IN SOME MODIFIED
AIR AND TEMPS WARM CLOSE TO 40. THE MID CLOUDS IN THE MORNING WILL
GIVE WAY TO SOME PARTIAL SUN DURING THE DAY...ONLY TO BE REPLACED
WITH ANOTHER BATCH OF WARM AIR ADVECTION/MOISTURE ADVECTION AND THE
ASSOCIATED CLOUDS TOWARDS SUNSET.

THE ONLY THING REALLY GOING FOR THE NEXT COLD FRONT THAT MOVES
THROUGH THE REGION LATER SATURDAY NIGHT AND INTO SUNDAY MORNING...IS
THE FRONT ITSELF. THERE IS JUST A BRIEF WINDOW OF WEAK FORCING AND
MODEST MOISTURE. THE DEFORMATION AND FGEN AS WEAK AS IT IS...IS
LIMITED TO THE TRI CITIES AND THUMB REGIONS. THERE IS ALSO A NARROW
BAND OF SYSTEM RELATIVE ISENTROPIC LIFT THAT OVERLAPS WITH JUST
ENOUGH MOISTURE TO PRODUCE SOMETHING. WILL HAVE LIKELY POPS FOR
HURON COUNTY WITH JUST CHANCE OR SLIGHT CHANCE POPS EVERYWHERE
ELSE.  BOUNDARY LAYER STAYS JUST WARM ENOUGH TO BRING A CHANCE OF
RAIN WITH THE SNOW IN THE WARM SECTOR BEFORE THE FRONTAL PASSAGE.

BEHIND THE FRONT ON SUNDAY AFTERNOON...THERE MAY BE A FEW FLURRIES
WITH TEMPERATURES NEARLY STEADY. THERE IS SOME INDICATION OF MOIST
LAPSE RATES WITH CONVECTIVE DEPTHS AS HIGH AS 5K TO 7K FT.

THEN ON MONDAY THE FLOW TURNS NORTHEAST TO EASTERLY AND INJECTS SOME
LAKE MOISTURE WITH MODEST UNSTABLE CONDITIONS OVER LAKE HURON.
ADDITIONALLY...A SHORTWAVE TROF AT 500 MB DEVELOPS OVER THE GREAT
LAKES IN RESPONSE TO THE NEXT SHORTWAVE MOVING TOWARD THE REGION.
AGAIN MODEL PROFILES INDICATE THIS MOISTURE WITH DECENTLY STEEP
LAPSE RATES WITH THE DIURNAL CYCLE.  WILL GO WITH A SMALL CHANCE OF
SNOW SHOWERS FOR THE THUMB AND TRI CITIES WITH THE BETTER LAKE HURON
EASTERLY FLOW.  JUST A CHANCE OF SPRINKLES OR FLURRIES FOR THE REST
OF THE REGION AS BOUNDARY LAYER TEMPS WARM.

THE EXTENDED FORECAST WILL BE MARKED BY WARMER TEMPS AS THE NEXT
SYSTEM OUT IN THE PLAINS APPROACHES THE REGION.  SOUTHEAST MICHIGAN
WILL BE IN BETWEEN A SURFACE LOW MOVING UP THE EAST COAST AND THE
NEXT DEVELOPING SYSTEM OUT WEST. 500MB TROUGH WILL MOVE THROUGH THE
AREA AND SLIDE EAST TUESDAY NIGHT AS A RIDGE BUILDS IN ON
WEDNESDAY.  MODELS ARE SHOWING A WEAK AREA OF VORTICITY MOVING JUST
TO THE SOUTH ON MONDAY WHICH MAY BRING SOME SHOWERS...WITH BETTER
CHANCES TOWARDS THE OHIO BORDER.  BETTER CHANCES FOR PRECIP WILL
COME IN THE MIDDLE OF THE WEEK.  MODELS CURRENTLY HAVE THE LOW
TRACKING ACROSS NORTHERN MINNESOTA WEDNESDAY AND THURSDAY WITH THE
ASSOCIATED COLD FRONT TRACKING ACROSS THE MIDWEST. EASTERLY WINDS
WILL START TO VEER MORE TO THE SOUTH AS THE WAA FROM THE APPROACHING
SYSTEM MOVES CLOSER EARLY WEDNESDAY MORNING. THE 12Z EURO IS
SLIGHTLY SLOWER WITH THE PASSAGE OF THE FRONT COMPARED TO THE FASTER
GFS...WHICH WILL NEED TO BE WATCHED FOR CHANGES TO PRECIP TYPES.
CHANCES FOR PRECIP INCREASE WEDNESDAY NIGHT AND PRECIP MAY START
OFF AS A MIX...ESPECIALLY FOR NORTHERN AREAS OF THE CWA...BEFORE
WARMER AIR WORKS IN AND CHANGES IT TO ALL RAIN ON THURSDAY.

THE WORKWEEK IN THE FIRST WEEK OF DECEMBER WILL CONTINUE TO SEE
TEMPERATURES RIGHT AROUND TO JUST ABOVE NORMAL.  TEMPS WILL START
OFF IN THE MIDDLE TO UPPER 30S BEFORE SLOWLY WARMING INTO THE LOWER
40S BY THE END OF THE WORKWEEK. WESTERLY WINDS BEHIND THE DEPARTING
SYSTEM FRIDAY WILL START TO COOL THINGS OFF...BUT TEMPS LOOK TO
REMAIN AROUND NORMAL.

MARINE...

WITH SOME CLEARING AT TIMES THROUGH THE DAY FOR DIFFERENT
LOCALES...THE VISIBLE SATELLITE IMAGE SHOWED A DECENT AMOUNT OF ICE
ON THE INNER SAGINAW BAY...AND SOME THINNER ICE FOR ANCHOR BAY AND
SOUTHEAST LAKE ST. CLAIR. THERE IS ENOUGH TO START INCLUDING THE
PHRASE OF WAVES IN ICE FREE AREAS.

HIGH PRESSURE OVER THE EASTERN GREAT LAKES WILL CONTINUE TO MOVE
EAST TONIGHT. THE GRADIENT BETWEEN THIS HIGH AND THE LOW OVER THE
SOUTH CENTRAL CANADA WILL MOVE OVER THE THE CENTRAL GREAT LAKES
LATER TONIGHT AND SATURDAY WHILE CONDITIONS WILL STILL BE MODESTLY
UNSTABLE OVER THE LAKES. THIS WILL PRODUCE STRONGER SOUTH WINDS THAT
WILL TURN TO THE SOUTHWEST BY SATURDAY AFTERNOON. THE WINDS LOOK TO
BE JUST BELOW GALE AND SMALL CRAFT ADVISORY CRITERIA. GIVEN THAT THE
PEAK OF THE WIND IS STILL ABOUT 24 HOURS OUT...WILL CONTINUE THE
GALE WATCH TO ALLOW FURTHER REFINEMENT OF THE WIND POTENTIAL.

WINDS WILL VEER AND WEAKEN WITH TIME SATURDAY NIGHT AND SUNDAY AS
THE LOW FROM SOUTH CENTRAL CANADA PASSES NORTH OF THE GREAT LAKES.

&&

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

&&

$$

AVIATION.....HLO
UPDATE.......HLO
SHORT TERM...SC
LONG TERM....RBP/SS
MARINE.......RBP


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