593
FXUS63 KDTX 140704
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
304 AM EDT MON OCT 14 2019
DISCUSSION
CONDITIONS TODAY WILL REMAIN GOVERNED BY COLD WEAKLY CYCLONIC FLOW,
AS SOUTHEAST MICHIGAN CONTINUES TO RESIDE WITHIN THE SOUTHERN
PERIPHERY OF A SPRAWLING MID LEVEL CYCLONE LIFTING ACROSS EASTERN
ONTARIO. THIS UNDERLYING PATTERN AUGMENTED BY THE DOWNSTREAM
ADVECTION OF MOISTURE OFF LAKE MICHIGAN AND DAYTIME HEATING WILL
SUPPORT A HIGHER COVERAGE OF STRATUS/STRATOCU THROUGHOUT THE
DAYLIGHT PERIOD. THE LIMITED INSOLATION POTENTIAL WILL EFFECTIVELY
REINFORCE AN ALREADY COLD RESIDENT ENVIRONMENT - EXISTING LOW LEVEL
THERMAL TROUGH DEFINED BY 850 MB TEMPERATURES NEAR -4C. THIS
SUPPORTS HIGHS OF UPPER 40S TO LOWER 50S...OR A SOLID 10 DEGREES
BELOW AVERAGE.
SURFACE RIDGING MARKING THE TRANSITION TOWARD DEEPER LAYER STABILITY
AS UPPER LEVEL FLOW TURNS WEAKLY ANTICYLONIC TAKES RESIDENCE
TONIGHT. THIS PROCESS FAVORS A PROGRESSIVE CLEARING OF ANY LINGERING
STRATOCU COINCIDENT WITH THE LOSS OF DIURNAL SUPPORT THIS EVENING,
WITH SIMPLY SOME THINNER HIGH CLOUD OVERNIGHT. A CORRESPONDING
REDUCTION IN THE NEAR SURFACE GRADIENT AND INCREASING DEPTH/
MAGNITUDE OF DRY AIR CONTINUE TO SIGNAL A RESPECTABLE RADIATIONAL
COOLING OPPORTUNITY. THIS WILL BRING MOST LOCATIONS DOWN INTO THE
MIDDLE 30S EARLY TUESDAY MORNING, ALLOWING FOR WIDESPREAD FROST
FORMATION. A FROST ADVISORY NOW IN EFFECT TO HIGHLIGHT THIS
EXPECTATION. RESIDENT THERMAL PROFILE SEEMINGLY JUST A TOUCH TOO
WARM TO SUPPORT A HIGHER COVERAGE OF LOW TEMPERATURES OF FREEZING,
ALTHOUGH THE VERY COLDEST LOCALES MAY NEAR THIS VALUE. THIS WILL
PRECLUDE CONSIDERATION OF A FREEZE HEADLINE.
NORTHERN STREAM SHORTWAVE NOW EJECTING OUT OF BRITISH COLUMBIA WILL
STRENGTHEN OVER THE NEXT 36 HOURS AS IT DIGS SOUTHEAST ACROSS THE
NORTHERN CONUS. THE RESULTING DEEP MID LEVEL CIRCULATION WILL THEN
PIVOT ACROSS THE GREAT LAKES TUESDAY NIGHT INTO EARLY WEDNESDAY. A
PERIOD OF MODEST WARM AIR ADVECTION WILL EMERGE DOWNSTREAM OF THESE
HEIGHT FALLS TUESDAY. THIS WILL NET ROUGHLY A 10 DEGREE WARMING
TREND FROM READINGS NOTED MONDAY - HIGHS MID 50S NORTH TO LOWER 60S
SOUTH. WHILE DEEP LAYER NORTHWARD MOISTURE TRANSPORT WILL GENERALLY
BE LACKING WITH THIS SYSTEM GIVEN THE MEAN WESTERLY MID LEVEL FLOW,
THERE EXISTS A WINDOW /MAINLY LATE IN THE DAY/ FOR SHOWERS TO EMERGE
WITHIN THE ONGOING ISENTROPIC ASCENT. GREATER POTENTIAL WITH
NORTHWARD EXTENT WITH ANY LEAD ACTIVITY. HIGHER LIKELIHOOD FOR
RAINFALL /LESS THAN 0.25"/ TUESDAY NIGHT TIED TO THE ATTENDANT COLD
FRONTAL PASSAGE AND ASSOCIATED INCREASE IN MID LEVEL DYNAMICS WITH
THE INBOUND UPPER CIRCULATION.
COLD CYCLONIC FLOW WILL AGAIN GRIP SOUTHEAST MICHIGAN WEDNESDAY.
INITIAL PERIOD OF POST-FRONTAL COLD AIR ADVECTION CURRENTLY
PROJECTED TO LACK THE STRENGTH NOTED FOR TODAY /850 MB TEMPERATURES
NEAR -1C/, BUT WILL EFFECTIVELY MAINTAIN BELOW NORMAL CONDITIONS.
THE ONGOING CYCLONIC VORTICITY ADVECTION CAPITALIZING ON A DIURNALLY
ENHANCED STEEP LAPSE RATE ENVIRONMENT WILL LIKELY SUPPORT A FEW
SHOWERS THROUGH THE DAY. MODEST MIXING OF A FIRM WEST TO NORTHWEST
GRADIENT WILL BRING GUSTY CONDITIONS FOR THE AFTERNOON -
POTENTIALLY IN EXCESS OF 30 MPH AT TIMES.
RESIDENT COLDER PATTERN HOLDS FIRM WEDNESDAY NIGHT THROUGH THURSDAY
NIGHT, AS DEEP LAYER NORTHWEST FLOW DICTATES CONDITIONS. MAINTENANCE
OF A SUFFICIENT BOUNDARY LAYER GRADIENT PRECLUDES FROST CONCERNS
WEDNESDAY NIGHT, WITH GREATER POTENTIAL THEN AGAIN THURSDAY NIGHT AS
SURFACE RIDGING BUILDS BACK IN. SUBSTANTIAL HEIGHT RISES CONCURRENT
WITH INCREASING SOUTHERLY FLOW WILL THEN TRANSLATE INTO A SOLID
WARMING TREND STARTING FRIDAY, WITH LATEST MODEL GUIDANCE SUGGESTING
THIS TREND CONTINUES RIGHT INTO NEXT WEEKEND. HIGHS OVER THE WEEKEND
BACK INTO THE 60S.
MARINE
ELEVATED WESTERLY GRADIENT REMAINS IN PLACE ACROSS LAKE HURON TODAY
AS THE CENTER OF BROAD LOW PRESSURE CONTINUES TRACKING TOWARD JAMES
BAY AND HIGH PRESSURE BUILDS INTO THE OHIO VALLEY. AMPLE COLD AIR
MOVING OVER THE REGION IN THE WAKE OF THE DEPARTING SYSTEM MAKE
WATERSPOUTS POSSIBLE TODAY, PARTICULARLY ACROSS NORTHERN LAKE HURON.
WINDS WEAKEN TONIGHT INTO EARLY TUESDAY, THEN BACK TO THE SOUTHEAST
AND RESTRENGTHEN IN ADVANCE OF A DEVELOPING LOW PRESSURE SYSTEM
SET TO TRACK THROUGH THE NORTHERN GREAT LAKES TUESDAY NIGHT. FRESH
COLD ADVECTION AND STRONG NORTHWEST FLOW IN THE WAKE OF THE SYSTEM
WILL HAVE GOOD POTENTIAL TO PRODUCE GALES BY LATE WEDNESDAY.
PREV DISCUSSION
ISSUED AT 1155 PM EDT SUN OCT 13 2019
AVIATION...
COLD CORE OF UPPER LEVEL LOW IS CURRENTLY BULLDOZING THROUGH
SOUTHEAST MICHIGAN. STRONG 900-800MB COLD ADVECTION WILL BEGIN JUST
AFTER THE START OF THE FORECAST PERIOD LEADING TO STOUT STRATUS DECK
FOR ALL AREAS. OBSERVATION TRENDS UPSTREAM OVER PORTIONS OF
SOUTHWEST MICHIGAN SUPPORTS THIS IDEA. THE STRATUS DECK IS EXPECTED
TO BLANKET THE AREA THROUGH THE MORNING AND TRANSITION INTO
STRATOCUMULUS AS DAYTIME HEATING RAISES CLOUD BASES. PRESSURE
GRADIENT REMAINING IN PLACE WILL ALLOW WINDS TO INCREASE MODESTLY
10-20 KNOTS AGAIN MONDAY.
DTW THRESHOLD PROBABILITIES...
* HIGH FOR CIG AOB 5KFT TONIGHT AND MONDAY MORNING.
DTX WATCHES/WARNINGS/ADVISORIES
MI...FROST ADVISORY FROM 2 AM TO 8 AM EDT TUESDAY FOR MIZ047>049-053>055-
060>063-068>070-075-076-082-083.
LAKE HURON...SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR LHZ421-422-
441.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
DISCUSSION...MR
MARINE.......TF
AVIATION.....CB
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