Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 290746
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
346 AM EDT FRI APR 29 2016

.DISCUSSION...

SE MICHIGAN POSITIONED EARLY THIS MORNING UNDER WEAK DEFORMATION
EXTENDING FROM A CLOSED MID LEVEL CIRCULATION ANCHORED JUST
UPSTREAM.  THIS PERTURBED MID LEVEL FIELD SUSTAINING SOME POCKETS OF
LIGHT SHOWERS...ABOVE A LOW LEVEL PROFILE CHARACTERIZED AS
SEASONABLY COOL UNDER PERSISTENT NORTHEAST FLOW.  A COOL AND
UNSETTLED PATTERN WILL HOLD TODAY...REINFORCED BY THE EASTWARD
EJECTION OF THE AFORMENTIONED UPPER LOW THROUGH MID AFTERNOON. SOLID
INCREASE IN DCVA AND CONVERGENCE ACCOMPANYING THIS FEATURE...WITH A
NOTED SPIKE IN MID LEVEL LAPSE RATES BENEATH THE ASSOCIATED MID
LEVEL COLD POOL.  AN ADDITIONAL DIURNAL CONTRIBUTION WILL
SUBSEQUENTLY SUPPORT AN INCREASE IN SHOWER COVERAGE FROM MID MORNING
INTO EARLY AFTERNOON.  LATEST HI RES GUIDANCE PROJECTS A SLIGHTLY
GREATER RESPONSE ACROSS THE HEART OF THE FORECAST AREA /BETWEEN I-69
AND I-94/...STRONGER SIGNAL OF CONVERGENCE ALIGNING ACROSS THIS
CORRIDOR.  PRECIPITATION AND CORRESPONDING HIGHER CLOUD COVERAGE
WILL AGAIN ACT TO RESTRICT THE DIURNAL TEMPERATURE RESPONSE OF AN
ALREADY COOL RESIDENT THERMAL PROFILE /850 MB TEMPS NEAR FREEZING/.
HIGHS LARGELY IN THE LOWER 50S.

EMERGING WEAK MID LEVEL SUBSIDENCE AND GENERAL DRYING THROUGH THE
COLUMN WILL SUPPORT A CLEARING TREND TONIGHT IN THE WAKE OF THIS
SYSTEM.  A PERSISTENT LIGHT NORTHEAST LOW LEVEL GRADIENT WILL CAP
THE OVERALL RADIATIONAL COOLING RESPONSE...BUT OVERALL MAGNITUDE OF
THE EXISTING COLDER PROFILE WILL STILL BRING LOWS SATURDAY MORNING
INTO THE 30S NEARLY ALL LOCALES.  SOME POCKETS OF FROST NOT OUT OF
THE QUESTION /PARTICULARLY IN THE THUMB/...BUT AGAIN THE GRADIENT
WILL BE A LIMITING FACTOR.  GIVEN THIS AND THE FACT THAT THE GROWING
SEASON IS STILL LAGGING ACROSS THE TRI-CITIES AND THUMB...WHERE
FROST WOULD BE MORE LIKELY...WILL REFRAIN FROM A MENTION AT THIS
STAGE.

GENERAL SURFACE RIDGING AND CORRESPONDING DRY LOW LEVEL EASTERLY
FLOW...TUCKED BENEATH WEAKLY CONFLUENT MID LEVEL WESTERLIES...WILL
PRESENT A BENIGN PERIOD OF WEATHER FOR SATURDAY.  SOME OF EARLY DAY
SUN BEFORE HIGH CLOUDS THICKEN IN ADVANCE OF THE NEXT SYSTEM.
INCREASING THICKNESSES AND THE ADDED INSOLATION WILL BRING DAYTIME
TEMPERATURES INTO THE 55 TO 60 DEGREE RANGE.

SHORTWAVE ENERGY PIVOTING THRU THE PERIPHERY OF A CLOSED LOW PARKED
OVER THE CENTRAL PLAINS WILL ELICIT A SOLID LOW/MID LEVEL RESPONSE
IMMEDIATELY DOWNSTREAM EARLY THIS WEEKEND...THIS PROCESS TARGETING
SE MICHIGAN BY SATURDAY EVENING/NIGHT.  THE REGION WILL RECEIVE A
GLANCING SHOT OF THE ATTENDANT NORTHEAST SURGING MOISTURE PLUME /PW
NEAR 1 INCH/ BACKED BY A FORMIDABLE LOW LEVEL JET ARCING THROUGH THE
MIDWEST AND STRENGTHENING ISENTROPIC ASCENT.  UPGLIDE ALONG THE
ISENTROPIC SURFACE WILL DRIVE THE EARLY STAGES OF THE EFFECTIVE
RAINFALL AXIS EARLY SATURDAY NIGHT...BEFORE A TRANSITION TOWARD MID
LEVEL DEFORMATION NORTH OF THE SURFACE LOW RACING THROUGH THE OHIO
VALLEY.  SOME UNCERTAINTY YET ON THE NORTHWARD EXTENT OF THE BOTH
THE BETTER FORCING AND DEEPER MOISTURE...BUT CERTAINLY GROWING
CONFIDENCE ON WITNESSING A SOLID PERIOD OF RAIN ACROSS AT LEAST THE
SOUTHERN HALF SATURDAY NIGHT.  CORRESPONDING NUDGE UPWARD IN POPS
ACROSS THIS CORRIDOR.

SHOWERS MAY REMAIN PREVALENT THROUGH EARLY SUNDAY AS LINGERING
DEFORMATION SLOWLY RELEASES EASTWARD.   REGARDLESS...TEMPERATURES
LIKELY TO TAKE STEP BACK FROM THOSE NOTED SATURDAY...UNDER RENEWED
COOLER NORTHEAST FLOW AND PLENTY OF RESIDUAL CLOUDINESS.  THE
SUPPRESSED UPPER HEIGHTS AS MID LEVEL TROUGHING EASES THROUGH WILL
CONTRIBUTE TO THE COOLER TREND.  READINGS SUNDAY BROADLY
DISTRIBUTED IN THE 50S.

&&

.MARINE...

LIGHT TO MODERATE BREEZE EXPECTED THROUGH MIDDAY SATURDAY. A WEAK
LOW LIFTING THROUGH THE OHIO RIVER VALLEY WILL THEN PROVIDE SEVERAL
HOURS OF MODERATE TO FRESH ONSHORE FLOW LATE SATURDAY THROUGH
SUNDAY. THE PROLONGED PERIOD OF ONSHORE FLOW WILL LIKELY NECESSITATE
SMALL CRAFT ADVISORIES FOR ELEVATED WAVE CONDITIONS FOR THE
NEARSHORE WATERS OF LAKE HURON DURING THIS TIME.

&&

.AVIATION...ISSUED 1232 AM EDT FRI APR 29 2016

THE DEFORMATION AXIS WILL CONTINUE TO YIELD SCATTERED LIGHT RAIN
SHOWERS OVERNIGHT. THE MAIN CORRIDOR OF THE RAIN SHOWERS OVER THE
PAST FEW HOURS HAS BEEN OVER THE NORTHERN CWA INCLUDING THE SAGINAW
BAY REGION. EXPECTATIONS ARE FOR VFR CIGS TO HOLD THROUGHOUT THE
NIGHT. THE POTENTIAL FOR SHOWERS WILL INCREASE DURING THE LATE
MORNING HOURS AS THE MAIN MIDLEVEL LOW PRESSURE SYSTEM APPROACHES
SOUTHEASTERN MICHIGAN. INCREASED CONVERGENCE AND DCVA IMMEDIATELY IN
ADVANCE OF THIS FEATURE WILL BRING A BETTER POTENTIAL FOR LIGHT RAIN
DURING THE 13-19Z TIME WINDOW. THE BEST SIGNAL FOR ACTIVITY
CONTINUES TO APPEAR ALONG AND SOUTH OF THE I 69 CORRIDOR.
AGAIN...LIGHT RAIN ACTIVITY WITH PERSISTENT VFR CONDITIONS.

FOR DTW...PERSISTENT DRY EASTERLY FLOW IS EXPECTED TO KEEP
CONDITIONS AT VFR BOTH IN RESPECT TO CIG HEIGHTS AND VSBYS THROUGH
TONIGHT.

//DTW THRESHOLD PROBABILITIES...

* HIGH FOR CEILING 5000 FEET OR LESS TONIGHT THROUGH FRIDAY.

&&

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

$$

DISCUSSION...MR
MARINE.......JVC
AVIATION.....JVC


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