Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
975
FXUS63 KDTX 291237
AFDDTX

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


.AVIATION...

WIDESPREAD VFR THROUGH MOST OR ALL OF THE PERIOD AS SCATTERED LIGHT
SHOWERS WORK THROUGH MORNING. BEST COVERAGE OF SHOWERS IS EXPECTED
TO BE FOCUSED IN THE KFNT/KPTK CORRIDOR WHERE A BRIEF DIP TO MVFR
WILL BE POSSIBLE. OBSERVATIONS INDICATE ENCROACHING MVFR FROM THE
SOUTHWEST, BUT DRY NE FLOW IN THE LOWER-LEVELS HAS KEPT EASTWARD
PROGRESS HALTED THROUGH THE EARLY MORNING, A TREND THAT SHOULD
LARGELY CONTINUE. WINDS REMAINS OUT OF THE EASTERLY QUADRANT THROUGH
THE PERIOD.

FOR DTW...WIDESPREAD CLOUD COVER BELOW 5KFT IS EXPECTED TODAY. ANY
DIP TO MVFR SHOULD BE BRIEF. EAST WIND WILL DEVELOP LATE TONIGHT,
INCREASING TO 15 KTS EARLY SATURDAY.

//DTW THRESHOLD PROBABILITIES...

* HIGH FOR CIG AOB 5KFT.

&&

.PREV DISCUSSION...ISSUED 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.

&&

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

$$

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


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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.