Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 271647
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1247 PM EDT MON APR 27 2015

.AVIATION...

EXISTING EXTENSIVE MVFR DIURNAL CLOUD FIELD WILL GRADUALLY LIFT INTO
VFR THROUGH THE AFTERNOON.  CLOUD COVERAGE WILL DIMINISH WITH TIME
THROUGH THE EVENING PERIOD AS DAYTIME HEATING WANES.  A NORTH TO
NORTHEAST WIND FIELD MAY DRAW ADDITIONAL MOISTURE INTO THE REGION
TONIGHT.  THIS WILL SUPPORT ADDITIONAL POCKETS OF VFR CLOUDS.  THERE
IS AT LEAST A LOW POTENTIAL FOR CEILINGS TO DIP BELOW 3K FT
WEDNESDAY MORNING AS THE INVERSION LEVEL DROPS...PARTICULARLY AT
PTK/FNT.

//DTW THRESHOLD PROBABILITIES...

* HIGH IN CEILINGS BELOW 5000 FT THROUGH THE AFTERNOON...LOW THIS
  EVENING AND TONIGHT.

&&

.PREV DISCUSSION...ISSUED 322 AM EDT MON APR 27 2015

SHORT TERM...TODAY AND TONIGHT

EARLY MORNING US/CANADIAN RADAR COMPOSITE LOOP HAS BEEN SHOWING A
REGION OF SHOWERS ADVANCING ACROSS LAKE HURON AND THE THUMB. THESE
SHOWERS ARE ASSOCIATED WITH A COMPACT MID LEVEL SHORT WAVE NOW
DROPPING INTO LAKE HURON FROM THE NORTHEAST. THE MAIN RIBBON OF
LARGE SCALE ASCENT VIA GOOD DCVA WILL PRECEDE THE WAVE...WHICH IS
FORECAST TO ROTATE ACROSS SE MI DURING THE COURSE OF THE MORNING.
THE ASSOCIATED MID LEVEL COLD POOL AND RESULTANT STEEP MID LEVEL
LAPSE RATES WILL DROP SOUTH ACROSS THE THUMB AND POINTS EAST THIS
MORNING. THIS IS ALSO WHERE THE POOL OF DEEPER MOISTURE WILL RESIDE.
THUS THE GREATER COVERAGE OF EARLY MORNING SHOWERS WILL REMAIN
ACROSS THE THUMB INTO THE NORTHEASTERN DETROIT SUBURBS...WITH
COVERAGE DECREASING TO THE WEST. ANY HIGHER INTENSITY RAIN SHOWERS
THIS MORNING WILL BE VERY BRIEF...SO OVERALL QPF AMOUNTS ARE
EXPECTED TO ONLY BE A FEW HUNDREDTHS OF AN INCH OR LESS.

A MID LEVEL SUBSIDENCE BUBBLE WILL THEN SPREAD ACROSS SE MI THIS
AFTERNOON IN THE WAKE OF THIS SHORT WAVE. THE CORRESPONDING MID
LEVEL WARMING WILL REDUCE THE AFTERNOON CONVECTIVE CLOUD DEPTHS
SUBSTANTIALLY AND SUPPORTS THE CURRENT DRY FORECAST. SE MI WILL
REMAIN ON THE WESTERN EDGE OF A BROAD REGION OF LOW LEVEL CYCLONIC
FLOW EXTENDING ALL THE WAY TO NEW ENGLAND. UPSTREAM SATELLITE AND
SFC OBSERVATIONS TO THE NORTHEAST OF LAKE HURON SUGGEST AMPLE LOW
LEVEL MOISTURE WILL REMAIN IN PLACE TODAY...WHICH WILL EVOLVE INTO A
FAIRLY EXTENSIVE STRATO CU FIELD UNDER THE MID LEVEL INVERSION THIS
AFTERNOON. DESPITE THE EXPECTED CLOUD COVER...NAM AND RAP SOUNDINGS
STILL SUGGEST STEEPENING LOW LEVEL LAPSE RATES AND RISING MIXING
DEPTHS DURING THE AFTERNOON WILL SUPPORT HIGHS WELL INTO THE 50S.
NORTHERLY WINDS OFF LAKE HURON WILL AGAIN KEEP THE SHORELINE LOCALS
SEVERAL DEGREES COOLER.

LOW LEVEL CYCLONIC FLOW WILL EASE ITS GRIP ON SE MI TONIGHT AS
HIGH PRESSURE NUDGES INTO LOWER MI FROM THE WEST. ANOTHER MID
LEVEL SHORT WAVE /ALBEIT MUCH WEAKER/ WILL SLIDE SOUTH ACROSS ERN
LOWER MI TONIGHT WITHIN THE PERSISTENT MID LEVEL CYCLONIC FLOW.
THIS FEATURE WILL LIKELY JUST LEAD TO SOME PERIODIC MID CLOUDS.
MODEL RH PROGS DO HOWEVER SUGGEST THE EROSION OF THE DIURNALLY
ENHANCED CU FIELD WILL TAKE WELL INTO THE NIGHT...LIKELY A RESULT
OF THE PERSISTENT INVERSION. THESE FACTORS WILL SUPPORT LEANING ON
THE HIGH END OF MOS GUIDANCE FOR MIN TEMPS /RANGING FROM THE MID
30S IN THE THUMB TO LOW 40S IN METRO DETROIT/.

LONG TERM...TUESDAY THROUGH SUNDAY

A MORE COMFORTABLE STRETCH OF SPRING WEATHER IS EXPECTED TUESDAY AND
WEDNESDAY WITH PREDOMINATELY DRY CONDITIONS AND MODERATING
TEMEPRATURES.

PERSISTENT STRATOCUMULUS SHOULD LET UP BRIEFLY AT THE START OF THE
PERIOD TUESDAY WITH TWO GOOD SURGES OF SUBSIDENCE AND A FAIRLY RAPID
LOSS IN DEEP CYCLONIC FLOW. THIS LOSS IN LOW CLOUD SHOULD ONLY BE
TEMPRORARY AS A GOOD SIGNAL EXISTS THAT LOW LEVEL RESIDUAL MOISTURE
WILL THEN BLOSSOM INTO A FAIRLY ROBUST DIURNAL CU RESPONSE. HIGHS ON
TUESDAY ARE EXPECTED TO CLIMB A COUPLE OF DEGREES ABOVE
60...ALTHOUGH AREAS HUGGING THE LAKESHORE WILL BE A FEW DEGREES
COOLER.

MUDDY MID TO UPPER LEVEL RIDGING AND LACK OF FLOW IN THE COLUMN WILL
LEAD TO PERSISTENCE FOR WEDNESDAY. THE LOW LEVELS ARE FORECASTED TO
BE MARGINALLY DRIER WHILE THERE IS SOME SIGNAL FOR SOME MIDLEVEL
MOISTURE TO POOL OVER LOWER MICHIGAN AHEAD OF THE NEXT SHORTWAVE.
STILL EXPECTING SOME MIDCLOUD...BUT BETTER LOW LEVEL LAPSE RATES
SHOULD SUPPORT HIGHS IN THE MIDDLE 60S ON WEDNESDAY.

MODEL DATA IS AGGRESIVE WITH AN UPPER LEVEL ENERGY/VORTICITY MAXIMUM
DROPPING STRAIGHT SOUTHWARD INTO THE LAKE MICHIGAN VICINITY
WEDNESDAY NIGHT AND THURSDAY. THE BOOK HASNT BEEN WRITTEN YET ON
SPECIFICS WITH MODELS TRENDING WESTERLY WITH THE QPF AXIS.
REGARDLESS...FAIRLY ROBUST SHORTWAVE AND INBOUND TRAJECTORY OF AIR
PARCELS SUPPORT AN INCREASINGLY GOOD POTENTIAL FOR A COOL DOWN AND
RAIN SHOWERS WEDNESDAY NIGHT AND THURSDAY. BUMPED POPS UPWARD FROM
THE OFFERED GRIDDED GUIDANCE. TEMPERATURES THURSDAY COULD STRUGGLE
TO CLIMB INTO THE 50S...ESPECIALLY ACROSS THE NORTHERN CWA.

MARINE...

NORTHERLY FLOW WILL WEAKEN WITH TIME TODAY AS THE MIDLEVEL TROUGH
AXIS SWINGS SOUTHWARD AWAY FROM THE STATE. A RIDGE OF SURFACE HIGH
PRESSURE WILL THEN BUILD INTO THE STATE...ESPECIALLY TONIGHT. THIS
AREA OF HIGH PRESSURE IS EXPECTED TO YIELD A RUN OF WEAK WINDS OVER
THE MARINE AREAS TUESDAY AND WEDNESDAY. A NEXT SURGE IN NORTHERLY
WINDS IS EXPECTED TO DEVELOP ON THURSDAY IN THE WAKE OF A WEAK
SURFACE LOW OR TROUGH AXIS.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LHZ421-
     441>443.

LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
&&

$$

AVIATION.....MR
SHORT TERM...SC
LONG TERM....CB
MARINE.......CB


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



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