Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 051801
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
201 PM EDT THU MAY 5 2016


.AVIATION...

ONSET OF DAYTIME HEATING HAS ALLOWED SCT-BKN CU TO DEVELOP. BEST
COVERAGE IS EXPECTED FROM PTK SOUTHWARD...WHERE MOISTURE WILL BE
SLIGHTLY GREATER BEHIND LOW PRESSURE DEPARTING TO THE SOUTHEAST. DRY
AIR IN THE MIXED LAYER WILL TRY TO LIMIT COVERAGE OF CU THIS
AFTERNOON...EVEN TOWARDS THE DETROIT-AREA TERMINALS. OVERALL
CONFIDENCE IN CEILINGS BKN BETWEEN 4500-6000 FOR MORE THAN AN HOUR
OR TWO IS NOT HIGH. CU WILL DISSIPATE THIS EVENING...LEAVING CLEAR
SKIES OVERNIGHT. NORTHERLY FLOW WILL BE THE OTHER NOTABLE WEATHER
ELEMENT THIS AFTERNOON...WITH GUSTS TO AROUND 20 KNOTS DISSIPATING
AROUND SUNSET. WINDS WILL BE LIGHT OVERNIGHT...GENERALLY 5 KTS OR
LESS.

FOR DTW...DRIER AIR MIXING INTO THE LOWER LEVELS MAY LIMIT CU
COVERAGE THIS AFTERNOON...BRINGING SOME UNCERTAINTY TO HOW LONG BKN
CEILINGS CAN LAST. ALSO EXPECT TO SEE BASES RISE FROM 4500 FEET TO
6000 FEET BY LATE AFTERNOON DUE TO THE DRIER AIR. WINDS ARE MORE
LIKELY TO HAVE A SLIGHT NORTHEAST COMPONENT THROUGH THE MID-
AFTERNOON BEFORE THEY BECOME MORE SOLIDLY OUT OF THE NORTH.

//DTW THRESHOLD PROBABILITIES...

* LOW IN CEILINGS BELOW 5000 FEET THIS AFTERNOON.

&&

.PREV DISCUSSION...ISSUED 310 AM EDT THU MAY 5 2016

DISCUSSION...

HIGH AMPLITUDE PATTERN ACROSS THE CONUS THIS MORNING WITH DEEP
CLOSED LOWS FLANKING A STRONG LONGWAVE RIDGE CENTERED OVER THE
WESTERN HIGH PLAINS. GRADUAL EASTWARD PROGRESSION IN THE WAKE OF
THIS MORNING`S DEPARTING LOW WILL SPELL STEADY HEIGHT RISES FOR THE
NEXT TWO DAYS AS HIGH PRESSURE BUILDS OVER THE GREAT LAKES.

FOR TODAY, DEEP LAYER CYCLONIC FLOW PERSISTS AGAINST THE BACKGROUND
HEIGHT RISES. THE SHEAR AXIS DEMARCATED BY THE RIBBON OF DRY AIR ON
WV IMAGERY OVER WESTERN LAKE MICHIGAN WILL GRADUALLY BE PULLED SOUTH
AND EAST. ATTENDANT FORCING/WEAK PV ADVECTION MAY BE JUST ENOUGH TO
AGITATE A LOW-TOPPED CU FIELD CAPABLE OF PRODUCING AN ISOLATED
SHOWER OR TWO OVER THE WESTERN CWA DURING PEAK HEATING.
ATTM...NOTHING WORTH A WX MENTION IN THE GRIDS. EAST OF THE US-23
CORRIDOR EXPECT COMPARATIVELY LESS CU COVERAGE WITH STABLE NORTH
FLOW COMING OFF OF LAKE HURON. H85 TEMPS IN THE MID SINGLE DIGITS
UNDER MOSTLY CLEAR SKIES WILL PROMOTE A DEEP MIXED LAYER SUPPORTIVE
OF HIGHS IN THE LOW TO MID 60S...HIGHEST READINGS FURTHEST FROM LAKE
HURON OVER INTERIOR/WESTERN AREAS AS WELL AS DETROIT METRO.

SHORTWAVE RIDGE EMBEDDED WITHIN THE FLOW AROUND THE LONGWAVE RIDGE
OVER THE CENTRAL CONUS WILL UNDERGO AMPLIFICATION TONIGHT AS THE
NEXT ROUND OF HIGH-LATITUDE PAC ENERGY DIVES SE OUT OF NW CANADA.
SUBSEQUENT AMPLIFICATION WILL SUPPORT AGGRESSIVE SURFACE PRESSURE
RISES TONIGHT AND THE EVENTUAL INTRODUCTION OF ANTICYCLONIC FLOW AND
A BUILDING SUBSIDENCE INVERSION. NO COMPLAINTS WITH 00Z GUIDANCE
SUGGESTING LOWS IN THE LOW 40S TO UPPER 30S IN THE SAGINAW VALLEY
WHERE EVENTUAL DECOUPLING UNDER CLEARING SKY IS LIKELY.

FRIDAY WILL BE THE CHOICE DAY OF THE LONGER TERM PERIOD AS THE RIDGE
AXIS IS FORCED OVERHEAD AND THE LOW-LEVEL GRADIENT TURNS SW.
ADIABATIC MIXING AND FULL INSOLATION WILL SUPPORT TEMPERATURES NEAR
70 BY FRIDAY AFTERNOON. CONTINUED SW GRADIENT FLOW WILL KEEP FRIDAY
NIGHT LOW TEMPS WELL ABOVE NORMAL AROUND 50 DEGREES.

AFOREMENTIONED CANADIAN ENERGY IS PROGGED TO CLOSE OFF OVER ONTARIO
AS THE STRENGTHENING SURFACE LOW WRAPS NORTHEASTWARD TOWARD JAMES
BAY. ATTENDANT COLD FRONT WILL SWEEP THROUGH THE STATE ON SATURDAY.
NORTHERN ORIGINS OF THE FRONT WILL LIMIT MOISTURE QUALITY, BUT
STRONG DYNAMIC FORCING SUPPORTS HIGH LIKELY POPS DURING THE DAY.
MODEST DIURNAL DESTABILIZATION WILL SUPPORT THUNDER MENTION BUT CAPE
PROFILES ATTM APPEAR SKINNY DUE TO LACK OF SUFFICIENT MID-LEVEL
LAPSE RATES THUS LIMITING SEVERE WX CONCERN.

MARINE...

MODERATE NORTHERLY WINDS WILL HOLD FIRM TODAY IN BETWEEN EXITING LOW
PRESSURE AND THE NEXT HIGH PRESSURE CENTER BUILDING TOWARD THE
REGION.  DESPITE THE EXISTING ONSHORE FLOW...WAVE GROWTH WILL REMAIN
RELATIVELY MODEST ACROSS SOUTHERN LAKE HURON.  THIS WILL MAINTAIN
CONDITIONS JUST BELOW SMALL CRAFT ADVISORY THRESHOLDS AND NO
HEADLINES WILL BE ISSUED AT THIS TIME.  STRETCH OF FAVORABLE MARINE
CONDITIONS TONIGHT THROUGH FRIDAY WITH HIGH PRESSURE SETTLING IN.
THE NEXT COLD FRONT MOVES THROUGH ON SATURDAY...BRINGING ONLY A
MODEST INCREASE TO THE WINDS ON EITHER SIDE OF THE FRONT.  THIS
FRONT WILL BRING THE POTENTIAL FOR THUNDERSTORMS.

&&

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

$$

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


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