Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 200352
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1152 PM EDT TUE MAY 19 2015


.AVIATION...

THE 4000-4500 FT STRATO CU FIELD WILL CONTINUE TO ERODE OVER THE
NEXT COUPLE HOURS AS HIGH PRESSURE BUILDS IN FROM THE WEST. THIS
HIGH PRESSURE SYSTEM WILL INFLUENCE SE MI THROUGH WEDNESDAY.
THIS WILL SUSTAIN LIGHT WINDS AND CLEAR SKIES BELOW 10K FT.

//DTW THRESHOLD PROBABILITIES...

* NONE.

&&

.PREV DISCUSSION...ISSUED 955 PM EDT TUE MAY 19 2015

UPDATE...

THE 00Z DTX AND APX SOUNDINGS SHOWED A SHALLOW LAYER OF SATURATION
UNDER A VERY DEEP INVERSION. THIS HAS ALLOWED CLOUDS TO HOLD
FAIRLY STEADY OVER A GOOD PORTION OF THE FORECAST AREA THIS
EVENING. OVER THE LAST HOUR THERE HAS BEEN A MORE SUBSTANTIAL
CLEARING TREND OVER WRN LOWER MI AS THE LOW LEVEL FLOW BECOMES
MORE STRONGLY ANTICYCLONIC. THE SFC HIGH WILL PUSH INTO SE MI
OVERNIGHT AND WILL ALLOW A MORE AGRESSIVE CLEARING TREND ACROSS
THE FORECAST AREA OVER THE NEXT FEW HOURS. TAKING THIS INTO
CONSIDERATION AND GIVEN CURRENT SFC OBSERVATIONS...NO CHANGES IN
THE FROST/FREEZE HEADLINES WILL BE MADE THIS EVENING.

PREV DISCUSSION...ISSUED 312 PM EDT TUE MAY 19 2015

SHORT TERM...THIS AFTERNOON AND TONIGHT

CLOUDY SKIES FROM EXTENSIVE STRATUS/STRATO-CU DECK WITHIN COLD AIR
ADVECTION REGIME IN WAKE OF PASSING SHORTWAVE TROUGH WILL GRADUALLY
SCATTER OUT THIS EVENING AS SURFACE HIGH PRESSURE...ALONG WITH AN
UPPER LEVEL SHORTWAVE RIDGE...EXPAND INTO THE GREAT LAKES AND LEAD
TO AN BROADENING AREA OF SUBSIDENCE.

WHILE CONDITIONS THROUGH THIS EVENING ARE NOT ESPECIALLY CONDUCIVE
TO STRONG COOLING...CLEARING SKIES AND A GRADUAL DECREASE IN WEST TO
NORTHWEST WINDS WILL ALLOW TEMPERATURES TO FALL WELL INTO THE 30S
OVERNIGHT. WITH SURFACE DEW POINTS IN THE UPPER 20S TO LOWER 30S
JUST UPSTREAM FROM THE SAGINAW VALLEY...FEEL A FREEZE WARNING IS
WARRANTED AS THIS PORTION OF THE CWA WILL ALSO SEE THE QUICKLY
CLEARING AND LIGHTEST WINDS...UNDER 5 MPH...AFTER MIDNIGHT.

WILL BUFFER THIS WARNING WITH A FROST ADVISORY DOWN THROUGH THE I-69
CORRIDOR COUNTIES. WILL TENTATIVELY EXTEND THIS ADVISORY UP THROUGH
THE THUMB REGION AS EVEN THOUGH WINDS WILL TAKE A BIT LONGER TO
SUBSIDE...INTERIOR SECTIONS AWAY FROM LAKE HURON SHOULD SEE LOW
TEMPERATURES AOB 35F WITH A FAIR AMOUNT OF LOW LEVEL MOISTURE
AVAILABLE FOR FROST FORMATION.

FURTHER SOUTH...PATCHY FROST IS ALSO POSSIBLE...PARTICULARLY SOUTH TO
ABOUT M 59...BUT WITH TEMPERATURES HOLDING IN THE 35-40F RANGE...DO
NOT FEEL CONDITIONS QUITE WARRANT AN ADVISORY AT THIS TIME.

LONG TERM...

DRY AIRMASS...850 MB THETA-E MINIMUM...WILL BE IN CONTROL OF THE
GREAT LAKES REGION ON WEDNESDAY...AS RIDGE OF PRESSURE 1022-1024 MB
EXTENDS INTO THE THE CENTRAL GREAT LAKES. 850 MB TEMPS RISING
SLIGHTLY ABOVE 2 C POINTS TO HIGHS AT OR SLIGHTLY ABOVE 60 DEGREES
WITH MID MAY INSOLATION. NAM SOUNDINGS INDICATE THE TOP OF THE
BOUNDARY MIXED LAYER WILL BE JUST DRY ENOUGH TO PREVENT MUCH IN THE
WAY OF CU DEVELOPMENT.

UPPER WAVE COMING OUT THE CENTRAL ROCKIES WILL BE CUT OFF BY
NORTHERN STREAM TROUGH AXIS DROPPING SOUTH OUT OF CENTRAL
CANADA...FORCING/SHUNTING THE SYSTEM ALONG THE SOUTHERN MICHIGAN
BORDER WEDNESDAY NIGHT. WITH THE DRY AIRMASS IN PLACE...IT IS
EXPECTED TO REMAIN DRY...BUT 700 MB FGEN IS A SLIGHT CONCERN TOWARD
THE OHIO BORDER. AT THE VERY LEAST...SHOULD SEE PLENTY OF MID/HIGH
CLOUDS WHICH ARE EXPECTED TO HOLD MINS IN THE UPPER 30S TO MID 40S.

PER 12Z EURO...FURTHER MODIFICATION OF THE AIRMASS WILL TAKE PLACE ON
THURSDAY...AS 850 MB TEMPS WARM TO AROUND 5 C...WITH FAVORABLE LOW
LEVEL WESTERLY FLOW SENDING TEMPS INTO THE MID/UPPER 60S AS A DRY
COLD FRONT SLIDES THROUGH SOUTHERN LOWER MICHIGAN THURSDAY NIGHT.

MAIN ISSUE IN THE EXTENDED FORECAST...WHICH COVERS THE HOLIDAY
WEEKEND...IS THE CHANCES FOR PRECIPITATION TOWARDS THE END OF THE
FORECAST PERIOD.  DRY CONDITIONS WILL HOLD INTO THE START OF THE
WEEKEND BEFORE PRECIPITATION POTENTIAL INCREASES DURING THE SECOND
HALF.  HIGH PRESSURE AND UPPER LEVEL RIDGING WILL BE INFLUENCING THE
GREAT LAKES REGION THROUGH AT LEAST SATURDAY NIGHT IF NOT INTO MOST
OF SUNDAY BEFORE TROUGHING AND ASSOCIATED LOW PRESSURE MOVE TOWARDS
THE AREA SUNDAY INTO MONDAY.  LATEST MODEL RUNS HAVE SLOWED THE
ONSET OF PRECIP INTO THE AREA...WHILE ALSO KEEPING THE MAJORITY OF
THE ACTIVITY FOCUSED ON MEMORIAL DAY.  A WARMING TREND WILL FINALLY
TAKE OVER...AS HIGHS WARM BACK INTO THE 70S THIS HOLIDAY WEEKEND AND
APPROACHING THE 80S BY EARLY NEXT WEEK.

MARINE...

STRONG NORTHWEST FLOW UP TO 30 KNOTS OVER NORTHERN LAKE HURON WILL
SLOWLY EASE TONIGHT AS RIDGE OF HIGH PRESSURE BUILDS INTO THE
CENTRAL GREAT LAKES TOMORROW MORNING. HOWEVER...COLD AIRMASS COMING
OVER THE WATERS WILL LEAD TO UNSTABLE CONDITIONS CONDUCIVE TO
GOOD WAVE GROWTH...AND SMALL CRAFT ADVISORIES CONTINUE THROUGH
TONIGHT FOR MUCH OF THE NEARSHORE WATERS OF LAKE HURON.

WITH SURFACE HIGH PRESSURE HOLDING WEDNESDAY AND THURSDAY...BOATING
CONDITIONS WILL BE FAVORABLE WITH LIGHT WINDS AND DRY
CONDITIONS...LIKELY PERSISTING INTO THE WEEKNIGHT.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...FREEZE WARNING UNTIL 8 AM EDT WEDNESDAY FOR MIZ047-048-053.

     FROST ADVISORY UNTIL 8 AM EDT WEDNESDAY FOR MIZ049-054-055-060>063.

LAKE HURON...SMALL CRAFT ADVISORY UNTIL 10 AM EDT WEDNESDAY FOR LHZ421-441>443.

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

$$

AVIATION.....SC
UPDATE.......SC
SHORT TERM...DG
LONG TERM....SF/SS
MARINE.......SF


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



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