Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 010352
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1152 PM EDT THU APR 30 2015


.AVIATION...

REMAINING 6-10KFT DECK ASSOCIATED WITH SPOKE OF VORTICITY ROTATING
BACK WEST INTO AREA AROUND UPPER LOW TO THE SOUTHEAST WITH SCATTERED
OUT OVERNIGHT WITH GENERALLY SCT CONDITIONS PERSISTING FOR THE MOST
PART ON FRIDAY....SAVE A FEW POCKETS OF BKN060 DURING PEAK DIURNAL
CUMULUS DEVELOPMENT. NORTHERLY WINDS WILL BECOME EAST TO NORTHEAST
WITH LAKE BOUNDARIES 22Z-02Z FRIDAY AND THEN BASICALLY CALM FRIDAY
NIGHT AS HIGH PRESSURE PASSES OVER THE REGION.

//DTW THRESHOLD PROBABILITIES...

* NONE.

&&

.PREV DISCUSSION...ISSUED 347 PM EDT THU APR 30 2015

SHORT TERM...THROUGH TONIGHT

THE UPPER LEVEL LOW STEERING THE SHORT TERM FORECAST HAS DROPPED
SOUTH THROUGH WESTERN MI AND IS NOW SOUTH OF THE STATE LINE. THIS
LOW HAS PRODUCED SEVERAL BANDS OF RAIN SHOWERS WHICH LINE UP WELL
WITHIN THE 295K-300K ISENTROPIC SURFACE WITH SOME ADDITIONAL SUPPORT
FROM MID LEVEL VORTICITY LOBE ROTATING AROUND THE PARENT LOW. THE
FIRST BAND STALLED EARLIER THIS MORNING AS IT PIVOTED OVER SE MI AND
IS CURRENTLY DROPPING THROUGH LENAWEE AND MONROE COUNTIES ON ITS WAY
SOUTH. THE NEXT BAND HAS BEEN DEVELOPING OVER THE LAST COUPLE HOURS
OVER SOUTHERN ONTARIO AND IS TRACKING WEST TOWARD PORT HURON. THE
WESTWARD MOTION WILL NOT LAST LONG AS THE STEERING FLOW TURNS MORE
NORTHERLY IN RESPONSE TO THE UPPER LOW DRIFTING SO FAR SOUTH.
CURRENT WATER VAPOR IMAGERY SHOWS THIS ENHANCED PLUME OF MOISTURE
RICH AIR CO-LOCATED WITH AFOREMENTIONED FORCINGS WHICH WILL ALLOW IT
TO WORK INTO SE MI BEFORE RUNNING INTO SUBSIDENCE BUILDING IN FROM
THE NORTH. THIS SUBSIDENCE WILL MAKE IT HARD TO DISTINGUISH A
NORTHERN AND WESTERN EDGE TO THE PRECIP BUT SEEING THE DISSIPATION
ALREADY COMMENCING ON THE NORTHERN EDGE FEEL CONFIDENT LEAVING POPS
OUT OF THE NORTHERN THUMB AND SAGINAW VALLEY. WENT WITH CHANCE POPS
ALONG THE EASTERN COUNTIES FROM ST CLAIR DOWN TO THE OHIO BORDER AS
THIS FEATURE SLIDES INTO AND SOUTHWARD THROUGH THE AREA THIS
EVENING.

CLOUDS WILL BEGIN TO SCATTER/CLEAR OUT FROM NORTH TO SOUTH TONIGHT
AS SUBSIDENCE INCREASES AND HEIGHTS BEGIN TO CLIMB SLOWLY WITH
RIDGING BUILDING INTO THE WESTERN GREAT LAKES. THIS WEAK WAA PATTERN
WILL LIMIT NOCTURNAL COOLING CONDITIONS AND HOLD TEMPERATURES IN THE
LOW 40S.

LONG TERM...

FLOW REGIME ACROSS THE GREAT LAKES FOR FRIDAY AND SATURDAY WILL BE
DRIVEN BY A COUPLE OF WAVES ROTATING AROUND THE LARGE POLAR
CIRCULATION PRESENTLY OVER NUNAVUT. HEIGHTS WILL REBOUND FRIDAY AS
THE CLOSED LOW OVER THE OHIO VALLEY DEPARTS AND THE UPSTREAM RIDGE
DAMPENS AS IT IS FORCED EAST BY THE FIRST SUCH WAVE. WARMER 850MB
TEMPERATURES AROUND 6C WILL FOLD INTO THE AREA BY FRI MORNING.
STRONG INSOLATION WILL SUPPORT STEEP BOUNDARY LAYER LAPSE RATES AND
MIXING AS HIGH AS 800MB SUPPORTING SIGNIFICANT RECOVERY OVER TODAY
WITH HIGHS FORECAST TO NEAR 70F. INSOLATION SHOULD BE NEAR MAXIMIZED
IN MOST LOCATIONS, BUT THE CORRIDOR OF MID-LEVEL MOISTURE RESIDING
OVER THE ONTARIO PENINSULA BETWEEN GEORGIAN BAY AND LAKE ONTARIO
WHICH GAVE RISE TO DIURNALLY FORCED CLOUDS TODAY IS PROGGED TO BE
CENTERED OVER THE SOUTHERN THIRD OF THE CWA BY AROUND 15Z FRIDAY
MORNING. INCREASING DRY ADVECTION AND INLAND PUSH OF THE AFTERNOON
MARINE LAYER WILL HELP SCOUR THE BOUNDARY LAYER OF THESE CLOUDS, BUT
LOCATIONS ROUGHLY ALONG/SOUTH OF I-96 MAY SEE A DECENT CU BUILD-UP
THROUGH LATE MORNING/MID AFTN.

EXPANSIVE SURFACE HIGH PRESSURE WILL DOMINATE EAST OF THE ROCKIES
SATURDAY INTO SATURDAY NIGHT. ANOTHER CANADIAN WAVE WILL FORCE A
DOWNSTREAM SHORTWAVE RIDGE ACROSS THE AREA DURING THIS TIME WHICH
WILL ALLOW THE SURFACE RIDGE TO STRENGTHEN NORTHWARD. THE GRADIENT
WILL REMAIN QUITE LIGHT THROUGH SATURDAY WITH NOTHING MORE THAN
EPISODIC CIRRUS EXPECTED GIVEN RELATIVELY FLAT ZONAL FLOW ACROSS THE
NORTHERN TIER. HIGHS SHOULD EASILY REACH 70 DEGREES. INCREASING
SOUTHWEST GRADIENT SATURDAY NIGHT IN RESPONSE TO DEPRESSED HEIGHT
FIELD ACROSS SOUTHERN CANADA WILL LIMIT COOLING POTENTIAL AND MAY
EVEN RESULT IN A SLIGHT RISE IN OVERNIGHT TEMPS. NUDGED SAT NIGHT
LOWS UP A COUPLE DEGREES INTO THE LOW 50S.

SUNDAY STILL ON TRACK TO BE A FAIRLY STELLAR DAY. MOSTLY
SUNNY SKIES AND 70 DEGREES STILL LOOK HIGHLY FAVORABLE THROUGH MID
AFTERNOON...WITH INCREASING CLOUDS AND CHANCES OF RAIN DEVELOPING
LATE. THERE COULD BE A FEW RUMBLES OF THUNDER AS MID LEVEL TROUGH
PULLS A VORT MAX ACROSS SAGINAW BAY AND THE THUMB DURING THE WEE
HOURS MONDAY MORNING. SHOWERS WILL CONTINUE WITH POPS GOING UP
MONDAY AFTERNOON THROUGH MOST OF TUESDAY. POTENTIAL FOR SCATTERED
SHOWERS AND THUNDERSTORMS WILL REMAIN IN PLACE THROUGH THE REST OF
THE WEEK AS WARM MOIST FLOW AND UNSETTLED PATTERN CONTINUE.

MARINE...

GENTLE TO MODERATE NORTHERLY BREEZE TODAY AND FRIDAY WILL GIVE WAY
TO LIGHT AIR ACROSS THE WATERS FRIDAY NIGHT INTO EARLY SATURDAY.
MARINE CONDITIONS WILL REMAIN RATHER QUIESCENT UNTIL THUNDERSTORM
POTENTIAL RETURNS TO THE WATERS SUNDAY NIGHT THROUGH TUESDAY.

&&

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

$$

AVIATION.....DG
SHORT TERM...DRK
LONG TERM....JVC/DE
MARINE.......JVC


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



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