Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

Home | Current Version | Previous Version | Graphics & Text | 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
000
FXUS63 KDTX 020358
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1158 PM EDT WED JUL 1 2015

.AVIATION...

00Z UPPER AIR SOUNDINGS FROM APX AND DTX INDICATE STRONG POTENTIAL
FOR LOW CLOUDS TO FILL BACK IN OVER SE MICHIGAN DURING THE NIGHT.
THE APX SOUNDING WAS LAUNCHED WITH CLOUDS IN PLACE WHILE THE DTX
SOUNDING SHOWS AN EXTENSION OF THE SUBSIDENCE INVERSION AROUND 850
MB THAT WILL PROVIDE A DUCT FOR LOW LEVEL MOISTURE AND MVFR CLOUDS
TO RETURN DURING THE NIGHT. THIS WILL OCCUR AS LOW LEVEL WINDS
CONTINUE TO VEER FROM NORTHWEST TO NORTHEAST OVER THE REGION AS A
BROAD AREA OF HIGH PRESSURE BUILDS OVER THE CENTRAL GREAT LAKES.
EXCEPT FOR A BRIEF SHOWER OFF SAGINAW BAY IN THE MBS AREA...THE HIGH
WILL MAINTAIN DRY CONDITIONS BUT LOW LEVEL WIND PATTERN WILL HELP
SPREAD MVFR CEILING FROM NORTHEAST TO SOUTHWEST OVER THE TERMINAL
CORRIDOR WHILE BEING BOOSTED BY AN INFUSION OF MOISTURE FROM LAKE
HURON. DRY AIR WILL THEN MAKE A STRONGER PUSH INTO THE AREA FROM THE
SURFACE HIGH AND BRING SOME IMPROVEMENT DURING THE AFTERNOON AND
THEN PROMOTE A CLEARING TREND INTO THURSDAY EVENING.

FOR DTW... MVFR CEILING WILL REACH DTW LATER THAN THE OTHER TERMINAL
SITES AND THE WIND TRAJECTORY COULD PROVIDE MORE OF A GLANCING SHOT
OF COVERAGE. OBSERVED CLOUDS AT PHN COMBINED WITH THE DTX SOUNDING
SUPPORTS A MORE PESSIMISTIC FORECAST FOR NOW.

//DTW THRESHOLD PROBABILITIES...

* MODERATE FOR CEILING 5000 FT OR LESS LATE TONIGHT THROUGH THE
  MORNING.

&&

.PREV DISCUSSION...ISSUED 333 PM EDT WED JUL 1 2015

SHORT TERM...THIS EVENING AND TONIGHT
LARGE MID LEVEL TROUGH OVER THE GREAT LAKES WILL CONTINUE TO PROVIDE
CYCLONIC FLOW TONIGHT.  PLENTY OF LOW LEVEL MOISTURE TRAPPED JUST
BELOW 700MB INVERSION PER APX/DTX 12Z SOUNDING HAS PROVIDED PLENTY
OF CLOUD COVER TODAY AND HAS KEPT SURFACE TEMPS QUITE LOW FOR THIS
TIME OF YEAR. CLOUDS HAVE MIXED OUT SOMEWHAT ACROSS SOUTHWESTERN
LOWER WHERE LOW LEVEL MOISTURE WAS NOT QUITE AS DEEP.  THIS MIXING
IS SLOWLY WORKING EASTWARD AND LIKELY WILL BRING CLEARING INTO THE
CWA INTO THE EVENING...ESPECIALLY WESTERN PART.  MODELS ARE SLIGHTLY
UNDERDONE ON LOW LEVEL MOISTURE THIS AFTERNOON AS MIXING WITH DRY
LEVELS ABOVE HAS NOT OCCURRED AS MUCH AS ADVERTISED.  THINKING IS
THOUGH SOME DECENT SUN WILL BREAK OUT LATER THIS EVENING...AS NIGHT
FALLS AND INVERSION STEEPENS...THERE WILL STILL BE PLENTY OF LOW
LEVEL MOISTURE TO AT LEAST PRODUCE BROKEN STRATUS DECK AND EVEN MID
LEVELS CLOUDS AS WEAK SHORTWAVE ENERGY MOVES THROUGH TROUGH FIRST
PART OF THE NIGHT.  DRIER AIR AND SUBSIDENCE BEHIND THIS SHORTWAVE
ENERGY WILL WORK INTO SOUTHEAST MICHIGAN LATE TONIGHT BRINGING
CLEARING FROM THE NORTH INTO THE SAGINAW VALLEY AND THUMB REGION
TOWARD DAYBREAK.  TEMPERATURES WILL REMAIN ON THE COOL SIDE FOR THE
BEGINNING OF JULY WITH LOWS MOST LOCATIONS IN THE 50S AND A SOME
ISOLATED UPPER 40S POSSIBLE INTERIOR NORTHERN COUNTIES IF CLEARING
ARRIVES EARLIER.

LONG TERM...

PROMINENT UPSTREAM FEATURE ON NATIONAL WATER VAPOR IMAGERY IS THE
STRONG SHEAR MAX PROPAGATING OUT OF AB/SK INTO THE NORTHERN PLAINS
THIS AFTERNOON. EMBEDDED IN THE UPSTREAM SIDE OF THE EASTERN CONUS
LONGWAVE TROUGH, THIS SHORTWAVE WILL TRACK SAFELY SOUTH OF LOWER
MICHIGAN. IF ANYTHING, IT APPEARS STRONGER THAN MODELED, ADDING
CONFIDENCE TO A MORE SOUTHERLY TRACK INTO THE LOWER OHIO VALLEY. THE
ONLY LOCAL IMPACT BEING THE POTENTIAL FOR SOME CIRRUS STREAMING OFF
OF THIS FEATURE AND ACROSS SOUTHERN AREAS DURING THE DAY THURSDAY.

BACKGROUND HEIGHT RISES OWING TO COMPACTING WAVELENGTH OF THE
RESIDENT LONGWAVE TROUGH AS ENERGY WRAPS UP OVER QUEBEC COMBINED
WITH A LOW AMPLITUDE SHORTWAVE RIDGE EMBEDDED IN MEAN NORTHWEST FLOW
REGIME WILL FORCE HIGH PRESSURE PRESENTLY OVER THE WESTERN AND
NORTHERN GREAT LAKES TO EXPAND EAST THROUGH THURSDAY. INCREASING
ANTICYCLONIC FLOW IN THE LOWER LEVELS AND DRY ADVECTION WILL SCOUR
OUT LINGERING STRATUS FROM NORTH TO SOUTH THROUGH THE MORNING.
SUPPRESSED HEIGHTS WILL FAVOR HIGH TEMPERATURES ON THE LOWER SIDE OF
NORMAL, PARTICULARLY FOR LOCATIONS IN THE LAKE HURON SHADOW UNDER
LIGHT NORTHEAST FLOW. COOLER COLUMN WILL FAVOR DEEP BOUNDARY LAYER
MIXING FAVORABLE FOR A PARTIAL COVERAGE OF DIURNAL CU. DESPITE A
CLOUDY START BENEATH WHAT REMAINS OF TODAY`S STRATUS FOR THE
SOUTHERN HALF, THURSDAY WILL SHAPE UP TO BE A SUNNY/COOL DAY BY
AFTERNOON.

SPLIT NATURE OF NORTHWEST FLOW ACROSS THE GREAT LAKES WILL FAVOR
CLEAR SKIES THURSDAY NIGHT. THIS WILL ALLOW FOR HEALTHY EARLY JULY
RADIATIVE COOLING WITH LAKE ENHANCED HIGH PRESSURE ANCHORED IN PLACE
AT THE SURFACE. MOST LOCATIONS WILL EASILY FALL INTO THE LOW/MID 50S
FOLLOWING THE COOLER AFTERNOON TEMPS, BUT THE PREDOMINANTLY
AGRICULTURAL LANDS OF THE THUMB COULD MAKE A HEALTHY RUN TOWARD 40
DEGREES BY FRIDAY MORNING. USED A 12Z MET/MAV BLEND TO NUDGE TEMPS
DOWNWARD A BIT FOR THURSDAY NIGHT.

PERSISTENCE IS IN PLAY FOR FRIDAY AS THE LAKES HANG ON TO SURFACE
HIGH PRESSURE IN SPITE OF THE GRADUAL DEPARTURE OF THE PASSING
SHORTWAVE RIDGE AXIS. LIGHT GRADIENT AND CONTINUED CLEAR SKIES
SUGGEST A SIMILAR DAY TO THURSDAY WITH THE ADDITION OF SOME AIRMASS
MODIFICATION AND MINUS THE LAKE SHADOWING EFFECTS IN THE THUMB.
HEIGHT FALLS IN ADVANCE OF A COMPACT CANADIAN WAVE TRACKING NORTH OF
THE GREAT LAKES WILL INTRODUCE DEEPER LAYER CYCLONIC FLOW BY FRIDAY
NIGHT AND THE EVENTUAL SOUTHEASTWARD PROGRESS OF ASSOCIATED MID/HIGH
CLOUD IN ADVANCE OF THE ATTENDANT COLD FRONT WHICH WILL BE OVER
NORTHERN LOWER BY SUNRISE SATURDAY.

SOUTHERN EXTENSION OF A PV ANOMALY WILL SCRAPE ACROSS LAKE HURON ON
THE 4TH WITH A WEAKENING COLD FRONT/TROUGH PROGGED TO PASS THRU
NORTHERN MI AND WASH OUT AROUND MID-MICHIGAN. MODELS ACCORDINGLY
PAINTING SOME LIGHT QPF ACROSS NORTHERN MI AND SOME ACTIVITY COULD
BLEED INTO THE TRI-CITIES. FOR NOW THOUGH...WILL KEEP THE FORECAST
DRY DUE TO WEAK FORCING AND LACK OF MOISTURE AND INSTABILITY. THE
WEEKEND INTO MONDAY AS A WHOLE LOOKS TO BE DRY WITH NEAR TO SLIGHTLY
ABOVE NORMAL TEMPS AND A GOOD DEAL OF SUN. BUMPED TEMPS UP A FEW
DEGREES FROM SUPERBLEND ACCORDINGLY. STILL SOME MODEL DIFFERENCES
WITH THE NEXT SYSTEM SET TO BRING THUNDERSTORM CHANCES TO SE MI BUT
WILL CONTINUE TO KEY IN ON THE MONDAY NIGHT/TUESDAY TIMEFRAME.

MARINE...

LIGHT TO MODERATE WINDS THROUGH THE PERIOD AS HIGH PRESSURE
DOMINATES THE GREAT LAKES REGION. THE LONE EXCEPTION WILL BE A
PERIOD OF ENHANCED MODERATE TO FRESH NORTHEAST FLOW INTO SAGINAW BAY
DURING THE FIRST HALF OF THURSDAY. AT THIS TIME...SMALL CRAFT
ADVISORY CONDITIONS ARE NOT ANTICIPATED.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.

&&

$$

AVIATION.....BT
SHORT TERM...DRC
LONG TERM....JVC/DT
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.