Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 030806
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
406 AM EDT MON AUG 3 2015

.SHORT TERM...TODAY AND TONIGHT

DEEP CYCLONIC FLOW IS OVERSPREADING SOUTHEASTERN MICHIGAN THIS
MORNING AS A CLOSED LOW HEIGHT ANOMALY QUICKLY AMPLIFIES OVER MUCH
OF EASTERN CANADA. NWP AND SATELLITE IMAGERY SUPPORTS A LACK OF ANY
SIGNIFICANT SHORTWAVE ENERGY OR CYCLONIC VORTICITY ADVECTION FOR
TODAY UNDERPINNING WHAT WILL BE A LACK OF SYNOPTIC SCALE FORCING FOR
ASCENT. RATHER OVERALL DYNAMICS APPEAR TO BE GOVERNED BY ISENTROPIC
DOWNGLIDE. AN EXCEPTION FOR A COMPLETELY DRY FORECAST WILL BE OVER
PORTIONS OF NORTHERN LOWER...NORTHERN LAKE HURON...AND DOWN INTO THE
NORTHERN THUMB WHERE A LOW CHANCE OF A SHOWERS WILL EXIST. A STEEP
LAPSE RATE 800-700MB LAYER IS FORECASTED TO STREAM INTO THESE AREAS
DURING THE LATE AFTERNOON AND EVENING HOURS. MODEST DEFORMATION AND
FGEN FORCING WILL BE POSSIBLE AHEAD OF LOW TO MIDLEVEL TEMPERATURE
GRADIENT WITH THE SHALLOW NATURE OF THE HIGH BASED INSTABILITY
LIMITING THE OVERALL POTENTIAL. DAYTIME TEMPERATURES WILL RANGE IN
THE UPPER 70S OVER MUCH OF THE AREA WITH SOME SNEAKY LOW TO POSSIBLY
MID 80 DEGREE READINGS FOR THE HIGHER SURFACE PRESSURE AREAS/HEAT
ISLAND SOUTH AND EAST OF THE TERRAIN.

&&

.LONG TERM...

VERY LARGE UPPER LEVEL LOW/CIRCULATION ENCOMPASSING CENTRAL/EASTERN
CANADA EARLY THIS WEEK. SEVERAL UPPER LEVEL DISTURBANCES PINWHEELING
AROUND THE CIRCULATION. ONE SUCH UPPER WAVE DESCENDING FROM WESTERN
HUDSON BAY EARLY THIS MORNING IS EXPECTED TO SWING THROUGH THE
NORTHERN GREAT LAKES ON TUESDAY...TIGHTENING UP THE 500 MB
TEMPERATURE GRADIENT ACROSS THE CENTRAL GREAT LAKES. HOWEVER...WITH
DRIER LOW LEVEL AIR (SURFACE DEW PTS IN THE 50S) IN PLACE...LI`S
LOOK TO REMAIN POSITIVE. HOWEVER...GOOD 850-700 MB LAPSE RATES SHOULD
SUPPORT A SUBSTANTIAL CU UP DURING THE DAY WITH CAPES AROUND 100 J/KG
...AND WILL MAINTAIN LOW CHANCE POPS ACROSS THE NORTH FOR LIGHT
SHOWERS...ESPECIALLY ACROSS THE NORTHERN THUMB REGION...WHERE ADDED
MOISTURE BOOST FROM SAGINAW BAY MAY COME INTO PLAY. 850 MB TEMPS
RANGING FROM UPPER SINGLE NUMBERS NORTH TO LOWER TEENS NEAR THE OHIO
BORDER...TRANSLATING TO HIGHS IN THE MID 70S TO AROUND 80 DEGREES.

CONTINUED MODEST COOLING WEDNESDAY AND THURSDAY AS HIGH PRESSURE
BUILDING OVER LOWER MICHIGAN PROMOTES LESS DAYTIME
MIXING...RESULTING IN HIGHS IN THE 70S. FAVORABLE RADIATING NIGHTS
TRANSLATING TO MINS IN THE 50S. WILL HAVE TO WATCH UPPER WAVE
COMING OUT OF THE FOUR CORNERS REGION...AS 00Z EURO TRACKS THE 500
MB TROUGH THROUGH THE OHIO VALLEY DURING THURSDAY...AND IT IS
POSSIBLE A FEW SHOWERS COULD SNEAK TO THE SOUTHERN MICHIGAN BORDER
OR JUST NORTH....DEPENDING ON STRENGTH AND EXACT LOCATION OF THIS
MID LEVEL CIRCULATION.

&&

.MARINE...

COLD FRONT HAS CLEARED THE CENTRAL GREAT LAKES THIS MORNING...AND
LOOKING AT WEST TO NORTHWEST WINDS OF 10 TO 20 KNOTS THROUGH THE
DAY. ALL SMALL CRAFTS ADVISORIES HAVE BEEN ALLOWED TO EXPIRE. A
SECONDARY FRONT AND COOLER AIR ARRIVING FOR TUESDAY WILL INCREASE
WINDS OVER NORTHERN LAKE HURON INTO THE 20 TO 25 KNOT RANGE
HOWEVER...SLOWLY DECREASING AS WE HEAD INTO WEDNESDAY. HIGH PRESSURE
IN CONTROL FOR THURSDAY WILL THEN PROVIDE AND LIGHT AND VARIABLE
WIND FIELD.

&&

.AVIATION...ISSUED 125 AM EDT MON AUG 3 2015

LINE OF THUNDERSTORMS HAS SETTLED INTO PORTIONS OF OHIO AND INDIANA.
TRAILING STRATIFORM PRECIPITATION WITH EMBEDDED LIGHTNING WILL
IMPACT THE SOUTHERN TERMINALS INTERMITTENTLY DURING THE FIRST
HOUR OR TWO OF THE TAF CYCLE. RESIDUAL MOISTURE WITH ONSET OF LOW
LEVEL COLD AIR ADVECTION SHOULD ALLOW IFR STRATUS DECK TO FILL IN
ACROSS THE NORTHERN HALF OF THE AREA. OBSERVING PLATFORMS HAVE
RECORDED THE IFR CIGS NOW ITS A QUESTION OF OVERALL DEVELOPING
COVERAGE. KEPT CIGS AT BORDERLINE IFR/MVFR FOR THE DETROIT
TERMINALS. DEVELOPING BOUNDARY LAYER TODAY WILL LEAD TO WEST WINDS
OF 10 TO 20 KNOTS. LOSS OF DAYTIME HEATING AND DRY AIR ADVECTION
IS EXPECTED TO LEAD TO PREDOMINATELY SKC CONDITIONS TONIGHT.

//DTW THRESHOLD PROBABILITIES...

* MEDIUM IN ISOLATED CLOUD TO GROUND LIGHTNING STRIKES BETWEEN 06-
  08Z.

* HIGH FOR CIGS BELOW 5000 FT AGL. LOW CONFIDENCE IN POTENTIAL FOR
  CIGS OF LESS THAN 1000 FT.

&&

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

$$

SHORT TERM...CB
LONG TERM....SF
MARINE.......SF
AVIATION.....CB


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


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