Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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 011051
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
651 AM EDT FRI AUG 1 2014


.AVIATION...

//DISCUSSION...

SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY OVER
SOUTHEAST MICHIGAN...BUT COVERAGE AND TIMING UNCERTAINTY PRECLUDES
MENTION AT THE TAF SITES...WITH CIGS ABOVE 5000 FEET OUTSIDE OF THE
ACTIVITY. LIGHT SOUTH TO SOUTHWEST WINDS DURING THE DAY...WITH LIGHT
FOG POSSIBLE TONIGHT AS WINDS TREND CALM.

//DTW THRESHOLD THREATS...

* LOW CONFIDENCE IN CEILINGS BELOW 5000 FT TODAY AND TONIGHT.

* LOW CONFIDENCE IN THUNDERSTORMS THIS AFTERNOON.

&&

.PREV DISCUSSION...ISSUED 328 AM EDT FRI AUG 1 2014

SHORT TERM... TODAY AND TONIGHT

BROAD UPPER LEVEL TROUGHING WILL PERSIST OVER THE GREAT LAKES
REGION...SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS
AS VARIOUS EMBEDDED UPPER WAVES TRAVERSE THROUGH THE AREA. DIURNAL
ENHANCEMENT EXPECTED...AS MLCAPES REACH 1500 J/KG...TO POSSIBLY AS
HIGH AS 2000 J/KG. IDEAL FREEZING LEVELS AROUND 10500 FEET WITH
DESCENT CAPE DENSITY AROUND THAT LEVEL WILL ALLOW FOR HAIL...AND
CALLING FOR UP TO NICKEL SIZE WITH THE STRONGEST CELL...ALTHOUGH 1
INCH DIAMETER HAIL REPORTS WERE NOTED YESTERDAY OVER WISCONSIN.
850 MB TEMPS LOOK TO BE ABOUT 0.5 C DEGREE WARMER THIS
AFTERNOON...AND MAXES SHOULD BE PREDOMINATELY IN THE LOWER 80S
(PER INHERITED FORECAST) WITH THE WEAK LOW LEVEL SOUTHWEST FLOW.
INSTABILITY WILL BE SLOW TO WANE TONIGHT...AS SHOWALTER INDEX
CONTINUES TO HOVER BELOW ZERO PER NAM...AND YET ANOTHER SUBTLE
UPPER WAVE/850-700 MB THETA-E SURGE WILL MAINTAIN LOW CHANCE POPS
AS THE TROUGH AXIS ALSO SHARPENS UP.

LONG TERM...SUNDAY THROUGH THURSDAY

A PERSISTENCE FORECAST REMAINS THE MOST LOGICAL APPROACH AS BROAD
UPPER LEVEL TROUGHING REMAINS IN PLACE OVER THE REGION INTO NEXT
WEEK. ANOTHER NOTABLE SHORTWAVE TROUGH DIGGING SOUTHEAST DOWN THE
SOUTHWEST SIDE OF HUDSON BAY WILL ENSURE THAT THE CURRENT TROUGH
CONFIGURATION IN PLACE WILL CHANGE VERY LITTLE OVER THE CENTRAL
GREAT LAKES FOR A GOOD PORTION OF THE LONG TERM FORECAST PERIOD.

WHAT THIS MEANS FOR OUR WEATHER OVER SOUTHEAST MICHIGAN IS MORE OF
THE SAME AS HIGH TEMPERATURES CLIMB TO AROUND 80 DEGREES...GIVE OR
TAKE A FEW DEGREES...FOR HIGH TEMPERATURES AND FALL INTO THE UPPER
50S AND LOWER 60S FOR LOW TEMPERATURES.

IT ALSO MEANS A PERIODIC CHANCE OF ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS...PARTICULARLY DURING THE AFTERNOON/EARLY EVENING HOURS
AS VARIOUS WEAK SHORTWAVE IMPULSES RIDE THROUGH NORTHWEST FLOW
AROUND THE BASE OF AFOREMENTIONED UPPER TROUGH. AS SUCH...ONLY MINOR
ADJUSTMENTS WILL BE INCLUDED WITHIN THIS FORECAST PACKAGE.

ECMWF/GFS SUGGEST AN APPRECIABLY STRONGER SHORTWAVE WILL TRACK INTO
THE NORTHERN TIER OF THE UNITED STATES LATE IN THE FORECAST. ECMWF
REMAINS THE SLOWER OF THE SOLUTIONS...WHICH MAKES MORE SENSE GIVEN
THE AMPLITUDE OF THE SYSTEM AND SEPARATION FROM THE NORTHERN STREAM
STORM TRACK. WITH THIS IN MIND DO NOT EXPECT THIS SYSTEM TO IMPACT
THE REGION UNTIL LATE NEXT WEEK.

MARINE...

A WEAK AREA OF HIGH PRESSURE REMAIN IN PLACE THROUGH THE UPCOMING
WEEKEND. THIS WILL LEAD TO A WEAK WIND PROFILE WITH WIND SPEEDS
REMAINING AT 10 KNOTS OR LESS. THIS...IN TURN...WILL INHIBIT WAVE
GROWTH. WIDELY SCATTERED SHOWERS/THUNDERSTORMS WILL BE POSSIBLE
DESPITE THIS HIGH PRESSURE...BUT WILL FAVOR LAND AREAS AS LAKE
BREEZE BOUNDARIES PROVIDE THE PRIMARY FOCUS DURING THE AFTERNOON AND
EARLY EVENING HOURS.

&&

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

&&

$$

AVIATION.....99
SHORT TERM...SF
LONG TERM....DG
MARINE.......DG


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.