Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 042317
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
717 PM EDT SAT JUL 4 2015

.AVIATION...

AN ISOLATED SHOWER OR THUNDERSTORM REMAINS POSSIBLE IN THE MBS AREA
DURING THE EARLY EVENING AS THE WEAK FRONT THROUGH CENTRAL LOWER
MICHIGAN CONTINUES TO WASH OUT. COVERAGE WILL BE TOO LOW TO INCLUDE
IN THE FORECAST CONDITIONAL ON ACTUAL DEVELOPMENT. ELSEWHERE...THE
DISSIPATION OF THE FRONT WILL ALLOW HIGH PRESSURE TO BECOME
REESTABLISHED OVER THE REGION AND LEAD TO VFR CLEAR CONDITIONS WITH
LIGHT WIND OVERNIGHT THROUGH SUNDAY. A BRIEF PERIOD OF SHALLOW FOG
COULD OCCUR AROUND SUNRISE. TIMING AND DURATION POTENTIAL WILL
CONTINUE TO BE EVALUATED THROUGH THE NIGHT.

//DTW THRESHOLD PROBABILITIES...

* NONE.

&&

.PREV DISCUSSION...ISSUED 349 PM EDT SAT JUL 4 2015

SHORT TERM...THIS EVENING AND TONIGHT

AXIS OF LOWER MID LEVEL HEIGHTS/TROUGHING NOW EXITING TO THE EAST...
SE MICHIGAN AT THE INFLECTION POINT BETWEEN THIS FEATURE AND THE
INBOUND UPPER RIDGE NOW CENTERED OVER THE MISSISSIPPI RIVER.
ATTENDANT LOW LEVEL FRONT CURRENTLY EASING SOUTHEAST ACROSS NORTHERN
LOWER MI WILL BECOME INCREASINGLY DIFFUSE AS UPPER HEIGHTS BEGIN TO
REBOUND...THIS BOUNDARY STRUGGLING TO REACH MUCH BEYOND THE TRI-
CITIES/NORTHERN THUMB BEFORE WASHING OUT THIS EVENING.  A PERIOD OF
LOCALIZED FORCED ASCENT...PERHAPS AUGMENTED BY LAKE BREEZE
INTERACTIONS...WILL MAINTAIN A WINDOW FOR ISOLATED SHOWER/
THUNDERSTORM DEVELOPMENT ACROSS THIS CORRIDOR THROUGH THE EVENING
ASSUMING ADEQUATE INSTABILITY. 12Z NAM AND CANADIAN SOLUTIONS
REMAIN OVERZEALOUS WITH THE NEAR SURFACE MOISTURE CONTENT
/DEWPOINT OF MID 60S/ RELATIVE TO CURRENT OBSERVATIONS...YIELDING
A MORE UNSTABLE CONVECTIVE BOUNDARY LAYER AND CORRESPONDING
GREATER COVERAGE OF CONVECTION. VARIOUS HI RES MODEL OUTPUT DO
LEND SUPPORT TOWARD SEEING A COUPLE CELLS EMERGE AS PEAK HEATING
WANES...WITH JUST ENOUGH INSTABILITY WITHIN THE COLUMN. SBCAPE IN
THE BALLPARK OF 600-800 J/KG PER LATEST SPC MESOANALYSIS.

ELSEWHERE...HIGHER DEGREE OF STABILITY WITH NO TANGIBLE FORCING WILL
SUSTAIN A TRANQUIL 4TH OF JULY EVENING UNDER A CLEAR SKY. STEADY
INCREASE IN UPPER HEIGHTS THROUGH THE NIGHT...UPPER RIDGE AXIS
SETTLING ACROSS THE REGION BY MID MORNING SUNDAY. THIS WILL
PROVIDE A NOTEWORTHY INCREASE THROUGHOUT THE THERMAL PROFILE. LOWS
RANGING FROM MID 50S NORTH TO LOWER 60S METRO DETROIT.

LONG TERM...

SHORTWAVE RIDGE OVER THE UPPER MS VALLEY WILL TRANSIT THE CENTRAL
GREAT LAKES ON SUNDAY BRINGING CONTINUED DEEP LAYER SUBSIDENCE. LACK
OF FORCING AND A STRONG 700MB INVERSION WILL MAINTAIN CLEAR SKIES
AND SUPPORT A DRY FORECAST WHILE MIXING TO 850MB TEMPERATURES AROUND
12C SUPPORTS HIGHS AT LEAST IN THE LOW 80S. EXPECTATION FOR FULL SUN
SUGGESTS POTENTIAL FOR OVERACHIEVING TEMPS...NO CHANGE TO THE
INHERITED FORECAST OF AROUND 85 DEGREES. WEAK HEIGHT FALLS AND
INCREASINGLY CYCLONIC FLOW WILL SPREAD INTO SOUTHEAST MICHIGAN
MONDAY IN ADVANCE OF AN AMPLIFYING TROUGH OVER THE NORTHERN TIER OF
THE UNITED STATES. INCREASING SSW GRADIENT WILL ADVECT EVEN WARMER
AIR INTO LOWER MICHIGAN WITH 850MB TEMPERATURES PROGGED TO RISE TO
AROUND 17C. MID-LEVEL THETA-E AXIS WILL REMAIN WELL UPSTREAM, OVER
THE WESTERN GREAT LAKES, WITHIN THE CORRIDOR OF STRONGEST FORCING
ASSOCIATED WITH THE UPPER WAVE AND STRENGTHENING LLJ. THUS, ANOTHER
DRY DAY ANTICIPATED WITH HIGH TEMPERATURES IN THE UPPER
80S...PERHAPS A 90 DEGREE READING IN THE SAGINAW VALLEY. NOCTURNAL
WARM ADVECTION WILL BE ONGOING IN ADVANCE OF THE FRONT MONDAY NIGHT,
SO FURTHER BUMPED UP MONDAY NIGHT LOW TEMPS TO 70 DEGREES.

DECENT COLD FRONT STILL ON TRACK FOR TUESDAY. THERE STILL SEEMS TO
BE SOME SLIGHT DIFFERENCES IN TIMING BETWEEN MODELS. NAM BEING A BIT
FASTER ON THE LEADING EDGE OF THE PRECIPITATION. THAT BEING
SAID...TUESDAY IS STILL SHAPING UP TO BE A WET DAY FOR SOUTHEAST
MICHIGAN. PRESENT CONSENSUS HAS SOME SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS POSSIBLE FOR THE WEE HOURS TUESDAY WITH RAIN CHANCES
RAMPING UP TO THE LIKELY CATEGORY FOR THE MORNING COMMUTE. RAIN AND
THUNDERSTORM POTENTIAL STAY ELEVATED INTO TUESDAY EVENING. SEVERE
WEATHER THREAT STILL NOT SHOWING A GREAT DEAL OF OOMPH WITH BOTH
CAPE AND SHOWALTER REGISTERING LOW POTENTIAL AND NEWER MODEL RUNS
TRENDING THE JET DIVE TO OUR WEST. STILL TOO EARLY TO MAKE ANY
DEFINITIVE CALLS. FRONT PROGGED TO MOVE THROUGH LATE TUESDAY/EARLY
WEDNESDAY WITH A DECENT TEMP FALL. MID TO UPPER 80 DEGREE DAYS HELD
OVER FROM THE WEEKEND WILL DWINDLE BELOW THE SEASONAL AVERAGE ONCE
AGAIN. HIGHS BACK INTO THE MID 70S WEDNESDAY AND THURSDAY WITH
OVERNIGHT LOWS IN THE MID 50S TO LOW 60S. REMAINDER OF THE PERIOD
CARRIES WEAK CHANCES OF SHOWERS AND THUNDERSTORMS IN RESPONSE TO A
MID LEVEL TROUGH PERSISTING OVER THE AREA.

MARINE...

TRANQUIL MARINE CONDITIONS THIS WEEKEND AS A WEAK PRESSURE GRADIENT
WILL PERSIST ACROSS THE GREAT LAKES. SOUTHERLY WINDS WILL GRADUALLY
INCREASE SUN NIGHT INTO MONDAY AHEAD OF A COLD FRONT APPROACHING THE
WESTERN GREAT LAKES. STRONG OVER LAKE STABILITY WILL HOLD GUSTS
BELOW 20 KNOTS. THE FRONT IS FORECAST TO TRAVERSE THE REGION LATE
MONDAY NIGHT INTO TUESDAY...LEADING TO A VEERING OF THE WINDS TOWARD
THE W-NW AND A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS.

&&

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

$$

AVIATION.....BT
SHORT TERM...MR
LONG TERM....JC/DE
MARINE.......JC


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



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