Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 281947
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
347 PM EDT TUE APR 28 2015

.SHORT TERM...THROUGH TONIGHT

CYCLONIC FLOW THAT HAD PERSISTED OVER THE CWA THE PAST FEW DAYS HAS
SINCE MOVED OFF TO THE EAST.  THIS HAS BEEN REPLACED BY HIGH
PRESSURE RESULTING IN A QUIET AND PLEASANT DAY ACROSS SOUTHEAST
MICHIGAN.  FORECAST CHALLENGE TODAY HAS BEEN WITH THE AMOUNT OF
MOISTURE AND CLOUDS AS MODELS WERE SHOWING A CU FIELD DEVELOPING
THIS AFTERNOON...HOWEVER DRIER AIR FILTERING IN HAS HELD OFF ANY
DEVELOPMENT.  THERE WERE A FEW AREAS THAT SAW SOME CLOUDS...BUT
OVERALL THE ENTIRE CWA HAS STAYED MOSTLY CLEAR.  THERE IS STILL THE
POTENTIAL FOR SOME DEVELOPMENT OVER THE NEXT COUPLE OF HOURS AS
NORTHERLY FLOW HELPS TO BRING IN SOME MOISTURE OFF THE LAKES.
TEMPERATURES HAVE RESPONDED NICELY DUE TO THE LACK OF CLOUD COVER
WHICH IS A BIG CHANGE FROM YESTERDAY.  WITH HIGH PRESSURE
OVERHEAD...WINDS WILL SLACKEN AND BECOME CALM THROUGH THE OVERNIGHT
PERIOD.

&&

.LONG TERM...WEDNESDAY THROUGH TUESDAY

RESIDUAL WEAK LOW-MID LEVEL RIDGING TRANSLATES EASTWARD EARLY
WEDNESDAY...AS UPPER HEIGHTS STEADILY LOWER IN RESPONSE TO A
DEEPENING MID LEVEL CIRCULATION DIVING ACROSS THE WESTERN GREAT
LAKES.  CENTER OF THIS CLOSED SYSTEM REMAINS FORECAST TO PROPAGATE
DUE SOUTH ACROSS LAKE MICHIGAN/WESTERN LOWER MI WEDNESDAY EVENING
THROUGH THURSDAY MORNING.  BULK OF THE DAYTIME PERIOD ON WEDNESDAY
LARGELY JUST A CLOUD ISSUE...GRADUAL LOW LEVEL DESTABILIZATION VIA
DAYTIME HEATING PROMOTING AND/OR REINFORCING A BROAD STRATOCU FIELD
BENEATH THE EXISTING INVERSION.  RESIDENT AIR MASS ROUGHLY 2-3
DEGREES WARMER WITHIN THE 850-925 MB LAYER RELATIVE TO TODAY.  THIS
SUGGESTS HIGHS OF LOWER AND MIDDLE 60S /COOLER EASTERN THUMB/ ARE
ATTAINABLE UNDER GOOD MIXING DESPITE THE THICKENING CLOUD COVER.

HEIGHTENED REGION OF CVA ALONG THE EASTERN FLANK OF THIS SYSTEM WILL
PIVOT EAST-SOUTHEAST AND ACROSS AT LEAST SOUTHERN SECTIONS WEDNESDAY
EVENING.  THIS WILL OCCUR COINCIDENT WITH AN INCREASE IN MID LEVEL
LAPSE RATES AS THE ATTENDANT COLD POOL EXPANDS IN AREAL COVERAGE.  A
WEAKLY UNSTABLE PROFILE...MUCAPE STILL PROJECTED BELOW 100 J/KG...
WILL AUGMENT THIS FORCING TO SUPPORT SOME DEGREE OF SHOWER
DEVELOPMENT BY EARLY EVENING.  12Z MODEL GUIDANCE CONTINUE TO FAVOR
THE EXPANSION AND PROPAGATION OF THIS MOISTURE FROM SOUTH-CENTRAL
INTO SOUTHEAST MI /BEST POTENTIAL SOUTH OF I-69/ BETWEEN 22Z AND
04Z.  ADDITIONAL SHOWER DEVELOPMENT WILL REMAIN PLAUSIBLE THROUGH
THE NIGHT AREAWIDE AS THE INCREASING INFLUENCE OF COOLER CYCLONIC
FLOW MAINTAINS STEEPER MID LEVEL LAPSE RATES.  LOWS PREDOMINATELY
UPPER 30S AND LOWER 40S.

SE MICHIGAN REMAINS WITHIN THE CYCLONIC PERIPHERY OF THE EXITING
UPPER LOW ON THURSDAY.  DAYTIME HEATING WILL PROVIDE A NOTABLE
INCREASE IN SFC-3 KM LAPSE RATES...BENEATH A DOME OF COOLER MID
LEVEL TEMPERATURES.  THIS WILL ESTABLISH A FAIRLY DEEP CONVECTIVE
LAYER BY EARLY AFTERNOON.  THIS PROFILE WITHIN A BACKGROUND OF
CONTINUED CYCLONIC FLOW AND ADEQUATE MOISTURE WILL AGAIN SUPPORT
SHOWER PRODUCTION THROUGH THE PEAK HEATING CYCLE...CERTAINLY WORTHY
OF THE GOING CHANCE POPS.  THE MORE LIMITED INSOLATION POTENTIAL
UNDER NORTHERLY LOW LEVEL FLOW WILL CAP THE TEMPERATURE RESPONSE TO
SOME DEGREE.  HIGHS A FEW DEGREES BELOW NORMAL...MID 50S TO AROUND
60.

SCATTERED RAIN SHOWERS MOVE INTO THE FORECAST SATURDAY AFTERNOON
WITH A MID LEVEL TROUGH THAT DIPS ACROSS THE AREA. SHOWERS DIE OFF
BY LATE EVENING...BUT RESUME AGAIN ON SUNDAY WITH ANOTHER UPPER
LEVEL TROUGH MOVING OVER THE GREAT LAKES REGION. THE UP AND DOWN
PATTERN CONTINUES INTO THE FORESEEABLE FUTURE...PRODUCING CHANCES
FOR RAIN SHOWERS AS WELL AS A POTENTIAL FOR A FEW THUNDERSTORMS.
TEMPERATURES LOOKING MORE SPRING-LIKE...WITH HIGH TEMPS IN THE LOW
70S SUNDAY THROUGH TUESDAY.

&&

.MARINE...

WEAK HIGH PRESSURE DRIFTING THROUGH THE CENTRAL GREAT LAKES WILL
MAINTAIN A LIGHTER WIND FIELD AND LOW WAVE CONDITIONS THROUGH
WEDNESDAY.   PROLONGED PERIOD OF LIGHT NORTH TO NORTHEAST FLOW
EXPECTED THROUGH THE END OF THE WEEK.  THIS MAY PROVIDE A FAVORABLE
ENVIRONMENT FOR GREATER WAVE GROWTH UNDER LONG DURATION ONSHORE
FLOW.

&&

.AVIATION...ISSUED 140 PM EDT TUE APR 28 2015

DAYTIME HEATING HAS LED TO THE SLOW DEVELOPMENT OF THE CU FIELD
ACROSS PARTS OF THE AREA ALTHOUGH NOT AS EXPANSIVE DUE TO THE LACK
OF MOISTURE. THERE IS STILL A SHORT WINDOW FOR CU TO DEVELOP YET
LATER THIS AFTERNOON.  WITH HIGH PRESSURE CONTINUING OVER THE AREA
THROUGH THE OVERNIGHT HOURS...WINDS WILL WEAKEN AND BECOME VARIABLE
LATER THIS EVENING.  CLOUDS DO START INCREASING IN COVERAGE ONCE
AGAIN ON WEDNESDAY WITH VFR CONDITIONS PREVAILING THROUGH THE TAF
CYCLE.

FOR DTW...ASIDE FROM THE POTENTIAL FOR DAYTIME CLOUD ENHANCEMENT
THIS AFTERNOON...A WEAK SFC GRADIENT WILL SUPPORT LAKE BREEZE
DEVELOPMENT IN THE 21 TO 23Z TIME FRAME.

//DTW THRESHOLD PROBABILITIES...

* MEDIUM IN CLOUDS AT OR BELOW 5000 FT THIS AFTERNOON AND INTO THE
  EVENING.

&&

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

$$

SHORT TERM...SS
LONG TERM....MR/DE
MARINE.......MR
AVIATION.....SS


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