Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 260758
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
358 AM EDT SUN APR 26 2015

.SHORT TERM...TODAY AND TONIGHT

SUPPRESSION OF GEOPOTENTIAL HEIGHTS OVER THE SOUTHEASTERN UNITED
STATES WILL ALLOW THE BROADENING CLOSED LOW ANOMALY OVER PORTIONS OF
NORTHEASTERN NORTH AMERICA TO REACH BACK AND REGAIN AN INFLUENCE
OVER THE GREAT LAKES REGION TODAY AND TONIGHT. THE STRENGTHENING
DEEP COLUMN CYCLONIC FLOW WILL NOT ONLY BRING ANOTHER DAY OF BELOW
NORMAL TEMPERATURES...IT WILL BACKDOOR A COUPLE OF SPOKES OF WEAK
SHORTWAVE ENERGY AND RIBBONS OF DEEPER MOISTURE FROM NORTHEAST TO
SOUTHWEST ACROSS LAKE HURON AND DOWN INTO INTERIOR SECTIONS OF THE
LOWER PENINSULA.

FOR THE SHORT TERM FORECAST...THE ITEM OF UNCERTAINTY IS WHEN CLOUDS
WILL PUSH ACROSS THE LAKE AND SPREAD ACROSS THE CWA. THE MODEL
CONSENSUS IS VERY BULLISH...SUGGESTING CLOUDS WILL BE HERE ALREADY
BY MID TO LATE MORNING. THE PROBLEM IS CURRENT...IR SATELLITE
IMAGERY SHOWS AREAS VOID OF CLOUD CLEAR BACK ACROSS LAKE HURON TO
ONTARIO. THE POCKET OF CLOUD THAT HAD ADVECTED DOWN INTO THE SAGINAW
BAY AREA EARLIER HAS SINCE ERODED. FOR SKY COVER...WENT WITH A BLEND
OF GUIDANCE AND GUT FEELING. OVERALL...FAVOR MORE SUN DURING THE
MORNING BEFORE CLOUDS INCREASE DURING THE AFTERNOON EITHER FOR
INCREASE IN DIURNAL CUMULUS/STRATOCUMULUS OR ADVECTION OF MIDLEVEL
CLOUD. ADDING TO THIS POINT...FIRST SPOKE OF CVA IS EXPECTED TO
COLLAPSE DOWN UPON THE AREA DURING THE LATE AFTERNOON. THE SECOND
SPOKE OF MIDLEVEL ENERGY WILL ARRIVE LATE TONIGHT...LIKELY AFTER 9Z.
MODEL SOUNDINGS SUPPORT A FAIRLY RESPECTABLE DEPTH OF DEEPER
MOISTURE WITH THIS SECOND WAVE. KEPT THE SLIGHT TO LOW CHANCE OF A
RAIN SHOWER FOR THE EASTERN THUMB/LAKE HURON SHORELINE. THE
POTENTIAL MAY HINGE ON MORE OF A DRIZZLE/WEAK STRATIFORM RAIN
POTENTIAL WITH VERY WEAK LAPSE RATE STRUCTURES FORECASTED.

&&

.LONG TERM...MONDAY THROUGH SATURDAY

DEEP LAYER N-NE FLOW WILL PERSIST ACROSS SE MI ON MONDAY AS THE
FORECAST AREA WILL REMAIN UNDER THE INFLUENCE OF AN UPPER LOW AND
ELONGATED TROUGH AXIS EXTENDING FROM NRN NEW ENGLAND ACROSS THE
GREAT LAKES. A REGION OF MID LEVEL SUBSIDENCE WILL HOWEVER
OVERSPREAD THE FORECAST AREA MON AFTERNOON IN THE WAKE OF A MID
LEVEL SHORT WAVE IMPULSE DROPPING SOUTH ACROSS ERN LOWER MI. WHILE
SOME DEGREE OF LOW-MID LEVEL MOISTURE WILL CONTINUE TO STREAM INTO
SE MI FROM THE NORTHEAST...MID LEVEL WARMING WILL LIMIT CONVECTIVE
CLOUD DEPTHS. THIS WILL SUPPORT A DRY AFTERNOON FORECAST...ALTHOUGH
THERE IS LIKELY TO BE A HEALTHY CU/STRATO CU FIELD. THE CONTINUED
NORTHERLY FLOW AND DAYTIME CLOUD COVER WILL KEEP MONDAY HIGHS IN THE
50S. A HIGH AMPLITUDE MID LEVEL RIDGE WILL THEN BUILD INTO LOWER MI
ON TUES. THE LOSS OF THE NORTHERLY WIND COMPONENT AS SFC HIGH NUDGES
INTO THE AREA FROM THE WEST AND BETTER DIURNAL HEATING POTENTIAL
WILL SUPPORT TUES HIGHS INTO THE LOW 60S AFTER RELATIVELY CHILLY
EARLY MORNING TEMPS IN THE 30S.

THE 00Z GFS HAS TRENDED STRONGER WITH MID LEVEL SHORT WAVE ENERGY
DROPPING INTO THE GREAT LAKES FROM CENTRAL CANADA IN THE WED-THURS
TIME FRAME AND ACTUALLY DEVELOPS A CUT OFF CIRCULATION OVER LOWER MI
WED NIGHT. THE 00Z ECMWF /WHOSE SOLUTION FOR THE WED-THURS TIME
FRAME HAS BEEN BY FAR MORE CONSISTENT/ IS ALONG A SIMILAR LINE
ALTHOUGH NOT NEARLY AS DEEP AS THE GFS. A DRY FORECAST WILL BE
MAINTAINED IN THE WED-THURS TIME FRAME WITH CONTINUED MODEL
DISCREPANCIES AND IN CONSIDERATION OF THE OVERALL DRY AIRMASS
RESIDING OVER THE GREAT LAKES. IN LIGHT OF THE TRENDS...HIGH TEMPS
FOR THURS HAVE BEEN NUDGED DOWN A FEW DEGREES /UPPER 50S TO LOW
60S/. THE DEPARTURE OF THIS SYSTEM LATE IN THE WEEK WILL THEN OFFER
AN OPPORTUNITY FOR A SUBSTANTIAL WARMING TREND HEADING INTO NEXT
WEEKEND AS MID LEVEL HEIGHTS REBOUND ACROSS THE REGION.

&&

.MARINE...

PERSISTENT LOW PRESSURE ALONG THE EAST COAST AND STRENGTHENING HIGH
PRESSURE BUILDING ACROSS THE WESTERN GREAT LAKES TODAY INTO TONIGHT
WILL ACTUALLY STRENGTHEN THE N-NW GRADIENT ACROSS LAKES HURON AND
ERIE TODAY INTO TONIGHT. THE NET RESULT WILL BE A STRENGTHENING OF
THE N-NW WINDS THIS AFTERNOON THROUGH TONIGHT. WINDS AND WAVES WILL
THEN SLOWLY DECREASE MONDAY INTO TUESDAY MORNING AS HIGH PRESSURE
BUILDS INTO THE REGION FROM THE WEST.

&&

.AVIATION...ISSUED 1155 PM EDT SAT APR 25 2015

SOUTHEAST MICHIGAN WILL REMAIN UNDER THE INFLUENCE OF DRY
NORTHEASTERLY FLOW TONIGHT AS WEAK SURFACE RIDGING BUILDS IN.  THIS
WILL ENSURE A MOSTLY CLEAR SKY BELOW 10K FT THROUGH THIS TIME.
PERSISTENT NORTHERLY FLOW WILL RETAIN VFR CONDITIONS THROUGHOUT
SUNDAY.  A POCKET OF MOISTURE ROTATING THROUGH THE RIDGE PERIPHERY
WILL LEAD TO AN INCREASE IN DIURNAL STRATOCU BY EARLY AFTERNOON.

//DTW THRESHOLD PROBABILITIES...

* LOW IN CEILINGS AT OR BELOW 5000 FEET SUNDAY AFTERNOON AND EVENING.

&&

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

$$

SHORT TERM...CB
LONG TERM....SC
MARINE.......SC
AVIATION.....MR


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


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