Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

Home | Current Version | Previous Version | Text Only | 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 111756
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
156 PM EDT FRI APR 11 2014


.AVIATION...

//DISCUSSION...

WEAK SURFACE HIGH PRESSURE WILL SLIDE OFF TO THE NORTHEAST THIS
AFTERNOON AS A WEAK SURFACE TROUGH TRACKS ACROSS THE NORTHERN GREAT
LAKES REGION. MAJORITY OF THE MOISTURE AND RESULTING PRECIPITATION
ASSOCIATED WITH THIS FRONT WILL STAY TO THE NORTH OF THE TAF SITES.
CURRENTLY THE ONLY IMPACT ON THE AIRPORTS WILL BE SOME INCREASED
CLOUD COVERAGE AND LOWERED CEILINGS. OVERCAST SKIES ARE EXPECTED TO
STICK AROUND THROUGH MOST OF SATURDAY AS THE NEXT DISTURBANCE ARRIVES.

//DTW THRESHOLD THREATS...

* NONE

&&

.PREV DISCUSSION...ISSUED 429 AM EDT FRI APR 11 2014

SHORT TERM...TODAY AND TONIGHT

A VERY WEAK SURFACE HIGH WILL DRIFT ACROSS SOUTHEASTERN MICHIGAN
THIS MORNING. POSITIONING AND TIMING OF THE WEAK ANTICYCLONE
SUGGESTS THAT FORCING IS PURELY THAT OF LOW LEVEL COLD AIR ADVECTION
THAT OCCURRED BEHIND THE DEPARTING FRONT. THE SURFACE HIGH AND 300MB
RIDGE AXIS WILL EVENTUALLY PASS EAST OF THE CWA TODAY WHICH WILL
ALLOW SOUTHERLY FLOW TO BUILD BACK INTO THE CWA. OVERALL WIND
POTENTIAL IS A DIFFICULT FORECAST. THE REASON IS MIXING DEPTHS ARE
EXPECTED TO REACH 6000 FT. ON THE OTHER HAND...RAW MODEL OUTPUT
ALONG WITH THE EXPECTED WEAK SURFACE PRESSURE GRADIENT SUGGESTS
WINDS WILL BE HARD PRESSED TO REACH 10 KNOTS. THE INBOUND HIGH CLOUD
NOW ADVANCING THROUGH WISCONSIN IS ANOTHER COMPLICATING MATTER. NOT
SEEING ENOUGH TO GO AGAINST GUIDANCE AND WILL FORECAST 10 TO 15 MPH
WITH SLIGHTLY HIGHER VALUES FOR THE SAGINAW VALLEY. LOOKING FOR
OVERACHIEVING HEIGHT TEMPERATURES TODAY WITH THE HIGH MIXING HEIGHTS
AND MODEL LOW BIAS. SURFACE HIGHS ARE EXPECTED TO REACH THE LOW TO
MIDDLE 60S.

A DEEPER TROUGH AXIS 500-300MB WILL EVENTUALLY PASS OVER THE CENTRAL
GREAT LAKES BY THIS EVENING. A SHORTWAVE COLLECTED WITHIN THE MID TO
UPPER LEVEL WIND SHIFT IS EXPECTED TO TRACK DIRECTLY THROUGH THE CWA
BETWEEN 00-06Z. MODELS HAVE BEEN ADVERTISING SOME LIGHT QPF
POTENTIAL PRIMARILY WITH THE CVA AND SOME WARM AIR ADVECTION ALOFT.
SOUNDINGS ARE NOT SUPPORTIVE...WITH A TOTAL LACK OF MOISTURE AND
ACTUALLY LOWERING SUBSIDENCE IN THE 10-19 KFT AGL LAYER. MODELS
TYPICALLY UNDERACHIEVE IN NOCTURNAL WAA ALOFT SCENARIOS AND WILL KEEP
THE SLIGHT CHANCE GOING FOR THE SAGINAW VALLEY. IN THIS
CASE...OVERACHIEVING WOULD ONLY BE MEASURING A FEW HUNDREDTHS.

LONG TERM...SATURDAY THROUGH THURSDAY

AN APPROACHING LOW PRESSURE SYSTEM WILL BRING INCREASING CHANCES FOR
RAIN DURING THE WEEKEND AS A WARM FRONT LIFTS NORTH THROUGH
SOUTHEAST MICHIGAN ON SATURDAY. AS THE LOW APPROACHES FROM THE WEST
THIS BOUNDARY WILL SERVE AS THE FOCUS FOR HEAVY RAIN SHOWERS DURING
THE WEEKEND AS THE WARM MOIST AIR BRINGS THE CHANCE FOR
THUNDERSTORMS ALONG WITH THE CHANCE FOR RAIN SHOWERS WITH THE AREA
WELL IN THE WARM SECTOR. ANOTHER LOW PRESSURE SYSTEM TRACKING
THROUGH THE GREAT LAKES ON MONDAY WILL BRING ANOTHER ROUND OF HEAVY
RAIN ON MONDAY WITH COLD AIR FILTERING IN BEHIND THE DEPARTING LOW
MONDAY NIGHT AND TUESDAY. THESE MULTIPLE ROUNDS OF HEAVY RAIN WILL
BRING FLOODING CONCERNS TO SOUTHEAST MICHIGAN...HOWEVER THE FLOODING
WILL BE DEPENDENT ON THESE MULTIPLE ROUNDS. IF THE FIRST ROUND DOES
NOT MATERIALIZE OR THE SECOND ROUND IS FURTHER WEST FLOODING WILL BE
AT A MINIMUM...THEREFORE WILL WAIT TO SEE HOW THESE ROUNDS SET UP
BEFORE THINKING ABOUT ANY HEADLINES FOR FLOODING.

BEHIND THE FRONT WE WILL COOL FROM THE 60S AND 70S BACK INTO THE 40S
TUESDAY AND WEDNESDAY AS HIGH PRESSURE BRINGS A STRETCH OF QUIET
WEATHER BACK TO THE CENTRAL GREAT LAKES. TEMPERATURES WARM UP A BIT
ON THURSDAY AS ANOTHER WARM FRONT LIFTS THROUGH THE CENTRAL GREAT
LAKES. THERE IS QUITE A BIT OF DIFFERENCE BETWEEN THE MODELS ON
THURSDAY AS THE GFS FOCUSES THE WARM FRONT FURTHER SOUTH WITH RAIN
SHOWERS WHILE THE ECMWF LIFTS THE FRONT FARTHER NORTH WITH SOUTHEAST
MICHIGAN IN THE WARM SECTOR AND DRY. GIVEN THE DIFFICULTIES OF
LIFTING A WARM FRONT THAT FAR NORTH WITH A STILL COOL GREAT LAKES
WILL PUT IN A SLIGHT CHANCE WITH THIS FORECAST ISSUANCE.

MARINE...

LIGHT FLOW WILL RULE TODAY AND TONIGHT AS A WARM FRONT LIFTS THROUGH
THE CENTRAL GREAT LAKES TONIGHT. THIS FRONT WILL SERVE AS A FOCUS
FOR SHOWERS AND THUNDERSTORMS DURING THE WEEKEND AS MODERATE
SOUTHERLY WINDS TURN SOUTHWESTERLY ON SATURDAY NIGHT. MODERATE
SOUTHERLY WINDS WILL RETURN SUNDAY NIGHT BEFORE TURNING
NORTHWESTERLY MONDAY AND MONDAY NIGHT BEHIND A COLD FRONT.

&&

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

&&

$$

AVIATION.....RK
SHORT TERM...CB
LONG TERM....KURIMSKI
MARINE.......KURIMSKI


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.