Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 202335
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
735 PM EDT MON OCT 20 2014


.AVIATION...

(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 130 AM EDT WED SEP 3 2014

//DISCUSSION...

THE MOISTURE IN THE LOW LEVELS WILL CONTINUE TO BE TRAPPED OVER
THE REGION AS THE SFC LOW CONTINUES TO MOVE TO THE EAST OF THE
UPPER GREAT LAKES. WHILE THERE IS A TEMPO AREA OF VFR CIGS
CURRENTLY MOVING THROUGH SE LOWER MI, UPSTREAM THERE ARE STILL
MVFR AND IFR CIGS WHICH WILL MOVE BACK INTO THE TAF SITES OVER THE
EVENING TIME FRAME. SHOWER WILL STILL BE A THREAT FROM TIME TO
TIME, ALTHOUGH WITH THE LOW CLOUDS THAT ARE MOVING INTO THE REGION
THE EXPECTATION IS FOR PATCHY DRIZZLE. THERE WILL BE A FEW
SHORTWAVE TROUGHS THAT WILL ROTATE INTO THE SE LOWER MI OVERNIGHT
AND TUESDAY MORNING THAT WILL CONTINUE THE THREAT FOR LIGHT RAIN
SHOWERS. BY TUESDAY AFTERNOON, THE WINDS WILL INCREASE AND DRIER
AIR SHOULD BEGIN TO WORK ITS WAY INTO THE REGION, SO THAT MBS AND
FNT WILL BEGIN TO SEE PARTIAL CLEARING BY 00Z, WHILE THE REST OF
THE TAF SITES PROBABLY WON`T SEE ANY CLEARING UNTIL AFTER 00Z.

//DTW THRESHOLD THREATS...

* HIGH CONFIDENCE OF MVFR CIGS LATER TONIGHT INTO EARLY TUESDAY
  MORNING.

&&

.PREV DISCUSSION...ISSUED 344 PM EDT MON OCT 20 2014

SHORT TERM...TONIGHT

DEEP LAYER TROUGHING WILL CONTINUE TO ROTATE ACROSS THE REGION
TONIGHT. LOW LEVEL MOISTURE IS EXTENSIVE...WITH WIDESPREAD STRATUS
EXTENDING ACROSS CENTRAL AND NORTHERN MICHIGAN...WITH CLOUDY SKIES
DOMINATING RIGHT UP THROUGH SOUTHERN CANADA. WITH THAT
SAID...FORCING FOR ASCENT IS NOT OVERLY IMPRESSIVE...ALTHOUGH POCKET
OF ENHANCED MID LEVEL SUPPORT DOES ROTATE THROUGH THE AREA THIS
EVENING INTO THE EARLY OVERNIGHT HOURS. NOT OVERLY CONFIDENT ON
SHOWER POTENTIAL...ESPECIALLY GIVEN LACK OF RETURNS TO OUR NORTH.
WILL KEEP THINGS SIMPLE...KEEPING SCATTERED/CHANCE WORDING TO
ACCOUNT FOR ANY LIGHT SHOWER ACTIVITY. OTHERWISE...CLOUDS WILL
DOMINATE...KEEPING THE NOCTURNAL RESPONSE SOMEWHAT MUTED...WITH LOWS
ONLY FALLING INTO THE LOWER AND MIDDLE 40S.

LONG TERM...TUESDAY THROUGH MONDAY

RATHER CHALLENGING FORECAST TUESDAY/TUESDAY NIGHT WITH DEEP LAYER
TROUGHING SLOW TO EXIT OFF TO THE EAST...ITSELF REINFORCED BY
SECONDARY ENERGY DROPPING DOWN ITS BACKSIDE INTO THE MID ATLANTIC
STATES BY TUESDAY EVENING. THIS LATTER FEATURE WILL HELP COMPLETE
THE CLOSING OFF PROCESS...WITH GRADUAL DEVELOPMENT OF RATHER
RESPECTABLE EAST COAST LOW PRESSURE THROUGH MID AND LATE WEEK. H9-H8
THERMAL TROUGHING CENTERS OVERHEAD DURING THE DAY TUESDAY...SLOW TO
EXIT OFF TO THE EAST TUESDAY NIGHT AS EAST COAST CYCLOGENESIS
COMMENCES. PERUSAL OF MODEL DERIVED SOUNDINGS/CROSS SECTION
MOISTURE ANALYSIS SHOWS MAINTENANCE OF MOISTURE RICH LOW LEVELS
RIGHT THROUGH TUESDAY EVENING...WITH SAID THERMAL TROUGHING/WEAK
SURFACE TROUGH AND POSSIBLE LAKE HURON CONTRIBUTION ONLY HELPING THE
CLOUD PRODUCING AND LIGHT SHOWER CAUSE. PATTERN RECOGNITION/TIME OF
YEAR CONCUR...AND WILL CONTINUE PESSIMISTIC TREND...KEEPING
CONDITIONS CLOUDY AND OCCASIONALLY WET (MORE SO EARLY)
TUESDAY...AND ADVERTISING ONLY A SLOW "CLEARING" TREND FROM
NORTHWEST TO SOUTHEAST TUESDAY NIGHT. A CHILLY TUESDAY...WITH CLOUDS
AND OVERHEAD COOL AIRMASS KEEPING HIGHS IN THE UPPER 40S AND LOWER
50S. NOCTURNAL RESPONSE TUESDAY NIGHT NOT NEARLY AS IMPRESSIVE AS IT
COULD BE...WITH SLOW DEPARTURE OF CLOUDS AND MAINTENANCE OF LIGHT
NORTHERLY FLOW KEEPING READINGS IN THE UPPER 30S/LOWER 40S.

A WELL DESERVED REPRIEVE FROM THE RECENT WET WEATHER STILL APPEARS A
SAFE BET HEADING INTO THE MID AND END PORTIONS OF THE WEEK...WITH
EARLIER MENTIONED EASTERN SEABOARD LOW PRESSURE TAKING ITS TIME TO
WORK UP THE COAST...ALL-THE-WHILE SHARP DEEP LAYER RIDGING SETTLES
OVERHEAD. ATTENDANT SUBSIDENCE WILL BE IMPRESSIVE...AND WHEN
COMBINED WITH PERSISTENT DRY LOW LEVEL NORTHERLY FLOW...SHOULD BRING
CLEARING SKIES WEDNESDAY...WITH MOSTLY CLEAR CONDITIONS PREVAILING
RIGHT THROUGH THURSDAY EVENING. SUPPORT IS GROWING FOR A RATHER
APPRECIABLE WAVE TO DROP ACROSS THE LAKES OVERNIGHT THURSDAY INTO
FRIDAY. SIMPLY NO DECENT PRE-SYSTEM MOISTURE ADVECTION...HOWEVER...
WITH ALL DEEP LAYER MOISTURE TIED UP WELL TO OUR EAST. WOULD EXPECT
TO SEE SOME INCREASING MID AND HIGH LEVEL CLOUDS...BUT SUB CLOUD
LAYER PROFILES WILL REMAIN AWFULLY DRY...LIKELY NEGATING ANY
PRECIPITATION FROM REACHING THE SURFACE (SUPPOSE A FEW SPRINKLES ARE
POSSIBLE...BUT IN NO HURRY TO ADD SUCH DETAIL JUST YET).

EAST COAST SYSTEM FINALLY GETS THE BOOT NORTHEAST...WITH ADDITIONAL
ENERGY DROPPING IN BEHIND IT TO HELP CARVE OUT EASTERN CANADA
TROUGHING THIS WEEKEND. FLOW PATTERN OVER THE NORTHERN CONUS BECOMES
MORE PROGRESSIVE...WITH RIDGING ONCE AGAIN BUILDING OVERHEAD HEADING
THROUGH THE END OF THE WEEKEND. STILL SOME QUESTIONS ON JUST HOW
MUCH COLD AIR BLEEDS INTO THE AREA...WITH POSSIBILITY OF A WEAK COLD
FRONTAL PASSAGE ON SATURDAY. GUIDANCE TRENDS HAVE DEFINITELY BEEN
FOR A LESS AGGRESSIVE COLD AIR PUSH...WHICH FITS WELL WITH THE
INHERITED FORECAST AND NEW GUIDANCE BLEND APPROACH. SUPPORT REMAINS
STRONG FOR DRY CONDITIONS TO PREVAIL RIGHT THROUGH THE WEEKEND.

MARINE...

WINDS WILL CONTINUE TO VEER NORTHWEST THIS EVENING...AND
EVENTUALLY NORTH TO NORTHEAST LATER TONIGHT INTO TUESDAY BEHIND A
PASSING COLD FRONT. INCREASING PRESSURE GRADIENT AND ONSHORE FLOW
WILL BRING A PERIOD OF GUSTY WINDS AND BUILDING WAVES THROUGHOUT
CENTRAL AND SOUTHERN LAKE HURON THROUGH TUESDAY. THE POTENTIAL FOR
GUSTS AROUND 30 KNOTS LOOKS SOLID WITH A LOWER PROBABILITY FOR BRIEF
GUSTS TO GALES EARLY TUESDAY. THE COLDER AIR OVER THE WARM LAKE
WATER WILL YIELD STRONG INSTABILITY BUT MAY ALSO LIMIT THE POTENTIAL
FOR GALE FORCE GUSTS BY ALTERING THE PRESSURE FIELD AND LIMITING THE
GRADIENT FLOW. NO GALE HEADLINES ARE PLANNED AT THIS TIME...WITH
SMALL CRAFT ADVISORIES ALREADY ISSUED FOR ALL NEARSHORE WATERS OF
LAKE HURON INCLUDING SAGINAW BAY. CONDITIONS ARE EXPECTED TO SLOWLY
IMPROVE TUESDAY NIGHT...WITH MAINLY QUIET WEATHER EXPECTED FOR THE

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.

LAKE HURON...
     SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS
     FROM PORT AUSTIN TO HARBOR BEACH...FROM 5 AM TUESDAY TO 6 AM
     WEDNESDAY.

     SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM HARBOR BEACH TO PORT
     HURON...FROM 8 AM TUESDAY TO 6 AM WEDNESDAY.

     SMALL CRAFT ADVISORY...INNER SAGINAW BAY...FROM 8 AM TUESDAY TO 10
     PM TUESDAY.

LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.

&&

$$

AVIATION.....99
SHORT TERM...MSB
LONG TERM....MSB
MARINE.......MSB


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





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