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204
FXUS63 KDTX 232305
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
705 PM EDT TUE SEP 23 2014

.AVIATION...

//DISCUSSION...

IDEAL AVIATION CONDITIONS TONIGHT THROUGH WEDNESDAY WILL BE DRIVEN
BY A BROAD EXPANSE OF SURFACE HIGH PRESSURE CENTERED OVER THE NEW
ENGLAND STATES. THE LOCATION OF THE HIGH FAVORS A LIGHT SOUTHEAST
WIND ACROSS THE GREAT LAKES. THERE IS SOME ADDED POTENTIAL FOR FOG
WITH THE SE TRAJECTORY FROM LAKE ERIE INTO DTW BUT THE AIR IS DRY
ENOUGH TO DOUBT THE EFFECTIVENESS OF THE LAKE MOISTURE CONTRIBUTION.
THIS WILL BE MONITORED BUT VISIBILITY RESTRICTION WILL OTHERWISE BE
LIMITED TO GROUND FOG IN LOW LYING/PRONE AREAS FOR A SHORT PERIOD
AROUND SUNRISE GIVING WAY TO ANOTHER DAY OF FULL SUN THROUGH THE
REST OF THE DAY.

//DTW THRESHOLD THREATS...

* NONE.

&&

.PREV DISCUSSION...ISSUED 329 PM EDT TUE SEP 23 2014

SHORT TERM...TONIGHT

AT PEAK MIXING TODAY...DEWPOINT TEMPERATURES REGISTERED IN THE LOW
50S AND UPPER 40S. THIS WILL LIKELY CORRESPOND WITH OUR MIN TEMPS
FOR TOMORROW MORNING UNDER LIGHT WINDS AND CLEAR SKIES. THERE ARE
WARM ADVECTION PROCESSES ONGOING DURING THE PERIOD...SO THIS ALSO
LEADS TO OVERNIGHT MIN TEMPS COMING IN A BIT WARMER THAN THIS
MORNING. NO CLOUD COVER TO SPEAK OF ON REGIONAL SATELLITE VIEWS. THE
ONLY WEATHER CONCERN IS THE FORMATION OF PATCHY FOG WEDNESDAY
MORNING. THE ONLY MOISTURE PRESENT IS IN THE LOWEST 2KFT OF THE
ATMOSPHERE. AS THE OVERNIGHT INVERSION LOWERS AND COMPRESSES THIS
MOISTURE...EXPECT PATCHY FOG TO DEVELOP IN THE USUAL LOW TERRAIN AREAS.

LONG TERM...WEDNESDAY THROUGH MONDAY

HIGH PRESSURE...BOTH AT THE SURFACE AND ALOFT...WILL CONTINUE TO
PRODUCE PLEASANT WEATHER THROUGH THE UPCOMING WEEKEND. THE UPPER
LEVEL RIDGE WILL ENGULF THE MAJORITY OF THE CONUS WITH ALL JET
ENERGY SHUNTED NORTH OVER CANADA. ONLY REAL ACTION OVER THE CONUS
WILL BE A SHEARED PIECE OF UPPER LEVEL ENERGY CURRENTLY BEING CUTOFF
FROM THE MAIN FLOW WHICH WILL THEN MEANDER ABOUT THE CENTRAL PLAINS
AND MIDWEST THROUGH THE WEEKEND.

TEMPERATURES WILL STAY PRETTY STABLE MIDWEEK WITH 850MB TEMPS
HOVERING AROUND 11-13C. THIS WILL MAX OUT ON WEDNESDAY AS THE SFC
HIGH DRIFTS EASTWARD RESULTING IN WEAK SOUTHWESTERLY FLOW...BUT A
PIECE OF THE SHEARED UPPER LEVEL LOW WILL DRIFT OVERHEAD BRIEFLY
LOWERING HEIGHTS WITH SLIGHTLY COOLER AIR ALOFT. ONLY THING WE MAY
SEE FROM THIS IS SOME THIN CIRRUS CLOUDS AS THE AMOUNT OF DRY AIR IN
THE COLUMN REMAINS HIGH WITH PWATS AROUND 0.6 INCHES THROUGH THE
PERIOD. IF THERE IS SOMETHING TO KEEP AN EYE OUT FOR...IT WILL BE
MORNING FOG. THIS WILL BE MOSTLY A PATCHY COVERAGE OF SHALLOW FOG AT
BEST AS MODEL SOUNDING SHOW DRY AIR EXTENDING ALL THE WAY TO THE
SFC. WITH FAVORABLE RADIATIONAL COOLING CONDITIONS...DRY AIR...HIGH
PRESSURE...CALM WINDS...CLEAR SKIES...WE SHOULD DROP TO AROUND 50
EACH NIGHT. MOST OF THE DEWPOINTS THROUGHOUT THE REGION RANGE FROM
MID 40S TO LOW 50S SO WE COULD REACH SATURATION FOR A COUPLE HOURS
TOWARD MORNING. DO NOT FEEL CONFIDENT ENOUGH TO INCLUDE IN THE
FORECAST AT THIS TIME SO WILL TAKE IT DAY BY DAY TO SEE HOW THE
DAILY MIXING TAKES ITS TOLL ON THE LL MOISTURE.

ALL SIGNS POINT TO A GLORIOUS WEEKEND AS THE UPPER JET IS DISPLACED
FAR TO THE NORTH OVER HUDSON BAY. WEAKNESS IN THE UPPER RIDGE
UNLIKELY TO IMPACT SENSIBLE WEATHER LOCALLY AS MODELS PROJECT LOW
COLUMN RH. 12Z GFS/EC DEPICTING BACKDOOR COLD FRONT DROPPING DOWN
SUNDAY NIGHT/MONDAY BUT WITH LACK OF MOISTURE AND LONG TIME HORIZON
WILL KEEP EXTENDED PERIOD DRY. EXPECT HIGHS IN THE 70S AND LOWS IN
THE 50S THROUGH THE END OF THE PERIOD.

MARINE...

HIGH PRESSURE WILL HOLD OVER THE GREAT LAKES THROUGH THE WEEK
PROVIDING FAVORABLE MARINE CONDITIONS WITH LIGHT WINDS AND WAVES
LARGELY UNDER 2 FEET. THERE IS NO THREAT OF PRECIPITATION THROUGH
THE PERIOD.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

AVIATION.....BT
SHORT TERM...MM
LONG TERM....DRK/DT
MARINE.......DRK


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