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000
FXUS63 KDTX 181945
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
345 PM EDT FRI APR 18 2014

.SHORT TERM... THROUGH TONIGHT

UPPER LEVEL TROUGH AXIS IS LOCATED OVER THE GREAT LAKES. HEIGHTS
WILL RISE OVERNIGHT AS UPPER LEVEL FLOW BECOMES NORTHWESTERLY AND
SURFACE HIGH PRESSURE BUILDS INTO THE NORTHERN GREAT LAKES AND NOSES
INTO LOWER MICHIGAN. THE HIGH HAS NOT BEEN ABLE TO ASSERT ITSELF
OVER LOWER MICHIGAN AS OF YET...HOWEVER. AN ELEVATED THETA E
BOUNDARY PASSED SLOWLY THROUGH THIS MORNING...WHICH WAS ASSOCIATED
WITH SHOWER ACTIVITY. IN ITS WAKE...SURFACE WINDS HAVE BECOME
NORTHWESTERLY AND DECENT MIXING HAS OCCURRED...CAUSING TEMPS TO RISE
INTO THE UPPER 50S AND LOWER 60S ROUGHLY ALONG AND WEST OF I75. TO
THE EAST...WEAK PRESSURE GRADIENT HAS ALLOWED LAKE HURON RELEASE TO
OCCUR...LIMITING TEMPERATURES TO THE 40S EAST OF ROUGHLY M53. THE
LAKE INDUCED BOUNDARY IS EVIDENT ON 88D REFLECTIVITY...BISECTING
WAYNE COUNTY AS OF 1930Z. ITS PROGRESS SHOULD SLOW AS IT ENCOUNTERS
INCREASING NORTHWESTERLY FLOW. A GENEROUS CU-UP HAS OCCURRED IN THE
WAKE OF THE THETA-E BOUNDARY...BUT COVERAGE IS EXPECTED TO DIMINISH
INTO THE EVENING AS DIURNAL PROCESSES CEASE.

CLEARING SKIES AND SOME DECOUPLING WILL ALLOW FOR LOWS TO DROP INTO
THE UPPER 20S NORTH. A SLIGHTLY STRONGER PRESSURE GRADIENT WILL
PREVENT DECOUPLING LONGER IN THE SOUTH AND ALLOW LOWS TO STAY IN THE
MID-30S. THERE IS CONCERN FOR SOME PATCHY FOG AND/OR LOW STRATUS
OVERNIGHT IN THE THUMB WITH CONTINUED MOIST LOW-LEVEL FLOW OFF LAKE
HURON. MOIST SOIL FROM THIS MORNING/S RAINFALL MAY HELP IN THIS
PROCESS...HOWEVER...CONFIDENCE IS ONLY HIGH ENOUGH FOR A PATCHY
MENTION IN THE THUMB.

&&

.LONG TERM...SATURDAY THROUGH NEXT FRIDAY

STRONG SURFACE HIGH PRESSURE WILL EXPAND INTO THE NORTHERN AND
CENTRAL GREAT LAKES BY TOMORROW MORNING. THIS WILL KEEP DRY AND
QUIET WEATHER OVER THE AREA. TEMPERATURES HOWEVER WILL RUN BELOW
NORMAL AS A STRONG SUBSIDENCE INVERSION CONFINES MIXING HEIGHTS TO
NEAR/BELOW 4500 FEET AND EASTERLY FLOW DEVELOPS OFF THE COLD WATERS
OF THE GREAT LAKES. WITH GOOD INSOLATION EXPECTED...HIGHS IN THE
LOW/MID 50S STILL LOOK REASONABLE...WITH COOLER READINGS NEAR THE
LAKESHORES.

THE HIGH WILL SHIFT EAST LATE SATURDAY NIGHT INTO SUNDAY AS THE
UPPER WAVE NOW NEAR THE MONTANA/ALBERTA BORDER BEGINS TO TRACK
ACROSS NORTHERN ONTARIO. THE PASSAGE OF THIS SYSTEM WILL DROP A COLD
FRONT ACROSS NORTHERN MICHIGAN AND LAKE HURON LATE SATURDAY NIGHT
INTO SUNDAY...WITH THE FRONT REMAINING QUASI-STATIONARY ON SUNDAY AS
MOISTURE BEGINS TO RIDE OVER IT AND RIGHT ENTRANCE REGION FORCING
FROM A JET STREAK BECOMES POSITIONED OVERHEAD. IT LOOKS AS IF
PRECIPITATION THROUGH LATE SUNDAY SHOULD REMAIN MOSTLY TO OUR
NORTH...WITH JUST A FEW SHOWERS POTENTIALLY BRUSHING THE SAGINAW
VALLEY AND NORTHERN THUMB. A SECOND LOW PRESSURE SYSTEM WILL THEN
LIFT UP INTO THE SOUTHERN GREAT LAKES FROM THE CENTRAL PLAINS ON
MONDAY...AHEAD OF A PIECE OF UPPER ENERGY THAT WILL BREAK OFF THE
UPPER LOW NOW PUSHING TOWARDS THE WEST COAST. AS THE LOW TRACKS
THROUGH THE AREA...IT WILL PULL MOISTURE UP INTO SOUTHEAST
MICHIGAN...BEFORE DRAWING THE FRONT HOLDING OVER NORTHERN MICHIGAN
SOUTHWARD. THIS SHOULD ALL PROVIDE A GOOD CHANCE FOR RAIN SHOWERS
MONDAY AND MONDAY NIGHT. THERE REMAIN SOME MODEL DIFFERENCES WITH
THE TIMING OF THE FRONTAL BOUNDARY...AND WILL CONTINUE TO FAVOR THE
MORE CONSISTENT CONSENSUS OF THE GFS/EURO/GEM INSTEAD OF THE FASTER
NAM WHICH IS AN OUTLIER WITH THE WAY IT HANDLES BOTH LOW PRESSURE
SYSTEMS EARLY NEXT WEEK. TEMPERATURES WILL REBOUND AHEAD OF BOTH
THESE SYSTEMS...FIRST WITH THE PASSAGE OF A WARM FRONT LATE SATURDAY
NIGHT AND THEN WITH WARM AIR ADVECTION CONTINUING ON SUNDAY AND
AGAIN MONDAY AS THE SECOND LOW APPROACHES. HIGH LOOK TO PUSH INTO
THE 60S TO NEAR 70 BOTH AFTERNOONS.

LOW PRESSURE EXITS TO THE EAST NORTHEAST BY TUESDAY BRINGING IN A
DRY NORTHERLY FLOW THROUGH WEDNESDAY NIGHT. A LOW PRESSURE SYSTEM
SETTING UP OVER THE NORTHERN PLAINS IS EXPECTED TO USHER IN ANOTHER
CHANCE OF RAIN SHOWERS FOR THURSDAY AND FRIDAY...WITH HIGH PRESSURE
RETURNING FOR SATURDAY.

&&

.MARINE...

WINDS WILL CONTINUE TO GUST UP TO 25 KNOTS OVER NORTHERN AND CENTRAL
LAKE HURON INTO THIS EVENING AS COOLER AIR FILTERS INTO THE REGION
BEHIND A COLD FRONT. STRONG HIGH PRESSURE CENTERED OVER ONTARIO WILL
THEN EXPAND INTO THE NORTHERN AND CENTRAL GREAT LAKES TONIGHT
THROUGH SATURDAY NIGHT...BRINGING MORE TRANQUIL WEATHER. TWO LOW
PRESSURE SYSTEMS WILL THEN PASS NEAR THE AREA INTO EARLY NEXT WEEK.
THE FIRST WILL TRACK ACROSS ONTARIO ON SUNDAY...DROPPING A COLD
FRONT DOWN INTO LAKE HURON. THE FRONT WILL REMAIN QUASI-STATIONARY
OVER THIS AREA UNTIL ANOTHER LOW PRESSURE SYSTEM DRAWS IT SOUTHWARD
MONDAY AND MONDAY NIGHT. STRONGER NORTH WINDS ARE THEN POSSIBLE
ACROSS THE AREA LATE MONDAY NIGHT INTO TUESDAY BEHIND THE FRONT.

&&

.AVIATION...ISSUED 147 PM EDT FRI APR 18 2014

//DISCUSSION...

GOOD COVERAGE OF CU HAS SPRUNG UP IN THE WAKE OF THIS MORNING/S
FRONTAL PASSAGE. AFTER AREAS OF MVFR AND EVEN A FEW IFR CEILINGS
THIS MORNING...EXPECT VFR CEILINGS WITH A RISING TREND THE
REMAINDER OF THE DAY. WINDS WILL SHIFT TO NORTH/NORTHEASTERLY
LATER THIS EVENING DUE TO A COMBINATION OF BACKDOOR COLD FRONT AND
LAKE EFFECTS. OTHER ISSUE OF CONCERN IS THE POTENTIAL FOR FOG OR
LOW STRATUS OVERNIGHT. TRAJECTORIES OFF LAKE HURON COMBINED WITH
MOIST GROUND FROM THIS MORNING/S RAINFALL COULD LEAD TO SOME LOW
LEVEL MOISTURE...WITH NAM FORECAST SOUNDINGS SHOWING SOME MOISTURE
BEING TRAPPED BELOW AN INVERSION. CONFIDENCE WAS NOT HIGH ENOUGH
TO INCLUDE IN THE TAFS AT THIS TIME...BUT THIS WOULD BE MOST
LIKELY OVER PTK/FNT IF IT WERE TO DEVELOP.

FOR DTW...SCT/BKN SUB-5000 FT CLOUDS SHOULD CONTINUE THIS
AFTERNOON INTO EARLY EVENING...BUT CEILINGS WILL UNDERGO A RISING
TREND. A WIND SHIFT TO NORTH/NORTHEASTERLY IS EXPECTED AROUND 00Z.

//DTW THRESHOLD THREATS...

* MODERATE CONFIDENCE IN CEILINGS BELOW 5000 FT THROUGH 00Z.


&&

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

&&

$$

SHORT TERM...DT
LONG TERM....HLO/DE
MARINE.......HLO
AVIATION...DT


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