Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 052033
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
333 PM EST FRI FEB 5 2016

.DISCUSSION...

12Z DTX SOUNDING REVEALED AN 850 MB TEMP OF -12 C...A TOUCH COLDER
THAN MODEL INITIALIZATIONS. SOLID LOW LEVEL (925-850 MB) THETA-E
RIDGE/(2+ G/KG OF SPECIFIC HUMIDITY)/CONVERGENCE/ TRAVERSING THROUGH
LOWER MICHIGAN TODAY GENERATING SOME LAKE MICHIGAN ENHANCED
SCATTERED LIGHT SNOW SHOWER/FLURRY ACTIVITY (MAINLY NORTH OF I-
69)...DESPITE BEING EMBEDDED UNDERNEATH AN UPPER LEVEL RIDGE OUT
AHEAD OF THE CENTRAL NORTH AMERICAN TROUGH.

MAJORITY OF THE UPPER LEVEL ENERGY/PV OVER THE PLAINS WILL DROP INTO
TEXAS TONIGHT...WITH DEEP COLD LOW/PV ANOMALY ROTATING THROUGH
NORTHERN ONTARIO. STILL...A MODEST 500 MB HEIGHT FALL CENTER TO
TRACK THROUGH SOUTHERN LOWER MICHIGAN...BUT LOW LEVELS WILL BE
DRYING OUT WITH WESTERLY FLOW...AND EXPECTING SNOW SHOWER/FLURRY
ACTIVITY TO END WITH MAINLY JUST MID/HIGH CLOUDS AS THE UPPER LEVEL
SHEAR AXIS TRACKS THROUGH SATURDAY MORNING.

THE WEEKEND WILL FEATURE A MODEST WARMUP...AS POTENT UPPER LEVEL
ENERGY/JET OFF THE COAST OF THE PACIFIC NORTHWEST SPILLS INTO THE
NORTHERN PLAINS AND INTO THE WESTERN GREAT LAKES...WITH 500 MB
CLOSED LOW/CIRCULATION DEVELOPING. SUBSEQUENT LARGE SCALE
ASCENT/DEVELOPING OCCLUSION/NARROW MOISTURE PLUME (PW VALUE AROUND
HALF AN INCH) ON SUNDAY SUPPORTING CHANCE POPS...EXPANDING TO LIKELY
POPS SUNDAY NIGHT...ALONG WITH SUFFICIENT COOLING EXPECTED TO TREND
PRECIPITATION TO ALL SNOW WITH LIGHT ACCUMULATIONS.

PER 12Z EURO...925 MB TEMPS RISING TO -4 TO -2 C ON SATURDAY WITH
FAVORABLE SOUTHWEST FLOW EXPECTED TO TRANSLATE TO HIGHS IN THE MID
30S TO AROUND 40 DEGREES (SIMILAR TO TODAY). HIGHS IN THE LOW TO MID
40S ARE THEN EXPECTED ON SUNDAY AS 925 MB TEMPS SNEAK ABOVE ZERO.
SUFFICIENT CLOUDS PERSISTING DURING NIGHT HOURS EXPECTED TO HOLD MINS
IN THE 20S.

CHANGES COMING ABOUT EARLY IN THE NEW WORK WEEK. A STRONG POLAR JET
DIVING THROUGH THE MIDWEST WILL CARVE OUT A DEEP TROUGH WHICH WILL
HOLD THROUGH THE END OF THE WEEK. TEMPERATURES ON MONDAY WILL
MAKE A RUN AT 40F ONE LAST TIME BEFORE MUCH COLDER AIR FILTERS
INTO THE REGION. HIGH TEMPS WILL FALL INTO THE 20S BY
WEDNESDAY...HOLDING THERE THROUGH THE REMAINDER OF THE WEEK. THE
UPPER LOW WILL STALL OVER THE GREAT LAKES THE FIRST HALF OF THE
WEEK KEEPING SNOW CHANCES IN THE FORECAST THROUGH THAT STRETCH.

&&

.MARINE...

WEAK SHORTWAVE RIDGING WILL MAINTAIN QUIET WEATHER FOR FEBRUARY
STANDARDS THROUGHOUT MUCH OF THE WEEKEND. MODEST SOUTHWESTERLY WINDS
WILL INCREASE DURING THE DAY SATURDAY IN ADVANCE OF A CLIPPER LOW
PRESSURE SYSTEM. WIND GUSTS WILL APPROACH 30 KNOTS SATURDAY
AFTERNOON OVER CENTRAL LAKE HURON. WIND DIRECTIONS WILL EVENTUALLY
BACK TO THE SOUTHEAST SUNDAY BEFORE AN EXPANSIVE SURFACE LOW SETTLES
AND STALLS OVER THE CENTRAL GREAT LAKES.

&&

.AVIATION...ISSUED 1248 PM EST FRI FEB 5 2016

WEAK SHORTWAVE ENERGY RESIDES ALONG THE LEAD WARM ADVECTION SURGE TO
THE RISING HEIGHTS. THIS SHORTWAVE WILL TRACK THROUGH THE SAGINAW
VALLEY AND NORTHERN THUMB THIS AFTERNOON....BRINGING A CHANCE FOR
LIGHT SNOW SHOWERS TO THE NORTHERN TERMINALS. RECENT SURFACE
OBSERVATIONS AND MODEL DATA SUPPORTS ENOUGH OF A FAVORABLE
ENVIRONMENT TO SUPPORT A POTENTIAL WINDOW BETWEEN 19-23Z FOR IFR
VISIBILITY RESTRICTIONS IN LIGHT SNOW. WARM BOUNDARY LAYER
TEMPERATURES AT OR JUST ABOVE FREEZING WILL MITIGATE MUCH OF THE
IMPACTS. FARTHER SOUTH...THERE WILL BE A CHANCE FOR P6SM
FLURRIES...DURING THE LATE AFTERNOON BUT THE OVERALL CONVERGENCE
SIGNAL WITHIN THE DATA THAT FAR SOUTH IS WEAK WITH LOW CONFIDENCE.
WEAK SHORTWAVE RIDGING TONIGHT WILL SUPPORT A RETURN TO VFR CIGS
THROUGH THE END OF THE PERIOD WITH SOUTHWESTERLY WIND DIRECTIONS
EXPECTED TO PERSIST.

FOR DTW...RISING HEIGHTS LED TO A PERIOD OF WIDESPREAD VFR
CONDITIONS THIS MORNING. SHORTWAVE ENERGY PASSING TO THE NORTH OF
THE TERMINAL WILL BRING THE POTENTIAL FOR A P6SM SNOW SHOWER CHANCE
THIS AFTERNOON...BUT CONFIDENCE IS TOO LOW FOR EXPLICIT MENTION.
WILL ALSO MONITOR THE EXPANSION OF THE MVFR STRATOCUMULUS OVER
PORTIONS OF IL/IN DURING THE AFTERNOON. THIS CLOUD RESIDES IN AN
AREA OF COLD ADVECTION THAT IS FORECASTED TO SLIDE THROUGH
SOUTHEASTERN MICHIGAN THIS EVENING. CONFIDENCE IN WHAT THIS CLOUD
WILL DO IS VERY LOW AS THERE IS CURRENTLY A DIURNAL HEATING BOOST.
THIS POTENTIAL FOR MVFR WAS REFERENCED IN THE PRIOR DISCUSSION FOR
01-03Z.

//DTW THRESHOLD PROBABILITIES...

* HIGH FOR CIGS AOB 5KFT DURING THE LATE AFTERNOON AND EVENING. LOW
  FOR LATE TONIGHT.

&&

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

$$

DISCUSSION...SF/DK
MARINE.......CB
AVIATION.....CB


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