Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 250552
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
152 AM EDT WED MAR 25 2015

.UPDATE...
ISSUED AT 1006 PM EDT TUE MAR 24 2015

QUIET AT THE MOMENT. CIRRUS GRADUALLY EXPANDING INTO NORTHERN
LOWER MI FROM THE SW. ACTUAL PRECIP IS ADVANCING ACROSS SW WI AND
NORTHERN IL. THIS IS ACTUALLY A LITTLE AHEAD OF SCHEDULE COMPARED
TO MOST SHORT-TERM MODEL GUIDANCE. NOTE THAT SAID GUIDANCE IS VERY
SLOW TO ADVANCE PRECIP INTO THE REGION...WITH THE NAM DRY NORTH OF
A PETOSKEY-OSCODA LINE THRU 12Z. AGAIN...THAT LOOKS A LITTLE TOO
SLOW GIVEN UPSTREAM RADAR TRENDS.

GIVEN THE ABOVE...HAVE PUSHED BACK THE START TIME FOR THE ADVISORY
IN THE NE HALF OF NORTHERN LOWER UNTIL 5 AM.

A VARIETY OF PRECIP TYPES ARE POSSIBLE RIGHT AT ONSET...GIVEN THE
BONE-DRY AIR IN PLACE (00Z APX SOUNDING PWAT WAS 0.13 INCHES).
HOWEVER...A SUBSTANTIAL WARM NOSE ALOFT (4C AT 850MB OVER GLR AT
12Z) WILL RAPIDLY TURN THIS INTO A FZRA VS RA DISCUSSION OVER MOST
OF NORTHERN LOWER. EVERYONE HAS SOME FZRA POTENTIAL AT ONSET.
PLACES NEAR LAKE MI (MBL-TVC-CVX) WILL SEE A DEVELOPING
DOWNSLOPING SE WIND THAT WILL WILL BOOST TEMPS FAIRLY QUICKLY
AFTER PRECIP ONSET. ICING POTENTIAL REMAINS HIGHER OVER THE HIGH
TERRAIN...CAD-GLR-HTL-MIO. ONLY SMALL ADJUSTMENTS MADE TO POP AND
WX FORECAST FOR OVERNIGHT...MAINLY TO REFLECT THE ABOVE.

&&

.NEAR TERM...(THIS EVENING THROUGH TONIGHT)
ISSUED AT 406 PM EDT TUE MAR 24 2015

...PERIOD OF FREEZING RAIN LATE TONIGHT INTO THE MORNING HOURS...

HIGH PRESSURE WILL CONTINUE TO PROVIDE CLEAR SKIES AND LIGHT WINDS
THE REST OF THE DAY AND THROUGH THE EVENING HOURS. THIS HIGH
PRESSURE WILL GIVE WAY TO AN AREA OF LOW PRESSURE CURRENTLY OVER
MISSOURI AND ANOTHER AREA OVER THE DAKOTAS WHICH WILL PHASE TOGETHER
OVER THE GREAT LAKES REGION BY SUNRISE. NORTHERN MICHIGAN WILL BEGIN
TO BE IMPACTED BY THIS AREA OF LOW PRESSURE DURING THE OVERNIGHT
HOURS OVER OUR SOUTHWESTERN CWA (MANISTEE...WEXFORD...BENZIE
COUNTIES) BETWEEN 2 AND 4AM AND PROGRESS NORTHEASTWARD THROUGHOUT
THE REMAINING OVERNIGHT HOURS AND INTO THE MORNING. WITH A WARM NOSE
OF AT LEAST 5C AND SURFACE TEMPERATURES BELOW FREEZING THE FORECAST
SOUNDINGS ARE TEXTBOOK FOR AN ONSET OF FREEZING RAIN. SO FAR IT
APPEARS THAT ICE ACCUMULATIONS WILL BE THE HIGHEST OVER OUR
SOUTHWESTERN CWA WHERE IT STARTS THE EARLIEST AND LASTS THE LONGEST
BEFORE DAYBREAK...WHEN TEMPERATURES RISE TO ABOVE FREEZING. ICE
ACCUMULATIONS ARE FORECAST TO BE BELOW ICE STORM WARNING
CRITERIA...WITH 0.05 TO 0.20 INCHES POSSIBLE THROUGHOUT THE FREEZING
RAIN EVENT...WITH THE HIGHER AMOUNTS OVER THE AFOREMENTIONED AREAS.
UPSTREAM OBSERVATIONS (OVER CENTRAL IOWA) HAVE ALREADY BEEN
REPORTING FREEZING RAIN AND UNKNOWN PRECIPITATION FOR A LITTLE OVER
2 HOURS NOW WITH SURFACE TEMPERATURES NEAR FREEZING. WITH CLEAR
SKIES THROUGH MOST OF THE EVENING AND INTO TONIGHT BEFORE THE SYSTEM
ARRIVES...TEMPERATURES WILL DROP INTO THE 20S...WELL ENOUGH TO DROP
THE CURRENTLY 70 DEGREE ROAD TEMPERATURES INTO THE 20S ONCE AGAIN
TONIGHT BEFORE THE ONSET OF THE LIQUID PRECIPITATION. WE HAVE A
WINTER WEATHER ADVISORY OUT FOR THE ANTICIPATED FREEZING RAIN WHICH
WILL CAUSE SLICK TRAVEL THROUGHOUT ALL OF NORTHERN LOWER IN ADDITION
TO ICE ACCUMULATION ON TREES AND POWER LINES...ESPECIALLY OVER THE
HIGHER TERRAIN OF NORTHERN LOWER MICHIGAN.

&&

.SHORT TERM...(WEDNESDAY THROUGH FRIDAY)
ISSUED AT 406 PM EDT TUE MAR 24 2015

...MESSY WEDNESDAY MORNING...

HIGH IMPACT WEATHER POTENTIAL: WINTRY MIX OF PRECIPITATION RESULTING
IN SLICK ROADS WEDNESDAY MORNING.

PATTERN SYNOPSIS/ANTICIPATED EVOLUTION: ALL EYES ON STRONG AND
COMPACT SHORTWAVE CURRENTLY ROTATING INTO KANSAS...PART OF BROADER
TROUGHING EXTENDING NORTH THROUGH THE NORTHERN PLAINS INTO SOUTHERN
CANADA. TROUGH AXIS TAKES ON AN INCREASINGLY NEGATIVE TILT WITH TIME
...WITH SAID SHORTWAVE HELPING SPAWN WEAK SURFACE LOW THAT WILL
QUICKLY DRIVE UP THROUGH OUR AREA WEDNESDAY MORNING. POTENT...ALBEIT
SHORT DURATION...SURGE OF WAA WILL SPAWN A WINTRY MIX OF
PRECIPITATION ACROSS OUR AREA DURING THE MORNING. PATTERN REMAINS
AMPLIFIED THEREAFTER...WITH RENEWED TROUGHING DRIVING AN
UNSEASONABLY CHILLY AIRMASS INTO THE NORTHERN LAKES THURSDAY NIGHT
AND FRIDAY.

PRIMARY FORECAST CONCERNS/CHALLENGES: PRECIPITATION TYPE AND
TEMPORAL EVOLUTION WEDNESDAY.

DETAILS: SLUG OF WARM AIR ADVECTION DRIVEN PRECIPITATION EXPECTED TO
BE RACING NORTH WEDNESDAY MORNING...LIKELY ALREADY REACHING NEAR THE
M-68 CORRIDOR BY SUNRISE. FORCING/DEEP MOISTURE OF LIMITED
DURATION...AND EXPECT JUST A FEW HOUR WINDOW OF HIGH PRECIP RATES AS
ACTIVITY BOWS NORTH...REACHING EASTERN UPPER THROUGH THE MORNING.
PRECIPITATION TYPE REMAINS A FORMIDABLE CHALLENGE. RECENT TRENDS
HAVE REVERSED COURSE...NOW FEATURING A MORE AGGRESSIVE WARM NOSE
CENTERED ~5K FEET...PLENTY DEEP/WARM ENOUGH ACROSS MOST OF NORTHERN
LOWER TO ALLOW FULL MELTING OF FALLING SNOW. LOW WET BULB
TEMPERATURES/INITIAL DRY LOW LEVEL AIRMASS DEFINITELY SUPPORTS
FREEZING RAIN DURING THE EARLY MORNING HOURS BEFORE SURFACE
TEMPERATURES WARM. LIMITED DURATION OF FREEZING RAIN SHOULD KEEP ICE
ACCUMULATIONS LIMITED...BUT DEFINITELY ENOUGH TO CAUSE SIGNIFICANT
TRAVEL IMPACTS ACROSS NORTHERN LOWER (SEE NEAR TERM FOR HEADLINE
DECISIONS). FURTHER NORTH...WARM NOSE NOT QUITE AS SIGNIFICANT OVER
EASTERN UPPER...BUT ENOUGH TO SUPPORT SNOW/SLEET MIXTURE.
SNOW/LIQUID RATIOS SHOULD BE LOW...KEEPING SNOW/SLEET ACCUMULATIONS
GENERALLY UNDER 3 INCHES. MID LEVEL DRYING FOLLOWS IMMEDIATELY
BEHIND PRECIP SHIELD...LARGELY SUPPORTING A MOSTLY DRY AFTERNOON.

DRY SLOT REMAINS OVERHEAD WEDNESDAY NIGHT ACROSS NORTHERN
LOWER...WITH JUST DEEP ENOUGH MOISTURE NORTH OF THE BRIDGE TO
SUPPORT SOME LIGHT SNOW SHOWERS. MAIN TROUGH AXIS ROTATES OVERHEAD
THURSDAY INTO FRIDAY...SUPPORTING ADDITIONAL LIGHT SNOW SHOWER
CHANCES. BIGGER STORY NO DOUBT CENTERED ON ATTENDANT SURGE OF
UNSEASONABLY CHILLY AIR...WITH HIGHS BY FRIDAY LIKELY NOT EXCEEDING
THE LOWER/MIDDLE 20S (UPPER TEENS FOR EASTERN UPPER!).

&&

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 406 PM EDT TUE MAR 24 2015

PATTERN OVERVIEW/FORECAST: A FAIRLY PROGRESSIVE...LOW AMPLITUDE FLOW
PATTERN REMAINS IN PLACE THROUGH THE LOWER 48 STATES TODAY WITH
SEVERAL SHORT WAVES ROLLING THROUGH THE WESTERN AND CENTRAL CONUS
AND LOW AMPLITUDE RIDGING IN THE GREAT LAKES. BUT THINGS STILL
LOOKING TO TAKE A TURN TOWARD COLD OVER THE NEXT FEW DAYS AS
AFOREMENTIONED SHORT WAVE ENERGY UNDERGOES SOME DEGREE OF PHASING
WITH DEEPER/CLOSED LOW PRESSURE IN NORTHERN CANADA...DIGGING OUT
SUBSTANTIAL TROUGHING OVER EASTERN NOAM. THIS WILL DRAG ANOTHER
CORE OF COLD AIR DOWN THROUGH EASTERN CANADA INTO THE GREAT LAKES
DURING THE FRIDAY-SATURDAY TIMEFRAME.

WEATHER-WISE...A QUIET START TO THE WEEKEND AS LARGE EXPANSE OF
HIGH PRESSURE BUILDS DOWN THROUGH THE GREAT LAKES AND INTO THE
OHIO VALLEY...FRIDAY NIGHT THROUGH SATURDAY. WILL CERTAINLY BE A
COLD ONE SATURDAY MORNING WITH SINGLE DIGIT LOWS COMMON AND
POSSIBLY SOME OF THE COLD SPOTS GOING BELOW ZERO (WHAT DATE IS IT
AGAIN??). BUT TEMPS WILL REBOUND BACK INTO THE 30S DURING THE DAY.
SECOND HALF OF THE WEEKEND TURNS A BIT MORE ACTIVE AGAIN AS
CLIPPER TYPE SYSTEM TRACKS THROUGH THE GREAT LAKES SUNDAY-SUNDAY
NIGHT BRINGING ANOTHER ROUND OF LIGHT PRECIP. P-TYPE ISSUES MAY
CREEP INTO THE EQUATION DURING THE DAY SUNDAY AS STRONG SW FLOW
DRAGS WARMER AIR BACK INTO THE STATE AHEAD OF THE LOW... ALTHOUGH
THERE IS SOME SIGNIFICANT GUIDANCE DIFFERENCES IN JUST HOW WARM
ALOFT THINGS GET (GFS IS DEEPER/COLDER). FOR NOW...WILL GO WITH A
GENERIC RAIN/SNOW MIX ACROSS NRN LOWER MICHIGAN AND JUST SNOW IN
EASTERN UPPER MICHIGAN.

BEYOND THAT...LARGE EXPANSE OF CANADIAN HIGH PRESSURE REBUILDS OVER
THE REGION TO KICK OFF THE NEW WORK WEEK WITH A TREND BACK TO DRY
WEATHER. SEASONAL TEMPS FOR MONDAY AND WARMING TREND HEADING INTO
TUESDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 140 AM EDT WED MAR 25 2015

...DETERIORATING CONDITIONS...

A SWATH OF PRECIPITATION WILL RUN THROUGH THE AIRPORTS THIS
MORNING AND LAST ABOUT 4-6 HRS...STARTING AS EARLY AS 08Z-09Z AT
MBL...AND EXIT APN LATER TODAY AROUND 17Z-18Z. THE ONSET WILL BE
FREEZING RAIN AND SOME SLEET...BEFORE WARMING SFC TEMPERATURES
WILL CHANGE THE BACKSIDE OVER TO RAIN/POSSIBLE DRIZZLE. TOTAL ICE
ACCUMULATIONS 0.08-0.14"...ROUGHLY. A LIGHT AND PERIODICALLY GUSTY
SE SFC WIND WILL HAVE SIGNIFICANTLY INCREASED WINDS JUST ABOVE
GROUND FOR WIND SHEAR ISSUES.

WINDS SHIFT ABRUPTLY OUT OF THE SW THIS AFTERNOON AND WILL BE
GUSTY INTO THE EVENING...WITH SKIES GENERALLY MVFR MOSTLY CLOUDY.
APN MAY SEE LESS CLOUDS AND LIKELY CIGS WILL BE INTO THE VFR
CATEGORY.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY UNTIL 11 AM EDT THIS MORNING FOR MIZ020-
     021-025>028-031>035-041-042.

     WINTER WEATHER ADVISORY FROM 5 AM TO 11 AM EDT THIS MORNING FOR
     MIZ016>019-022>024-029-030-036.

LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

UPDATE...JAZ
NEAR TERM...TJL
SHORT TERM...MSB
LONG TERM...ADAM
AVIATION...SMD


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