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Central PA and the fringes - Feb. 2014 Part IV


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With the full Euro via AccuWeather Pro I did some delving into some of the finer details I can look at. Had a look at the U-wind anomalies at 850mb and discovered that there is a tremendously anomalous easterly fetch off the Atlantic. The eastern two-thirds of PA are under at least -3 to -4 st deviations.. and probably even more than that in eastern PA where there is a region of >25 m/s (50knots) winds. The 0z GFS was similar to the Euro but not as strong or expansive (focusing more on the eastern third of PA)...but still strong. Either way, the highly anomalous fetch is a big time sign of a major snowstorm. 

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With the full Euro via AccuWeather Pro I did some delving into some of the finer details I can look at. Had a look at the U-wind anomalies at 850mb and discovered that there is a tremendously anomalous easterly fetch off the Atlantic. The eastern two-thirds of PA are under at least -3 to -4 st deviations.. and probably even more than that in eastern PA where there is a region of >25 m/s (50knots) winds. The 0z GFS was similar to the Euro but not as strong or expansive (focusing more on the eastern third of PA)...but still strong. Either way, the highly anomalous fetch is a big time sign of a major snowstorm.

It's also a sign for bust potential with a retreating high pressure system. The March storm last year was a good example of this. Now, the LLJ from the east and snowpack may wash each other out, but I'm still concerned guidance isn't picking up the magnitude of the warmer gulf stream air that will be wrapped into this thing.

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PAZ035-036-056>059-063-122100-
/O.UPG.KCTP.WS.A.0004.140213T0600Z-140214T0300Z/
/O.EXA.KCTP.WS.W.0005.140213T0600Z-140214T0300Z/
FULTON-FRANKLIN-PERRY-DAUPHIN-SCHUYLKILL-LEBANON-CUMBERLAND-
INCLUDING THE CITIES OF...MCCONNELLSBURG...CHAMBERSBURG...
NEWPORT...HARRISBURG...HERSHEY...POTTSVILLE...LEBANON...CARLISLE
420 AM EST WED FEB 12 2014

...WINTER STORM WARNING IN EFFECT FROM 1 AM TO 10 PM EST
THURSDAY...

THE NATIONAL WEATHER SERVICE IN STATE COLLEGE HAS ISSUED A WINTER
STORM WARNING FOR HEAVY SNOW...WHICH IS IN EFFECT FROM 1 AM TO 10
PM EST THURSDAY. THE WINTER STORM WATCH IS NO LONGER IN EFFECT.

* LOCATIONS...SOUTH CENTRAL MOUNTAINS...THE LOWER SUSQUEHANNA
VALLEY...AND WESTERN POCONOS.

* HAZARD TYPES...SNOW...HEAVY AT TIMES.

* ACCUMULATIONS...6 TO 10 INCHES OF SNOW.

* TIMING...SNOW WILL DEVELOP FROM SOUTH TO NORTH ACROSS THE REGION
SHORTLY AFTER MIDNIGHT TONIGHT...AND BECOME HEAVY AT TIMES FROM
THE MID MORNING...THROUGH LATE AFTERNOON HOURS. THE SNOW WILL
TAPER OFF TO PERIODS OF LIGHT SNOW THURSDAY EVENING...WITH THE
CHANCE OF SOME FREEZING DRIZZLE.

* IMPACTS...WIDESPREAD HAZARDOUS AND SLOWED TRAVEL DUE TO SNOW
COVERED ROADS AND TIMES OF POOR VISIBILITY IN HEAVY FALLING AND
BLOWING SNOW.

* WINDS...NORTHEAST 5 TO 15 MPH IN THE MORNING ...BECOMING NORTH
15 TO 20 MPH WITH GUSTS TO 25 MPH THURSDAY AFTERNOON.

* TEMPERATURES...IN THE MID 20S TO LOWER 30S.

* VISIBILITIES...ONE QUARTER MILE OR LESS AT TIMES.

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It's also a sign for bust potential with a retreating high pressure system. The March storm last year was a good example of this. Now, the LLJ from the east and snowpack may wash each other out, but I'm still concerned guidance isn't picking up the magnitude of the warmer gulf stream air that will be wrapped into this thing.

 

I think in this case we'll be okay, at least in our subforum. Without the exact specifics on that March storm, it appears we'll have more of a northeasterly vs easterly fetch with this one... and we also have the benefit of being almost a month earlier. East of I-95 could be another story.

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PAZ035-036-056>059-063-122100-

/O.UPG.KCTP.WS.A.0004.140213T0600Z-140214T0300Z/

/O.EXA.KCTP.WS.W.0005.140213T0600Z-140214T0300Z/

FULTON-FRANKLIN-PERRY-DAUPHIN-SCHUYLKILL-LEBANON-CUMBERLAND-

INCLUDING THE CITIES OF...MCCONNELLSBURG...CHAMBERSBURG...

NEWPORT...HARRISBURG...HERSHEY...POTTSVILLE...LEBANON...CARLISLE

420 AM EST WED FEB 12 2014

...WINTER STORM WARNING IN EFFECT FROM 1 AM TO 10 PM EST

THURSDAY...

THE NATIONAL WEATHER SERVICE IN STATE COLLEGE HAS ISSUED A WINTER

STORM WARNING FOR HEAVY SNOW...WHICH IS IN EFFECT FROM 1 AM TO 10

PM EST THURSDAY. THE WINTER STORM WATCH IS NO LONGER IN EFFECT.

* LOCATIONS...SOUTH CENTRAL MOUNTAINS...THE LOWER SUSQUEHANNA

VALLEY...AND WESTERN POCONOS.

* HAZARD TYPES...SNOW...HEAVY AT TIMES.

* ACCUMULATIONS...6 TO 10 INCHES OF SNOW.

* TIMING...SNOW WILL DEVELOP FROM SOUTH TO NORTH ACROSS THE REGION

SHORTLY AFTER MIDNIGHT TONIGHT...AND BECOME HEAVY AT TIMES FROM

THE MID MORNING...THROUGH LATE AFTERNOON HOURS. THE SNOW WILL

TAPER OFF TO PERIODS OF LIGHT SNOW THURSDAY EVENING...WITH THE

CHANCE OF SOME FREEZING DRIZZLE.

* IMPACTS...WIDESPREAD HAZARDOUS AND SLOWED TRAVEL DUE TO SNOW

COVERED ROADS AND TIMES OF POOR VISIBILITY IN HEAVY FALLING AND

BLOWING SNOW.

* WINDS...NORTHEAST 5 TO 15 MPH IN THE MORNING ...BECOMING NORTH

15 TO 20 MPH WITH GUSTS TO 25 MPH THURSDAY AFTERNOON.

* TEMPERATURES...IN THE MID 20S TO LOWER 30S.

* VISIBILITIES...ONE QUARTER MILE OR LESS AT TIMES.

Getting home for a reason!

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Newly expanded Winter storm watch north of the warnings.

 

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE STATE COLLEGE PA
420 AM EST WED FEB 12 2014

...HEAVY SNOW POSSIBLE WEDNESDAY NIGHT INTO THURSDAY...

.A STRONG STORM WILL MOVE UP THE EAST COAST WEDNESDAY NIGHT AND
THURSDAY...BRINGING HEAVY SNOW TO PARTS OF SOUTHEAST
PENNSYLVANIA. ALTHOUGH THE EXACT STORM TRACK REMAINS SOMEWHAT
UNCERTAIN...AREAS SOUTH AND EAST OF HARRISBURG APPEAR LIKELY TO
SEE THE HEAVIEST ACCUMULATION.

PAZ026>028-033-042-049>053-122100-
/O.EXA.KCTP.WS.A.0004.140213T0600Z-140214T0300Z/
HUNTINGDON-MIFFLIN-JUNIATA-SOMERSET-SULLIVAN-UNION-SNYDER-MONTOUR-
NORTHUMBERLAND-COLUMBIA-
INCLUDING THE CITIES OF...HUNTINGDON...MOUNT UNION...LEWISTOWN...
MIFFLINTOWN...SOMERSET...LAPORTE...LEWISBURG...SELINSGROVE...
DANVILLE...SUNBURY...SHAMOKIN...BLOOMSBURG...BERWICK
420 AM EST WED FEB 12 2014

...WINTER STORM WATCH IN EFFECT FROM LATE TONIGHT THROUGH
THURSDAY EVENING...

THE NATIONAL WEATHER SERVICE IN STATE COLLEGE HAS ISSUED A WINTER
STORM WATCH...WHICH IS IN EFFECT FROM LATE TONIGHT THROUGH
THURSDAY EVENING.

* LOCATIONS...PORTIONS OF THE LAUREL HIGHLANDS...SOUTH CENTRAL
MOUNTAINS AND MIDDLE SUSQUEHANNA RIVER VALLEY.

* HAZARD TYPES...HEAVY SNOW.

* ACCUMULATIONS...POTENTIAL FOR 6 INCHES OR MORE OF SNOW.

* TIMING...SNOW WILL DEVELOP FROM SOUTH TO NORTH ACROSS THE REGION
BETWEEN 1 AND 3 AM THURSDAY...AND COULD FALL HEAVY AT TIMES FROM
THE MID MORNING...THROUGH LATE AFTERNOON HOURS. THE SNOW WILL
TAPER OFF TO PERIODS OF LIGHT SNOW THURSDAY EVENING...WITH THE
CHANCE OF SOME FREEZING DRIZZLE.

* IMPACTS...WIDESPREAD HAZARDOUS AND SLOWED TRAVEL DUE TO SNOW
COVERED ROADS AND TIMES OF POOR VISIBILITY IN HEAVY FALLING SNOW.

* WINDS...NORTHEAST WIND 5 TO 10 MPH WITH GUSTS UP TO 20
MPH...BECOMING NORTH AT THE SAME SPEEDS IN THE AFTERNOON.

* TEMPERATURES...IN THE MID 20S TO AROUND 30.

* VISIBILITIES...MAINLY AROUND 1 MILE...BUT ONE QUARTER MILE OR
LESS AT TIMES IS POSSIBLE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WATCH MEANS THERE IS THE POTENTIAL FOR SIGNIFICANT
SNOW...SLEET...OR ICE ACCUMULATIONS THAT MAY IMPACT TRAVEL. FOR
THE LATEST WEATHER INFORMATION...GO TO WEATHER.GOV/CTP OR STAY
TUNED TO NOAA WEATHER RADIO.
 

 

 

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I think in this case we'll be okay, at least in our subforum. Without the exact specifics on that March storm, it appears we'll have more of a northeasterly vs easterly fetch with this one... and we also have the benefit of being almost a month earlier. East of I-95 could be another story.

It is a different set up (Miller A vs a clipper/coastal transfer with last year's storm) so a prolonged fetch of easterly winds may not develop. But I am weary with no dominating high to our north to funnel arctic air in. The high is progged to retreat into Maine...which is not exactly what you want to see for a big snowstorm. However, many signs point to us "threading the needle" and still getting dumped on without it.

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PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
432 AM EST WED FEB 12 2014


VALID 12Z WED FEB 12 2014 - 12Z SAT FEB 15 2014
....
THIS LOW WILL INTENSIFY RAPIDLY
AND TRACK NORTHEASTWARD UP ALONG THE MID ATLANTIC/NORTHEAST
COAST... AS THE PHASED TROUGH ASSUMES A NEGATIVE TILT. THE
GUIDANCE ALL HAVE THIS FORECAST SCENARIO OF A CLASSIC COASTAL
WINTER STORM BUT STILL DIFFER ON SOME OF THE IMPORTANT DETAILS...
MAINLY THE CRITICAL THERMAL PROFILES AND IF THE TREMENDOUS
ATLANTIC INFLOW HAS AN IMPACT OR NOT ON THE RAIN/SNOW LINE. LIKE
THE LAST FEW NIGHTS... WPC STAYED VERY CLOSE TO A BLEND/COMPROMISE
OF THE GFS/ECMWF AND SREF MEAN ON SYNOPTIC SCALE FEATURES BUT
CLOSER TO THE ECMWF/SREF MEAN FOR THERMAL PROFILES
... AS THE GFS
APPEARS TO CONTAIN SOME FEEDBACK ALONG THE IMMEDIATE COASTLINE
THAT IS NOT ONLY IMPACTING THERMALS BUT KEEPING QPF AMOUNTS LOWER
OVER THE MID-ATL REGION.
 THUS WPC STILL EXPECTS A HEALTHY AXIS OF
HEAVY DEFORMATION/DYNAMIC COOLING SNOWFALL JUST WEST OF I95 OR
MORE SNOW FOR DC/BALT UP THROUGH ERN PA INTO INTERIOR NEW ENGLAND.

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Considering the nature and severity of this storm, should I (or someone) make a separate obs thread for CPA, or will one general thread suffice for the duration of the storm? My thought: the regular thread is going to get choked with obs, model discussion, forecast updates, and radar presentations, and could be difficult to follow at times.

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Considering the nature and severity of this storm, should I (or someone) make a separate obs thread for CPA, or will one general thread suffice for the duration of the storm? My thought: the regular thread is going to get choked with obs, model discussion, forecast updates, and radar presentations, and could be difficult to follow at times.

Go ahead and make an obs thread and we will keep this one for model discussion, forecasts, etc.

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With the full Euro via AccuWeather Pro I did some delving into some of the finer details I can look at. Had a look at the U-wind anomalies at 850mb and discovered that there is a tremendously anomalous easterly fetch off the Atlantic. The eastern two-thirds of PA are under at least -3 to -4 st deviations.. and probably even more than that in eastern PA where there is a region of >25 m/s (50knots) winds. The 0z GFS was similar to the Euro but not as strong or expansive (focusing more on the eastern third of PA)...but still strong. Either way, the highly anomalous fetch is a big time sign of a major snowstorm. 

http://journals.ametsoc.org/doi/pdf/10.1175/WAF964.1

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