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PHL Jan 17-19 Snow/Ice/Rain Storm Obs


am19psu

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You do know that my software updates every 5 minutes do you not? Hence why my software shows a temp drop when your Automated Surface observing System has a different temp...

For example currently it says Precipitation at 21 degrees.. which means while ABE is still reporting 22 degrees ..it has dropped back to 21 degrees...

I am not sure why you even asked that question?

Because your reply made it seem like you were referring to ASOS like it was a piece of software.

Anyway, back to obs...

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From the latest meso discussion

HEIGHT FALLS ATTENDANT TO EWD PROGRESSION OF A LONGWAVE TROUGH INTO THE ERN STATES AND EMBEDDED SHORTWAVE TROUGHS TRACKING NEWD FROM THE OH VALLEY AND SRN ATLANTIC COAST WILL SUPPORT A STRENGTHENING /50-60 KT/ SLY LLJ FROM COASTAL MID ATLANTIC STATES TO THE LOWER HUDSON/CT RIVER VALLEYS BY 12-15Z. STRONG LOW LEVEL WAA IN THE 800-900 MB LAYER ALONG THE LLJ WITH TEMPERATURES RISING ABOVE 0 C WILL PROMOTE A PTYPE CHANGE FROM SNOW TO BRIEFLY SLEET AND THEN FREEZING RAIN... GIVEN SUB FREEZING SURFACE TEMPERATURES. PERSISTENT AND INCREASING LOW LEVEL WAA WILL SUPPORT SURFACE TEMPERATURES RISING ABOVE 32 F FROM NERN NJ THROUGH LONG ISLAND TO COASTAL CT AFTER 12Z PER TRENDS FURTHER S ACROSS CENTRAL/SRN NJ. N/NELY SURFACE WINDS FROM SRN NEW ENGLAND INTO ERN PA SUGGEST SUB FREEZING SURFACE TEMPERATURES SHOULD BE MAINTAINED ASIDE FROM THE AFOREMENTIONED AREAS CLOSER TO THE COAST. MEANWHILE...FARTHER N FROM UCA-GFL...VERTICAL THERMAL STRATIFICATION PER FORECAST SOUNDINGS SUGGEST THIS AREA WILL BE TOO FAR N FOR STRONGER LOW LEVEL WAA TO BOOST THE 800-900 MB LAYER ABOVE 0 C. THUS...SNOW SHOULD MIX WITH SLEET...BUT NOT CHANGE OVER TO FREEZING RAIN. AN INCREASE IN PW VALUES WILL HOWEVER SUPPORT AN INCREASE IN SNOW/SLEET RATES WITHIN REGION OF ISENTROPIC ASCENT/WAA.

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A saving grace might be the speed. Radar trends suggest most of the precip might be over by 11am. Once the precip lightens up, odds are the temps warm above freezing in the LV...Poconos might be a different story.

actually sometimes its the opp. When you have frz rain the hvr it is the more warm air it draws down from aloft. To keep colder temps and best ice accrual is lgt precip. Ray or adam might have a better idea if this is true or not, but thats what i would think. When it snows and you have heavier precip it brings it down to the surface.

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actually sometimes its the opp. When you have frz rain the hvr it is the more warm air it draws down from aloft. To keep colder temps and best ice accrual is lgt precip. Ray or adam might have a better idea if this is true or not, but thats what i would think. When it snows and you have heavier precip it brings it down to the surface.

The theory is that once you have a strong warm layer aloft, more intense freezing rain will tend to warm the low levels faster, both due to the warmer rain from aloft falling down into the cold layer and sharing the warmth, and also by way of the latent heat release from the rain freezing upon hitting the ground.

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The theory is that once you have a strong warm layer aloft, more intense freezing rain will tend to warm the low levels faster, both due to the warmer rain from aloft falling down into the cold layer and sharing the warmth, and also by way of the latent heat release from the rain freezing upon hitting the ground.

So many times, at least here in the LV, when we go to drizzle is when we warm up and go above freezing, while the Poconos remain below. I've have seen it go the other way also.

BTW...Light freezing rain

Temp 24.8F

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So many times, at least here in the LV, when we go to drizzle is when we warm up and go above freezing, while the Poconos remain below. I've have seen it go the other way also.

BTW...Light freezing rain

Temp 24.8F

Of course there are other factors... the strength of the reinforcing northeast flow being the main one. If the flow is strong enough, or even if its not too strong but an area of snow/sleet is not far away (and thus not as strongly influenced), then the temp can sit still. In January '05 we had an ice storm in State College. Flow wasn't particularly strong, but just a few miles northeast it went to sleet, so we had a nearer source of less influenced air. It stuck right around to just below freezing for much of the night and we had more than a half inch of ice.

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000
NOUS41 KPHI 180937
PNSPHI
DEZ001>004-MDZ008-012-015-019-020-NJZ001-007>010-012>027-PAZ054-055-
060>062-067>071-182137-

PUBLIC INFORMATION STATEMENT
SPOTTER REPORTS
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
437 AM EST TUE JAN 18 2011

THE FOLLOWING ARE UNOFFICIAL OBSERVATIONS TAKEN DURING THE PAST 8 HOURS
FOR THE STORM THAT HAS BEEN AFFECTING OUR REGION.  APPRECIATION IS EXTENDED
TO HIGHWAY DEPARTMENTS...COOPERATIVE OBSERVERS...SKYWARN SPOTTERS 
AND MEDIA FOR THESE REPORTS.  THIS SUMMARY IS ALSO AVAILABLE ON OUR 
HOME PAGE AT WEATHER.GOV/PHI

********************STORM TOTAL SNOWFALL********************

LOCATION          STORM TOTAL     TIME/DATE   COMMENTS                   
                    SNOWFALL           OF 
                    /INCHES/   MEASUREMENT

DELAWARE

...NEW CASTLE COUNTY...
  WILMINGTON             0.7  1207 AM  1/18                          
  BEAR                   0.7  1208 AM  1/18                          

NEW JERSEY

...BURLINGTON COUNTY...
  FLORENCE               1.8   130 AM  1/18                          

...GLOUCESTER COUNTY...
  NATIONAL PARK          1.0   103 AM  1/18                          

...MERCER COUNTY...
  EWING                  1.4   414 AM  1/18                          

...MIDDLESEX COUNTY...
  METUCHEN               1.2   436 AM  1/18                          

PENNSYLVANIA

...CHESTER COUNTY...
  DOWNINGTOWN            2.0  1140 PM  1/17                          

...DELAWARE COUNTY...
  DREXEL HILL            1.2  1238 AM  1/18                          
  CHESTER                1.2  1150 PM  1/17                          

...LEHIGH COUNTY...
  ALLENTOWN              0.8   104 AM  1/18                          

...MONTGOMERY COUNTY...
  POTTSTOWN              3.0   336 AM  1/18                          
  WYNNEWOOD              1.3  1239 AM  1/18                          
  NORRISTOWN             1.3  1209 AM  1/18                          
  TRAPPE                 1.1  1238 AM  1/18                          
  BRYN MAWR              0.7  1232 AM  1/18                          

...NORTHAMPTON COUNTY...
  BERLINSVILLE           2.1   336 AM  1/18                          

...PHILADELPHIA COUNTY...
  PHILADELPHIA           1.0   102 AM  1/18                          
  SOMERTON               0.9   130 AM  1/18                          

$$

JH

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with the way the radar is looking, things look to be out of here by bout 7-8?

That was my first impression at this early hour. Radar doesn't look overly impressive for precipitation to last into the afternoon hours. Anyway, we are very light sleet/freezing rain here with a temp of 23.9 at 5:00AM. I measured an even 2 inches of frozen accumulation (snow/sleet).

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something off topic and pretty incredible. I believe now with the inch of snow phl got with this storm, they have over 100 inches in the last two winters.

We're about .7" behind 08-09's total for the winter. Been an impressive three season run of 20"+...haven't done that here since the early/mid 80's.

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