Jan 28-30 MidAtl/NE Storm, Reality: Short Range (0-3 Days Out) Forecasts Options

[Undertakerson]

Sterling VA
[attachment=187761:thck.gif]

Wow, those thickness lines really dive down the 95 corridor - compliments of the dual northern component to the HP structure where its 1035mb to the "weaker" 1034 down near the Carolinas. The surface observations show the surface flow is from the north anywhere N of 40N and from the south anywhere from NOVA and south.

FzRn is falling into more marginal air back out towards CHI as per the most recent SPC Meso Discussion.
http://www.spc.noaa.gov/products/md/md0052.html

So it's easy to see how areas east of the Apps can also see that result before the changeover, as the cold air would tend to hold strong within the next 12-15 hrs. (btw SPC Meso site provides short term RAP images as well for some of the maps)

Add to that the GOM is partly available (but not deep ATTM) so the 850 WAA transport should be moderate.

[WMDWXNUT]

I can see this being a very troublesome system for MD/NOVA. Dealing with these CAD scenarios is usually awful since it always takes longer for the cold air to erode than advertised. East of the mountains and west of the cities it seems that the cold air always becomes entrenched even as aloft the temps get pretty darn warm. We have had some pretty bad ice storms in the past and while the QPF output does not suggest major icing, I am worried many will go to bed not knowing that tomorrow could be very dangerous.

I agree 100%....Living in the Frederick area my whole life Ive noticed the same thing. In these types of situations I would not be surprised if from Frederick to Hagerstown to Westminster (roughly) stays below freezing for the majority of the event.

[FrederickMdSnow]

I agree 100%....Living in the Frederick area my whole life Ive noticed the same thing. In these types of situations I would not be surprised if from Frederick to Hagerstown to Westminster (roughly) stays below freezing for the majority of the event.

It really is quite amazing how these events hang on. The 18z gfs paints a very dangerous picture for our area and I'm concerned this is going to be bigger than advertised.

[phillyfan]

New tripoli? I'm out of the Germansville PennDOT stockpile.

You think sliding in a car is bad try sliding in a fully loaded dump truck with a plow on the front! Ice is the worst

Seen this happen in front of my house twice. Ended up hung up on guard rail and a fence both times. Usually anytime there's ice on my road they cinder the road in reverse instead now.

This post has been edited by phillyfan: Jan 27 2013, 06:31 PM

[LoveNYCSnow]

Not sure how much it means for tomorrow but dewpoints are really low right now.

[rtcemc]

Wow, those thickness lines really dive down the 95 corridor - compliments of the dual northern component to the HP structure where its 1035mb to the "weaker" 1034 down near the Carolinas. The surface observations show the surface flow is from the north anywhere N of 40N and from the south anywhere from NOVA and south.

FzRn is falling into more marginal air back out towards CHI as per the most recent SPC Meso Discussion.
http://www.spc.noaa.gov/products/md/md0052.html

So it's easy to see how areas east of the Apps can also see that result before the changeover, as the cold air would tend to hold strong within the next 12-15 hrs. (btw SPC Meso site provides short term RAP images as well for some of the maps)

Add to that the GOM is partly available (but not deep ATTM) so the 850 WAA transport should be moderate.

little confused by this one, radar looks healthy and overriding situation. Nothing to weaken it. Already worried about cold air not evacuating-they pretty much under estimate that here all the time, anyway. On top of this, could precip be more intense, and a more serious icing situation? Precip estimate seem rather low, IMHO.

[JDClapper]

Looking at the model info on Wunderground... looks like the start here in CPA is ~4:00am with snow, then a complete changeover to Freezing Rain between 9-10am. Approx ¾"-1¾" of snow before that happens though.

I'm hesitant to buy the idea that ice sticks around for a prolonged period (over 2 hours).. more often than not this valley gets to 34 degrees rather quickly once the changeover occurs. But, hey, maybe this one will surprise me.

The ~4:00am start time matches up well with real-time observations too.. Wintery Mix reported in Bucyrs, OH (cloudy in Mansfield, OH) and with the current speed the precip is advancing, ~4:00am is a good call. Matches up perfectly with the Advisory too..

http://www.srh.noaa.gov/data/CTP/ZFPCTP
PAZ046-280945-
SOUTHERN LYCOMING-
INCLUDING THE CITIES OF...WILLIAMSPORT
438 PM EST SUN JAN 27 2013

...WINTER WEATHER ADVISORY IN EFFECT FROM 4 AM TO 3 PM EST MONDAY...

.TONIGHT...MOSTLY CLOUDY. SNOW AFTER MIDNIGHT. SNOW ACCUMULATION
AROUND AN INCH. NOT AS COOL WITH LOWS AROUND 20. LIGHT AND VARIABLE
WINDS. CHANCE OF SNOW 90 PERCENT.
.MONDAY...SNOW. FREEZING RAIN WITH RAIN LIKELY WITH SLEET IN THE
AFTERNOON. TOTAL SNOW ACCUMULATION OF 1 TO 3 INCHES. ICE
ACCUMULATION OF UP TO A TENTH OF AN INCH. HIGHS IN THE MID 30S.
EAST WINDS AROUND 5 MPH. GUSTS UP TO 20 MPH IN THE AFTERNOON.
CHANCE OF PRECIPITATION NEAR 100 PERCENT.

[7.3powerstrokedi...]

Seen this happen in front of my house twice. Ended up hung up on guard rail and a fence both times. Usually anytime there's ice on my road they cinder the road in reverse instead now.

Funny you say that cuz when I left Friday the other driver said make sure your mirrors are clean for Monday because your gonna be backing up alot. Lol

[tool483]

Looks like things are moving pretty quick, latest SPC meso disc

MESOSCALE DISCUSSION 0053
NWS STORM PREDICTION CENTER NORMAN OK
0528 PM CST SUN JAN 27 2013

AREAS AFFECTED...LWR MI

CONCERNING...WINTER MIXED PRECIPITATION

VALID 272328Z - 280330Z

SUMMARY...WINTER MIXED PRECIPITATION IS BEGINNING A FEW HOURS
EARLIER THAN INITIALLY EXPECTED WITH A TRANSITION FROM MOD/HVY SNOW
TO SLEET/FREEZING RAIN EXPECTED DURING THE EVENING. SNOWFALL RATES
GREATER THAN 1 INCH/HR ARE POSSIBLE FOR A BRIEF PERIOD WHILE
FREEZING RAIN RATES IN EXCESS OF 0.05 INCH/HR ARE EXPECTED AFTER THE
TRANSITION.

DISCUSSION...RECENT SURFACE OBSERVATIONS INDICATE MODERATE TO HEAVY
SNOW IS BEGINNING TO FALL ACROSS SRN PORTIONS OF LWR MI. THIS IS
OCCURRING WELL AHEAD OF WHAT WAS INITIALLY FORECAST BY MOST MODEL
GUIDANCE /E.G. NAM AND NSSL 4KM WRF DO NOT PROG SNOW UNTIL AFTER 00Z
TONIGHT/. SURFACE TEMPERATURES REMAIN IN THE UPPER 20S WHILE A
RECENT ACARS SOUNDING FROM DTX REVEAL A SHALLOW WARM NOSE ABOVE
FREEZING BTW 900-800 MB. WAA ADVECTION IS EXPECTED TO PERSIST ACROSS
THE REGION WITH CONTINUED WARMING ABOVE THE COOL SURFACE. AS A
RESULT...A TRANSITION FROM SNOW TO SLEET/FREEZING RAIN IS
ANTICIPATED. THIS WILL LIKELY OCCUR WITHIN THE NEXT HOUR OR TWO WITH
MOST GUIDANCE INDICATING A HIGH LIKELIHOOD OF FREEZING RAIN RATES
ABOVE 0.05 IN/HR.

LATEST DTX RADAR IMAGERY IS BEGINNING TO SHOW A MELTING LAYER
ORIENTED APPROXIMATELY FROM LAN SEWD TO TTF...FURTHER INCREASING THE
CONFIDENCE A TRANSITION FROM SNOW TO FREEZING RAIN/SLEET WILL LIKELY
OCCUR SOON.

[NYCSuburbs]

Looks like things are moving pretty quick, latest SPC meso disc

MESOSCALE DISCUSSION 0053
NWS STORM PREDICTION CENTER NORMAN OK
0528 PM CST SUN JAN 27 2013

AREAS AFFECTED...LWR MI

CONCERNING...WINTER MIXED PRECIPITATION

VALID 272328Z - 280330Z

SUMMARY...WINTER MIXED PRECIPITATION IS BEGINNING A FEW HOURS
EARLIER THAN INITIALLY EXPECTED WITH A TRANSITION FROM MOD/HVY SNOW
TO SLEET/FREEZING RAIN EXPECTED DURING THE EVENING. SNOWFALL RATES
GREATER THAN 1 INCH/HR ARE POSSIBLE FOR A BRIEF PERIOD WHILE
FREEZING RAIN RATES IN EXCESS OF 0.05 INCH/HR ARE EXPECTED AFTER THE
TRANSITION.

DISCUSSION...RECENT SURFACE OBSERVATIONS INDICATE MODERATE TO HEAVY
SNOW IS BEGINNING TO FALL ACROSS SRN PORTIONS OF LWR MI. THIS IS
OCCURRING WELL AHEAD OF WHAT WAS INITIALLY FORECAST BY MOST MODEL
GUIDANCE /E.G. NAM AND NSSL 4KM WRF DO NOT PROG SNOW UNTIL AFTER 00Z
TONIGHT/. SURFACE TEMPERATURES REMAIN IN THE UPPER 20S WHILE A
RECENT ACARS SOUNDING FROM DTX REVEAL A SHALLOW WARM NOSE ABOVE
FREEZING BTW 900-800 MB. WAA ADVECTION IS EXPECTED TO PERSIST ACROSS
THE REGION WITH CONTINUED WARMING ABOVE THE COOL SURFACE. AS A
RESULT...A TRANSITION FROM SNOW TO SLEET/FREEZING RAIN IS
ANTICIPATED. THIS WILL LIKELY OCCUR WITHIN THE NEXT HOUR OR TWO WITH
MOST GUIDANCE INDICATING A HIGH LIKELIHOOD OF FREEZING RAIN RATES
ABOVE 0.05 IN/HR.

LATEST DTX RADAR IMAGERY IS BEGINNING TO SHOW A MELTING LAYER
ORIENTED APPROXIMATELY FROM LAN SEWD TO TTF...FURTHER INCREASING THE
CONFIDENCE A TRANSITION FROM SNOW TO FREEZING RAIN/SLEET WILL LIKELY
OCCUR SOON.

Events like this one occasionally tend to move through faster than expected... this one so far doesn't seem to be much different. NAM/GFS start precip only around 15z-18z (10am-1pm) from NYC to Albany, my thinking is precip should start a bit earlier than that.

[tool483]

Events like this one occasionally tend to move through faster than expected... this one so far doesn't seem to be much different. NAM/GFS start precip only around 15z-18z (10am-1pm) from NYC to Albany, my thinking is precip should start a bit earlier than that.

agreed, see how well it does with these low DP's, system does look pretty good currently though. Currently sitting at -6 for DP

Also hope to get into one of the meso discussions but highly unlikely here. . .this storm anyway

I can only hope, what ever hope i can muster up anyway

This post has been edited by tool483: Jan 27 2013, 07:01 PM

[NYCSuburbs]

FWIW, 18z RGEM is reasonably warmer than the 12z run, shifted the snow axis a bit north and is a good 3 hours faster with warming the mid levels, matching the trend with its recent bias of being too slow with mid level warming.

The RGEM snow totals (pic below, with mm - inches conversion) show less snow from S NY/N PA through the Hudson Valley and SNE, with more snow north of Albany, although it's likely a bit of a snowy outlier - it has nearly 4" in Albany and more to the north. In Albany, I would be surprised to see over 2", although near 2" is a reasonable possibility if the mid levels don't warm too quickly. Further north though I can see more widespread 3-4"+ totals.

mm - inches conversion:

1.0 mm = 0.04"
2.5 mm = 0.10"
5.0 mm = 0.20"
7.5 mm = 0.30"
10 mm = 0.40"




This post has been edited by NYCSuburbs: Jan 27 2013, 07:03 PM

[tool483]

FWIW, 18z RGEM is reasonably warmer than the 12z run, shifted the snow axis a bit north and is a good 3 hours faster with warming the mid levels, matching the trend with its recent bias of being too slow with mid level warming.

The RGEM snow totals (pic below, with mm - inches conversion) show less snow from S NY/N PA through the Hudson Valley and SNE, with more snow north of Albany, although it's likely a bit of a snowy outlier - it has nearly 4" in Albany and more to the north. In Albany, I would be surprised to see over 2", although near 2" is a reasonable possibility if the mid levels don't warm too quickly. Further north though I can see more widespread 3-4"+ totals.

mm - inches conversion:

1.0 mm = 0.04"
2.5 mm = 0.10"
5.0 mm = 0.20"
7.5 mm = 0.30"
10 mm = 0.40"

That could spell more ice for SNE and SNY as well. . . .This cold air is going to take some time to scour away

well, at least something frozen will be falling from the sky, would prefer sleet obviously!
tho i remember getting 6 inch's of sleet and talk about getting stuck in parking lots and secondaries, main roads were pretty much ok. . not seeing this as a sleet storm tho

This post has been edited by tool483: Jan 27 2013, 07:05 PM

[NYCSuburbs]

That could spell more ice for SNE and SNY as well. . . .This cold air is going to take some time to scour away

well, at least something frozen will be falling from the sky, would prefer sleet obviously!
tho i remember getting 6 inch's of sleet and talk about getting stuck in parking lots and secondaries, main roads were pretty much ok. . not seeing this as a sleet storm tho

The main issue is with the low levels, as the mid level warmth will quickly move in but the low level cold will hold in place longer. There is going to be some sleet involved but some freezing rain as well, which should especially be limited to PA, NW NJ, SE NY and parts of SW New England (since the storm starts to shift southeast over New England, places like Boston should see more snow).

[NYCSuburbs]

18z RGEM ice totals:

0.5 mm = 0.02"
1.0 mm = 0.04"
2.5 mm = 0.10"
5.0 mm = 0.20"

[NorEaster07]

OBS thread opened since virga is enter PA and precip should start falling in a couple hours. Be safe.