Increasing threat of eastern cyclogenesis February 5-7...
Another significant storm threat is headed towards areas east of the Mississippi River in the Friday to Sunday time frame. Recent guidance suggests an anomalous trough with accompanying shortwave causing the allowance of an increased chance of cyclogenesis along the eastern seaboard. But unlike the previous event, the polar vortex and 50/50 low remain slightly dislocated from a favorable position therefore allowing for effects to be reached farther inland. While this threat remains nearly 5-7 days in advance, this blog attempts to outlook the scenarios highlighting the highest threats at this point. Variability is likely throughout the week courtesy of a much more volatile H5 jet, which will allow for a much more difficult and complex forecast.
Lets dive right into the thick of things highlighting the favorable synoptic setup. MREF guidance using GFS ensembles, indicate spaghetti plots to have relatively high confidence in a disturbance located along the eastern seaboard with an anomalous trough.
The GEFS mean plot produces the polar vortex northeast towards Nova Scotia favoring a more southwest to northeast orientated jet streak, unlike the previous west to east suppressed flow. KU analogs suggest this to be a relatively favorable plot for at least 4-5 indirect matches. A relatively stagnant negative NAO will allow for continued blocking towards the Hudson Bay through Greenland, but a high amplitude ridge in the western Atlantic will be the catalyst for allowing confluence in New England to remain slightly disjointed.
0utc ECMWF 1/31 showed a few concerning factors that remain highly subjective in terms of snowfall potential.
First of critical note is the anomalous trough negative tilted orientation towards the Mississippi Valley. This is slightly farther west than favorable analogs therefore favoring phasing to occur a bit earlier than one might expect for a typical Miller A storm system. Origins are definitely out of the Gulf of Mexico, but with the 50/50 low dislocated (as highlighted above) to the northeast, the primary low may transverse towards the Tennessee Valley. The ECMWF remains the western outlier, but highlights a few critical concerns that the southeast biased GFS may be lacking. Also of importance, note the increasing amplitude in the western Atlantic ridge. If this increases in any more gains in northern amplitude, it may try to cut of all confluence in northern New England and southern Canada courtesy of the high pressure slightly disjointed towards western Newfoundland. But the ECMWF does support weak blocking upstream and a large negative EPO western ridge therefore supportive of an increasing threat of cyclogenesis and a widespread precipitation event across the eastern United States from Florida to Maine. More recently the 1/31 12utc ECMWF radically shifted farther south and east with the primary courtesy of 50/50 relocating more favorably towards 50N/50W. While this pattern remains highly subjective, guidance in this medium range is definitely diverging on a few solutions. The solution as listed above with several unfavorable factors fits the 'near miss' KU category favoring west Virginia up through western and central Pennsylvania up towards Albany, New York. In that scenario rain would be likely into areas east of the mountains at some point. Also of critical note is the closed 500mb low the ECMWF is highlighting in the 0z run up towards Kentucky, which is a good rule of thumb for precipitation type issues east of the Blue Ridge.
Despite the warmer, inland storm, the UKMET and GGEM remain steadfast on another very interesting scenario.
The 12utc GGEM 1/31 cycle indicates a more favorable scenario fitting the threshold for widespread significant snowfall over the eastern seaboard. The trough turns negatively tilted towards the southeast favoring rapid cyclogenesis as the low approaches Hatteras. There also remains more confluence to the north around northern New England to Nova Scotia, but make a critical note that the high pressure remains in a slightly unfavorable location. Lastly note the impressive 100knot jet streak along the east coast bringing +2SD moisture up the coastline from the Gulf of Mexico and Atlantic Ocean.
Looking at teleconnections, they remain supportive of east coast cyclogenesis with a negative NAO and positive PNA. Also favorable is the phase 7-8 MJO, which has finally remerged after a benign pattern most of January.
The MJO phases of 7,8, & 1 remain favorable for high amplitude in western United States ridging and anomalous east coast troughing. The benign MJO is part to blame for the zonal Pacific airmass January most of the United States record, so now we are in a pattern closer in relation to that of December 2009. The active subtropical jet remains the culprit for the shortwave over the southeast later this week that will ride along the eastern periphery of the trough; wherever that may be. All of this coupled with a significant statosphere warming event and near record negative AO, will keep confidence high in a major winter weather event towards the weekend.
Finally the 1/31 12utc GFS operational shows another scenario with some relation to the double barrel low feature on the 0z ECMWF.
The primary low tracks up through the Tennessee Valley with redevelopment near Hatteras before the PV kicks this system eastward before it can gain latitude. A critical note of 4-7 medium range guidance is for PV positions to be progged too far to the south and west. So taken in account the southeast bias of this current prognostic, this system would likely be allowed for more widespread impacts north of 40N. Phasing of the northern and southern stream will be critical with a more phased approach allowing for this low pressure to track closer towards the coast with a strong primary back through the Tennessee Valley and into Kentucky.
With all of this in mind, my mean solution at this point highlights some very critical features. First off the blocking and confluence seems very disjointed to classic nor'easter tracks with widespread snowfall. In fact the H5 pattern resembles that more of an Appalachian snowstorm than a suppressed event. Also some guidance is suggesting a weak S/W across the Great Lakes region, which in most past instances typically is not favorable for an east coast track with widespread snowfall. But that being said spaghetti plots are very indicative of a heavy precipitation event across the east coast in the Friday through Sunday time frame with potential high impacts especially as one gains latitude. Also of one concern is the trend of guidance suggesting a stronger initial catalyst shortwave out of the Rockies, which would therefore allowing phasing to occur sooner with an Ohio Valley track. Therefore with a steep trough and lack of significant blocking I put suppression with this system at less than 30%. For those steadily watching model runs, expect radical changes in each cycle throughout the week as the pattern is highly volatile. This will cause many forecasting headaches. As for recent model verification the GGEM leads the pack in the medium and short range for the synoptic cyclogenesis events this winter along the east coast, but still the ECMWF leads the way in medium range 500mb verification. The GFS remains poor, typically with a southeast cold bias. Looking in conclusion I am concerned for precipitation type issues from the Blue Ridge up through Pennsylvania on eastward, but especially from I-95 on eastward. And I still would not be surprised for this system to track along the coastal plain with heavy snow thrown back into the Appalachians. 12utc model cycle trends were encouraging as for the 50/50 low placement straying away from an Ohio Valley storm system. Keep in mind with many days of the week ahead, any solution remains on the table, but I hope I highlighted several of the more favorable scenarios to make tracking this storm threat a bit more simpler. As far as analogs I have highlighted March of 1959, February of 1964, and January of 1978 with slight synoptic similarities. But generally I would not focus too much on analogs considering the fragile pattern in which a good deal can go wrong for those southeast of Hagerstown-Harrisburg-Allentown. Have a wonderful day!!!
"Here northeast of Harrisburg 2009-2010 winter statistics"
(Snow Stats)
Current Snow Cover- 3.75in
Monthly Total- 3.75in
Seasonal Total- 21.85in
October Total- 0.0in
November Total- Trace
December Total- 16.0in
January Total- 2.1in
February Total- 3.75in
Winter Weather Advisories- 5
Winter Storm Warnings- 1
Ice Storm Warnings- 0
Blizzard Warnings- 0
Freezing Rain Advisories- 2
Winter Storm Watches- 1
(Temperature Stats)
Lowest High Temperature- 18.8F
Lowest Low Temperature- 11.7F
Wind Chill Advisories- 0
Wind Chill Warnings- 0
(Winter Storms Stats)
Dec 5 - 1.5in - First accumulating snow of season
Dec 8-9 - 2.5in - Snow changed to plain rain
Dec 13 - .1in - Freezing rain
Dec 19 - 9.0in - Heavy snow, higher amounts to south
Dec 31 - 3.0in - 2.5hr warm air advection event
Dec 31 #2 - .2in - Freezing rain/sleet later in day
Jan 8 - 1.5in - Light snow associated with clipper
Feb 2 - 3.75in - Weak coastal storm
Regional Radar...
Reader Comments
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Wonder what Blizz will post after school.
well 970 would be a pretty good bomb, though I don't know if that would mean the precip cutoff would be that much sharper or what. thanks for looking it up...
I'm Lactose-intolerant and on a Gluten free diet!! Should I buy milk and bread anyway?
Decisions , decisions.
Thank you. I'll be here all winter, no really.
NO SLEEP TIL SUNDAY, except at work.
I'll stick with beer!!!
Lewis Black said it best... It's not Soy Milk, it's Soy Juice. It's not Soy Milk because there is no soy breast. But everybody says Soy Milk, because when you say Soy Juice... you literally... start to gag.
I don't think many people on this blog would agree with him, but I thought it was too funny not to post... (I hope it is not over the line)
that is a serious dumping...
I've got to check it out- some of the stuff looks too funny... but not as funny as you torturing the people on other sites to the point of banishment- now that is really funny
Touché.
breathe.
Statement as of 2:45 PM EST on February 03, 2010
... Winter Storm Watch in effect from Friday morning through
Saturday evening...
The National Weather Service in Sterling Virginia has issued a
Winter Storm Watch... which is in effect from Friday morning
through Saturday evening.
* Precipitation type... snow.
* Accumulations... this storm is likely to produce 12 or more
inches of snow in the watch area... with a good chance for
localized amounts over 20 inches.
* Timing... snow is expected to begin late morning
Friday... continuing through Saturday evening.
* Temperatures... highs in the lower to mid 30s Friday. Friday
night and Saturday... temperatures will be 25 to 30 degrees.
* Winds... east 5 to 10 mph Friday and Friday night... becoming
north 10 to 20 mph Saturday.
Precautionary/preparedness actions...
This storm has the potential to be similar to the December 19th storm.
Plan for substantial disruptions to travel Friday afternoon through the
weekend.
increasing to 10-20 mph. gale warnings likely for the bay per lastest afd.
I still remember the 1978 Blizzard. It started at the worst time on Long Island. By noon, roads were becoming impassable.
Issued At 2/3/2010 - DISCUSSION AND FORECAST: Issued on 03 Feb 10 at 1554 by S. Fritch
NOTE: @1430, a WINTER STORM WATCH was put into effect by the National Weather Service.
Needless to say, much of the focus for the medium range forecast will be on the storm event this weekend. This system, currently over Texas, will continue to grow as it begins to interacts with a trough over the Great Plains. This system will continue to move over the Gulf of Mexico, adding "fuel" to the fire. Gulf moisture will assist in the Low strengthening and organizing before making its journey up the East Coast Friday. The storm's track beyond this is still uncertain. Due to model disagreement, we are hesitant to go into much detail about this storm but we have narrowed it down to two scenarios. Once the coastal Low moves up the coastline it will take one of two possible tracks. First, if the Low is pushed off the Carolina's, the heaviest precipitation will not been seen in our region (ideal for those with plans this weekend!) Temperatures are expected to stay close to freezing…resulting in snow being the precip type. This snow will be wet and possibly have some sleet mixed it so take proper precautions while driving this weekend. The second scenario is the Low moving off the Delmarva coast. This will bring the Low close to our region and result in heavier precipitation. In this situation, a significant snow event can be expected. Since the storm is still 48 hours out we will not go into too much detail (tune in to Thursdays forecast - when we have a better idea of the behavior.) Right now, we will give a brief overview of what is currently expected. The storm is predicted to arrive between Friday late afternoon and evening (keep in mind for those with a late Friday commute home!) The precipitation will continue overnight Friday and into Saturday. We are currently leaning towards the latter scenario that significant accumulation will occur Friday night - expected totals will be discussed tomorrow. By Saturday afternoon the heaviest snow will be out of our region with light snow showers remaining through the early evening. Windy conditions on Saturday will blow snow around…making visibility difficult. The system will move off the coast Saturday and cold NW air will come in…refreezing melted precipitation from the storm. Clearing skies and cold temperatures are expected through the first part of the week as we are under High pressure. The High will not stay with us long though as another system arrives Tuesday. Again, keep checking in for updated about this weekend's storm so we can properly prepare everyone!
FRIDAY: Mostly cloudy early becoming cloudy and breezy with snow likely, high 34°F, wind light and variable becoming ENE at 7-12 MPH increasing to 10-15G22 MPH. Cloudy and continued breezy with snow overnight, snow heavy at times, low 27°F, wind ENE becoming NNE-NE at 12-17G25 MPH.
SATURDAY: Cloudy and windy with snow likely, high 31°F, wind NNE-NE at 14-20G31 MPH decreasing to 10-15 MPH in the afternoon. Cloudy and cold with chance for scattered snow showers before midnight, low 19°F, wind N-NNE at 8-14 MPH. Wind chill in the single digits.
SUNDAY: Partly sunny and cold, high 30°F, wind NNW at 7-12 MPH. Partly cloudy and continued cold overnight, low 17°F, wind NNW at 7-12 MPH. Wind chill near 0°F.
MONDAY: Mostly sunny and cold, high 33°F, wind NW at 5-10 MPH early becoming light and variable. Partly cloudy becoming mostly cloudy overnight, low 18°F, wind light and variable.
and it looks like it won't be warming up....so you better get out and shovel or snowblow often
if anybody's interested, let me know... we'll find a centralized wal-mart (322 HBG probably)
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