Ph.D. Student - Earth System Science (UC Irvine), B.Sc. - Atmospheric Sciences (Cornell University)
By: Zachary Labe , 8:56 PM GMT on January 24, 2010
"Afternoon Thoughts" (Updated 1/24)
Perhaps one of the most skilled nature artists of the twentieth century is Ned Smith. Up along Berrysburg Mountain (elev ~1500ft) east of Millersburg in Dauphin County is the Ned Smith Center Link, which I make frequent visits throughout the year to see the special exhibits and galleries. Also at the environment center are a plethora of wildlife nature trails along the base of the mountain and up to about 1200ft also. There also lies the Wiconisco Creek, which is a well known trout stream in the region. Anyways recently Ned Smith's winter paintings were displayed for the special feature gallery capturing the typical winter in Pennsylvania. Ned Smith grew up in northern Dauphin County hiking through the mountains and exploring the beauty of wildlife's adaptations to the seasons. "Gone for the Day" is an interesting read detailing a diary depiction of wildlife interactions through the seasons over a several year period also containing some of his famous sketches. In any case through his 'Winter Color' exhibit the essence and beauty of winter is captured with the snow fresh fallen snow with rabbit and deer tracks intermingling each other. I always envision myself years from now in a wonderful log home up north of State College near Philipsburg with the whistling of winter's winds, crackling of the fireplace, and calmness of the fresh falling snow. For whatever reason, snow seems to cause an euphoric tone allowing for a quiet distance landscape as sound waves absorb into the snow. Life just goes by at a much slower and relaxed pace during a snowstorm as the winds whistle through the cracks. In any case if you are thinking of day trip to take the family, try the Ned Smith Center to see some of the special exhibits located about 20-30 minutes north of Harrisburg. Have a wonderful day!!!
"Current Surface Plot"
(Courtesy of HPC)
(Courtesy of Wunderground)
(Courtesy of NOAA)
"Forecast Discussion"(Pennsylvania, Maryland, Delaware)(Updated 1/24)
Impressive low level jet winds near 90knots over southern New England will allow for a strong influx of moisture from the Gulf of Mexico. Southerly winds will increase aloft with a tad easterly influence at the surface with some Atlantic moisture, especially east of the Appalachians. Recent HIRES NMM/WRF models indicate a 980mb low migrating northeast through the Great Lakes dragging along a trailing cold front. Anomalous PWATs increasing +3-4SD will allow for precipitative waters near 1.5in. With a slightly easterly component downwind areas of the Appalachians will feel the brunt of the heavy rainfall with model consensus QPF ranging from 1.5-2.5in. Courtesy of the impressive low level jet structure, I am nosing towards the higher end of consensus. Flash Flood Guidance is generally around 1in/12hr, which is very low. Flooding will likely occur with a moderate threat towards much of Pennsylvania with a lesser threat to the south. WRF simulated radar also indicates the potential for embedded convection Sunday evening causing rainfall rates in excess of 1in/hr for some locations particularly towards the Delmarva and southern Maryland region. But low inversion heights and cold air damming should inhibit thunder chances north of the Washington, DC - Salisbury, Maryland line. A few analogs arise considering the anomalous 700mb moisture field, including the heavy rain stratiform event of January of 1996. But with little to no river ice and snow pack confined to the mountains, flooding in this situation will be of no comparison, but QPF totals may be slightly similar. The height of the heavy rain will impact the northern Middle Atlantic Sunday night will localized areas of flooding towards Monday morning. There may also be briefly some light main stem river flooding especially over northern areas. Moderate flooding may occur with smaller streams and creeks also especially those that contain ice. The highest flood threat is for northeastern Pennsylvania. As the inversion erodes courtesy of the jet dynamics, temperatures should be on the rise throughout the entire northern Middle Atlantic with MOS likely a bit too cool, therefore I favor highs near 60F Monday morning for many areas along and south of I-76. By late Monday morning the cold front will pass through the region with temperatures falling to the low to mid 40s by dusk. Winds will shift to the west as H85s temperatures fall to below -5C over the northern Middle Atlantic causing a few orographically enhanced snow showers, especially towards Tuesday with a brief lake effect snow fetch. Temperatures generally look to deviate around normal for most of the week before colder air moves in by Thursday and Friday where temperatures fall below normal. The lake effect snow will diminish with veering wind profiles aloft as weak upper level ridging noses in towards Wednesday. By the end of the week a synoptic precipitation event approaches the region with polar air infiltrating from the north setting the stage for a major winter storm along the east coast in the form of an overrunning event transitioning to coastal low.
(Courtesy of Penn State Meteo.)
"Current Water Vapor Loop"
(Courtesy of Penn State Meteo.)
"7-Day Zonal Forecast Outlooks"(Pennsylvania, Maryland, and Delaware)(Updated 1/24)
Monday- Southerly winds ahead of a cold front will allow temperatures to spike to near 20F above normal over the entire region with upper 50s to low 60s along and south of the Pennsylvania turnpike into Maryland and Delaware with low to mid 50s north of that boundary. The heaviest rain will generally progressing east of the region by mid morning as the cold front moves east through the PA/NJ border by late morning. Additional rainfall amounts will generally be confined to areas along and east of I-81 ranging from .25-.35in. Minor to moderate flooding may be ongoing along may local streams/creeks and in areas of poor drainage for the Monday morning commute so plan ahead more time commuting. As the colder air filters into the region while winds shifts to the west, temperatures will diurnally fall throughout the day into the low to mid 40s for eastern areas by dusk and to around 32F west of I-81 by dusk with light snow flurries over the snow belt regions. Monday night will feature a few flurries over the mountains with breezy northwest winds gusting to 25mph. Low temperatures will range from the low 30s in Maryland, Delaware, and southern Pennsylvania to mid to upper 20s for areas to the north and west with partly cloudy skies.
Tuesday- Northwest winds will persist throughout the day with strato-cumulus across the western mountains above 1500ft west of the Blue Ridge front. Snow showers will be ongoing over the region with a westerly flow. But slightly unfavorable wind trajectories will allow for little to no snow accumulation during the daytime hours for the snow belts. Elsewhere downsloping winds will carve skies for partly cloudy conditions to clear skies along the I-95 corridor. High temperatures will range from the low 30s above 1000ft to low 40s near Washington DC to Philadelphia, PA. Tuesday night will feature a bit more northwest trajectory to the winds favoring in lake effect snow showers throughout the region with accumulations around 1-4in from McHenry, Maryland to Erie, Pennsylvania in the snow belt regions. Western favoring slopes in the southern Laurel Highlands will see the higher end of the accumulations in comparison to areas farther north and at a lower elevation. Lows will finally nudge back towards more seasonal values ranging from 22-29F over the northern Middle Atlantic.
Wednesday- Weak ridging aloft and high pressure will nose into the region for a generally pleasant day with partly cloudy conditions to generally sunny skies. Temperatures will remain near seasonal values with highs ranging from the low to upper 30s depending on elevation and geographic location. No additional snow accumulations are likely over the lake effect snow belts other than a few morning flurries before skies begin to clear. Wednesday night will feature cold temperatures with winds light and variable along with clear skies with lows ranging from the teens to low 20s for most locations, which should verify a few degrees below normal. Across Maryland and Delaware cirrus clouds will begin to stream over the region as an overrunning precipitation event approaches the region. Low temperatures will be mitigated by the cloud deck above allowing for lows in the mid to upper 20s. No precipitation is likely for southern areas through at least daybreak Thursday.
Thursday and Friday- A shortwave riding along a stationary boundary in the southern Middle Atlantic will be the catalyst for potential winter weather event favoring overrunning precipitation. Current prognostics indicate a strong buffering high pressure/PV to the north, but taken model biases into account precipitation may verify into the northern Middle Atlantic region. Many questions remain uncertain but a winter weather event is certainly possible along with a potential for this system to be suppressed towards the Southeast. In general precipitation chances remain above normal in this period along with below normal temperatures. Stay tuned for updates through the rest of the work week!
"Current River Ice Reports and Ski Conditions" (Updated 1/24)
Decaying frazil panes along main stem rivers in Pennsylvania through Maryland only continue to deteriorate as heavy rain approaches the region with hydrology concerns. Currently about 100% of the Susquehanna River main channel remains open even up through locations such as Williamsport on northward to Scranton up through New York State. The western branch towards Lock Haven as a few small ice jams along raised islands, but those remain of little concern. The Alleghany and Delaware also remain free of flowing ice courtesy of warmer temperatures. The height of the river ice expansion was towards the 7-10th of January, before a warmer pattern ensued. Also towards local streams and creeks, some of the slower moving and shallow beds remain frozen especially off of northern sides of the ridge tops. Ice is also along most local farm ponds from western Maryland through all of Pennsylvania. But looks may be deceiving as ice is melting from the bottom to the top with thicknesses very shallow in some regions. The best advice is to avoid all local waterways including ice fishing for the next week and a half before the colder air allows the thicknesses to grow once again especially for ice fishing. Ski conditions are also deteriorating as heavy rain approaches the region with warmer temperatures. The height of the ski seasons looks to have occurred during the second week of January in which much of the Laurel Highlands received 2-3ft of light powdery snow with snow ratios near 25:1. After the heavy rain, colder air will filter into the region and slopes will likely be repaired by ski crews. Lake effect snow may resume towards Tuesday as the flow shifts to the northwest with winds aloft near 30knots allowing for the transfer of moisture. Lake Erie remains about 70% free of ice, so that is plenty for widespread available moisture for an upslope event from Tuesday to Wednesday. NAM QPF is generally around .1-.25in for the favored snow belts favoring the Laurel Highlands. Snow accumulations are likely around 1-4in for the Laurel Highlands up through the northwestern snow belts favoring resorts such as Seven Springs, Four Seasons Hidden Valley, and Blue Knob. Also down through Garret County, Maryland ski resorts will likely see 1-3in of fresh powdery snow to restore the slopes after the high moisture content from the rain. A large-scale synoptic snow threat does loom towards the end of the week so generally after Tuesday ski conditions will be on the improve.
-Link to official reports page from NWS... Link.
-Link to local ski resort snow conditions... Link.
"Current Northeast Snow Depth and Northeast Wind chills"
(Courtesy of Wunderground)
"Lake Effect Snow Conditions" (Updated 1/24)
The core of cold air will transition towards western Pennsylvania Tuesday night into the first half of Wednesday. 1000-500mb thickness are progged by the GFS to be around 525-530dm in this time frame with decent Omega forcing. But 0-6km shear values near 40knots may not allow for organized banding, but more cellular activity. In any case 15:1 snow ratios with the dendritic growth layer around -12C will allow for a powdery snow with wind trajectories ranging from 280degrees on Tuesday to about 315degrees on Wednesday. Snow accumulations are likely to be minor and more of a nuisance but some of the western facing slopes in Westmoreland, Cambria, Somerset, and Garret Counties are likely to receive up to 3-4in of snow, which the valleys generally receive an inch or so. Northwestern Pennsylvania along the Alleghany plateau will likely receive 1-2in of snow favoring Erie, Crawford, and Warren Counties. As high pressure moves north of the region into southern New York towards Thursday, the lake effect fetch will shear out with only flurries expected. But a synoptic system approaches from Thursday to Saturday. As this low pressure pulls off the coast, once again winds will briefly become favorable for lake effect snow across the Laurel Highlands and northwestern Pennsylvania towards Sunday and Monday of next week. Nothing appears overly striking on model guidance for that event, so once again minor amounts are likely. It appears the largest orographic/upslope event has likely already occurred this winter. GFS QPF totals likely will allow for a 7 day total of 3-6in of lake effect snow in the snow belt regions favoring Somerset County above 2000ft.
"Current Lake Erie Wind Direction and Speed"
(Courtesy of NOAA)
"Current Lake Erie Water Temperature"
(Courtesy of NOAA)
"Long Term Outlook" (Updated 1/24)
The long term poses some interesting possibilities if one extrapolates teleconnection patterns and monsoonal positions across the eastern Hemisphere. A southern stream system will migrate across the continental United States after moving inland in southern California and transition along a thermal boundary Wednesday near the southern Mississippi Valley. Warm air from south rises above the cold air to the north along the boundary creating a classic warm air advection precipitation event towards the Tennessee Valley. Meanwhile the embedded shortwave along the thermal boundary strengthens slightly moving east-northeast. Farther north a 1024mb high noses southward with geopotential heights over the poles noting a critical placement of the Polar Vortex. This PV will prevent the inland track through the Ohio Valley, but exact position also may suppress this event. As the shortwave advances east the 850hPa low appears to track across central or southern Virginia with the heaviest precipitation falling north of the low track. H5 wavelength analog patterns are favorable for snow with most analogs acclaiming a high potential for 4in+ of snow for KDCA. Model biases appear evident in this situation with the GFS typically underestimating the WAA precipitation with isentropic lift. GGEM past verification usually does pretty well with 850hPa low position, while the GFS typically trends northward in the stationary boundary position therefore impacting the track of the S/W. Recent 5-8 day NCEP verification indicates the ECMWF leading the pack in 500mb wavelength verification with the UKMET, GFS, and GGEM behind with similar accuracy numbers. GFS tends to hold these PVs too far south also. Impressive thermal gradient along geopotential heights in southern Middle Atlantic will allow for the isentropic lift and frontogenesis to aid in pretty heavy QPF, but the question is where. I have no doubt in my mind someone will get a pretty decent thump of snow along the east coast. In general watch the strength of the shortwave when it enters the West Coast in 60hrs along with tracking the thermal boundary and PV position. For those north of the Mason-Dixon Line suppression looks to definitely be the highest threat against the storm system and I put probabilities for that occurring a bit higher than an actual snow event. Towards DCA the synoptic setup is a bit more favorable. In general a widespread precipitation is likely to occur on the cold dense side of the boundary towards the Thursday to Saturday time period. Of other note the models seem indicative of a second wave amplifying along the coastline from Hatteras towards the Delmarva as high pressure carves a track cone in this region. This would only enhance precipitation furthermore towards Saturday. Stay tuned for this event as teleconnections also support this with an amplified negative EPO ridge and negative to positive trending NAO. By the way three events I have been slightly bullish on a week in advance including the December 19th blizzard which was nailed nearly two weeks in advance along with the New Year's multi-wave event, which still caused a light to moderate snow followed by ice. This event is the third event I am highlighting as potentially pretty significant.
As far as the rest of the long term pattern goes, I have extremely high optimism towards February. In fact the period from 2/7 to about 3/5 may pertain to some very impressive storms across the continental United States. Teleconnections show a step down pattern, which coincides wonderfully with my January forecast down below. A step down pattern is where a series of cold fronts gradually carve colder and colder air with a transient pattern before a pattern finally sets in stone. This occurred back in the end of November and beginning of December. This is already evident where each storm along the east coast, excluding the current Great Lakes cutter, verifies colder and colder. The MLK storm was snow generally for New England and the higher elevations, then the recent overrunning event carved ice for the Middle Atlantic, and now finally a snow threat is going to be possible. While the flow generally remains zonal for the first week of February, a deep trough may set in courtesy of the anomalous negative AO, which will build in once again. As the MJO remerges into stages 6, 7, 8 we should see an increase in cyclogenesis along the eastern seaboard. Teleconnections and wavelength patterns are all setting the stage for a snowy February. Also of interest is the ongoing an increasing stratospheric warming event, which correlates to below normal temperature typically for much of the northern United States and Canada.
"Current NAO and PNA Predictions"
(Courtesy of NOAA)
"Anchorage, Alaska Tower Cam"
*Note I am only posting this tower cam until snow starts falling over the northern Middle Atlantic, lol. For now we can all be jealous of the Alaskan snow.
"Monthly Outlook" (January)
In general I am extremely pleased with my December Outlook. While forecasting for long term, it is important not to focus on the minute details, but look at the general idea and/or perspective. The temperature anomaly outlook for the month came in a shy warm with forecasts for (+.5)-(-.5). In general across the northern Middle Atlantic, temperature anomalies for the month were around (-.5)-(-1.0). Now diving in a bit deeper, the general temperature trends were forecast near accurately. The increasing warmth around Christmas went ideally with the forecast of warmer anomalies towards the end of the month courtesy of some weak undefined southeast ridging. In actual verification a La Nina like pattern for a few days allowing for a large Great Lakes storm complex with temperature anomalies over the east near +5.0 for the time period. Also what seems to be accurate is the idea of a cold regime towards the beginning of January and in near verification it appears an arctic blast is headed across the northern two thirds of the United States. In general the temperature forecast was relatively accurate with a slight warm bias for the overall anomaly. Precipitation for December was again a shy warm with snowfall across the entire Northern Middle Atlantic averaging well above normal. But once again diving deeper into the forecast, the forecast for first accumulating snow on December 5 went perfectly with a general 1-5in over the northern Middle Atlantic. Also my best forecast here on Wunderground occurred this month with the advertisement of the December 19 KU storm nearly 10-12 days in advance. But my forecast for normal snowfall and above normal snowfall over the northwest fell a tad too dry. Once again I am pleased for December. Now we look towards January...
Temperature- January will be an interesting month. Teleconnections point to in general a well below normal month. Interestingly enough the Arctic Oscillation Index is towards record values of below -5 and -6. In fact the CPC had to enlarge their AO index chart to include values as low as -6. An interesting of note was also accompanied by similar values and that would be 1976-1977, which was one of the coldest winters on record for a majority of the northern United States. Also the NAO is diving through negative values and as this closed low becomes cutoff towards the Gulf of Maine up through Nova Scotia and Newfoundland towards January 1, this will reestablish a more favorable 50/50 low position allowing with retrograding the negative NAO towards more west-based. This all may allow for a favorable storm track most of this month along with steep troughing over the east coast. Looking though at long range H85 temperature anomalies they are showing above normal temperatures towards Canada. This may have implications farther down the road for a temporary relief from the cold. Currently it appears my forecast will generally appeal to an arctic blast towards the first two weeks of January with perhaps a few record numbers being broken especially across the lower Middle Atlantic where ECMWF and GFS numbers indicate H85 anomalies near -3SD. Towards the last two weeks of the month may be a more thaw-like pattern as the cold air retrogrades back across the arctic before another 'step down' pattern towards February. Keep in mind considering January climatology even occasion warm patterns favor snow. Overall anomalies for the month I am going pretty cold with (-1.5)-(-2.5) for the entire Northern Middle Atlantic.
Precipitation- Forecasts for monthly precipitation are generally the most difficult as one large storm system can throw a monkey wrench into the forecast. This was evident back in December where the historical Middle Atlantic snowstorm caused many areas in Virginia and parts of Maryland to receive nearly their average seasonal snow total in one event. But considering an Arctic blast poised to enter the region along with a cutoff low allowing for a cyclonic flow for nearly a week, it is a likely call for above normal snowfall for northern and western areas especially towards the snowbelts. This also includes western Maryland too from Frostburg on westward. Being an arctic air mass, dew points are usually dry and storm systems are typically suppressed, but considering the El Nino climatology and brief warmer temperatures towards the end of the month normal to above normal snowfall is likely for a majority of the northern Middle Atlantic. I do not have any storm dates currently other than lake effect from January 1-6.
"Temperature and Precipitation Outlooks from Climate Prediction Center for next 30 days"
(Courtesy of NOAA)
-Winter Outlook 2009-2010... Link.
"Here northeast of Harrisburg 2009-2010 winter statistics"
Current Snow Cover- 0.00in
Monthly Total- 2.1in
Seasonal Total- 18.1in
October Total- 0.0in
November Total- Trace
December Total- 16.0in
January Total- 2.1in
Winter Weather Advisories- 5
Winter Storm Warnings- 1
Ice Storm Warnings- 0
Blizzard Warnings- 0
Freezing Rain Advisories- 2
Winter Storm Watches- 1
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
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.
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