Cold temps set in early this week,
but transient ups & downs continue Get The Forecast!

*Indications of above or below average temperatures in the table above are relative to what is considered “normal” using data collected over the long term for a particular date. This is collected and maintained by the National Climatic Data Center in conjunction with the National Weather Service actual data from previous years collected at official ASOS/climatology stations across our coverage area. Also note that as time moves forward into a different period as shown above, average temperatures for those dates will also change. See the example below using Philadelphia, PA as the climo station:

The departure from normal uses the average temperature for the date, averaging temps over 24 hours for any given location, using both high and low temperatures hourly during any particular day. This outlook determines warm vs. cool periods relative to normal temperatures.

Technical discussion below will feature two (2) subcategories: Precipitation, and Pattern Discussion. Storm possibilities will be discussed exclusively in the Premium Forum with intense model analysis leading up to any major snow, ice, or rain events, not publicly. To join this discussion and hear the updated thoughts from our team, visit The My Pocket Meteorologist Page by clicking HERE and select the “Premium Weather Forum” option.

Precipitation:

For the remainder of January, there are a few notable systems that could affect the region, the near term system on Saturday is certain, but doesn’t carry with it a high amount of quantitative (melted down equivalent) precipitation with it. There is another moderately high chance for a storm next Saturday, and perhaps again to end the month. Since precipitation is lagging slightly below average thus far, projections for the month as a whole have been adjusted to near average (-0.5″ to +0.5″) for the month as a whole by month’s end.

The first system will affect the region Saturday, and currently projections for snow and ice appears on the Weather Alerts page here: http://epawaweather.com/weather-alerts/. Rather than be redundant, I included the link for you to read up on that system. It is overrunning precip ahead of a warm front that will bring snow initially, then sleet, and for some southern areas, freezing rain and rain. Focusing on the next system next Saturday, models have been back and forth on this time frame this past week, at times showing a colder snow event, others showing snow/mix to rain, and more recently, a cutting system into the Great Lakes that invites warm air on the eastern side and predominantly rain for our area. This coincides with an expected period of transient milder temps that longer term models and ensembles have adjusted to recently. We favor a predominantly rain solution for this system, but several ensemble members, most notably the EPS, are suggesting a wintry component to that system still as of their most recent runs. As such, and considering the range, we will continue to monitor throughout the week and keep all options on the table. But highest probability is for a cutting storm that yields rain as the predominant precipitation type at this time.

Two separate Winter Storm signals were grouped in the same time frame in this outlook, the first signal around the 28th which could be marginal, and the 2nd signal is closer to February 1st/2nd, where a better potential exists for a snow event. Signals are not guarantees for winter storms, but rather highlight periods of interest that supports snow or ice to occur. Future outlooks and daily forecasts/videos will better handle these systems on a shorter term basis once we are closer to that time period.

The precipitation departure from average for the month of January we project will finish near average (-0.5″ to +0.5″) with high confidence, with a few more potentially moisture-laden systems to deal with through the end of the month. Early look at the month of February would suggest slightly above average precipitation (+0.5″ to +1.0″) by months end, using a blend of ensembles, climate models, and our privately shared 2019-2020 Winter Outlook projections.

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Breakdown of precipitation departures from normal over the next several weeks:

January 20th-January 26th:  Near average

January 27th-February 2nd:  Near average

February 3rd-February 9th:  Near to slightly above average

February 10th-February 16th:  Near to slightly above average

Public/free available maps will be updated when a threat is imminent for significant weather on the weather alerts page throughout the year:  http://epawaweather.com/weather-alerts/

Note:  Any image in the outlook is clickable for larger viewing

12z NAM 3km precipitation type progression simulation shows the Saturday overrunning snow, changing to sleet as warm air advection works in aloft. This will be mainly an interior/northern event for best snow/ice totals.

Recent guidance trends are toward milder next weekend, and as such, this supports next Saturday’s storm being rain at present time. Still some ensemble members suggesting a wintry side, so we’ll monitor this week.

Pattern:

The Madden-Julian Oscillation (MJO): The Madden-Julian Oscillation is currently in phase 6, a milder phase, then is expected to propagate through phase 7, which in January is typically a colder phase in the eastern US. This will lend a hand to the colder period expected in much of the week ahead. Heading into the tail end of January, MJO projections become less clear and variable, and most guidance has an entry into the circle of death. Some more aggressive MJO projections from the CFS and Australian BOMM suggest a visit to phase 8 late month, which is why we are seeing quite a bit of disagreement in longer range forecasts. With a recent +AAM spike observed, it supports a continued eastward propagating MJO wave and increased convection approaching the Dateline in phase 7 in the nearer term. We are now starting to see a poleward injection of westerly momentum north of the equator. This process will, if nothing else, enhance the subtropical jet during early February. Variable longer-term MJO projections should be taken with a grain of salt beyond January 28th.

Recent guidance attempts to lock in the cold pattern for the foreseeable future have failed, and this is mainly tied to longer range suggestions of a -EPO and -NAO becoming more dominant players. It’s tough to get sustained cold for a long period of time when you don’t have a sustained -EPO and/or -NAO, and the tropospheric Polar Vortex is not positioned over Northern Canada. As such, the cold will come in waves through the end of the month, and in between we will continue to see transient milder periods. Models still suggest this up and down pattern continues into February, and less than favorable teleconnections at times (+EPO, +AO, +NAO. -PNA) and we will have to rely on timing the cold shots to coincide with storms and storm signals. It is very possible that February continues this up and down trend that we expect through the end of this month, and a lot of marginal events will continue. A bigger storm threat would be more of the thread-the-needle variety, and likely the exception. Without sounding too doom and gloom for the snow lovers, I have to acknowledge that February can go either way. Bust or boom. There are too many mixed signals right now to make a definitive projection, so confidence in the chart is lowered to moderate to low in the chart for this reason. Analogs would still suggest a snowy February, but analogs haven’t been the most reliable this winter either thus far, so there’s that…

The month of January we project we’ll see above average temperatures (+5.0°F to 8.0°F) with a very mild first half thus far that will skew the mean/average for the remainder of the month. Despite the colder expectations at times for the last 1/3rd of the month, the month as a whole still averages above normal. Early look at the month of February suggests a flip to slightly below average (-1.0°F to -3.0°F) temperatures for the month as a whole, using longer range climate ensembles, global observation trends, and the leading analogs from our privately shared (premium forum) 2019-2020 Winter Outlook.

Snowfall: Next chance for wintry weather arrives Saturday 1/18, which is our short-term threat. At this point, next weekend looks like a milder/rain system, but some ensemble members continue to suggest a wintry side. We will monitor closely throughout the week. Additional storm signals that could bring wintry weather exists at the tail end of the month and early February, but too early for any specifics or higher confidence.

Note:  Any image in the outlook is clickable for larger viewing

Behind our Saturday winter storm, it turns much colder for several days, especially from later Sunday through Wednesday of next week. Highs will be below freezing for many areas during this time period, but also dry.

Later in the week next week, milder air starts to advect and ridging temporarily builds in. This is a transient milder period in between shots of cold, but just so happens to coincide with a storm cutting into the Great Lakes.

Average snowfall for January and February for select areas

Images below are clickable for better viewing

Days 1-5 – confidence VERY HIGH

Days 6-10 – confidence HIGH

Days 11-15 – confidence MODERATELY HIGH

Days 16-20 – confidence MODERATE

Below is a look at the latest Soil Moisture Anomaly for the Contiguous United States. This is used by NOAA/CPC for the purpose of drought monitoring and drought outlooks.

This image will automatically update daily.

Winter-only text alerts and premium forum options for the 2019-2020 Winter are now available for purchase. A nominal one-time fee will bring you detailed alerts throughout the Winter between November 1st, 2019 and March 31st, 2020, or last snowfall. Visit http://epawaweather.com/winter-weather-alerts/ for full details, or simply click on the banner below.

Forecaster: EPAWA Meteorologist Bobby Martrich
Discussion last updated: Friday January 17th, 11:45am