Arctic blast to arrive end of week,
but it’s expected to be transient…

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:

OVERVIEW:  The month of January will likely finish with slightly above average precipitation and below average snowfall…and in most southeastern areas, there has yet to be measurable snowfall, most notably nearest the I-95 corridor in PA, DE, and NJ and points SE toward the coast. Going forward into February, there will be two potential systems moving through the region in the next week, and combined with the expected colder/below average temperatures at that time, both could have wintry implications for parts of the region. Looking at the month of February as a whole suggests a slightly above to above average precipitation departure (+0.5″ to +1.5″) with near average snowfall as our current projection.

Shorter term, a weak cold front crosses the region Sunday night, which is followed by a secondary front on the lead of the cold air that will follow on Monday. On both occasions, a few isolated rain showers are possible, but rather insignificant. As a boundary becomes established south of the region Tuesday, a wave of low pressure may ride along the boundary Tuesday night into Wednesday AM. If the boundary is close enough, parts of the area could see some light snow or snow showers from what would likely be a weaker low and overrunning event. It is possible the cold overwhelms and keeps the boundary farther to the south, which would result in any precipitation remaining suppressed to our south as well. A winter storm signal was maintained this week for the February 4th/5th time frame with a possible coastal storm, but the highly uncertain track at this point will rely on speed and position of several key features in order to produce snow for this region. Cold air will likely be firmly in place at this time, so that doesn’t appear to be an issue. An additional storm signal, although not necessarily wintry with more marginal temperatures at that time, may present itself in the February 9th/10th period and was added this week.

The month of January we project to finish with a slightly above average (+0.0″ to +1.0″) precipitation departure for the month as a whole, using longer term climate models and global observation trends. Snowfall will finish below average in the interior, with SE and coastal regions seeing nothing at all this month. February’s projection is for a wet month, slightly above to above average (+0.5″  to +1.5″) precipitation departure for the month as a whole with near average snowfall.

Follow our social media channels for updates:

EPAWA Facebook:  https://www.facebook.com/epawawx/

Meteorologist Bobby Martrich [EPAWA] on Twitter:  https://twitter.com/epawawx

YouTube channel/daily forecast video: https://www.youtube.com/user/eastpaweather

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

January 28th  – February 3rd: Slightly below average

February 4th  – February 10th: Near to slightly above average

February 11th  – February 18th: Slightly above average

February 19th  – February 25th: Slightly above to above average

February 26th  – March 4th: Slightly above average

March 5th  – March 11th: 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 below is clickable for larger viewing  

A weak cold front moves through Sunday night and brings a few isolated rain showers later Sunday and Sunday night, then a reinforcing secondary front moves through Monday on the lead of a trough.

A shortwave moving along a baroclinic boundary expected to be just south of the region on the ECMWF ensembles (pictured) could bring light snow or snow showers Tuesday night into Wednesday AM.

Pattern:

OVERVIEW: The month of January began much warmer than average, and has generally remained on at least the slightly milder side of average since that point. Going forward, the outlook is for much of the same for the next several days through the 30th, then colder air arrives on the final day of the month. As a result of this progression, above average temperatures (+5.0°F to +8.0°F) is likely to be the monthly departure when the dust settles January 31st. We maintained projections this week for the month of February for near to slightly below average temperatures (-0.0°F to -2.0 °F) for the month as a whole ending February 28th, with a below average first week of the month followed by some moderation weeks 2 and most notably week 3 before abating late month into early March.

The Madden-Julian Oscillation (MJO) best forcing currently resides in phase 3 in the Indian Ocean, and the expectation is for tropical forcing to continue in phase 3 through early February, then perhaps a brief stint in phase 4 (Maritime Continent) before collapsing into the Circle of Death (COD) during week 2 of February. A pattern more conducive of colder temps and wintry weather will be contingent on La Niña continuing to weaken. If ENSO neutral can be reached during February, the Madden-Julian Oscillation takes on different meaning with regard to the resultant downstream 500mb heights configuration and their resultant temperature patterns. Simply stated, the SE ridge has more of an effect in those phases in a La Niña than in an ENSO neutral state, and less influence = less warmth. The background state (La Niña vs. ENSO neutral) will be critical to how February plays out. A phase 3 pattern is a colder phase in February for our region, which will have effect on our sensible weather during the first full week of February and presents a narrow window of opportunity for wintry weather. It continues to be the opinion of this forecaster that February individually most likely doesn’t “save” Winter as a whole, but there will be numerous chances throughout the month. No read on whether there will be a major snowfall in the mix in February at this point, but it is certainly possible, most notably during the bookend weeks of the month…weeks 1 and 4.

Average high temperatures are currently in the 36-41°F range from north to south across our coverage region, which is about the same as this time last week. Temperatures are at the tail end of the climatological annual minimum period currently, and temperatures will slowly climb out of those minimums in February and onward. Any above or below average stretches listed in the outlook will be relative to seasonal norms at that time, and it is important to note that cooler/warmer periods will be relative to the time of year we are talking about. For example, the below average temperatures listed in the January 31st through February 7th time frame will generally feature highs in the upper 20s to mid 30s for the majority of that stretch across the region. Use the average highs/lows chart below that provides a point of reference for what average is for each corresponding date, with the examples used for the Philadelphia region, which is one of our warmest climate sites.

The month of January will finish with a solidly well above average (+5.0°F to +8.0°F) temperature departure for the month as a whole with very high confidence. We maintained projections this week for the month of February for a near to slightly below average (-0.0°F to -2.0°F) temperature departure for the month as a whole, using longer term climate guidance and seasonal observation trends

Note:  Any image below is clickable for larger viewing

Slightly above to above average temperatures through the 30th, then a trough arrives 1/30 which lowers temps behind it, and the pattern turns much colder again through the first week of February.

Average snowfall picks up a bit during the month of January, and peaks on average in February. The average snowfall at each location is an average of the 1991-2020 climate period.

Outlook table last updated: Friday January 27th, 11:15 AM. Next scheduled update: Friday February 3rd.

This is a weekly updated public long range guidance product from EPAWA. For daily long range updates and more detailed updates M-F, please join the EPAWA forum. More information/sign-up at: http://epawaweather.com/mpm/ 

*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.

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.

Forecaster: EPAWA Meteorologist Bobby Martrich
Discussion last updated: Friday January 27th, 11:15 AM