Long range signals for an early Spring
and signs of warmth on the horizon…

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: What seems like an endless bad dream for those that have grown tired of the snow this month (this forecaster included) and a moment of rejoicing for snow lovers will continue to pose threats for snow through the end of February, at least for a portion of each threat. Most areas are well above average snowfall for February, and most locations away from the far SE areas are above average Winter snowfall marks. Quantitative precipitation, or liquid equivalent this month is also considerably above average. Three separate systems remain a threat in different ways for the remainder of this month, then a near to slightly above average March is expected to follow.

The first chance for precipitation listed in this outlook is not a large system and is relatively quick moving. Snow looks to overspread the region on Monday morning from W-E, and this presently looks like an interior Pennsylvania deal. North of I-78 may remain snow throughout the day on Monday where it remains colder, while areas nearest I-78 corridor will likely mix with rain in the afternoon. South of I-78, a complete changeover is anticipated to rain after beginning as snow, then the system exits early Monday evening. We will monitor evolution closely over the weekend.

The next two systems are storm signals, and will also be monitored closely in the week ahead. First chance at the end of next week could provide a wintry solution and more snow across the region if the timing is right to link up two separate northern and southern stream energy pieces at the right point to deliver an accumulating snowfall. Given how the month has gone with these signals, I wouldn’t bet against it, but carried moderate confidence for now. A second signal was also listed at the tail end of this month and to begin March, but at present time appears to be perhaps a wintry start if timing/track is right, then changing to rain everywhere as temperatures sufficiently warm.

The month of February we project will finish with above average (+1.0″ to +2.0″) precipitation departures for the month as a whole with very high confidence. Snowfall thanks to the historic storm to begin the month and several subsequent events will be well above average, and we may add to those totals in the next week or so. Looking ahead to the month of March suggests a near to slightly above average precipitation (+0.0″ to +0.5″) anomaly for the month as a whole, with near to slightly below average snowfall favoring earlier in the month using long range climate guidance and global observational trends.

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

February 21st – February 27th:  Near to slightly below average

February 28th – March 6th:  Slightly above average

March 7th – March 13th:  Near average

March 14th – March 20th:  Near to slightly above average

March 21st – March 27th:  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  

Using the NAM 12km, the next system moves in Monday, with snow to start for interior Pennsylvania locales, and remaining snow north of I-78, snow to a mix along I-78, and a change to rain south of I-78.

Next storm signal is listed for the end of next week, which will be dependent on northern/southern stream energy pieces coming together at the right time. GFS is largely south, but will move around a bit.

Pattern:

OVERVIEW: The Madden-Julian Oscillation (MJO) is currently in phase 7 in the Western Pacific but is expected to collapse into the Circle of Death (COD) over the weekend. Phase 7 is typically associated with slightly milder conditions, however a 2nd Sudden Stratospheric Warming Event (SSWE) occurred at the end of January has maintained a much colder pattern over our region. The tropospheric polar vortex that resulted from this displacement that brought record cold and snow/ice as far south as Texas this week, while we remained on the easternmost periphery of that cold, is in process of retreating back toward the polar regions. The MJO is largely expected to remain in the COD over the next few weeks, leading to a more zonal and seasonably milder pattern heading into March.

The overall colder pattern seen over much of this month will begin to relax a bit in the week ahead, with the period starting off cold this weekend, then up and down through the remainder of February. March begins near average during the first week, then a very slight step back week 2. As we approach the Spring equinox, temperatures are expected to moderate in weeks 3 and 4 of the month, and seasonable to end March and begin April.

Average highs and lows are continuing to slowly rise out of our annual climatological minimums last month, and normal high temperatures are in the 38-45° range from north to south across our coverage region. Any above or below average stretches listed in the outlook will be relative to seasonal norms at that time. It is important to note that cooler/warmer periods will be relative to the time of year we are talking about. For example, near average temperatures listed during the first week of March will likely yield highs in the middle to upper 40s in most areas with respect to the normal/average highs at that time. During February, normal highs and lows only BARELY moderate from annual climatological minimums, but rise about 10°F or so from late February to late March. Use the average highs/lows chart above that provides a point of reference for what average is for each corresponding date, with the examples used for the Philadelphia region.

Snowfall: Several chances for snow or ice will present itself over the next week or so, most notably in the shorter term on Monday for interior Pennsylvania. Additional signals are less certain and may carry other precipitation types as part of the storm(s) in question in their entirety through the end of the month, and best chance for any wintry weather in March favors the first half of the month and the interior locales from a probabilistic standpoint.

For the month of February, we expect slightly below average temperatures (-1.0°F to -3.0°F) when the dust settles February 28th with high confidence. Looking at the month of March as a whole suggests a near average month (-2.0°F to +2.0°F) using long term climate models and seasonal/global observation trends.

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

The chart below provides a point of reference for what average/normal snowfall should be at several select climo locations within our region. This is the same chart used in the Sunday Weather Weeklies videos.

Outlook table last updated: Friday February 19th, 11:45 AM. Next scheduled update: Friday February 26th.

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/my-pocket-meteorologist/ 

*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 February 19th, 11:45 AM