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Unsettled on several occasions this
week, with a few breaks in between
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Long Range Outlook

Important information:

  • Eastern PA Weather Authority is no longer, and we have changed the business name to EPAWA Weather Consulting, LLC as of October 26th, 2018. Same great products, both free and paid, just a new name that better reflects what we do as the business of EPAWA.
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Screenshot (1)
DatesThreatsSignificanceConfidence
4/20-4/22TemperatureNear to slightly above averageVery high
4/23TemperatureAbove averageVery high
4/24-4/25TemperatureNear to slightly above averageHigh
4/26-4/30TemperatureSlightly above to above averageModerately high
5/1-5/2TemperatureSlightly above averageModerately high
5/3-5/6TemperatureSlightly above to above averageModerate
5/7-5/13TemperatureNear to slightly above averageModerate
5/14-5/20TemperatureSlightly above to above averageModerately low
4/20-4/22Cut-off upper level lowA cut-off upper level low will influence the region over the weekend, and while it will not be raining the entire time, scattered showers will be possible both days while the cut-off ULL is nearby. Best chance to see showers is Saturday morning and spotty Sunday afternoon. Some showers may linger into Monday with the attendant surface low nearby just offshore.High
4/23Cold frontA cold front will move through the region on Tuesday night, and will be preceded by scattered showers and perhaps thunderstorms as early as late Tuesday afternoon/evening.Moderately high
April as a wholeTemperaturesAbove average (+3.0°F to +6.0°F)High
April as a wholePrecipitationSlightly above average (+1.0" to +2.0")High
April as a wholeSnowfallBelow averageVery high
May as a wholeTemperatureAbove average (+3.0°F to +6.0°F)Moderately high
May as a wholePrecipitationNear average (-0.5" to +0.5")Moderate

Outlook table last updated: Friday April 19th, 11:35am. Next scheduled update: Friday April 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:

DateAverage Hi/LoEPAWA projection
April 20th66°F/46°FNear to slightly above average
April 27th68°F/48°FSlightly above to above average
May 4th70°F/50°FSlightly above to above average
May 11th72°F/52°FNear to slightly above average
May 18th74°F/55°FSlightly above to above average

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.

Long range analysis: Technical discussion is below for advanced readers:

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 rain or severe events, not publicly. To join this discussion and hear our updated thoughts from our team, visit The My Pocket Meteorologist Page by clicking HERE and select the “Premium Weather Forum” option.

Precipitation Discussion:

Precipitation:

The period starts off unsettled with a cut-off upper level low that will bring a few showers in the Saturday through Monday time frame until it completely clears the region later on Monday, but this entire time is not a washout by any means. Best chance time frame(s) to see showers is Saturday morning, then again Sunday overnight through parts of Monday. Any shower that occurs on Easter Sunday will likely be in the afternoon, and more of the stray variety. Those precipitation chances then increase Sunday night and Monday. Plenty of clouds dominate with the upper level low influence over the region through the period, whether raining or not.

The next chance for precipitation comes late Tuesday or Tuesday evening with a cold front advancing toward the region. Prior to its arrival, it is very warm with temperatures well into the 70s to near 80° and there will be scattered showers and thunderstorms that precede the front prior to its full passage Tuesday overnight.

Beyond this point, precipitation may quiet down a bit. There will be opportunities for precipitation toward the end of the month, but too far of a range to speculate on specifics. A slightly drier than average first half of May is expected to follow.

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

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

April 22nd-April 28th: Near to slightly above average

April 29th-May 5th: Near average

May 6th-May 12th: Slightly below average

May 13th-May 19th: Slightly below 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

The NAM 3km for 8:00am Saturday still shows some scattered shower activity across mainly eastern areas, which will end mostly before noon. It remains cloudy or mostly cloudy, but dry after thru at least Sunday afternoon.

nam3

The GFS for Sunday evening shows the cut-off upper level low that was previously to our west now making its way through the region. This will lead to a second round of showers from late Sunday/Sunday night thru Monday.

gfs1

Pattern Discussion:

Pattern:

The Madden-Julian Oscillation (MJO): The Madden-Julian Oscillation is currently in a weaker phase 2, and will likely split time in the next 7-10 days migrating from phase 2 to phase 3. After that point, we see a progression into the Maritime Continent, which correlates to consistently warmer than average conditions. This past month has seen a lot of ups and downs, but most areas are above average for the month as a whole. This was in part due to a +AAM and some blocking episodes at times that kept the variability in place.

The Southern Oscillation Index (SOI) remains in negative territory, which combined with the MJO phases would normally suggest a cooler than average period. But with an expected +EPO pattern developing, this will mitigate the cooler risks and we should predominantly remain on the warmer side of average as a result. Nothing outstanding, but warmer than average temperatures nevertheless. Once we reach May, the +EPO will likely continue, and a drop in the AAM to negative values will also support the warmer than average temperatures, and both the Euro weeklies and Euro monthlies are suggesting that as well. The warmer May temperatures coincides with our privately shared (premium forum) Spring Outlook and leading analogs chosen for the projection.

The April temperature outlook we continue to project will be an above average month (+3.0°F to +6.0°F) as a whole by month’s end, and the majority of the region is currently above average in the temperature department by several degrees. Using a blend of leading analogs from our privately shared Spring Outlook and extended range climate and ensemble guidance, the month of May early projections are for an above average temperature month (+3.0°F to +6.0°F) by months end.

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

The ensemble guidance shows that after the cut-off upper level low moves out on Monday, a very warm surge of temperatures follow on Tuesday, which is pictured. This is all ahead of a cold front which arrives on Tuesday night.

gefs2

The ensembles also agree that after the front moves through, we see temperatures drop back for two days, April 24-25th with near to slightly above average days and temps in the 60s. This will be transient however, and short-lived.

gefs3

Next 3 weeks of US temperature departures

Images below are clickable for better viewing

Days 1-5 – confidence VERY HIGH

1-5

Days 6-10 – confidence HIGH

6-10

Days 11-15 – confidence MODERATELY HIGH

11-15

Days 16-20 – confidence MODERATE

16-20

Current U.S. Soil Moisture Anomaly

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.

My Pocket Meteorologist

The My Pocket Meteorologist text alert program is a year-round program, and seasonal options for Spring/Summer will be available soon. Click on the image below for more information.

mpm3

Forecaster: EPAWA Meteorologist Bobby Martrich
Discussion last updated: Friday April 19th, 11:35am