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 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 Discussion

OVERVIEW: Most areas within our region are generally 2-3 inches above average month to date, thanks in large part to receiving nearly a month's worth of rainfall in just the first 4 days of April in a multi-day anomalous event. Going forward from this point, there will still rain at times, but these will generally be fast-moving systems and fronts that are rather "usual" and expected occurrences. Overall, while there will be some drier periods at different points of the remainder of April, the precipitation departure is still expected to remain above average (+1.0" to +2.0") for the month as a whole, largely due to the very wet start and the multi-day system that affected the region early in April. The month of May was maintained this week for a near to slightly above average (+0.0" to +1.0") precipitation departure with a zonal flow leading to more fast-moving systems and less in the way of extreme events like seen in early April. The presence of thunderstorms can skew monthly projections of rainfall on a hyper-local basis, and it is important to understand that the projections heading into storm season are a composite average based on synoptic events, not mesoscale-based activity. 

Shorter term, we have a system moving through the region today culminating with a cold front passage around noon or shortly thereafter. Any trailing precipitation with the upper level trough should be light through early Saturday after the front clears. The next fast-moving system will propagate through Sunday afternoon and early evening, and will feature a line of scattered showers and thunderstorms with a weak cold front associated with low pressure passing across NY State. It quickly clears out Sunday night, then a couple of dry/warm days follow early next week. A warm front approaches Tuesday night with a few showers, then the trailing cold front moves through Wednesday afternoon and evening. This doesn't appear to be an impactful system as the best forcing will be found much farther to the north. A more organized and stronger cold front on the lead of a trough will cross Friday afternoon and evening with scattered showers and thunderstorms. There could be stronger storms associated with this front, but it will come timing dependent and better known throughout the week. Temperatures ahead of the front will be in the 70s, and 50s are expected in its wake. 

Our projection for the month of April as a whole was maintained this week for an above average (+1.0" to +2.0") precipitation departure along with below average snowfall…or for most areas, none at all. This has likely already occurred in northern areas that saw minor snow earlier in the month, and is not as likely for the remainder of April outside of elevations. The month of May projections were maintained this week for near to slightly above average (+0.0" to +1.0") precipitation departure for the month as a whole.

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

April 13th – April 19th: Near to slightly above average

April 20th – April 26th: Slightly below average

April 27th – May 3rd: Near to slightly above average

May 4th – May 11th: Near average

May 12th – May 18th: Near to slightly above average

May 19th – May 25th: 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 system passing north of the region Sunday will drag a weak cold front through the area that may bring a line of scattered showers and thunderstorms Sunday afternoon and evening
A series of fronts move quickly through mid to late week, with a warm front Tuesday night followed by a cold front Wednesday afternoon; a stronger cold front follows Friday afternoon or evening

Pattern Discussion

OVERVIEW: A chilly start to the month over much of the first 6 days has been offset since with milder temperatures over the past few days. We expect a chilly day Saturday with windy conditions in the wake of today's cold front, then a remarkable turnaround to much milder temperatures on Sunday. The entire work week next week we expect above average temperatures to continue with highs in the 70s throughout. This will send temperatures to above average levels month-to-date through this time next week, but is likely to be offset by a cooler pattern that dominates the remainder of April. We project this to arrive next weekend in the wake of Friday's cold front and will be most notable in the 20th-23rd period before moderating closer to average to close out April. The projection for the month of April as a whole is for a near average (-1.0°F to +1.0°F) temperature departure, with the expectation that milder periods next week will be offset with the cooler end to the month. Our projections for the month of May was adjusted this week to a near to slightly below average (0.0°F to -2.0°F) temperature departure for the month as a whole, but this will be relative to seasonal average at that time, and not cold by any means. See the average highs and lows chart below which provides some transparency of what average temperatures are for our major climate sites throughout the region going forward over the next 6 weeks.

The Madden-Julian Oscillation (MJO) is currently in the Circle of Death. and is expected to remain there through at least the middle of May. This means that tropical forcing in the equatorial Pacific will have little effect on the overall pattern, and other teleconnections run the pattern instead. In the case of this month, we'll still see an amplified pattern across the US and Canada that will lead to warmth this upcoming week beginning on Sunday, then a sharp drop in temperatures beginning next Saturday, lasting for several days as a trough settles into the region. After that point, and through much of May, the pattern is relatively zonal, which means temperatures shouldn't stray too far from average, and less in the way of extremes above or below average. The pattern does lean very slightly cooler than average overall, but this will be relative to average highs and lows at the time. Average highs for most areas are getting into the 70s in May, so even though it may be slightly cooler than average, it certainly won't be cold. The zonal flow will also mean less-amplified systems and faster-moving, but frequency of fronts and events are generally higher. 

Average high temperatures are currently in the 60-64°F range from north to south across our coverage region, which is about 3 degrees higher than at this time last week. Temperatures will continue to climb and maintains a 3°F increase per week in April, then slows that climb slightly May to about a 2°F per week increase. 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 for the April 20th-23rd period generally features highs in the mid to upper 50s across the region, coming at a time when average highs are in the middle to upper 60s. 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.

Our projection for the month of April was maintained this week for a near average (-1.0­°F to +1.0°F) temperature departure. We are generally near average to this point of the month, and the expectation of a mild week between the 14th and 19th will be offset by cooler than average temperatures immediately following beginning next weekend, then leaning on the cooler side of average for the remainder of April. The month of May was adjusted this week for a near to slightly below average (0.0°F to -2.0°F) temperature departure expectation, using longer term climate guidance and global observation trends. Despite leaning to the cooler side of average, it will be relatively close to normal temperate conditions expected in May.

Note:  Any image below is clickable for larger viewing`

A warm week is expected for much of the work week next week (beginning Sunday) then a trough arrives next weekend that switches above average temps to below average fairly abruptly
Average temperatures over the next 6 weeks are shown below at our major climate sites throughout the region, with a steady increase of average temperatures as we move through Spring

Long Range Outlook Table

 

Date(s)ThreatsSignificanceConfidence
4/13TemperatureSlightly  below to below averageVery high
4/14-4/19Temperature Above average High
4/20-4/23TemperatureSlightly below to below averageModerately high
4/24-4/25TemperatureSlightly below averageModerately high
4/26-4/30TemperatureNear to slightly below averageModerate

5/1-5/7
TemperatureNear to slightly below averageModerate
5/8-5/14TemperatureNear to slightly below averageModerately low
5/15-5/21TemperatureNear averageLow
5/22-5/28TemperatureNear to slightly below averageVery low
4/14Showers/storms

A fast-moving shortwave moving north of the region drags a cold front across the area Sunday afternoon and evening. A line of scattered showers/storms are possible at that time.

Moderately high
4/17Warm and cold frontsA warm front will approach the region Tuesday night with scattered showers, then is quickly followed by more showers in association with the trailing cold front Wednesday PM and evening.Moderate
4/19Cold frontA stronger cold front will cross the region Friday afternoon and evening with scattered showers and thunderstorms. There may be some stronger storm potential with this front, but timing of the front will dictate.Moderate
April as a wholeTemperatureNear average (-1.0°F to +1.0°F)Moderately high
April as a wholePrecipitationAbove average (+1.0" to +2.0")Moderately high
April as a wholeSnowfallBelow average or noneVery high
May as a wholeTemperatureNear to slightly below average (0.0°F to -2.0°F)Moderate
May as a wholePrecipitationNear to slightly above average (+0.0" to +1.0)Moderate

Outlook table last updated: Friday April 12th, 11:30 AM. Next scheduled public update: Friday April 19th.

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/ 

Climatology

*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/Lo (°F)Current EPAWA projection
April 13th64°F/43°FSlightly below to below average
April 20th67°F/46°FSlightly below to below average
April 27th69°F/48°FNear to slightly below average
May 4th71°F/51°FNear to slightly below average
May 11th73°F/53°FNear to slightly below average
May 18th75°F/55°FNear average
May 25th77°F/57°FNear to slightly below 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.

Climate Prediction Center (CPC) Graphical Products

These products are from the NOAA Climate Prediction Center (CPC) and do not necessarily reflect the EPAWA forecast which is detailed above. All images below update automatically as the CPC releases new graphical products

CPC 6-10 day temperature outlook
CPC 6-10 day precipitation outlook
CPC 8-14 day temperature outlook
CPC 8-14 day precipitation outlook
CPC weeks 3-4 temperature outlook
CPC weeks 3-4 precipitation outlook
CPC next 3 months temperature outlook
CPC next 3 months precipitation outlook

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.

US drought monitor (NE US)

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Forecaster: EPAWA Meteorologist Bobby Martrich
Discussion last updated: Friday April 12th, 11:30 AM