Trough axis settles in for several days;
cooler than average through midweek Join the Discussion!

*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 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:

We head back into a more unsettled pattern for this first week, with several fronts bringing the chances for scattered showers and thunderstorms. Although no washout is expected on any day, and convection chances mainly occur in the afternoon and evening on any given day, chances for precipitation exists on 4 of the next 7 days. A warm front is advancing toward the region on Friday at the time this outlook was drafted, and will remain in the vicinity on Saturday 6/17, close enough to produce scattered thunderstorms nearest the boundary. Most of Sunday looks dry, although an isolated t-storm threat still exists.

A more concentrated area of showers and thunderstorms are likely on Monday with the advent of a strong cold front. The NWS/Storm Prediction Center has already highlighted the severe threat in our region for Monday afternoon and evening, and we agree with the assessment. Expectations are that the cold front will be aided by the right entrance region of the jet near our area on Monday, and ample instability, lift, and shear are forecast, in addition to high dewpoints ahead of the front. We will handle any severe threat on a short term basis as we get closer to the potential event.

A trailing shortwave will drag a cold front through the region on Wednesday, with scattered showers and perhaps a thunderstorm possible with the front, mainly during the daylight hours. Another warm front could bring more showers/thunderstorms to the region next Thursday night and/or Friday.

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

June 17th-June 23rd: Slightly above normal

June 24th-June 30th: Near normal

July 1st-July 7th: Slightly below normal

July 8th-July 15th: Slightly above normal

All public/freely available maps will be updated when the threat is imminent for severe weather on the weather alerts page throughout the Spring and Summer: http://epawaweather.com/weather-alerts/

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

The GFS shows with a warm front still in the vicinity on Saturday the opportunity for scattered showers and thunderstorms, mainly in the afternoon and early evening hours, but relatively disorganized and scattered over parts of the region.

A strong cold front on Monday as shown by the GFS will be accompanied by scattered showers and thunderstorms, and carries with it the potential for severe t-storms. Primary threat is for damaging winds greater than 60mph in linear segments.

Pattern:

A recent heat wave has effectively turned around the cooler start in the first week of June and below normal temperature departures, to near to slightly above normal temperature departures month to date across the region. Latest observations show most climo locations at between +0.0°F and +1.0°F through the 15th. We have leveled off and backed off some in the extremes, and aside from the occasional transient spike in temperatures in between troughs, most of the rest of the month should average near to slightly above average, making June average slightly above average as a whole.

The persistent negative Southern Oscillation Index (SOI) this month has led to a continuation of troughs invading the northern parts of the country from time to time. This pattern will likely continue for awhile, but the troughs are more effective to our north and northwest, with below average anomalies found in the upper Midwest, Great Lakes, and New England. In our area, the trough does not have as much influence, but will keep temperatures near average on several occasions, the first between the 20th and 22nd of next week. The 2nd trough could affect the region toward the end of the month, generally speaking between the 25th and 30th.

The early outlook for 4th of July weekend shows temperatures returning to slightly above average levels, and right now looks for that first week of July to look on the drier side. That doesn’t mean that weekend will be necessarily rain-free, and we’ll address the holiday weekend a little more closely with next week’s update. July as a whole looks to end up above average, however, as a dip in the AAM to low negative values and a La Niña atmospheric base state should promote the typical summer warmth with the summer anticyclone getting established.

June as a whole we think averages slightly above average (+0.5°F to +1.5°F) when the dust settles June 30th, with high confidence.

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

The GEFS (GFS ensemble) shows a trough moving into the upper Plains and Great Lakes region, but our area will be on the outer periphery of this trough, so only near average temperatures are expected, and not below average next week.

GEFS shows another trough to end the month between the 25th and 30th time frame, but again, not only is the trough itself not as effective, the core of the cooler anomalies remain N&W of the region, and near average temps are expected here.

EPAWA 1-5 day temperature departure outlook

EPAWA 6-10 day temperature departure outlook

EPAWA 11-15 day temperature departure outlook

EPAWA 16-20 day temperature departure outlook

Below is a look at the latest soil moisture anomaly, which is an integral part of drought outlooks. Reds and oranges represent below normal soil moisture levels, greens represent above normal values.

This image will automatically update daily.

The My Pocket Meteorologist text alert program gearing up for the upcoming severe season. Seasonal options will be available beginning March 31st. Click on the image below for more information.

Forecaster: EPAWA Meteorologist Bobby Martrich
Discussion last updated:  Friday June 16th, 10:30am