Series of troughs settle into the area
this week, keeping temps a bit cooler 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.

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Precipitation:

The period starts off unsettled with a warm front pressing back northward and settling over our region from late Saturday through Sunday. Scattered showers and thunderstorms will be present late Saturday and Saturday night, and again Sunday afternoon and evening due to the close proximity of this boundary to our region. Precipitation will still be possible overnight Sunday night until a trailing cold front ushers out the heat/humidity and unsettled weather Monday morning from west to east. Behind the front, a strong trough settles in for several days, leading to near to slightly below average temperatures, and comfortable/lower humidity for a few days.

A reinforcing cold front on the lead of a secondary trough will arrive Thursday with more scattered showers and thunderstorms possible. This front will reinforce the existing cooler temperature/low humidity environment heading into next weekend.

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

July 22nd-July 28th:  Slightly above average

July 28th-August 3rd:  Slightly below average

August 4th-August 10th:  Slightly below average

August 11th-August 17th: Near to slightly below average

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

The GFS shows a warm front approaching later Saturday, with partly cloudy skies to start, becoming mostly cloudy in the afternoon, and then scat’d showers/storms arrive toward evening and last through the night and again on Sunday as the front stalls over the region.

A reinforcing cold front will arrive on Thursday with more scattered showers and thunderstorms preceding the cold front. This will act to reinforce the already near to slightly below average airmass as we head into next weekend as the front clears by Friday morning.

Pattern:

The pattern starts off unsettled with the northern periphery of a “ring of fire” pattern taking shape over our region this weekend. This will be in response to strong ridging setting up in the southern Plains and western Tennessee Valley, and will force a cold front stalled south of the region back northward as a warm front over the weekend. As this ridge expands, it will be transient and be forced to shift westward as a deep trough settles into the Great Lakes, Northeast, and parts of the Mid-Atlantic next week.

The trough will also be transient, and briefly kick out on Thursday as another front approaches, but will have another reinforcing trough behind it keeping it slightly cooler than average through next weekend.

Moderation in temperatures are expected the following week but still will cooler risks toward the end of the first week of August that will likely keep temperatures that week near to slightly above average as a whole. This will likely be in response to a quick eastward progression of the Madden-Julian Oscillation (MJO), combined with another expected rapid drop in the  Southern Oscillation index (SOI).

The latest ECMWF weeklies highlight the 2nd week of August as a cooler than average period in response to that eastward propagation of the MJO and expected negative SOI values, and then it recovers week 3 with a warm look to nearly the entire CONUS for the 3rd week of August.

July as a whole we think averages above average (+1.5°F to +3.0°F) when the dust settles July 31st, with moderately high confidence, and for now we have backed off of August expectations in temperature resultant of the expected near/slightly below average periods in the first half of the month. Still, we expect August to average as a whole slightly above (+0.5°F to +2.0°F) average, and will adjust as needed in future updates.

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

The GEFS (GFS ensemble) shows strong ridging shifting westward and a reinforcing trough moving in for next weekend behind the first trough that exits just prior. This leads to a near to slightly below average stretch between Tuesday and Sunday of next week. 

The same GEFS suggests that next week the pattern relaxes, and as ridging continues to consolidate in the western US, the trough is rendered weaker and farther north. This results in slightly above average temperatures returning for much of the 1st week of August.

Above images courtesy TrueWeather models, which can be found as a subscription service at https://truewx.com/weather-models/

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.

Images below are clickable for better viewing

Days 1-5:

Days 6-10:

Days 11-15:

Days 16-20:

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 July 21st, 12:45pm