* Seasonable Week - Unsettled Weekend? *

11:00am Monday, April 21:
The week ahead will be rather typical for mid-April with a little bit of everything in store for us, including...patchy frost (this morning and Thursday morning), a gorgeous "perfect 10" day (today), a few April showers (Tuesday midday and maybe Friday morning), a blustery and unseasonably chilly day (Wednesday), and an unseasonably mild afternoon with highs in the 70s (Friday). There you have it--that's your 5-day forecast!

The weekend, however, is more complex and difficult to nail down as the long-wave jet stream pattern is showing mixed messages. On the continental scale, it looks like a deep trough will form and perhaps close off and linger over the southern Rockies next weekend into early next week--such a feature favors warm, dry conditions for much of the eastern US, while the west would be more unstable with Spring snows in some of the mountains (CA, UT, CO, NM, WY). The monkey wrench in the above scenario is a northern branch trough digging into the Great Lakes Friday into Saturday, which will bring a cold front with a chance of showers into the Northeast on Saturday. Some models show this upper trough cutting off over New England on Sunday...and while this is always a possibility in Spring, I'm not viewing it as a for-sure. Consequently, next weekend could break either way in terms of rain--either showers Saturday and a breezy, partly sunny and cool Sunday....or showers Saturday given way to a windy, cold and unstable Sunday with scattered showers (or a period of rain) and perhaps even mountain snow showers (high peaks of PA, NY, and New England). This situation will become more clear later in the week, so check back for an update on Wednesday or Thursday.

11:00am Thursday, April 17:
The first 15 days of April averaged 3 degrees above normal--the first above-average two-week period since the latter part of December. Of course, Tuesday's sharp cold front ushered in a brief shot of unseasonably cold air...and a light Onion Snow Tuesday night in parts of southern and eastern LanCo. Wednesday's high temps struggled to reach the mid 40s--a remarkably chilly day considering that the current sun angle is the same as late August! Fortunately, a rather zonal jet stream pattern means that any cold shot will be short lived. Consequently, a moderating trend begins today and it will lead to a return of mild conditions in the coming days. In general, I expect the second half of April will continue in a similar fashion to the first half of the month with mild days outnumbering cold days.

Looking ahead to the weekend, high pressure now over New England will slowly retreat off the coast. Daily high temps should increase a few degrees day over day, and thus be back to normal levels (low to mid 60s) for the weekend. The only slight flies in the ointment are weak easterly flow that may result in some morning clouds on Friday and/or Saturday and a weak upper-level disturbance passing through with some clouds Friday night. Otherwise, it looks like a decent weekend with dry conditions, cool mornings, and mild afternoons.

A Pacific disturbance passing nearby next Tuesday will bring the next threat of showers. While a chilly north wind may develop behind this system, I do NOT expect a cold shot of the same caliber as this week's. Zonal flow will then quickly turn flow out of the southwest, and so we have a good chance of temps returning to the 70s for a day or two later next week. Overall, it looks like an uncommonly nice pattern for April with a relative lack of April Showers.

Issued: 4-21-14 (Hörst)