Thursday, 11:45 a.m.
The blossoming of an upper-level ridge in the West has sent temperatures to their highest levels so far on 2014 in much of California, Oregon and Washington. How warm? Here's the maximum temperature chart from Wednesday:
Contrast that to how chilly it was from the eastern Rockies and Plains to the Mississippi Valley, with temperatures 10 or more degrees below normal in most locations. It was no higher than the 60s all the way down into North Texas, and only in the 50s over the eastern Rockies and central Plains, with 40s throughout the Midwest.
The western ridge is strong today and holds on into tomorrow. Here's the 12z May 1 NAM 500mb forecast for tomorrow morning:
That means another day of very warm weather in most of the region, as born out in the 6z May 1 GFS ensemble 2-meter temperature anomaly forecast for tomorrow:
This warmth will finally spread across the Rockies tomorrow afternoon, then out onto the Plains this weekend. The upper-level ridge won't be as sharp as it is now, but it will be plenty strong enough to pull some of the warmth out of the West and onto the Plains. Look at the ensemble forecast of 500mb heights and anomalies for Sunday afternoon:
How warm? Look at the operational European forecast of 2-meter maximum temperatures Sunday afternoon and evening:
Yes, that is a 100-degree contour along the Kansas-Oklahoma state line! 90s seem all but certain in parts of Kansas, Oklahoma and north Texas by Sunday afternoon, and a few places might get there as early as Saturday afternoon.
The question then becomes how fast will the warmth (heat) spread farther downstream. Well, with the flow aloft still from the west-northwest east of the Mississippi through the first part of next week, the warmth will be held out of the Midwest, the Great Lakes, the mid-Atlantic states and New England. It will try to sneak into the Ohio Valley Wednesday afternoon, but how far it succeeds will be determined by any disturbance embedded within that west-northwest flow aloft. And the models are not at all in agreement with these relatively small features! The GFS wants to spread the warmth quickly east and northeast, reaching the Ohio Valley Wednesday afternoon, expanding and strengthening there on Thursday while also expanding into the mid-Atlantic region, then reaching a peak in these areas next Friday before fading over the weekend. The European, on the other hand, still keeps a relative trough in place over the Northeast, keeping the frontal boundary between the cool, dry air there and the warmth over the Ohio and Tennessee valleys at bay through Friday. Obviously, one of these two ideas is not going to work!
However, the main message is that it WILL get warm in the Ohio Valley during the second half of next week as the 80s get to and beyond the Ohio River for at least two days. There may be some readings close to 90 in parts of Tennessee. It will eventually warm into the 80s in the mid-Atlantic, but it may wait until Friday, even Saturday in some areas. That's starting to sound a lot more like summer all of a sudden!
Another thing to eventually watch out for is an outbreak of severe weather late next week with the next cold front. This time there will be even more warmth and humidity available ahead of the front, so it could be every bit as volatile as what we just came through the past few days.
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