Tuesday, 11:30 A.M.
Sometimes it is not easy coming up with a "catchy" phrase for these daily posts, and I readily admit my creative synapses are not firing on all cylinders with this one! The idea I'm trying to convey in a brief nugget is that those areas of the country that have been wet in recent weeks are going to stay wet, while those parched for rain will see very little to none of it in the coming days. The pattern is such that with an upper-level ridge building over the Four Corners area and another in place off the East Coast, there will be a weakness between the two that will set up two areas of excessive moisture in the next week or so, while those underneath the upper-level ridge will be every bit as dry.
To illustrate, let's examine the most crop moisture index:
Note the areas across the Dakotas into the Midwest that are plenty wet, as well as the area from eastern New York and central and southern New England southward across the mid-Atlantic states into parts of the Southeast. Recall that this image is through the week ending June 22, so any rains over the past couple of days have not been included in these figures. In the East, there were scattered strong thunderstorms around yesterday afternoon and last evening, while across parts of the Midwest, particular in Iowa, some places picked up more than two inches of rain.
Unfortunately, this latter area is still in line to get pounced on by strong to severe thunderstorms in the next 36 hours. Here's the 12z 25 June NAM model total precipitation forecast from this morning through tomorrow evening:
Not TOO bad across the Dakotas into Minnesota and Wisconsin, but from eastern Iowa into the Ohio Valley and lower Lakes, the repeated nature of thunderstorms will lead to areas of flash flooding. And that does not take into account what occurs tomorrow night and Thursday! As the upper-level trough swings through the Great Lakes and Ohio Valley, it will generate more thunderstorms with excessive rains. A look at the same chart through Friday evening:
While this should not be taken as pure gospel, it should provide a good indication that there is a LOT of rain coming through the Ohio Valley into parts of the Northeast in the next three days!
And that's just as the front gets to the Eastern Seaboard. As pointed out in Monday's post, the following pattern set up is on tap for the weekend into next week:
With the trough axis WEST of the Appalachians, the upper-level flow will be from the southwest along the Eastern Seaboard, and with the upper-level ridge not budging off the East Coast, a corridor of moisture will be established from the tropics right through the Southeast on up into New England. That will keep the humidity high, and allow for multiple showers and thunderstorms over areas that are all but waterlogged from excessive rains so far this month.
Then, of course, there is the other side of that equation. If you refer back to the first graphic, you'll not the dry to excessively dry conditions prevailing from Texas to Colorado and Wyoming back to California. Now look at the GFS ensemble image above, and notice the strength of the ridge. It will lead to a lot of heat over the Rockies and interior west late this week and into the weekend, if not longer, with little in the way of rain. There may be a few token thunderstorms over central and eastern Colorado as early as Friday afternoon, and perhaps next week if an upper-level disturbance coming down through the Plains can have an impact that far west. Aside from that, though, it is going to be pretty dry for some time to come.
A building upper-level ridge of high pressure in the West will promote hot, dry weather in the Northwest, while a downstream trough brings cooling through the Midwest into the Great Lakes and Ohio Valley.
A pattern more typical of late July and early August is shaping up around the country, one with heat and humidity, but with fewer incidents of severe thunderstorms and flooding.
There will be plenty of heat and humidity from the southern Plains to the East Coast this week while much cooler air prevails for a time over the Northwest to the northern Plains.
Severe thunderstorms raked across the Midwest and Ohio Valley in the past 24 hours, with more on the way this afternoon. The pattern will repeat itself over the next week.