Posts

Premium: Intricate phase will determine magnitude of coastal storm

The details of a phase between a mid level disturbance over the Ohio Valley, one with surprising vigor, and a second disturbance dropping southward from Southeast Canada into the Northeast, will have significant impacts on the eventual evolution of a coastal storm system this weekend. The atmospheric evolution in the mid and upper levels is actually quite complex, and reminiscent of some of the storm systems that impact our area in the winter season.

The pattern actually begins becoming amplified and energetic today (Friday), as a large trough in the Western United States amplifies. This will force a large ridge axis to build to its east, over the Central Plains states. This ridge drives northward, amplifying into Central Canada. This sets the stage for a large and amplifying trough over the Eastern United States this weekend.

Read more

Coastal storm may bring heavy rain, wind on Saturday

Amazingly, we’re still talking about coastal storms during the middle weeks of May. A period long discussed as one that may favor a cutoff low or coastal storm seems to be coming to fruition, as forecast models have keyed in on a potential storm this weekend. Energy over the Ohio Valley will move eastward toward the Mid Atlantic, as additional shortwave energy drops southeastward from Canada toward the Mid Atlantic as well.

The resulting interaction will result in the development of a coastal storm, with a low pressure at the surface moving eastward towards the Mid Atlantic coast. But the exact track and intensity of the storm system will depend on the evolution in the mid and upper levels of the atmosphere. As the two pieces of energy interact and potentially phase, the surface low pressure will deepen — resulting in areas of heavy rain and strong winds developing to the north and northwest of the low pressure center.

Read more

Premium: Another ULL next week, warm temperatures follow

It’s May 11th, which means it’s getting in the late meteorological Spring season. Many of us often look forward to even warmer weather as we approach Memorial Day weekend and the beginning of meteorological summer. But the seasonal trends with blocking causing cool air intrusions are continuing over the last couple weeks, with omega blocking becoming a dominant presence. Now some high-latitude blocking is returning again for another cooler week of weather. But how cool will it actually be? And when will warmer weather return? We discuss more details on the overall pattern evolution for the rest of this month.

We start with a -EPO blocking ridge over Alaska. Shortwave energy coming downstream of this ridge will phase into a closed upper-level low over the Great Lakes later this week. Initially, this will cause heights to build over the Northeast. At the surface, high pressure will build over the Western Atlantic. More southerly flow around this high pressure will cause temperatures to rise near or slightly above normal for this coming Wednesday and Thursday.

Read more

Premium: Warmer than normal temperatures by late May

The news many have awaited for several weeks is finally here: We are forecasting the return of above average temperatures by the end of May. For the past few weeks, the hemispheric pattern has been stuck in a bit of a rut. High latitude blocking has maintained its control over the pattern, on both the Pacific and the Atlantic sides, forcing the development of anomalous cutoff lows and troughs into the Northern 1/3 of the United States. Colder than normal air with unsettled weather has been the dominant sensible weather in our area.

The transition out of this pattern is already underway. While high latitude blocking on the Pacific side (a -EPO) will again flex its muscles late this week, it will be more of a parting shot than anything else. An upper level low will form, as a response to the -EPO ridging, and push into the Great Lakes. But its presence will be mainly progressive, as a front swings through our area and the upper level trough elongates and moves to our northeast.

Read more