Saturday, June 22, 2019

June 30 - July 4 Potential Storm System

A potential storm system looks to impact the United States in the June 30th through July 4th timeframe.

MSLP and precipitation forecast for 1 AM Central Time, June 24.
Source: Tropical Tidbits
Model guidance sees a storm system moving northeastward parallel to the coast of Japan on June 23rd and 24th, as depicted in the image above. Upper-level flow indicates this system will be the finale for broadly stormy weather seen over the East Asian region as of late, and it is plausible that this will be the case in the United States as well.

Regular readers of this blog in the past will know that I frequently use a teleconnection whereby weather phenomena occurring over and near Japan correlate to similar phenomena in North America roughly 6-10 days later. I am employing this again here, and extrapolating the above model graphic gives us a potential storm system occurring in the United States in the June 30 - July 4 period.

Forecasted 500-millibar geopotential height anomalies for 7PM Central Time, July 1st.
Source: Tropical Tidbits
Ensemble guidance suggests ridging will become a predominant theme over the western two-thirds of the country as an upper-level low nudges its way on over Greenland to promote +NAO conditions (which bring about more zonal upper-level flow over North America), and troughing in the Gulf of Alaska supports a modest ridge in western Canada. The consequence looks to be lower heights evolving over the waters just offshore of the Eastern Seaboard, and it seems plausible that any storm system that comes about during this timeframe will be encouraged to traverse the South (or the nation's midsection) on a rather-zonal path before being drawn northeast as it approaches the Mid-Atlantic, with the storm seeking the path of least resistance towards those lower geopotential heights. Coming days will provide for more accurate forecasts as the potential storm approaches, of course, but at this time it appears as though any potential storm system in the June 30 - July 4 period will most likely impact the South and East U.S., as opposed to a storm track that takes in northeast across the Plains like we saw last month into early June.

To Summarize:

- There is potential for a storm system to impact the United States in the June 30 - July 4 period.
- Based on the projected atmospheric flow, any storm that does develop would be most inclined to move west-to-east across the South before perhaps trying to shift a bit northeast near the Eastern Seaboard.
- As always, considerable uncertainty exists, especially with regards to the projected track of any storm system.