Friday, June 29, 2012

June 29, 2012 Severe Thunderstorm Clouds

Copyright Vortex Weather Phoography

A Week of the Same Heat, Storms On The Way

The image shown below is the forecast at the 500mb level off the NCEP ensembles. Typically, as we have seen today, thunderstorms are inclined to form along the rim of such summer high pressure systems. This continuous thunderstorm threat makes for the nickname of the 'Ring of Fire', for the intense storms that can move along the rim of the high pressure ridge.
If we see this dome of heat keep sitting over the area, the next 7 days could very well be more of what we saw today with storms in the Midwest, Ohio Valley, and Northern Plains.
Now, a few days after the image below, a storm system looks to push south and move the high pressure system west. However, the NCEP ensembles appear torn on that idea, which means it may never happen and the ridge just keeps in place.
This may be just as bad, as the Colorado fires could be helped or harmed by either storms along the rim of the ridge of high pressure, or the heat and sun from being inside the ridge.


Derecho Moving Through Ohio Valley; Moderate Risk Issued

Damaging Wind Probability
A moderate risk of severe weather has been issued by the Storm Prediction Center as a derecho moves through the Ohio Valley towards the Mid Atlantic. This is the same complex that gave me such pictures that I have posted on the Facebook pictures.

Radar imagery suggests these storms are very powerful, with intense gust fronts being shot out very fast. Severe thunderstorm warnings indicate violent winds of 80 MPH are expected.
Anyone in the moderate risk should immediately prepare for potentially life-threatening wind damage.


Triple Threat for Severe Weather Tomorrow

There are three areas of severe weather potential tomorrow across the eastern US. The largest risk area involves the Ohio Valley and Mid Atlantic into a portion of the Northeast. The other two risk areas are stationed in the Northern Plains.

At this time, the most risk appears to be placed in the Mid Atlantic-Ohio Valley risk outline as a frontal boundary initiates convective development for that area.
More on this risk later today and tomorrow.


Elongated Severe Weather Risk Cuts Through Nation's Midsection Today

The Storm Prediction Center has outlined an elongated region of severe weather potential across the Mid Atlantic into the Ohio Valley, back up through the lower Great Lakes and Northern Plains.

A sagging cold front will nearly stall out across these regions today, prompting the potential for storms at any given time of the day. 12z soundings from across the severe weather potential area show vast areas of instability, with over 7000 j/kg of CAPE located in the most unstable part of the lowest 700mb of the atmosphere. Today, the most unstable part of the lower 700mb is roughly in the 900mb level, which is very close to the surface, indicating that storms that fire could have a lot of energy right off the bat.
I am not going to use the RAP for today's forecast because it has severely underestimated CAPE values for 12z in its soundings forecasts. However, the HRRR model does fire a mesoscale convective system (MCS) around 1:00 PM CDT and shifts it south and east into the night as it works across the severe weather potential area delineated above by the SPC.

As for what the SPC put out, it appears the main threats are damaging wind and hail, and the center of those threats should be in northern Indiana and Ohio.


Colorado Wildfire Forecasts: June 29, 2012

Flagstaff Wildfire near Boulder, CO

High: 96
Wind: North between 3-11 MPH, gusts as high as 16 MPH.
Humidity: 14%
Dewpoint: 36
Precipitation Potential: 10%

High Park Wildfire near Fort Collins, CO

High: 97
Wind: Calm becoming south at 7-10 MPH. Gusts as high as 16 MPH.
Humidity: 15%
Dewpoint: 38
Precipitation Potential: 10%