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9/10/10 ~ Disorganized area of Low Pressure in the GOM


UPDATE: September 11, 2010:  The shower and thunderstorms around this area of low pressure have increased in coverage and intensity the last 12 hours.  The SST and lack of shear in the area should allow this area of low pressure to continue to develop and reach tropical cyclone status within the next 24 to 36 hours.  The movement is a bit uncertain, but looking at yesterday and today’s visible satellite images, it appears to be moving to the west into the western Caribbean Sea.

Old Discussion:
An area of low pressure and disorganized shower and thunderstorm activity has sprung up in the eastern Gulf of Mexico near the Windward Islands.  The National Hurricane Center has a 50% chance of this area of low pressure area organizing into a tropical cyclone within the next 48 hours.  More updates as this system evolves.

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FCST: 9/10/10 MO/KS

I  have not had a chance to focus on the severe potential for today due to personal and work obligations the last 48 hours.  Thought I would throw up some quick thoughts on the severe potential today and best target area if I were to be chasing.

Target Area: Emporia, KS

Discussion:
A complex forecast is unfolding today as a developing area of surface low pressure is forming in NE KS.  An associated warm front is draped over west central MO back into the MO bootheel at the noon hour.  A cold front runs through the central portion of KS back into OK.  This potent late season storm system that will provide the foci for strong to severe thunderstorms late this afternoon and evening.

The warm front is surging northward and developing a small warm sector this afternoon where temperatures have risen into the 80’s and dewpoints have climbed into the upper 60’s to low 70’s.  Strong to severe thunderstorms should be on-going by 5 p.m. this evening to the southwest of the KC metro area on the Kansas side.  The area along the the warm front and northeast of the low pressure center will be the area with highest tornado potential.  Needless to say surface and satellite observations are going to be key for tornadogenesis today and bagging a late season tornado!

Good luck and safe wishes to my chase partner Steve Polley and the other storm chasers as they get a last of the season chase in!

Summary:

Local Storm Report Data:

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Tropical Storm Igor ~ Eastern Atlantic

UPDATE: September 11, 2010:

Tropical Storm IGOR is located at 17.4N and 39.5W, about 1030 miles west of the Cape Verde Islands and 1470 miles east of the Leeward Islands, and is expected to be a Categor 1 Hurricane by this evening.  The maximum sustained winds are 70mph with higher gusts.  Tropical Storm force winds extend outward 115 miles from the center.  Igor is moving to the west at 20mph and forward propagation is forecast to increase.  The minimum central pressure is 995mb (29.38 inches).

This storm is forecasted to be a major hurricane by mid-week.  At this time, it does not appear Igor will have an affect on the US mainland.  The area of clouds off the east coast as well as over the central CONUS depcit troughs which will affect the track of Igor.  Current thinking is Igor will turn to the north/northeast well before being a major impact on the east coast of the US.

OLD DISCUSSION:
Tropical Storm Igor has formed in the eastern Atlantic and is showing signs of strengthening.  Currently Igor is located at 13.7N and 23.5W and about 95 miles south of the southernmost Cape Verde Islands in the far eastern Atlantic Ocean.  Igor is moving to the west at 8 mph and this course is forecasted to remain steadfast the next 48 hours with some slight increase in forward propagation.  The maximum sustained winds are currently 40mph with Tropical Storm force winds extending outward 50 miles from the center.  The minimum central pressure is 1005mb (29.68 inches of mercury),  with forecasted strengthening over the next few days.

Here is a look at the most recent forecasted track from the National Hurricane Center for Igor:

Here is the latest satellite imagery of Igor:

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Four Mile Canyon Fire ~ Boulder County, CO


UPDATE: September 10, 2010:

The Four Mile Canyon Fire continues to burn and currently involves 6,422 acres and is only 30% contained as of Friday evening September 9, 2010.  The terrain is difficult and fuel source is abundant so the chances of this fire growing is high. 

Currently, firefighters are being hampered by high winds gusting to 30mph in the Canyon.  A Type I incident management team is currently coordinating firefighting efforts.  The transition from a Type II incident to a Type I incident occurred on September 8, 2010.  There are 953 firefighters and assorted apparatus conducting fire suppression activities.

Current activities involve putting out hotspots and flame ups near residential areas.  The Boulder County OEM may begin allowing some residents access to their homes as of 9 a.m. MDT September 11, 2010.

Day 1 Fire Outlook and 24 Hour QPF:

Old Discussion:
A significant wildfire is currently burning approximately 5 miles west-northwest of Boulder, Colorado.  This fire began on September 6, 2010 and has charred over 7,100 acres and the fire is 0% contained as of 3 p.m. CDT September 8, 2010. 

Many homes have been destroyed and many others are threatened.  A total of 5 persons who did not heed evacuation warnings are reported as missing.  3,500 residents of the area are under mandatory evacuation.

Currently, there are over 200 hundred firefighters fighting this fire on the ground and from the air.  The cause of the fire cause is under investigation.

Current weather conditions in the fire area at 2 p.m. MDT September 8, 2010:
82F, winds out of the SE at 6, RH 19% (DP 36F) with conditions to remain static the next 24 hours. 

Here is a link to the NWS Incident Support Page:
http/www.crh.noaa.gov/bou/?n=fourmilefire_briefing

RadioReference Live Audio from Boulder County, Colorado:
http/www.radioreference.com/apps/audio/?ctid=247

Location of Four Mile Canyon:

Satellite Imagery from NASA of the FourMile Canyon Fire in the early stages:

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FCST: September 6, 2010 ~ Lots of shear but no moisture!!

TARGET: Cedar Rapids, IA by 20Z/6.

DISCUSSION:  A compact and potent late season shortwave (995 mb) is moving across the central plains this afternoon.  This storm system will provide the threat of severe thunderstorms across eastern IA, southern MN and western WI later this afternoon and evening. 

The storm has plenty of shear to work with, but the rounds of recent cold fronts have scoured out most of the moisture from the area.  Couple in the progressive nature of the trough and you get plenty of shear and no moisture!
 

A 45 to 55 kt low level jet will be working its way into the target area by 0Z.

Currently, warm air advection is ongoing across eastern KS and western MO but even wtih that dewpoints have only recovered into the upper 50’s to lower 60’s.  Forecasted dewpoints had been in the upper 60’s to lower 70’s.  I do not feel these dews are going to be realized over the aforementioned areas based on my current thinking.

CAPE is forecasted to be in the 1000 to 1500 J/kg range by this afternoon which is appreciable for severe weather. 

A stout EML is advecting into the region as well and will need the approaching shortwave to provide the needed forcing to oversome the capping inversion. I am anticipating some early, isolated supercells from Des Moines northeastward that will quickly congeal into an MCS and march eastward overnight creating a damaging wind threat.

The early storms will yield any tornado threat in the target area.   Helicity values are maximized in these areas and a strong tornado is possible, but not probable in this amateur forecasters opinion. ~ CS


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steve polley storm chaser