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Posted At: November 20, 2008 @ 12:47 PM

Posted By: Reed Timmer

Northerly and northwesterly flow lake effect bands have intensified overnight and today across the central Upper Peninsula of Michigan, and northern and southwest Lower Michigan, dropping up to 10 inches of new snow in the favored snow belt areas.  The highest 12 hour snowfall I could find was 10.2 inches at Fennville, MI in Allegan County, but I bet there were several localized reports exceeding this.  As the cold air rotates east, the heavy lake effect snow will develop downwind of Lakes Huron, Erie, and Ontario as well, where lake effect snow warnings and watches are also in effect.

Posted At: November 18, 2008 @ 9:28 PM

Posted By: Reed Timmer

Northwesterly flow lake effect has been pounding some of the "snow belt" locations downwind of the Great Lakes since yesterday, with up to a foot or more of new snow reported over parts of Michigan.  Significant snow has also been falling over the higher elevations of West Virginia, where over a foot of snow could fall by tomorrow morning!  Winds are expected to shift to a more northerly direction from west to east across the Great Lakes tonight, so lake effect snow watches have been issued for the favored northerly flow locations of the Upper Peninsula of MI and northern WI for tomorrow and tomorrow night.  The winter storm warnings (dark blue), watches (purple) and advisories (light blue and pink) are shown below:


Chris Chittick is currently in Spring Lake, MI, on the Lake Michigan shoreline, and experienced heavy lake effect snow squalls last night.  He sent me the pictures below..  3-4 inches of new snow fell there, but quickly melted as the sun came out this morning.  If anyone else would like to contribute photos of extreme weather to the blog, please email them to me at reed@tornadovideos.net

Posted At: November 17, 2008 @ 12:51 AM

Posted By: Reed Timmer

We need to do this next year!!!

Posted At: November 16, 2008 @ 10:09 PM

Posted By: Reed Timmer

Episode 5 of Storm Chasers did a very good job depicting many of the hurdles chasers have to overcome to see tornadoes.  Danny and Aaron sliding off the road was hilarious!  The road network in this area along and north of I-70 in Central Kansas is terrible for chasing, and to compound the problem, supercells were training over the same area for several days in a row!  The nearly impassable roads over Memorial Day weekend will be a huge issue in the next episode as well, which show the Quinter, KS tornado fest..  I look forward to your comments on the show so far!  Things will get much more intense during the last  episodes..

Posted At: November 15, 2008 @ 1:20 PM

Posted By: Reed Timmer

As a strong storm system continues to deepen over the Great Lakes, a strong LLJ will develop from the Mid-Atlantic to the Southeast U.S. with 50+ knots at 850 mb this afternoon and evening from New Jersey south to the eastern Carolinas.  Sufficient instability and a weak cap will also be present in the warm sector, allowing for supercells and convective line segments to develop along a rapidly advancing cold front.  Given the extreme low-level helicity values, and storm initiation already underway, tornado watches have been issued by the Storm Prediction Center for Southeast PA, southern NJ southward to eastern NC.


Here is the 850 mb NAM analysis for 18z for the eastern U.S., showing the intense low-level flow to the east of the cyclone across the Mid-Atlantic and Southeast.  Check back for updates as this severe weather event unfolds..

Posted At: November 11, 2008 @ 2:06 PM

Posted By: Reed Timmer

Severe weather will be possible this afternoon along the trailing end of a cold front sagging southward toward the Gulf of Mexico.  Weak instability, and marginal low-level wind shear should limit any tornado threat, but strong straight-line winds and marginally severe hail are possible as a convective complex drifts south and eastward.  The most intense development will occur later this afternoon near the southwestern end of this line, where the atmosphere will be less tainted by convective debris and clouds.  This could be the last severe weather chance for a long time!  Then its time to chase lake effect blizzards..

Posted At: November 10, 2008 @ 11:07 AM

Posted By: Reed Timmer

A mesoscale discussion has been issued for parts of Central Texas, east of an advancing dryline where sun and destabilization has been occurring this afternoon.  The wind shear will be supportive of supercells, but the low-level shear will becoming and less favorable with time for tornadoes this afternoon and evening as the LLJ ejects northeast.  Meanwhile, a classic "cold-core" setup is underway further northwest across the OK Panhandle and southwest KS.  TVN stream 1 will be chasing the cold-core today, where tornadoes area also possible.  We are closely monitoring the northern end of the MD below, and may head-out in the next 30 minutes.  Check back for updates!

Posted At: November 9, 2008 @ 11:34 PM

Posted By: Reed Timmer

The Storm Prediction Center has issued a slight risk for much of central Texas and southern Oklahoma for this afternoon and evening.  The best area for tornadoes will likely be along the I-20 corridor east of Abilene, extending southeastward to the Austin, TX area.  Check out the TVN live streaming as the severe weather unfolds!!!

Posted At: November 9, 2008 @ 12:12 PM

Posted By: Reed Timmer

A strong trough of low pressure will eject from the Southern Rockies on Monday afternoon, inducing an intense low-level jet over much of central and northern Texas, that will pump moisture northward from the Gulf of Mexico.  Modest CAPE values of 1000-1500 J/kg will develop in a sufficiently wide axis east of the dryline, with the highest values over the Texas Hill Country, as seen below in the NAM forecast for 00z tomorrow evening.


While the strongest 850 mb flow ejects northeast to the Ozark Mountain region, there will still be 35-45 knot flow lagging behind to the dryline over West Texas, resulting in sufficient wind shear for tornadoes.  Storm motions will also be more easterly than on Nov 5, which would be more favorable for tornadic storms as well.  TVN will definitely be chasing this event tomorrow, so check out the live tracker by afternoon! 

Posted At: November 5, 2008 @ 9:26 PM

Posted By: Reed Timmer

Here is video shot by Joel, Chris, and John Harris from the supercell that tracked north of Oklahoma City.  The supercell had a massive base and a nice wall cloud, but never could quite produce a tornado.  The highlight of the chase though, was when the TVN team was nearly struck by lightning once again!  The bolt struck only feet away and started a grass fire right next to the vehicle!  Check out the highlight clip below:

Posted At: November 5, 2008 @ 9:43 AM

Posted By: Reed Timmer

The moderate risk has been issued for south-central KS and northern OK for this afternoon and evening, with a 15% hatched area for strong tornadoes across the same area.  In this localized region, 0-1 km helicity values are forecast to be 200 m2/s2 and higher, with a large uncapped instability axis.  A majority of the strong tornado potential will occur near and just after sunset as the low-level jet intensifies rapidly.  As always, check back for updates and stay tuned to the live tracker this afternoon!  IT'S HAPPENING!!!!

Posted At: November 5, 2008 @ 8:37 AM

Posted By: Reed Timmer

Based on the depth of moisture in the morning soundings, and an expected realization of 2000+ J/kg CAPE values and no CIN over southeast KS into northeast OK, the Storm Prediction Center has decided to upgrade to a moderate risk in the 1630z outlook over this localized region.  With the cold front surging south to the north of this area, it looks like the triple point will setup near south-central KS this afternoon, with an enhancement in the low-level shear just to the east.  I would not be surprised at all if strong tornadoes happened this afternoon and evening.  The TVN live streaming teams are targeting this area, with Rob MacDonald and Justin Hobson playing the northern mode near Sioux City.  Check out the live streaming page later this afternoon for tornadoes in real-time! 

Posted At: November 5, 2008 @ 12:31 AM

Posted By: Reed Timmer

The new forecast model runs show even higher instability over eastern KS northward to extreme southeast SD by this afternoon, with the highest CAPE values over southeast KS by 00z.  Wind shear will be extreme from SD south to OK, with 40-50+ knot flow just above the surface.  The area where the best shear and instability are co-located is Eastern KS into extreme Northeast OK, where 0-1 km EHI values are near 2, which is sufficient for tornadoes.  TVN will have at least 3 live streaming teams documenting this late season severe weather event, so check out the live tracker page this afternoon to check up on our progress!  Right now Joel and Chris are targeting northeast OK into southeast OK, Dick M is targeting eastern KS, and Rob and Justin H. are targeting southeast SD driving south from Manitoba..


The Storm Prediction Center has issued a slight risk for today, with a 5% area of tornadoes over southeast KS into northeast OK where the highest forecast 0-1 km EHI values reside.  I am a little surprised the tornado chances are not higher for the northern mode in southeast SD and northeast NE...I bet they will be increased in later outlooks, however, given the insane low-level wind shear and no cap in that area this afternoon.  Check back for updates!

Posted At: November 3, 2008 @ 2:21 PM

Posted By: Reed Timmer

Strong low-level and deep layer wind shear, as well as sufficient instability for supercells will develop over parts of the Central and Southern Plains on Wednesday, as a strong trough ejects from the Southern Rockies by afternoon.  Based on the 18z NAM, the best low-level wind shear will exist from Central Kansas into eastern Nebraska by 21 to 00z on Wednesday, where a 50+ knot low level jet will reside.  However, the best instability will be further south from Central Kansas to Oklahoma, where 60s dewpoints will result in ~1500-2000 J/kg CAPE.  The highest 0-1 km EHIs (combination of CAPE and low-level shear) are forecast to be over southern KS into Oklahoma, but initiation is more of an uncertainty there.  The 18z NAM is forecasting storm development between 21 and 00z from Nebraska south to Oklahoma (earlier north, later south), but if the system slows down, then most of the convection will hold off until after dark.  Further north across central and eastern South Dakota, sufficient instability will exist for supercells in an environment with extreme low-level shear, so tornadoes will be possible there as well.  There is potential for a widespread severe weather outbreak across the Central and Southern Plains on Wednesday, and across the MS River Valley on Thursday as the system moves rapidly to the east.  TVN will have multiple teams chasing this event, so check back for updates...finally a fall chase!  Shown below are the forecast CAPE and 850 mb winds for Wednesday evening from the 18z NAM.

Posted At: November 1, 2008 @ 1:11 PM

Posted By: Reed Timmer

A strong trough of low pressure is forecast to amplify and move east across the Southern Rockies during the middle of next week, bringing a chance for severe weather on Nov 4-5 from the Great Plains eastward.  The only limiting factor for a widespread tornado threat will be moisture, with less than 60F dewpoints forecast across a majority of the Central and Southern Plains.  Still though, given the very cold air aloft there will still be at least marginal instability, especially over the Southern Plains.  Shown below is the NAM forecast 300 mb flow for Wednesday afternoon...Check back for updates as this potential severe weather event unfolds!  We'll be posting often as the model forecasts evolve.