Severe Weather Discussion for July 6 - 12, 2009. Valid: 07/05/2009.
Highlights:
- A return to summer conditions for the region. Temperatures on Monday near 90F, Tuesday - Wednesday mid 90s, Thursday - Sunday upper 90s.
- Tropics are seasonably quiet.
Probabilities:
- Severe Thunderstorms in Oklahoma: < 5% - Storm Chase: < 5% - Tropical Development: < 5%
Discussion:
Very nice couple of days in Oklahoma for early July. Unfortunately it will not last and climatology will once again rule. ECMWF has been in good agreement with the development and subsequent movement of an eastward U.S. longwave trof the next few days. By Thursday it builds in the 594dm ridge over Oklahoma and appears it is here for a while. Normal high is 92F, working up to 94F by the 17th.
Tropics are quiet and see nothing on the models or in NHC discussions about development. Would expect possibly some activity within the next two weeks per climao.
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Severe Weather Discussion for June 29 - July 5, 2009. Valid: 06/28/2009.
Highlights:
- Temperatures in the mid 90s Monday - Wednesday, upper 90s Thursday-Friday, low 90s Saturday-Sunday. Slight chance of rain Saturday.
- Slight chance of tropical development as a system is located near the Yucatan, however NHC notes less than 30% chance.
Probabilities:
- Severe Thunderstorms in Oklahoma: < 5% - Storm Chase: < 5% - Tropical Development: 10%
Discussion:
Upper ridge has been displaced as of today and will shift westward over AZ/NM for much of the week. Additionally, the ridge will be weaker than the past few days with heights across Oklahoma around 590dm or less. This will make for cooler temperatures the first part of the week. Towards the end of the work week, temperatures will likely increase some as the high attempts to migrate east. A 500mb longwave trof will setup over the eastern U.S. and have some presence all week. A cold front is possible next week and temperatures have been cooled somewhat for this potential. Also, added slight chance of POPs on Saturday. Overall a typical early July week with the normal high of 91F.
Tropics have a little activity, but nothing major is expected per climo.
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Severe Weather Discussion for June 22 - 28, 2009. Valid: 06/21/2009.
Highlights:
- Temperatures will be in the mid 90s Monday - Sunday, all pops zero.
- Summer officially started this morning.
Probabilities:
- Severe Thunderstorms in Oklahoma: < 5% - Storm Chase: < 5% - Tropical Development: < 5%
Discussion:
Subtropical ridge will retrograde west during the next 24 hours and setup over Oklahoma for much of the week. Precipitation chances are near zero through Friday, with temperatures in the mid 90s. Heights won't get above 594dm given the current forecast, so I'm not going 100F for OKC. The FHBC of northwest and north-central OK will likely see near 100F given dark ground in that area. Saturday/Sunday the models indicate the ridge may weaken but there isn't great agreement on this potential. I'm sticking with persistence and keeping things dry under the 588dm ridge. I'd expect temperatures to continue slowly creeping up as the ground dries out and the ridge strengthens. OKC has had around 1.3 inches of rain for June, a small drop in the bucket given the average near 5 inches.
Models don't show any tropical activity at this point and NHC shows things are also quiet. For now will follow climo on tropical storm chances.
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...SUMMARY OF STORM IMPACTS FROM JUNE 10 THROUGH JUNE 14...
AN UNUSUALLY ACTIVE SERIES OF SEVERE WEATHER EVENTS...EVEN BY NORTH TEXAS STANDARDS...IMPACTED THE AREA FROM THE LATE AFTERNOON OF JUNE 10 THROUGH THE EARLY MORNING HOURS OF JUNE 14. BASED ON RADAR DATA...STORM SPOTTER REPORTS...AND COORDINATION WITH LOCAL OFFICIALS...HERE IS A BRIEF PRELIMINARY SUMMARY OF THE STORM IMPACTS.
JUNE 10...
A CLUSTER OF SEVERE STORMS DEVELOPED OVER WEST CENTRAL TEXAS AND MOVED EAST. THE STORMS ORGANIZED INTO A BOW ECHO JUST WEST OF THE DALLAS-FORT WORTH METROPLEX AND PRODUCED EXTREMELY STRONG WINDS.
NUMEROUS 70-80 MPH WIND GUSTS OCCURRED ACROSS NORTHERN PARKER...
SOUTHERN WISE...NORTHERN TARRANT...SOUTHERN DENTON...NORTHERN DALLAS...AND SOUTHERN COLLIN COUNTIES. WIND GUSTS IN EXCESS OF 60 MPH OCCURRED ACROSS MUCH OF THE REMAINDER OF THE METROPLEX.
WITHIN THE BROAD AREA OF DAMAGING WINDS...AT LEAST THREE BRIEF TORNADOES OCCURRED. SPOTTERS OBSERVED THE TORNADOES FROM ROANOKE TO TROPHY CLUB AT APPROXIMATELY 640 PM...IN FLOWER MOUND AT ROUGHLY 650 PM...AND IN THE COLONY-HEBRON AT ROUGHLY 705 PM. THE ROANOKE AND COLONY TORNADOES WILL LIKELY BE RATED EF-0...WHILE THE FLOWER MOUND TORNADO WILL LIKELY WARRANT AN EF-1 RATING. FURTHER INVESTIGATION MAY REVEAL ADDITIONAL BRIEF TORNADOES WITHIN THE DAMAGE SWATH.
JUNE 11...
THE STORMS FROM THE EVENING OF JUNE 10 LEFT BEHIND AN AREA OF RAIN-COOLED AIR. THE BOUNDARY BETWEEN THE RAIN-COOLED AIR AND THE WARM HUMID AIR SAGGED TO THE SOUTH OF THE I-20 CORRIDOR. WARM MOIST AIR WAS FORCED UP AND OVER THE BOUNDARY...RESULTING IN A NEARLY CONTINUOUS STREAM OF THUNDERSTORMS DURING THE MORNING AND EARLY AFTERNOON OF JUNE 11. MORE THAN THREE INCHES OF RAIN FELL FROM JACK COUNTY SOUTHEAST TO HENDERSON COUNTY. THE HEAVIEST RAIN FELL FROM NORTHERN TARRANT TO KAUFMAN COUNTY...WITH MORE THAN EIGHT INCHES ACROSS MUCH OF DALLAS COUNTY. THE RESULTING HEAVY RAIN CAUSED WIDESPREAD FLOODING IN THE AREA.
A SEPARATE CLUSTER OF SEVERE THUNDERSTORMS DEVELOPED WEST OF THE HEAVY RAIN AREA...FROM EASTLAND COUNTY SOUTHWARD. LARGE HAIL FELL FROM NEAR CISCO TO NORTH OF LAMPASAS...WITH THE HAIL REACHING BASEBALL SIZE IN LAMPASAS COUNTY.
JUNE 12...
A SUPERCELL THUNDERSTORM DEVELOPED OVER NORTHERN JACK COUNTY AND MOVED SOUTH-SOUTHEAST. THE STORM PRODUCED AT LEAST TWO CONFIRMED TORNADOES...WINDS IN EXCESS OF 70 MPH...AND HAIL LARGER THAN BASEBALLS. THE TORNADOES WERE APPROXIMATELY 5 MILES SOUTH OF JACKSBORO JUST BEFORE 530 PM...AND JUST WEST OF PERRIN AT AROUND 550 PM. DAMAGE TO OUTBUILDINGS AND ROOFS RESULTED...AND THESE WILL LIKELY BE RATED AS EF-1.
AS THE STORM MOVED THROUGH WESTERN PARKER COUNTY...POSSIBLE TORNADOES IMPACTED AREAS NEAR THE COMMUNITY OF COOL...AND TO THE SOUTHWEST OF WEATHERFORD. THE STORM UPROOTED TREES AND DESTROYED STORAGE BUILDINGS IN THESE LOCATIONS. THE STORM CONTINUED PRODUCING LARGE HAIL AND SEVERE WINDS INTO JOHNSON...HOOD...AND BOSQUE COUNTIES.
TO THE SOUTHWEST...A CLUSTER OF SEVERE STORMS MOVED INTO COMANCHE AND MILLS COUNTIES. HAIL UP TO NICKEL SIZE WAS REPORTED WITH THESE STORMS.
JUNE 13-14...
A COMPLEX OF THUNDERSTORMS MOVED THROUGH WEST CENTRAL TEXAS ON THE EVENING OF JUNE 13. THE STORMS MOVED INTO YOUNG AND MONTAGUE COUNTIES BEFORE WEAKENING. DAMAGING WINDS IN EXCESS OF 70 MPH MOVED THROUGH THE NOCONA AREA SHORTLY AFTER MIDNIGHT JUNE 14. A LARGE TREE WAS BLOWN DOWN WEST OF NOCONA...AND ROOF DAMAGE OCCURRED IN NOCONA.
YOUR NATIONAL WEATHER SERVICE WILL CONTINUE INVESTIGATING THE IMPACTS FROM THIS SERIES OF SIGNIFICANT THUNDERSTORM EVENTS.
ADDITIONAL DETAILS AND INFORMATION WILL BE PROVIDED IN UPDATED STATEMENTS AND POSTED TO OUR WEBSITE. FOR THE LATEST INFORMATION...
Severe Weather Discussion for June 15 - 21, 2009. Valid: 06/14/2009.
Highlights:
- Active severe weather day is possible on Monday across the northwest 1/2 of Oklahoma. Slight chance of storms may exist Friday and Saturday.
- Temperatures will be in the low 90s Monday - Sunday.
Probabilities:
- Severe Thunderstorms in Oklahoma: 35% - Storm Chase: 40% - Tropical Development: < 5%
Discussion:
Most exciting part of this forecast appears to be on Monday as strong mid-level flow remains across Oklahoma. A shortwave trof will translate eastward during the day and should combine with decent instability to produce severe thunderstorms. A dryline is expected to form in the Texas panhandle and surge east to at least the TX/OK border. Storms are expected to develop late afternoon or early evening along this feature and in the higher terrain of Colorado. These storms should move east into Oklahoma during the evening hours. Degree of instability and shear will support supercells. Models are seemingly having trouble with CAPE values, especially the NAM. The 18z GFS seems to have gotten a clue. None of them develop precip tomorrow but then again many didn't this afternoon either where a tornado has been reported in NW Texas.
After Tuesday the 588dm ridge over Texas is expected to build into the region. This should limit thunderstorm chances and warm things up a little. I've tempered the warming some to the low 90s for now. This is also playing the middle of the road as the models disagree on the ridge axis much of the week. There is a chance the ridge may weaken some Friday/Saturday as stronger mid-level flow moves across the region. If so, then precip chances would return. I kept slight POPs for this time period.
The group is looking to chase on Monday, current target is Shattuck to Gage.
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PUBLIC INFORMATION STATEMENT NATIONAL WEATHER SERVICE NORMAN OK 1217 PM CDT SAT JUN 13 2009
...TORNADO IN NORMAN FRIDAY EVENING...
METEOROLOGISTS FROM THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN NORMAN CONDUCTED A SURVEY OF DAMAGE THAT OCCURRED IN NORMAN ON FRIDAY EVENING. THE SURVEY DOCUMENTED THAT A WEAK TORNADO OCCURRED AROUND 1030 PM ON FRIDAY JUNE 12 ALONG A 2 MILE PATH EXTENDING FROM NEAR SOUTHEAST 24TH AVENUE AND ALAMEDA STREET TO SOUTHEAST 48TH STREET AND LINDSEY STREET. CURRENT INDICATIONS ARE THAT THE TORNADO WILL BE RATED A LOW-END EF1 TORNADO. ALL OF THIS INFORMATION IS PRELIMINARY AND SUBJECT TO CHANGE AS THE INVESTIGATION CONTINUES.
THIS IS THE FIRST TORNADO TO OCCUR WITHIN THE CITY LIMITS OF NORMAN SINCE MARCH 13 1990 WHEN TWO TORNADOES OCCURRED IN NORMAN. ON THAT DAY...AN F2 TORNADO DEVELOPED 1 MILE WEST OF CRINER IN MCCLAIN COUNTY AND CAUSED DAMAGE IN NOBLE BEFORE DISSIPATING WITHIN THE SOUTHEASTERN PORTION OF NORMAN AT A POINT 5 MILES NORTHEAST OF NOBLE. A SECOND TORNADO /AN F1/ MADE A 5 MILE PATH THROUGH EAST NORMAN NEAR AND NORTH OF LAKE THUNDERBIRD.
AN EF0 TORNADO ON MAY 7 2008 OCCURRED JUST SOUTH OF THE NORMAN CITY LIMITS MOVING FROM JUST SOUTHEAST OF GOLDSBY TO NEAR 36TH AVENUE SOUTHEAST AND POST OAK ROAD.
Severe Weather Discussion for June 8 - 14, 2009. Valid: 06/08/2009.
Highlights:
- Showers and thunderstorms are possible Monday - Friday. Wednesday appears the best chance for widespread storms. While isolated severe thunderstorms are expected, a moderate end event is not.
- Temperatures will be in the upper 80s Tuesday - Wednesday, low 80s Thursday, mid 80s Friday-Saturday, low 90s Sunday.
Probabilities:
- Severe Thunderstorms in Oklahoma: 20% - Storm Chase: < 5% - Tropical Development: < 55
Discussion:
Split flow will continue this week with a rather weak southern stream. The northern jet stream will remain displaced unseasonably to the north. The presence of a 588dm ridge over Texas and a southern stream shortwave trof just west of California will provide for stronger flow aloft across the region this week. While it will likely yield organized severe thunderstorms, a medium-end event is not expected given lack of a well defined shortwave trof moving across the region. Models tend to agree that the shortwave trof just west of California will remain there this week as a blocking pattern continues in the southern jet. Recent ENSO update from NCEP (thanks Jay) indicates the presence of a weak El Nino and this pattern would certainly fit such an occurrence. Aside from a few MJO's in the Pacific, notable warming has occurred and the resultant teleconnections have limited severe thunderstorm episodes across Oklahoma. NCEP expects the El Nino to continue during the summer months. I'd expect will be seeing a moderate El Nino this coming winter, just a guess though.
Due to the presence of stronger flow aloft and a surface boundary, storm chances are kept for Tuesday-Friday. Wednesday appears the best chance for organized and widespread activity as the surface boundary will coincide with a weak shortwave trof. This weekend the ridge attemps to build back into the region and temperatures are increased back into the 90s. I didn't make much use of the model MOS this forecast cycle.
Significant tropical development is not expected this week per the models and NHC.
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PUBLIC INFORMATION STATEMENT NATIONAL WEATHER SERVICE NORMAN OK 150 PM CDT MON JUN 1 2009 ..MAY 2009 A SLOW MONTH FOR TORNADOES IN OKLAHOMA
PRELIMINARY NUMBERS FOR MAY 2009 SHOW ONLY FOUR TORNADOES WERE REPORTED IN OKLAHOMA DURING THE MONTH. ALL FOUR TORNADOES OCCURRED ON MAY 13TH.
MAY TYPICALLY MARKS THE PEAK OF TORNADO SEASON IN OKLAHOMA...WITH AN AVERAGE OF 20 TORNADOES...OR ABOUT 38 PERCENT OF THE ANNUAL TOTAL.
HOWEVER, 2009 WASN'T THE SLOWEST MAY FOR TORNADOES. IN MAY 2005, NO TORNADOES WERE REPORTED IN OKLAHOMA...AND MAY 1988 ONLY HAD TWO TORNADOES.
OTHER YEARS WITH LOW TORNADO TOTALS INCLUDE 1958 AND 1967, WHEN ONLY FOUR TORNADOES OCCURRED.
IT IS INTERESTING TO NOTE THAT THE MONTH OF FEBRUARY...USUALLY ONE OF THE QUIETEST TORNADO MONTHS...WAS MORE ACTIVE THAN MAY...WITH A TOTAL OF SIX TORNADOES...INCLUDING THE EF4 LONE GROVE TORNADO.
THESE NUMBERS ARE STILL PRELIMINARY AND SUBJECT TO CHANGE.
