Watching the Skies

DFW Airport reported 3.0 inches of snowfall As of 6:29pm 12/24/09, DFW Airport recorded 2.3 inches of snowfall, far exceeding the previous record for this date of a trace. Snowfall is starting to end across the metroplex and should be over by 9 to 10pm in all areas. Temperatures are forecast to drop to the low 20s across the region so any ice or snow accumulations in place now, will persist all night until Christmas day. Temps on Christmas day will rise above freezing in the afternoon, allowing the snow/ice to mostly melt off.

Road conditions around the region are in horrible shape. Numerous roads to our north and west have been closed including I-35 through most of Oklahoma. In fact, all interstates in the Oklahoma City metro area have been shut down for most of the afternoon.

I will send more complete updates after the snowfall ends and additional weather reports come in… Below is most recent daily climate report from DFW Airport:

CLIMATE REPORT
NATIONAL WEATHER SERVICE FORT WORTH TX
629 PM CST THU DEC 24 2009

...................................

...THE DALLAS FORT WORTH CLIMATE SUMMARY FOR DECEMBER 24 2009...
VALID TODAY AS OF 600 PM LOCAL TIME.

CLIMATE NORMAL PERIOD 1971 TO 2000
CLIMATE RECORD PERIOD 1898 TO 2009

WEATHER ITEM   OBSERVED TIME   RECORD YEAR NORMAL DEPARTURE LAST
                VALUE   (LST)  VALUE       VALUE  FROM      YEAR
                                                  NORMAL
..................................................................
TEMPERATURE (F)
 TODAY
  MAXIMUM         53    113 AM  88    1955  55     -2       57
  MINIMUM         29    626 PM   7    1983  35     -6       39
  AVERAGE         41

PRECIPITATION (IN)
  TODAY            0.42          1.41 1975   0.08   0.34     0.00
  MONTH TO DATE    1.49                      2.04  -0.55     0.12
  SINCE DEC 1      1.49                      2.04  -0.55     0.12
  SINCE JAN 1     40.53                     34.20   6.33    26.95

SNOWFALL (IN)
  TODAY            2.3 R         T    2002   0.0    2.3      0.0
                                      1975
                                      1943
  MONTH TO DATE    2.3                       T      2.3       T
  SINCE DEC 1      2.3                       T      2.3       T
  SINCE JUL 1      2.3                       0.2    2.1       T
  SNOW DEPTH       0

..................................................................

WIND (MPH)
  HIGHEST WIND SPEED    38   HIGHEST WIND DIRECTION    NW (310)
  HIGHEST GUST SPEED    46   HIGHEST GUST DIRECTION    NW (300)
  AVERAGE WIND SPEED    20.4

..........................................................

THE DALLAS FORT WORTH CLIMATE NORMALS FOR TOMORROW
                         NORMAL    RECORD    YEAR
 MAXIMUM TEMPERATURE (F)   55        78      1934
                                             1922
 MINIMUM TEMPERATURE (F)   35         6      1983

SUNRISE AND SUNSET
DECEMBER 24 2009......SUNRISE   728 AM CST   SUNSET   527 PM CST
DECEMBER 25 2009......SUNRISE   729 AM CST   SUNSET   528 PM CST

-  INDICATES NEGATIVE NUMBERS.
R  INDICATES RECORD WAS SET OR TIED.
MM INDICATES DATA IS MISSING.
T  INDICATES TRACE AMOUNT.

Update as of 7:49pm: DFW Airport now reports 3.0 inches of snowfall so far today:

...Record daily maximum snowfall set at Dallas/Fort Worth...

A record snowfall of 3.0 inches was set at dfw Airport today. This
is the first measurable snowfall on record for Christmas eve. Trace
snowfall amounts were previously recorded on December 24 in 1924...
1926...1943...1975...and 2002.

Storms are approaching the western side of the metroplex, moving NE at around 25 knots. I don’t see even a single lightning bolt appearing on my radar viewer which I suspect may be an error. Timing puts these storms around 3:10pm to Benbrook, 3:20pm to Watauga, and 4:15pm to Frisco. The storms have gusty winds but are not at severe criteria. I also see no hail with these storms… so the only thing worth mentioning at this time is the very heavy downpour and gusty winds with the storm passage.

I have been meaning to get this sent out for 5 days now and just never get a chance! October broke the record for fewest amount of sunshine ever recorded at DFW Airport for the month. Additionally October finished out as the 7th rainiest on record, with well below average temperatures.

For October, DFW Airport recorded only 8798 minutes of sunshine, officially marking this October as the gloomiest on record. The previous record holder was 9302 minutes set in 1984. This works out to only 40% sunshine during daylight hours, or 60% cloud cover average for the month. Source: http://www.srh.noaa.gov/news/display_cmsstory.php?wfo=fwd&storyid=35837&source=0

The month also finished out in 7th place for precipitation with 8.05 inches at DFW. The record was 14.18 inches set in 1981 so there was no chance at breaking this. Out of 31 possible days, 18 days recorded measurable precipitation, 20 days reported some form of precipitation, 8 days with thunderstorms, 19 days with fog. We were nearly double the normal October precipitation, receiving 3.94 inches more than average. Source: http://www.weather.gov/climate/getclimate.php?wfo=fwd

Lastly the month of October was significantly cooler than average as well, I believe we ranked within the top 10 coolest Octobers on record too, though I cannot find the exact numbers on this right now. Average temp was 62.7, 4.5 degrees lower than average. The month was very mild, with no temperatures higher than 90, or lower than 32. Additionally overnight lows were never higher than 80 degrees. I’d say this was a very comfortable month for temperatures. Source: http://www.weather.gov/climate/getclimate.php?wfo=fwd

So far in November we are off to a very comfortable start, clear skies and very mild temperatures that are favorable for leaving the windows open all day and night. The conditions will continue until possibly Sunday evening through Tuesday when a weak cold front will be in the vicinity and bump rain chances to around 20%. I will keep an eye on this, but so far this does not look to be much more than a rain event.

-- Weather in DFW Airport when posted --
Temp: 66.2 °F, Humidity: 58%
Wind: n/a at n/a
Sky: n/a

A Tornado Watch has been issued for Collin, Dallas, Tarrant counties as well as several others across central, east, and north Texas as well as eastern Oklahoma. The SPC has bumped this watch area up to a 10% tornado risk which is certainly worth paying attention to. While most of the metroplex is under a Tornado Watch, the cold front has mostly passed through the metroplex already so the threat is quite low, if not gone. There is currently a Severe Thunderstorm Warning for eastern Dallas county, but that storm has weakened and moved out of the warned area so I would expect this to expire shortly. Areas directly to the east and south of the Metroplex however should absolutely keep an eye on this situation since the severe weather threat and tornado potential is moderate.

Temperatures behind the front are 20 degrees lower, dropping temps from 75 down to 55 immediately behind.

URGENT – IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 781
NWS STORM PREDICTION CENTER NORMAN OK
1155 AM CDT THU OCT 29 2009

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

SOUTHEAST OKLAHOMA
NORTHEAST TEXAS

EFFECTIVE THIS THURSDAY MORNING AND EVENING FROM 1155 AM UNTIL
600 PM CDT.

TORNADOES…HAIL TO 1 INCH IN DIAMETER…THUNDERSTORM WIND GUSTS
TO 80 MPH…AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 50 STATUTE
MILES EAST AND WEST OF A LINE FROM 15 MILES EAST NORTHEAST OF
MUSKOGEE OKLAHOMA TO 40 MILES EAST SOUTHEAST OF TEMPLE TEXAS.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU1).

REMEMBER…A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

OTHER WATCH INFORMATION…CONTINUE…WW 780…

DISCUSSION…THUNDERSTORMS ARE EXPECTED TO CONTINUE TO INTENSIFY
ALONG SLOW EWD-MOVING COLD FRONT THIS AFTERNOON. RICH BOUNDARY LAYER
MOISTURE AND STRONG TO INTENSE LOW THROUGH MID-LEVEL WIND FIELDS
WILL SUPPORT INCREASINGLY ORGANIZED STORMS/CELLS. WHILE ACTIVITY MAY
EVENTUALLY CONSOLIDATE INTO A SQUALL LINE WITH DAMAGING
WINDS…INITIAL/DISCRETE STORMS WILL EXISTS WITHIN VERY SUPPORTIVE
ENVIRONMENT FOR PERSISTENT LOW-LEVEL ROTATION AND POSSIBLE
TORNADOES.

AVIATION…TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500.
MEAN STORM MOTION VECTOR 21045.

-- Weather in Frisco, TX when posted --
Temp: 64.4 °F, Humidity: 93%
Wind: n/a at n/a
Sky: n/a

Yesterday late afternoon the weather service noted that the squall line’s arrival would be delayed since winds backing it would end up becoming parallel with the line and thus slowing it down. So far that line has slowed way down and its eastward progression is only 10 knots or so. At that pace, the line would reach Fort Worth by 11am, DFW Airport by 12pm and Frisco at 12:30pm or so.

Overnight a Tornado Watch was issued, then subsequently canceled when the squall line abruptly lost forward momentum and severity. Currently the line of storms set to affect us still has good severe potential, but the only severe storms actually occurring are north of us between Tulsa and Oklahoma City. Instability is still limited as the overcast skies across our area will greatly limit daytime heating. Tornado genesis is still possible with any supercells or bow echos that may form due to the very strong low level shearing across the area. The primary threat from this event is still high winds at this time.

I will try to send out updates as I can on this if any severe storms or other interesting weather is set to affect our area.

-- Weather in Frisco, TX when posted --
Temp: 73.4 °F, Humidity: 100%
Wind: n/a at n/a
Sky: n/a

Now that the heaviest rains are beginning to exist the Metroplex as they move east, I will send a brief update on tonight’s severe weather impacts. Only a few reports of high winds around the area, none of them reporting any damage so far. Several large hail reports in Parker, Tarrant, Denton and Cooke counties. One report of lightning striking a home in Trenton, 30 miles NE of Frisco, though damage is unknown at this time. Flooding impacts however are notable… several high water rescues have been reported in Fort Worth due to flooding rains stranding motorists or entering houses. Extreme north Collin county shows an estimated 6.24 inches of rainfall in the last 5 hours! The city of Celina, just 12 miles north of Frisco is embedded in a swath of the heaviest rains, reporting flood waters entering houses as well. There are also some road closures due to high waters south, and west of McKinney.

Attached is rainfall estimates since 6:22pm Sunday 10/25. You can see the area 2.5 miles north of Weston, or extreme north Collin and south Grayson counties showing up to 6.24 inches of rain. This is a result of several thunderstorms training across this area. Frisco by comparison is estimated around 1.17 inches, and only 19 miles south of the heaviest rainfall.

Right on time, a Severe Thunderstorm Watch has been issued for the DFW Metroplex until 1:00am CDT. Scattered showers are developing around the area including several within a few miles of Frisco. Isolated supercells are still possible this evening, primary threats remain as wind and hail.

URGENT – IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 775
NWS STORM PREDICTION CENTER NORMAN OK
715 PM CDT SUN OCT 25 2009

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

SOUTHERN OKLAHOMA
NORTH CENTRAL TEXAS

EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 715 PM UNTIL
100 AM CDT.

HAIL TO 2 INCHES IN DIAMETER…THUNDERSTORM WIND GUSTS TO 70
MPH…AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 85
STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES SOUTHEAST OF
STEPHENVILLE TEXAS TO 40 MILES NORTHEAST OF ARDMORE OKLAHOMA.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU5).

REMEMBER…A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

DISCUSSION…SCATTERED THUNDERSTORMS ARE INCREASING ALONG AND AHEAD
OF AN APPROACHING COLD FRONT OVER SOUTHERN OK AND NORTH CENTRAL TX.
RATHER COOL TEMPERATURES ALOFT AND INCREASING LOW LEVEL MOISTURE
WILL PROMOTE STRONG UPDRAFTS…WHILE SUFFICIENT EFFECTIVE SHEAR IS
PRESENT FOR A FEW SUPERCELLS.  PRESENT INDICATIONS ARE THAT THE MAIN
THREAT WILL BE LARGE HAIL…AND ISOLATED DAMAGING WINDS.

AVIATION…A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM
MOTION VECTOR 24030.

Several Flash Flood Warnings are issued for Tarrant, Denton, Collin, Grayson, Cooke and other counties around the area. A band of very heavy rainfall has fallen creating flooding conditions most notably around Fort Worth where several high water rescues have been taking place after motorists get stranded in high waters. Additionally the Trinity river at Dallas is surpassing flood stage at this time, and is forecast to exceed flood stage by 4 feet. At 34 feet several low water crossings will flood. This heavy rainfall will continue for a few more hours at least until the cold front passes through Thursday before sunrise. The rain will likely come to an end sometime around 3am to 5am I am thinking. Until then, plan for continuous heavy rain and flash flooding potential.

Here is the storm total rainfall amounts so far, this is since 1:21am Wednesday morning. Blue areas are reaching up to 5.8 inches of rainfall. The green polygons indicate current Flash Flood Warnings, the green and blue FFL icons indicate reports of Flash Flooding including road closures and high water rescues.

-- Weather in Frisco, TX when posted --
Temp: 60.8 °F, Humidity: 100%
Wind: n/a at n/a
Sky: n/a

A band of moderate to heavy rainfall is sitting stationary just south and east of the DFW Metroplex, prompting Flash Flood Warnings and even a high water rescue in the city of Terrell.  Rain totals in these areas since 6 pm Monday are around 2.25 inches estimated, showing that the soil is so heavily saturated and unable to absorb any more rainfall.

Below is radar estimated rainfall since 6pm Monday, you can easily see the areas where rainfall is most concentrated… the Green FFL icons indicate reports of Flash Flooding, the green polygons show current Flash Flood Warnings.

-- Weather in Frisco, TX when posted --
Temp: 64.4 °F, Humidity: 100%
Wind: n/a at n/a
Sky: n/a

Hey everyone… looks like the end is near for these overcast skies. Last weekend ended up being overcast both days despite the previous forecasts for clear skies both days. This weekend we will try again with conditions clearing up Thursday and remaining clear through Sunday. Until then, expect rainy conditions from midnight Tuesday morning through mid-afternoon to maybe sundown, with some embedded heavy rains and occasional thunder.

Wednesday has 20% rain chances during the day and 40% in the evening with overcast skies. The Storm Prediction Center has a very small area from DFW and just to our east under a ‘Slight’ severe storm risk for Wednesday. The risk will be mainly isolated in nature as a strong atmospheric cap will be in place supressing storm development. However conditions aside from this cap are quite favorable for severe storm development, meaning any storms that do develop will become severe and likely supercellular in structure. Any supercells that develop will possibly have a tornado threat associated with them, so I will keep an eye on this for everyone. The SPC mentioned these storms will be quasi-discrete meaning individual supercells could develop along a dry line, rather than the unbroken squall line we typically see. Supercell storms produce large hail, high winds, and can generate tornadoes , so again I will keep an eye on this and see how this evolves.

Wednesday and Thursday warm up a tad with highs near 80 and lows in the mid 60s. The end of the week and weekend will cool off under the clear skies, highs in the upper 60s, lows in the upper 40s.

-- Weather in Frisco, TX when posted --
Temp: 60.8 °F, Humidity: 100%
Wind: n/a at n/a
Sky: n/a