I’m still waiting to see official observations from the CoCoRaHS network and other coop stations reporting to the National Weather Service…

SPC Day 1 Categorical Outlook, for Thursday 2/2/12. A slight risk of severe thunderstorms exists across parts of the southern plains.

On Thursday 2/2/12, while atmospheric conditions across the D/FW Metroplex are ripe for supporting thunderstorms, the lack of any lifting agent like a cold front or upper level trough will fail to spark any thunderstorm initiation during the daytime. Late Thursday into Friday however will be different…

SPC Day 2 Categorical Outlook, for Friday 2/3/12. A slight risk of severe thunderstorms exists between Oklahoma City, to Dallas/Fort Worth, then east to Little Rock.

Thunderstorm development should be in full swing across the Texas Panhandle on late Thursday near the center of the low pressure. A cold front attached to this low will be pushed eastward across our region and provide focus for significant thunderstorm development.

Scattered strong to severe thunderstorms are quite possible anytime between Thursday evening to Friday evening as the low pressure system strengthens. Dallas/Fort Worth will remain in the warm sector for most of this event, which places us in a zone of favorable thunderstorm development. While thunderstorms are quite possible Thursday evening through Friday evening, the main event in D/FW will occur Friday afternoon and evening.

Concerns outlined with the upcoming severe weather event are the standard hail and high winds, while a potential for tornadoes exists too. One other concern not typically observed with thunderstorms of this nature is flash flooding. Conditions may actually be favorable for multiple strong or severe thunderstorms to train over the same locations for hours at a time, leading to a localized flash flooding problem.

For a more advanced look into the upcoming weather, my own personal analysis of computer models shows a few separate instances of thunderstorm explosion. A few weak disturbances in the mid-atmosphere rotate around the jet stream and across the area before the main low pressure system arrives and cold front passes through. The atmosphere will be ripe for convection, so these weak disturbances rotating through should be all that is needed to kick off a few bursts of storms before the main event Friday evening. The first wave of t-storms may be very late evening Thursday, close to midnight.

BUFKIT displaying the NAM model’s forecast Skew-T Profile for Friday 2/3/12 1:00 AM. 

The above Skew-T profile shows ample lift in the mid-atmosphere (the white line around 20,000 ft indicates about -10 omega, or rising/lifting air) around 1:00AM Friday morning. CAPE values of around 1000 J/kg with no inhibition and ample moisture throughout the entire profile, and I’d say strong to possibly severe storms are expected. Lapse rates close to 7° C/km should support moderate hail development, and as the storms will be surface based a high wind risk exists too. Hodographs don’t appear ideal, but do show a potential for some tornado development.  0-2 KM shear of about 25kts and helicity of around 200 does indicate tornado development may be possible with some stronger storms, though these values aren’t ideal. Finally lifted index values of around -3° C do indicate a slightly to moderately unstable atmosphere throughout the entire event.

One final advanced analysis of the upcoming weather, flash flooding may actually be a concern with these storms. Storm motion appears to be NNE around 15 mph, but the overall propagation of thunderstorms may be southeastward near 10 mph. This sets up a scenario where multiple thunderstorms may train across the same areas for a few hours at a time, and create flash flooding concerns. Flash flooding may actually be the single most severe weather event out of these upcoming storms, funny enough.

Stay safe everyone, and keep watching the skies the next two days!

Radar estimates about 0.25 inches of rain across most of the metroplex, except north DFW where an estimated 1.5 inches fell.

You can see that CoCoRaHS reports actually verify the radar’s estimated rainfall fairly well. The radar may have even underestimated total rainfall in some areas.

CoCoRaHS.org volunteer network rain reports for the 24-hr period ending 1/26/12 7:00am CST. 

The entire region had at least some measurable precipitation the last 24 hours, which is great news for the drought stricken lone star state!

4.26 inches of rain fell at Dallas/Fort Worth Airport, while 4.49 inches fell at Dallas Love Field. See the complete list of 24-hour preliminary rainfall totals below.

EDIT: Several area lakes rose by several feet due to the widespread heavy rain as well. See below for lake level increases.

Radar estimated storm total rainfall as of 11:00am CST 1/25/12.

...Preliminary 24 hour rainfall totals ending at 11 am...

...Anderson...
psnt2    Palestine crn                        1.97

...Bell...
nelt2    Temple                               2.83
tpl      Temple AWOS                          1.98

...Bosque...
aqlt2    Aquilla                              3.71
vmat2    Valley Mills                         3.15
ctnt2    Clifton                              3.14

...Collin...
ddnt2    Dallas alert 735(preston @ Olive rd) 5.32
prpt2    Prosper                              4.90
dwht2    desert water coop#2                  4.65
mckt2    McKinney                             4.41
tki      McKinney ASOS                        4.31
bvwt2    Blue Ridge                           4.16

...Comanche...
dllt2    deleon                               3.46
dsbt2    deleon                               3.20
coat2    Comanche RAWS                        2.96
mkn      Comanche AWOS                        2.56

...Cooke...
vvwt2    Valley View 4s                       4.23
gllt2    Gainesville                          2.99
gle      Gainsville muncipal                  2.52

...Coryell...

...Dallas...
dcct2    west joe's creek @ Walnut Creek      5.04
Dal      Dallas Love ASOS                     4.49
rbd      Dallas Red Bird ASOS                 4.36
gprt2    Grand Prairie                        4.24
adst2    Addison Airport                      4.07
gpet2    Mountain Creek Lake                  4.03
lnc      Lancaster Airport                    3.72
chit2    Cedar Hill 4ne                       3.72
dalt2    Dallas                               3.66
cdht2    Cedar Hill S.P. RAWS                 3.64
cart2    Carrollton                           3.37

...Delta...
sclt2    jim Chapman Lake                     2.52
copt2    Cooper                               2.41

...Denton...
dcjt2    Justin                               4.21
sget2    Sanger                               3.98
dto      Denton ASOS                          3.49
eflt2    Lewisville                           3.19
rrlt2    lake ray Roberts                     3.01

...Eastland...
llet2    Lake Leon                            2.87

...Ellis...
lwwt2    Lake Waxahachie                      4.45
avat2    Avalon #2 larc                       3.49
jwy      mid-way regional ap                  3.36

...Erath...
Sep     Stephenville                          4.18

...Falls...
hibt2    Highbank                             2.27

...Fannin...
ladt2    Ladonia                              3.49
cddt2    Caddo wildlife mngt                  2.91

...Freestone...
stet2    Streetman                            2.88

...Grayson...
covt2    Collinsville                         4.80
gyi      Sherman/Denison ap                   3.91
cvet2    Collinsville                         3.28

...Hamilton...
hict2    Hico                                 4.02
hmlt2    Hamilton                             2.33

...Henderson...
tddt2    Trinidad                             2.29
rhat2    Athens RAWS                          2.19

...Hill...
bbdt2    Brandon                              4.78
bumt2    Blum                                 4.33
inj      Hillsboro Airport                    3.60
aqat2    Aquilla creek blw dam                2.88
alat2    Aquilla lake                         2.53
mlet2    Malone                               2.21

...Hood...
gryt2    Granbury RAWS                        5.13
gdj      Granbury Municipal ap                4.61

...Hopkins...
subt2    Sulphur Bluff                        2.36

...Hunt...
lvtt2    Celeste                              4.49
msct2    Commerce                             2.99
scst2    Commerce                             2.82
gelt2    Greenville RAWS                      2.62
gvt      Greenville Airport                   2.56
gnvt2    Greenville                           2.34

...Jack...
tbmt2    bear mtn reptr (post office)         2.79
jakt2    Jacksboro                            2.60
tant2    Antelope                             2.38
tvtt2    Truce                                2.14

...Johnson...
vnst2    Venus                                4.01
cpt      Cleburne municpal ap                 2.98

...Kaufman...
cnlt2    Crandall                             3.74
kaft2    Kaufman                              2.62
trl      Terrell ASOS                         2.26

...Lamar...
myst2    pat mayse dam                        2.81
prx      Paris AWOS                           2.76
roxt2    Roxton                               2.70
cppt2    Cooper                               2.61

...Lampasas...
ltct2    Lometa                               2.22
nnxt2    Lampasas                             2.03
lmot2    Lometa                               2.00

...Limestone...
grst2    Groesbeck                            2.95
llmt2    lake Limestone Marin                 2.13

...Leon...
llst2    lake Limestone                       2.11

...McLennan...
mcgt2    McGregor                             3.01
act      Waco ASOS                            2.87
crft2    Crawford                             2.81
megt2    McGregor RAWS                        2.64

...Milam...
tdct2    Thorndale                            3.30
cmnt2    Cameron                              2.42

...Mills...
gect2    Goldthwaite                          2.57

...Montague...
mgut2    Montague                             3.03
bcat2    lake amon Carter                     2.38
0f2      Bowie                                2.37

...Navarro...
crs      Corsicana ASOS                       3.04
trht2    Richland                             2.33
rcet2    Rice                                 2.28

...Parker...
weat2    Weatherford                          4.15
bnct2    Cresson                              4.05
twrt2    Springtown (walnut c                 3.98
dnnt2    Dennis                               3.85
wtht2    Weatherford                          3.62
tagt2    Agnes                                2.11

...Robertson...
lhb      Hearne Airport                       2.46
rprt2    Round Prairie RAWS                   2.15

...Stephens...
bkd      Breckenridge AWOS                    1.76

...Somervell...
glrt2    Glen Rose                            3.65
grot2    Glen Rose                            3.30

...Tarrant...
eamt2    Eagle Mountain Lake                  4.53
mnft2    Mansfield                            4.49
gky      Arlington ASOS                       4.28
dfw      Dallas/Fort Worth ap                 4.26
bcht2    Fort Worth                           4.17
fwdt2    NWS Fort Worth                       4.10
nfw      ftw joint Reserve base               3.91
afw      ftw Alliance ASOS                    3.90
ftw      ftw Meacham ASOS                     3.84
fwot2    Fort Worth                           3.75
wftt2    Fort Worth                           3.73
ermt2    Everman                              3.73
gpnt2    Grapevine dam wx sta                 3.65
bnbt2    lake Benbrook                        3.61
fwht2    Fort Worth                           3.59
wrpt2    Fort Worth federal bldg              3.53
twft2    trwd sump 13                         3.43
tcet2    Cement Lake                          3.19
bmct2    marys creek                          3.19
tctt2    trwd sump 17                         3.15
twvt2    trwd sump 3                          3.08
tmct2    marine Creek Lake                    2.99
flwt2    Lake Worth                           2.79
cfbt2    Benbrook                             2.64

...Wise...
boyt2    Boyd                                 3.86
lud      Decatur Municipal ap                 3.07
avot2    Alvord 4ne                           3.07
lbjt2    LBJ Grasslands RAWS                  2.88
tsat2    Paradise (salt creek)                2.82
tcft2    Crafton                              2.70
tbnt2    Boonsville                           2.59

...Young...
lmgt2    Lake Graham                          2.93
sout2    South Bend                           2.63

          ....North Texas lakes are on the rise...

The widespread heavy event of the past 24 hours has brought some
significant recharge to the lakes in North Texas. Rainfall totals
averaged 3 to 5 inches across the area from midday Tuesday through
noon Wednesday. 

Lake                Lake elevation gain through 3pm Wednesday

Grapevine           3.1 feet
Lewisville          1.8 feet
Joe pool            2.7 feet
Lavon               2.5 feet
ray Hubbard         1.4 feet
ray Roberts         1.5 feet
Arlington           5.4 feet
Eagle Mountain      2.2 feet
Bridgeport          1.3 feet
possum kingdom      1.2 feet
Granbury            3.6 feet
Bardwell            2.2 feet
Richland Chambers   0.5 feet
Cedar Creek         0.5 feet
Whitney             1.5 feet

The rain will start Tuesday 1/24 in the early afternoon as a weak front slides by and stalls just south of the region. Elevated CAPE values around 500 J/kg with no CIN to inhibit storm growth, plus mid-level lapse rates near 7 degrees C/km should allow the production of hail with some stronger t-storms. Thunderstorms will likely be scattered and embedded within the overall wide-spread rain, but an isolated severe t-storm is possible.

Forecast NAM model Skew-T chart for Tuesday Jan 24 8:00pm CST. Red line is temp, green line is dew point. White line is ‘Omega’, indicating rising or sinking air. Thin yellow line indicates CAPE. This chart shows an almost fully saturated atmosphere below 17,000ft with plenty of rising air, and 534 J/kg of CAPE with almost zero inhibition from about 3,000 ft.

The heavy rain will continue overnight into Wednesday morning. Some additional thunderstorm development is possible early Wednesday morning around or just before sunrise, but these storms wouldn’t be strong or severe.

Expect the Wednesday morning drive to be difficult as very heavy rain combines with urban street flooding. A flash flood watch or warning wouldn’t be surprising to see on Wednesday. The heaviest rain will ease late afternoon Wednesday.

The rain will likely continue as light sprinkles or scattered rain showers until Thursday afternoon when it will likely end.

Forecast NAM model precipitation per hour, and precipitation total. Heaviest rainfall appears likely during the daytime Wednesday 1/25. Time progresses from right to left.

Forecast NAM model 96-hr total rainfall, from 1/23 12:00pm CST to 1/27 12:oopm CST. North Texas looks set to receive very heavy rain, in the 2-4 inch range.

A widespread rain like this may actually bring parts of north central Texas out of any official drought category, and help relieve a large portion of central Texas’ extreme drought conditions. Widespread rain like this is encouraging, signs that the brutal back to back La Nina winter seasons may finally be reaching an end.

A severe thunderstorm risk exists for the entire D/FW Metroplex starting early to mid afternoon Wednesday 12/14. A low pressure system moving rapidly to the northeast will send a pacific cold front through the region.

Strong wind shear profiles, upper level dynamics, and rich surface moisture are all very favorable for severe weather development. Some limiting factors however are low to moderate instability due to heavy cloud cover blocking daytime heating, and poor wind shearing near the surface limiting tornado genesis.

These limitations aside, severe weather development still appears to be quite a possibility at this time. Storms would likely be linear in nature, eventually forming a nearly unbroken line of thunderstorms.

My own personal analysis of forecasted Skew-T charts for 3:00pm CST Wed 12/14 indicates a risk of microbursts, due to a very pronounced slot of dry air in the mid atmosphere around 15k to 18k feet above sea level. Lapse rates also appear favorable for hail development and a lightning risk.

Even without very ideal atmospheric instability, the other components of ample wind shearing being strong forcing along the cold front, and abnormally high moisture for this time of year will yield a risk of severe weather. At this point, determining the instability available will help determine just how severe the storms will be. If daytime surface temps rise into the 70s as expected after clouds break up and allow the sun to heat the ground, there will be a solid risk of severe weather for the region.

Storm total rain as of 3:48am CDT

Storm total rain, zoomed in on D/FW.

I took several long exposure photos and uploaded them into my galleries. Lightning tonight wasn’t very photogenic, but when stitched together in time lapse, you can see the evolution and approach of the strong thunderstorm outflow boundary.

23-Oct-2011 01:51PENTAX PENTAX K-5 , 7.1, 16.0mm, 10 sec, ISO 160	23-Oct-2011 01:47PENTAX PENTAX K-5 , 7.1, 16.0mm, 10 sec, ISO 160	23-Oct-2011 01:40PENTAX PENTAX K-5 , 7.1, 16.0mm, 10 sec, ISO 160
23-Oct-2011 01:32PENTAX PENTAX K-5 , 7.1, 16.0mm, 10 sec, ISO 160	23-Oct-2011 01:34PENTAX PENTAX K-5 , 7.1, 16.0mm, 10 sec, ISO 160	23-Oct-2011 01:22PENTAX PENTAX K-5 , 7.1, 16.0mm, 10 sec, ISO 160

Click here to view the complete gallery.

Storm development will likely begin across central Oklahoma near Oklahoma City, and south along I-35. Wind profiles support forward propagation of these storms southward into north Texas as a line likely developing along an outflow boundary. Storm timing appears a bit difficult to determine with great precision, but the storms may enter north Texas around 10:00pm tonight.

Tonight’s main risk will be severe hail, but high winds are also possible. Because of the hail and ice production expected with these storms, frequent cloud to ground lightning would be expected as well.

First off, below is radar estimated rainfall for the area on 9/29/11. Most areas around D/FW received 1/10th to 1/4th of an inch, with isolated areas receiving 1-2 inches of rain. We will see how these compare to actual observations once they come in later.

Storm reports from around the area show high winds were tonight’s main severe threat. Several reports of winds exceeding 50 to 60mph came in from Tarrant, Johnson, Dallas and Ellis counties. Multiple trees were reported down in River Oaks, just northwest of Fort Worth.

My favorite part of the evening was the amazing lightning however. Take a look below for some shots I’ve specifically selected.

29-Sep-2011 20:45PENTAX PENTAX K-5 , 4.0, 16.0mm, 10 sec, ISO 80	29-Sep-2011 20:42PENTAX PENTAX K-5 , 4.0, 16.0mm, 10 sec, ISO 80	29-Sep-2011 20:48PENTAX PENTAX K-5 , 4.0, 16.0mm, 10 sec, ISO 80
29-Sep-2011 20:52PENTAX PENTAX K-5 , 4.0, 16.0mm, 10 sec, ISO 80	29-Sep-2011 20:54PENTAX PENTAX K-5 , 7.1, 16.0mm, 30 sec, ISO 80	29-Sep-2011 21:00PENTAX PENTAX K-5 , 7.1, 16.0mm, 30 sec, ISO 80
29-Sep-2011 20:57PENTAX PENTAX K-5 , 7.1, 16.0mm, 30 sec, ISO 80	29-Sep-2011 21:55PENTAX PENTAX K-5 , 5.0, 16.0mm, 10 sec, ISO 160	29-Sep-2011 21:59PENTAX PENTAX K-5 , 5.0, 16.0mm, 8 sec, ISO 160

EDIT 12/3/2011: I created a combination of all lightning photos taken this evening into one epic lightning exposure.

Click here to view the complete gallery.

Radar estimated precipitation for all of north Texas.

Zoomed inview for the immediate D/FW Metroplex.

Location                              rainfall /inches/
==============================
=========================
cvlt2    Centerville                          3.25
avat2    Avalon #2 larc                       2.79
csat2    Corsicana                            2.40
llmt2    lake Limestone Marin                 2.38

Dckt2    Dallas alert 307                     2.33
mypt2    Maypearl                             2.18
dwct2    Dallas alert 205                     2.13
act      Waco ASOS                            2.13

Aqlt2    Aquilla                              2.06
waxt2    Waxahachie                           2.00
rcet2    Rice                                 2.00
ddct2    Dallas alert 485                     1.92

Subt2    Sulphur Bluff                        1.89
dwht2    desert water coop#2                  1.88
aqut2    Aquilla 1sse                         1.87
crs      Corsicana ASOS                       1.81

Ddkt2    Dallas alert 171                     1.77
dbjt2    Dallas alert 175                     1.74
dwht2    desert water coop#2                  1.71
ddjt2    Dallas alert 165                     1.69

Ddmt2    Dallas alert 504                     1.66
gect2    Goldthwaite                          1.61
grst2    Groesbeck                            1.58
pwg      McGregor municpal ap                 1.55

Dddt2    Dallas alert 635                     1.54
dadt2    Dallas alert 255                     1.50
dabt2    Dallas alert 415                     1.50
mbkt2    Mabank 4sw                           1.47

Mrlt2    Marlin 3ne                           1.45
rprt2    Round Prairie RAWS                   1.41
dcrt2    Dallas alert 613                     1.41
tki      McKinney ASOS                        1.36

Llst2    lake Limestone                       1.36
dalt2    Dallas                               1.36
ddit2    Dallas alert 129                     1.33
mckt2    McKinney                             1.29

Dayt2    Dallas alert 305                     1.26
alat2    Aquilla lake                         1.26
kaft2    Kaufman                              1.23
ddlt2    Dallas alert 377                     1.23

Dbgt2    Dallas alert 623                     1.22
damt2    Dallas alert 453                     1.22
gelt2    Greenville RAWS                      1.18
cwft2    Crawford                             1.17

Chit2    Cedar Hill 4ne                       1.17
bvwt2    Blue Ridge                           1.17
aqat2    Aquilla creek blw da                 1.16
actt2    Waco Lake                            1.16

Dcxt2    Dallas alert 413                     1.14
dbst2    Dallas alert 253                     1.14
mcgt2    McGregor                             1.13
fest2    Freestone 5sw                        1.10

Dcet2    Dallas alert 308                     1.10
daqt2    Dallas alert 451                     1.10
hibt2    Highbank                             1.09
vmat2    Valley Mills                         1.06

Dbdt2    Dallas alert 523                     1.06
east2    easterly                             1.04
bdwt2    Bardwell Lake                        1.03
lhb      Hearne Airport                       1.00

Dajt2    Dallas alert 185                     0.99
tddt2    Trinidad                             0.96
stet2    Streetman                            0.96
cnlt2    Crandall                             0.96

Lolt2    Long Lake                            0.92
scst2    Commerce                             0.89
dazt2    Dallas alert 553                     0.87
dakt2    Dallas alert 671                     0.87

Wlpt2    Wills Point                          0.86
lwwt2    Lake Waxahachie                      0.84
lvnt2    lake Lavon                           0.84
daot2    Dallas alert 455                     0.83

Daft2    Dallas alert 529                     0.82
dbit2    Dallas alert 195                     0.79
cdht2    Cedar Hill S.P. RAWS                 0.78
trl      Terrell ASOS                         0.76

Sclt2    jim Chapman Lake (co                 0.75
mlot2    Midlothian #2                        0.73
ctnt2    Clifton                              0.72
ddht2    Dallas alert 115                     0.67

Dbbt2    Dallas alert 677                     0.63
dbat2    Dallas alert 505                     0.63
dawt2    Navarro Mills Lake                   0.62
gvlt2    Greenville kgvl                      0.61

Bumt2    Blum                                 0.61
rsrt2    Rosser                               0.60
rhat2    Athens RAWS                          0.59
psnt2    Palestine crn                        0.59

Aplt2    Palestine RAWS                       0.59
lvtt2    Celeste                              0.58
dcpt2    Dallas alert 15                      0.55
prpt2    Prosper                              0.54

Copt2    Cooper                               0.54
hngt2    Honey Grove                          0.47
gky      Arlington ASOS                       0.46
jplt2    Lake Joe pool                        0.45

Dcnt2    Dallas alert 647                     0.44
rbd      Dallas Red Bird ASOS                 0.41
dbkt2    Dallas alert 689                     0.40
dczt2    Dallas alert 777                     0.39

Hqz      Mesquite Metro airpo                 0.38
gait2    Gainesville 1n                       0.37
gnvt2    Greenville                           0.36
bbdt2    Brandon                              0.35

Gtbt2    Grand Prairie alert                  0.31
lrit2    Little River                         0.30
bnmt2    Bonham 3nne                          0.30
mlet2    Malone                               0.29

Gpbt2    Grand Prairie alert                  0.28
psn      Palestine Municipal                  0.27
megt2    McGregor RAWS                        0.27
lmot2    Lometa                               0.27

Dwrt2    White Rock creek at                  0.27
dsbt2    deleon                               0.27
prx      Paris AWOS                           0.25
mlet2    Malone                               0.25

Gvt      Greenville Airport                   0.25