Saturday, February 21, 2015

NTX Winter Storm: A θe Approach

Here's an abbreviated synopsis on the meteorological factors that will lead to North Texas' winter storm overnight the 22nd into the 23rd.

This event will be mainly driven by isentropic lift over the cold front/dome that passed early morning on the 21st. Below is the forecasted 293K layer showing moist advection of parcels from the Gulf up and over pressure surfaces (more below)

And below is the forecasted SkewT from the ECMWF that shows classic winter storm sounding with just a small warm nose between 800-700mb, which means this will be primarily a sleet event over ice and snow.

This is also supported by the sref plumes 

Its also not out the question we could have a brief period of thunder sleet per elevated instability




Now for those that don't quite understand isentropic ascent Ive whipped out the ol whiteboard in the form of a schematic bc thats really only way I know how to best explain it. Below is a cross section looking E or NE with DFW on left and the Gulf of Mexico on right. Warm moist air parcels from the Gulf are advected north (movement of air). Early on they reach their LCL (liquid condensation level), which means the parcel has saturated and becomes a cloud; this is in the form of stratus. The moist air parcels continue to rise up and over pressure surfaces on its journey northward until they reach their LFC (level of free convection) and they start to precipitate in the form of snow (SN). However, in our case, we have a very slight above freezing warm nose (thin red line) in which the snow falls through before reaching the boundary layer. This causes the snow to briefly melt to liquid but it very quickly reencounters subfreezing air (cold dome) where it becomes a supercooled water droplet but the depth of the subfreezing air is deep enough in the PBL that it refreezes as an ice pellet/grapeul/sleet. 


UPDATE:

Here was the end result





Thursday, September 11, 2014

5 Day Forecast

Main concern with this forecast package is threat for heavy rainfall tonight
into Friday

OBSERVATIONAL ANALYSIS

At 1700 the stalled sfc front was located just south of a Hamilton to
Sulpher Springs line with 1km satellite showing well defined convective
circulations along the front.Temps South of the front were in the upper
80s to near 90 with cool...cloudy and moist 70s north of the front.
In the upper levels there are a number of features that will impact our
weather going forward...one is a tropical wave in the Bay of Campeche...
another is a tropical disturbance at the tip of Baja California...and third
is a mid-latitude shortwave diving down out of MT. On satellite...a convective
cluster of storms is moving out of the South Plains while it appears another
cluster is trying to form across parts of the Concho valley into the Big
Country. This is likely due to a weak wave embedded within the upper flow
emenating out of Chihuahua from the moisture feed of Odile.




FORECAST

Through the remainder of the diurnal heating cycle expect the front to move
very little without the aid of upper support. The combination of a somewhat
cool and moist boundary layer north of the front and a warm mC airmass south
of the front will create quite a temp discrepncy during the peak heating hours
...with temps south of the boundary heating into the mid to upper 90s and temps
in the upper 70s to near 80 north of the boundary. Precip chances today with
the front will mainly hinge on mesoscale convergence and solar heating as upper
support will be nill till after sundown. A secondary area of precip is possible
across the western zones with the wave discussed above. Models haven't picked up
on this feature but a moist column is in place so any wave/source of lift will result
in showers and storms with threat of heavy rainfall. Will go 30 pops about 30 miles
either side of the front as SPC mesoanalysis is still showing noteable moisture
convergence along the boundary and short term hi-res guidance does show a broken line
of showers and storms along a Goldthwaite to Waco to Palestine line much like we saw
yday in the NW zones. Main threat with these showers will be locally damaging winds
from microburts. Expect these cells to die off with the lost of daytime heating.
Will go 30 pops as well across the western and northwestern zones for any showers
and storms that develop there in the afternoon. Expect anything out west will be
scattered at best. Will keep an eye on this throughout the day and amend the forecast
as needed.



















Overnight the threat for heavy rainfall and potential flooding...mainly across
the southern zones...will increase due to a combination of several factors...
mainly being column moisture being 2 to 3 standard deviations above normal.
This moisture will come from the 2 tropical disturbances mentioned above. Lift
will come in the form of the aforementioned shortwave that will lead to isentropic
ascent along and north of the boundary. 850-700 flow will be nearly parallel to
the boundary so flash/flooding is/will be a concern during the overnight hours
into Friday morning. Large scale lift will begin to spread west to east from the
High Plains into North Texas with the aid of the shortwave approaching the region.
Hi res guidance such as the TT WRF show this well with large swath of precip
developing across the high terrain of West Texas late tonight. Have decided against
a Flash Flood Watch as (1) the upper wave will slide more through Central Plains and
(2) a lack of more robust instablity/lapse rates.  For those weather
geeks this setup is not all unlike that of a winter storm just without the Arctic
airmass.

By midday Friday the upper wave will begin ejecting out which will result in the 850
front being shunted through the region thus ending precip northwest to southeast. While
this will end precip it will not make for a beautiful crips Fall weekend unfortunately. Upper
pattern will continue to be progressive which means the sfc high will move more east than
south into the Southern Plains. This will result in continued weak moist flow as boundary
layer winds slowly veer from northeasterly Saturday morning to southeasterly Sunday moring.
This will keep moisture trapped in the boundary layer for Saturday resulting in considerable
overcast skies and thus cool temps in the 70s for much of the day. Will likely see more sun
on Sunday as return flow off the Gulf commences along with a warm up. Highs will climb back
into the 80s on Sunday. Temps into the first part of next will return to seasonal norms
with highs in around 90 and an upper pattern that is more summer like with a series of low
amplitude waves propogating through the northern tier of states.

Sunday, August 10, 2014

Oshkosh/Air Venture 2014

Below are some pics and videos of my trip to Rockford for B2OSH and subsequent time at Oshkosh/EAA Air Venture 2014

my B2OSH/Air Venture trip




Heres a GoPro video a colleague in the B2OSH formation put to together from the 2014 formation flight to Oshkosh, im in there somewhere


Heres a review of the Oshkosh/Air Venture 2014 that EAA put together

Friday, July 18, 2014

2100 KDFW TAF

For the 2100 TAF main concerns are low cigs and potential for any overnight fog.

 Very tricky overnight forecast once again as we have October like weather in July with an unseasonably cool airmass in place with saturated ground. This is compounded by quite a significant difference in LAMP guidance from HRRR and GFS. As of discussion time/21z, 1km vis and area obs showed widespread VFR cigs in place across the region. H850 streamline analysis shows weak CAA from OK where RHs arent much different than down here in NTX. With this in mind and no signs of sig clearing across the region, will side more with the GFS LAMP but not go as aggressive with the low cigs overnight as there is a bit more dryer air in the PBL than 24hrs ago, however, there is a small window of lowered cigs/vis before sunrise as PBL reaches max cooling, esp given breaks in clouds but will not insert any change groupings attm. Expect winds to gradually veer around to the SE through the nighttime hours.

KDFW 182120Z 1900/2000 01008KT P6SM SCT025 OVC035
     FM 190000 08005KT P6SM OVC035
     FM 190900 10003KT 3SM BR BKN025
     FM 191500 14008KT P6SM SCT040
     FM 192100 14010KT P6SM FEW040

Monday, July 14, 2014

Senior Capstone

final draft

Wednesday, July 2, 2014

WFAA Demo (PC Only)

video

I apologize for the occasional skipping, it came that way from the master cut

Thursday, April 10, 2014

4/9 CASA Executive Council Meeting (PC Only)

Below is a portion of the CASA Executive Council Meeting at North Central Texas Council of Governments (NCTCOG). I recommend turning your volume up to hear all the speakers. The room was somewhat large and the recorder didnt catch all the audio so I had to adjust during editing. Some key points include the following...
  • Unresolved technical issues with UNT radar
  • Addison radar to be up & running this weekend (4/12-13)
  • Cleburne radar May install
  • Ft. Worth radar June install
  • mobile Phased Array
  • CASA radar mobile app
The media reps included 3 Chief mets. From L to R-Pete Delkus (blue shirt/WFAA), David Finfrock (red tie/NBC5), and Larry Mowry (tan polo/CBS11)

Update: Below is a pic from the July 9th meeting ft Ashton Altieri & Colleen Coyle (WFAA), Larry Mowry (CBS11), David Finfrock (NBC5), and yours truly