1. IHOP Scientific Workshop
Analyses of the 10 June and 19 June 2002 IHOP Convection Initiation Cases (with a minor plug for BLE!)
Yvette P. Richardson
Nettie R. Arnott
James N. Marquis
Brian Monahan
June 14, 2004
IHOP Scientific Workshop
We will be looking at mobile radar data and aircraft insitu measurements across a cold front. Convection initiated just outside the IOR.

2. Surface Analysis 1900 UTC

3. Overall Evolution
Movie is there to capture peoples attention. After motivating studying CI, talk about movie. Shows cumulus development in the IOR (box) during the deployment. Notice how a storm formed very close to the IOR, but not in the IOR. More on that later…

4. 10 June 2002 IOR Data Collection: 1918 UTC – 2118 UTC CI: 2103 UTC
Red box = IOR. Point out radars, how they scanned into center of IOR. Point out King Air and P3 paths. Then say how convection initiated near star at 21:03. Move mouse to mobile sounding in center of IOR and click for a sounding. (If you also want to show sounding near CI, it is on slide number 26.

5. Sounding in IOR 2044 UTC Weak capping inversion
Dry air above boundary layer
Everything to say about this is labeled.
LCL
3 km AGL
Top of domain

6. Sounding near CI 1935 UTC
LCL
3 km AGL

7. High Temporal Resolution Loop

8. King Air W vs. Radar W King Air track = black line Warm colors = +w
Cold colors = -w
740 m AGL Correlation = 0.78
1230 m AGL Correlation = 0.83
A A’
A A’

9. Warm colors = convergence
23.0 km
100 m AGL
Warm colors = convergence
Cold colors =
Divergence
Contoured every
2 x 10 –3 s-1
(0 contour not shown)
23. 5 km
First say what everything is (vectors are horizontal winds at 100 m AGL). Then point out main features like cold front, HCRs, open cell and secondary convg line.

10. Warm colors = convergence
23.0 km
100 m AGL
Warm colors = convergence
Cold colors =
Divergence
Contoured every
2 x 10 –3 s-1
(0 contour not shown)
23. 5 km
Notice how the cold front and 2ndary line move closer to eachother.

11. Warm colors = convergence
23.0 km
100 m AGL
Warm colors = convergence
Cold colors =
Divergence
Contoured every
2 x 10 –3 s-1
(0 contour not shown)
23. 5 km
But now there is a weakening in convergence. Hard to see 2ndary line, and also not a line of convg along the cold front.

12. Warm colors = convergence
23.0 km
100 m AGL
Warm colors = convergence
Cold colors =
Divergence
Contoured every
2 x 10 –3 s-1
(0 contour not shown)
23. 5 km
Convection initiated at 2103 just ~5km west, but definitely not looking favorable now in the IOR!

13. Here’s all 4 times together
Here’s all 4 times together. Best looking time for CI in IOR ~ 2010, certainly not at 2107 when it initiated ~5km away

14. Parcel trajectory movies
Parcels reach 100 m AGL at 1953 UTC
Parcels reach 100 m AGL at 2017 UTC
Box =IOR
Height = 1.4 km
View Point: Ahead of the cold front looking towards the North West

15. 1955 UTC
1946 UTC
So what does convg evolution have to do with anything? Here is cumulus evolution. Can see them grow…

16. 2007 UTC
2010 UTC

18. IOR convergence beings weakening
2020 UTC
Cumulus are growing still, but conv has begun weakening

19. IOR convergence beings weakening
2025 UTC

20. IOR convergence beings weakening
2034 UTC
See a marked decrease in cumulus. Toggle between this and previous slide shows it well. Lag is consistent with how long it would take a parcel at top of IOR to reach LCL.

21. IOR convergence beings weakening
2039 UTC

22. IOR convergence beings weakening
2045 UTC
2037 UTC

23. IOR convergence beings weakening
2055 UTC
Storm has formed just west of IOR

24. 2056 UTC

25. 2143 UTC

26. Why was there no initiation of deep convection within the IOR?

27. Potential Temperature at 600 m AGL
Behind cold front Ahead of cold front
P3 Track
So what’s the deal? Why is convg weakening? Here we see that temperatures behind cold front warmed more than ahead of cold front.
1956 UTC
1939 UTC
2018 UTC
2035 UTC

28. Mobile Mesonet Warming

29. Convection did not initiate in IOR because…
Weakening temperature gradient across cold front led to weaker frontal circulation
Dry air aloft made growth difficult to sustain
2007 UTC
2056 UTC
Weakening convergence

30. Why did convection initiate so close by?
Enhanced convergence?
Cold front did not dissipate?
Boundary – cold front intersection? Hints of this in satellite and radar data
Did wave pattern along front have any influence?

31. Future Work ELDORA data near CI (with Kingsmill)
Photogrammetry to map clouds
Submit paper for Special Issue
Data assimilation / Numerical modeling
Fill in data gaps
Influence of nearby developing convection
Influence of warming and convective instability

32. June 19 CI Case
Dryline near Colby, KS

33. DOW2
DOW2
XPOL
IOR #1
IOR #2
XPOL
DOW3

34. DOW2
DOW2
XPOL
DOW3

35. Deployment #2 – 21:20+ UTC 25 14
13.5

36. Deployment B Loop 1
Deployment B Loop 2

37. Z=400m
Vorticity in Color
White contours of w
wmax
Strong misocyclones – separated from w by approximately ¼ wavelength

38. Z=400m
Vorticity in Color
White contours of w
Misocyclones similar intensity to previous time
Updraft filling in along line

39. Initiation of Deep Convection
Cells apparent at 21:23 in DOW3 scans
Initiation captured by XPOL but occurs ‘behind’ DOW3 while DOW2 is in motion
Unclear if origin can be traced to features within the IOR
Aircraft may be needed to fill in the gaps DZ
DOW3 21:23

40. Later Initiation
Deployment 2 Loop 3

42. Misocyclone Loop w/raw radar data

43. 4pm CDT Dustdevil
6 pm CDT Landspout

44. Future Work
Combine wind analyses with water vapor measurements (lidar, mobile mesonets, dropsondes, satellite, MIPS, mobile radiometer, etc.)
Perform trajectory calculations to look at initiation and misocyclone formation/evolution
Cloud Photogrammetry Analysis (with Erik Rasmussen)
Submit Paper for Special Issue

45. Boundary Layer Evolution (14 June 2002)
Fine Resolution Radar Loop from UTC