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.

Surface Analysis 1900 UTC

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…

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.

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

Sounding near CI 1935 UTC LCL 3 km AGL

High Temporal Resolution Loop

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’

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.

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.

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.

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!

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

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

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

2007 UTC 2010 UTC

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

IOR convergence beings weakening 2025 UTC

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.

IOR convergence beings weakening 2039 UTC

IOR convergence beings weakening 2045 UTC 2037 UTC

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

2056 UTC

2143 UTC

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

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

Mobile Mesonet Warming

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

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?

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

June 19 CI Case Dryline near Colby, KS

DOW2 DOW2 XPOL IOR #1 IOR #2 XPOL DOW3

DOW2 DOW2 XPOL DOW3

Deployment #2 – 21:20+ UTC 25 14 13.5

Deployment B Loop 1 Deployment B Loop 2

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

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

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

Later Initiation Deployment 2 Loop 3

Misocyclone Loop w/raw radar data

4pm CDT Dustdevil 6 pm CDT Landspout

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

Boundary Layer Evolution (14 June 2002) Fine Resolution Radar Loop from 1300-1900 UTC