MEG DISCUSSION Cloud Cover and Visibility Findings from

MEG DISCUSSION Cloud Cover and Visibility Findings from the RAPv 5/HRRRv 4 Evaluation This presentation mainly shows graphics from 12 Z 11/5/19 cycle, but is representative of 11/4/19 -11/8/19 week Shannon Shields November 21, 2019

Comparison Graphics for Real-Time Parallels https: //www. emc. ncep. noaa. gov/users/meg/rapv 5_hrrrv 4/comp/ 2

Physics Development Emphasis: Sub-Grid Clouds Explicit (Resolved) Clouds/Precipitation Sub-Grid (Unresolved) Clouds RAP and HRRR use the Thompson microphysics scheme with 5 hydrometeor types Adapted from Fig. 2 of Tompkins (2009) Assume a PDF of s (saturation ratio) Retrieve Cloud Fraction, Cloud Condensate Parameterize: assume subgrid PDFs for thermodynamic variables Chaboureau and Bechtold (2002)

HRRRv 3/v 4 Alaska 11/5/19

High-level Cloud Cover Initialized: 12 Z 11/5/19 Valid: 0 Z 11/6/19 5

Mid-level Cloud Cover Initialized: 12 Z 11/5/19 Valid: 0 Z 11/6/19 6

Low-level Cloud Cover Initialized: 12 Z 11/5/19 Valid: 0 Z 11/6/19 There is more low cloud cover in HRRRv 4 than v 3 which is biggest contribution to total cloud cover (next slide) Comparing to satellite image, HRRRv 4 seems to do better, especially in Bering Sea/Strait 7

Total Cloud Cover Initialized: 12 Z 11/5/19 Valid: 0 Z 11/6/19 There is more cloud cover in HRRRv 4 than v 3 Comparing to satellite image, HRRRv 4 seems to do better, especially in Bering Sea/Strait 8

Surface Visibility Initialized: 12 Z 11/5/19 Valid: 0 Z 11/6/19 Reduced sfc visibility over central AK in HRRRv 4 compared to HRRRv 3 9

Low-level Cloud Cover (Extended) Initialized: 0 Z 11/5/19 Valid: 0 Z 11/6/19 Comparing to satellite image, HRRRv 4 seems to do better 10

Total Cloud Cover (Extended) Initialized: 0 Z 11/5/19 Valid: 0 Z 11/6/19 Comparing to satellite image, HRRRv 4 seems to do better 11

RAPv 4/v 5 Alaska 11/5/19

High-level Cloud Cover Initialized: 12 Z 11/5/19 Valid: 0 Z 11/6/19 13

Mid-level Cloud Cover Initialized: 12 Z 11/5/19 Valid: 0 Z 11/6/19 14

Low-level Cloud Cover Initialized: 12 Z 11/5/19 Valid: 0 Z 11/6/19 There is more low cloud cover in RAPv 5 than v 4 Comparing to satellite image, RAPv 5 seems to do better 15

Total Cloud Cover Initialized: 12 Z 11/5/19 Valid: 0 Z 11/6/19 There is more cloud cover in RAPv 5 than v 4 Comparing to satellite image, RAPv 5 seems to do better 16

Surface Visibility Initialized: 12 Z 11/5/19 Valid: 0 Z 11/6/19 Mixed signal for RAPv 5 RAPv 4 sfc visibility difference field 17

Low-level Cloud Cover (Extended) Initialized: 3 Z 11/5/19 Valid: 0 Z 11/6/19 Comparing to satellite image, RAPv 5 seems to do better 18

Total Cloud Cover (Extended) Initialized: 3 Z 11/5/19 Valid: 0 Z 11/6/19 Comparing to satellite image, RAPv 5 seems to do better 19

RAPv 4/v 5 CONUS 11/5/19

High-level Cloud Cover Initialized: 12 Z 11/5/19 Valid: 18 Z 11/5/19 21

Mid-level Cloud Cover Initialized: 12 Z 11/5/19 Valid: 18 Z 11/5/19 22

Low-level Cloud Cover Initialized: 12 Z 11/5/19 Valid: 18 Z 11/5/19 There is more low cloud cover in RAPv 5 than v 4 Comparing to satellite image, RAPv 5 seems to do better (West Coast) 23

Total Cloud Cover Initialized: 12 Z 11/5/19 Valid: 18 Z 11/5/19 There is more cloud cover in RAPv 5 than v 4 Comparing to satellite image, RAPv 5 seems to do better 24

Surface Visibility Initialized: 12 Z 11/5/19 Valid: 18 Z 11/5/19 Mixed signal for RAPv 5 RAPv 4 sfc visibility difference field overall, but reduced visibility off West Coast is consistent 25

Surface Visibility Initialized: 12 Z 11/17/19 Valid: 18 Z 11/17/19 Different cycle shows reduced visibility over CA coast & western CA (consistent from 11/4 -8/19) 26

Surface Visibility -Reduced visibility in RAPv 5 possibly associated w/ lowlevel cloud cover in early morning over CA -Further investigation needed Initialized: 21 Z 11/17/19 Valid: 12 Z 11/18/19 27

Low-level Cloud Cover (Extended) Initialized: 0 Z 11/5/19 Valid: 18 Z 11/5/19 Comparing to satellite image, RAPv 5 seems to do better 28

Total Cloud Cover (Extended) Initialized: 0 Z 11/5/19 Valid: 18 Z 11/5/19 Comparing to satellite image, RAPv 5 seems to do better 29

Summary • More cloud cover in RAPv 5 and HRRRv 4 (due to retention of shallow clouds/cloudy air masses & sub-grid changes) • This increased cloud cover in RAPv 5 and HRRRv 4 more closely matches satellite verification compared to operational counterparts • RAPv 5 and HRRRv 4 capture clouds in Bering Sea/Strait better than RAPv 4 and HRRRv 3 • RAPv 5 CONUS captures clouds along West Coast and Midwest/Great Lakes better than RAPv 4 • Lower sfc visibility over central AK in HRRRv 4 compared to HRRRv 3 • Mixed signal for RAPv 5 and v 4 sfc visibility difference field compared to decreased sfc visibility over AK for HRRRv 4 and v 3 difference field • Decreased sfc visibility along West Coast in CONUS RAPv 5 compared to RAPv 4 30