Weather briefing – Thursday 11 June 2009 NCSU – team members… Note: Data from many of our usual forecast tools (e.g., Bufkit, SREF, high- resolution simulated radar, SPC mesoanalysis page, etc.) were not available in this retrospective mode… would show other/additional plots

5 Ops Objectives

Decisions/Things to Keep in Mind (as a forecaster) Mission has to decide where to fly and what category of objective they’re fulfilling The ER-2 needs 24 hours’ notice to fly The ER-2 crew has strict rest policies – 12 hours after missions – 14 if mission is 8 hours – No more than 3 days without a down day Calls need to be made about current missions with past and future missions in mind (for the above reasons) The Citation should stay out of >35 dBZ ER-2 takeoff no go if: – 25 knots maximum steady or 35 gusts regardless of dir. – 15 knot maximum crosswind – 1/4 mile minimum visibility – Lightning within 5 NM

ForecastMission Briefing Forecast through 4 days into the future Forecast for all possible mission areas and objectives Pertinent topics: Initiation TIMING (If precip) Mode Location Know GPM tracks (handled elsewhere?) Call in to NWS and WRB to corroborate Type of mission Aircraft involved Flight plans and strategy Instrument strategy ER-2 Call: 24 hrs notice Make call for later days to incorporate rest/down requirements Update What has changed since briefing? Is there model agreement? Less formal, direct interaction with mission Change flight plan/location Delay 24-hr notice for next day? T-4 hoursShort-term forecast for the next 4-12 hours (with respect to proposed mission) Go/No Go Delay Change of flight plan/location **Ops**If forecast support is viable (ie, has slept)** Monitor current situation for mission and safety concerns Modify flight plan and convey to Jan & pilots (for science reasons or something like ~35dBZ limit for Citation) **Post-Ops**If forecast support hour range forecast for next mission (if any) Review mission and make updated call for next mission if needed

Overview Day -1 (W 10 th ): Stationary front to north, zonal flow aloft. Humid & unstable with moderate shear. Organized convective storms in afternoon, some severe Day 0 (Th 11 th ): Instability and shear appear to have increased somewhat this morning, ingredients in place for organized convection. MCV to W this morning Day 1 (F 12 th ): Weak front drops southward during the day, possibly enhanced, organized convection over area Day 2 (Sa 13 th ) and beyond: Weak front to south of area, & weaker shear: Weaker, less organized convection. Potential for offshore convection with stalled front.

Day -1 surface analysis: 15 Z 10 June 2009

Day -1 (10 June) MCS move east, passed to south of study area, dissipated over GA New convection developed ahead of MCV, some severe (hail, wind) with these cells

Day -1 (10 June, UTC)

NAM 500-mb Z analysis: 00 Z 11 June 2009

Nashville sounding, 00 Z 11 June 2009

Analysis, Day 0 (11 June) Shear and instability have increased this morning (e.g,. ~2400 J/kg BNA at 12Z); MCV to west One MCS to our north this morning as well, in addition to MCV to west Diurnal heating possible this morning, further increasing severe threat Timing: MCS/MCV over TN, moving east. Storms in area by 18 Z? Severe threat increased

GOES-13 IR, 1215 Z 11 June

GOES-13 VIS, 1330 Z 11 June

NAM 500-mb Z,  analysis: 12 Z 11 June 2009

HPC surface analysis: 12 Z 11 June 2009

NAM SLP, theta-e 1000, 500Z valid: 12 Z 11 June

Nashville sounding, 12 Z 11 June 2009

SPC Day 1 outlook, valid 13Z 11 th – 12Z 12 th Primary: Hail, wind

SE Radar Mosaic, 0-14 UTC 11 June

SE Radar Mosaic, 14 UTC 11 June

SE Radar Mosaic, with NLDN, 14 UTC 11 June

Day 0 Forecast (11 June) Organized convection, MCV to west will approach study area today; MCV in NAM initial condition New convection could fire ahead of MCV currently over western TN (similar to yesterday) Timing: Convective storms likely to develop between 17-20Z across study region (from west) Aircraft threats: Lightning, afternoon, Convection (winds, hail, lightning) KAVL after 17Z

NAM 12-h CAPE, CIN valid 12 Z 11 June

NAM 18-h fcst, 6-h QPF, valid 18 Z 11 June

NAM 18-h fcst sounding, valid 18 Z 11 June KAVL WBZ: ~9200 ft Freezing level ~11,000 Sfc-6 km shear ~ 30 kt

Day 1 Forecast (Fri 12 June) Weak cold front approaches, opportunity for organized convection ahead of front Timing of weak front difficult to establish; merges with lee trough late in day (by 00Z Sat) Now appears that passage will be around mid-day Only weak drying, stabilization behind front, more so in wake of any organized convection that forms As front stalls along coast, offshore convection potential increases early morning Sat and Sun (Day 2,3)

F36 NAM SLP, theta-e, 12Z 12 June

F48 NAM SLP, theta-e, 00Z 13 June

Days 2-3 (Sat, Sun) Following weak cold front passage day 1, focus for convection shifts southward, and to offshore waters Shear, instability will weaken, but sufficient instability to support diurnal orographic showers Frontal boundary advances northward again towards study area, potential for more showers Days 2, 3 (Sat, Sun) GFS shows MCV-type feature bringing strong storms to area Sun, but skeptical given convective origin of forcing in model forecast

60-h NAM SLP, theta-e, 500 Z 12 Z 13 June

Days 4+ NW flow storms possible, shortwave passes north of area Saturday (model variability) With ridge axis to west (aloft), NW flow regime becomes established Longer term: Ensemble indicates very strong ridge developing over central US, study area in NW flow but dry with synoptic subsidence

60-h GFS 500-mb Z, SLP valid 12Z Sat 13 June

84-h GFS 500-mb Z, SLP valid 12Z Sun 14 June Spurious system?

120-h GFS 500 Z, SLP valid 00Z Tue 16 June