National Weather Service EXPLORING THE USE OF CONVECTIVE EXPLORING THE USE OF CONVECTIVE ALLOWING GUIDANCE TO IMPROVE ALLOWING GUIDANCE TO IMPROVE WARM SEASON QUANTITATIVE WARM SEASON QUANTITATIVE PRECIPITATION FORECASTS PRECIPITATION FORECASTS THE 2010 SPRING EXPERIMENT THE 2010 SPRING EXPERIMENT Bruce Sullivan, Faye Barthold, Richard Bann, Mike Bodner, David Novak, and Robert Oravec Hydrometeorological Predication Center Camp Springs, MD
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National Weather Service
EXPLORING THE USE OF EXPLORING THE USE OF CONVECTIVE ALLOWING GUIDANCE CONVECTIVE ALLOWING GUIDANCE
TO IMPROVE WARM SEASON TO IMPROVE WARM SEASON QUANTITATIVE PRECIPITATION QUANTITATIVE PRECIPITATION
FORECASTSFORECASTS
THE 2010 SPRING EXPERIMENTTHE 2010 SPRING EXPERIMENT
Bruce Sullivan, Faye Barthold, Richard Bann, Mike Bodner, David Novak, and Robert
OravecHydrometeorological Predication Center
Camp Springs, MD
National Weather Service
MotivationMotivation
HPC Monthly 1.00" Threat Score (June 2005 - March 2010)
0
0.1
0.2
0.3
0.4
0.5
0.6
Jun-0
5Oct Feb
Jun-0
6Oct Feb
Jun-0
7Oct Feb
Jun-0
8Oct Feb
Jun-0
9Oct Feb
•Typically a warm-season phenomenon
•Flash flooding is a leading cause of weather-related deaths in the U.S. (~130 deaths annually)
•Warm-season QPF is difficult
National Weather Service
Warm Season Forecasting ChallengesWarm Season Forecasting Challenges• Model initialization errors—limited observations on
convective scales• Mesoscale boundaries often dominate• Mishandling of MCVs• Model biases• Convection is parameterized in operational models
- Erroneous convective feedback- SREF not calibrated
0.50” in 6h @ F24
Perfec
t
SREF
National Weather Service
2010 Spring Experiment2010 Spring Experiment• GOAL: Explore use of convection-allowing
models (~4 km grid spacing)• 3 components (Severe, Aviation, QPF)• 5 week program (May 17- June 18)• Participants included researchers,
academia, operational forecasters, students• Rotation thru desks• Facilitator at each desk
National Weather Service
Models used in Spring ExperimentModels used in Spring Experiment
Experimental QPF forecasts out to 30 h
Provider Model Delta X Notes LabelCAPS WRF-ARPS
26 member ensemble
4 km Multi-model, multi-physics, multi-IC ensemble system with radar assimilation
Storm scale ensemble forecast (SSEF)
CAPS WRF-ARW 1 km 1 km resolution CAPS 1 km
NCAR WRF-ARW 3 km RUC ICs and GFS LBCs NCAR
NSSL WRF-ARW 4 km NAM ICs and LBCs NSSL
NCEP-EMC WRF-NMM 4 km NAM ICs and LBCs EMC-NMM
NCEP-EMC WRF-ARW 4 km NAM ICs and LBCs EMC-ARW
National Weather Service
The 2010 Spring ExperimentThe 2010 Spring ExperimentQPF Objective/GoalsQPF Objective/Goals
• Document strengths and weaknesses of high res QPF forecasts
• Determine appropriate ways to use operational mesoscale and experimental CAMS/SSEF models in a complementary manner
• Explore creation of probabilistic QPF products
Simply put, do the high res models add value to
the warm season forecast problem?
National Weather Service
Daily QPF ScheduleDaily QPF Schedule• Subjective verification of previous days forecast
• Synoptic overview• Produce experimental 6 hr probabilistic QPF
- .50” and 1” thresholds- Forecasts valid 18-00Z and 00-06Z
• Subjective evaluation of previous days experimental model guidance
• Afternoon briefing and discussion of daily forecasts