Presentation on theme: "Updates to LW Forecast System Alan Fox Fox Weather, LLC 726 13 th St. Fortuna, CA 95540 805 469-1368 707 725-8013 April 12, 2007."— Presentation transcript:
Updates to LW Forecast System Alan Fox Fox Weather, LLC 726 13 th St. Fortuna, CA 95540 805 469-1368 707 725-8013 firstname.lastname@example.org April 12, 2007
Developments Since Dec 2006 Upgrades to MtnRT Installed WRF and configured Forecast System for California regions MtnRT+WRF
Upgrades to MtnRT – Execution Speed Revised MtnRT to execute 2 times faster. Revised Mapper to execute 100 times faster. Entire MtnRT portion of the forecast sequence runs at Fox Weather in about ½ hour for all of NW Calif, or all of W and central Oregon, and about 15 minutes for S Calif and NW Calif.
Upgrades to MtnRT–Time and Resolution Revised Mtn1hrInterp to include radiation physics calculations, updated each minute of the 24hr period. Revised Mtn1hrInterp to extend out a full 7 days, i.e.Day0-Day6, inclusive. MtnRT and Mapper now runs at 1.5 km (down from 2.5 and 2.0 km, respectively).
Upgrades to MtnRT - Physics Mtn1hrInterp: Designed a model that calculates solar angle for every minute of the day for every day of the year at all latitudes/longitudes. Calculates altitude and azimuth of the sun. Mtn1hrInterp: Includes atmospheric extinction related to solar angle. Mtn1hrInterp: Includes heat budget calculations of atmosphere and ground over a land surface in order to generate realistic diurnal curves of solar radiation throughout the 24hr day down to time resolution of 1 minute. Mtn1hrInterp: Now blends the Tmax, Tmin, and GFS temperatures at intermediate hours with the energy budget curve to establish final shape of the curve for each 24hr day. Improved calculation of LW due to combination of rain and outputs from the Fuzzy Logic LW model. Implemented separate calculations of forecasted moist layer and inversion base height for each 0.5 degree latitude for forecast sounding interpolated from GFS
Sample Forecast Temperature/Dewpoint Curve over a 24hr day – Sample 1
Sample Forecast Temperature/Dewpoint Curve over a 24hr day – Sample 2
Sample Final Temp/Dewpt/LW Forecast for Sand Canyon, Orange County, Calif
WRF Implementation WRF=Weather Research and Forecast System – UCAR (University Corporation for Atmospheric Research). WRF uses some of the same well-tested algorithms from MM5, but is a different model, running on a server, rather than the clusters that are needed by MM5. New WRF forecast server was installed at Fox Weather on Mar 14 th. Currently Implemented: Dual Opteron 64 bit (2 processors, but can include two more processors). Preliminary results: –Download of GFS files for initialization takes 30 minutes, directly from NOAA servers in netCDF format. –<20 minutes to run each forecast day… gives about 2 hours to run the full 7 days. Job starts at 2:00am, and finishes about 4:30am daily, including time for downloads of netCDF files. –36 km resolution, time resolution of forecast: 1 hour –Grid domain 48.0 to 31.0N -125.0 to -105.0 –We have a running 60 day archive of the GRIB WRF forecast data. WRF is currently being ported into Fox Weather’s Yosemite weather display system via a cron job each morning for processing and map viewing. Some examples are presented. GEMPAK, and open-source graphics package is also being used to display WRF forecasts. An example is presented. We plan to use WRF as input to MtnRT. This will take us with a start grid of 36 km, and MtnRT grid to 1.5 km.
WRF Products Available Available preducts relevant to disease weather forecasting and LW forecasting are: –Rain –Temperature –Dew Point Temperature –RH –Wind Speed\Direction (i.e. wind barbs)
WRF Product Samples CURRENT DOMAIN FOR FOX WEATHER’S WRF (INCLUDES S BORDERS OF ARIZONA AND CALIFORNIA AND NORTH SHORE OF GULF OF CALIF)
Some Preliminary Comparisons: WRF and MtnRT Skin Temp Ramona, CA station 33.03/-116.88 42hr forecast: 92F, observed Tmax 76 Riverside, CA 42hr forecast: 88, observed Tmax 81
Some Preliminary Comparisons: WRF and MtnRT Skin Temp Ramona, CA station 33.03/-116.88 48hr forecast: 74.5F, observed Tmax: 76. Riverside, CA 48hr forecast 75, observed Tmax 81
Nearby Station Observations for 4/4/2007 RIV=Riverside, RNM=Ramona, ONT=Ontario
CONDITIONS AT 850 MB (1500 M) AND 700 MB (3000 M) AT 00Z APR 5, 2007, (1600 PST APR 4) Note the east (downslope) wind at 700 mb (nominally 3000 m) and SE (marginally downslope) at 850 mb (1500 ft) iI II
Getting Higher Resolutions from WRF and Implications for MtnRT 1) WRF 36 km data is too smooth to give realistic nighttime skin temperatures during current southern California frost events (4 th and 13 th April). 2) We will be producing a 7 km WRF forecast over small sub-domains, and testing for N Calif to determine the increase in Tmin forecast skill realized by the higher resolution grid.. 3) WRF Help advises us that the resolution of nested grids should not be less than about 1:5. 4) It is unreasonable to go from 100 km GFS to 12km WRF or 4km WRF, but it is reasonable to go from 100km GFS to 36km WRF then nest a 7.2 km WRF subgrid. It is unreasonable to go from 36km WRF to a 4 km subgrid with one nest.
Our Plans for: The Weather Research and Forecast Model (WRF) Model Use WRF data as input for MtnRT. –Note: Regional forecast errors in MtnRT are related to using an initial data set that has too large a grid resolution. Regional variations that could be resolved are not because the higher resolution data from WRF is not used. WRF is considered as the state-of-art model for midwestern US forecasting (mesoscale convective systems and squall lines). There is more to learn about WRF’s capabilities. WRF takes a long time to do nested model runs (7.2 km). Reading the WRF-EMS Manual We currently don’t have WRF temperature data that adequately represents surface temperature data covering at 24 hr period. Skin daytime temp too hot, skin nighttime temperature too smooth for Tmin, 1013 mb day and night temperature too smooth and not able to represent variability in day and night temperature related to topography. We DO have MtnRT data that adequately represents a 24hr period for particular locales. Alan Fox to go to WRF_EMS training at UCAR. Training concentrates on the meteorological principles behind WRF. Purpose: to learn how to best represent parameters from WRF relating to LW at smaller resolution in the midwest and west, e.g. 7 km.
Some Benchmark Times for OR/S_WA and NORCAL One-Way Nest 9 hrs 10 min from start to finish (including data download (30 min), processing and post-processing for OR/S_WA (2 processors). One-Way Nest 7 hrs 10 min from start to finish including downoad, processing and post- processing for OR/W_WA (4 processors). One-Way nest 6 hours for NORCAL-sized region (2 processors), and 4.5-5.0 hours for NORCAL- sizedd region (4 processors).
Summary With its 36 km grid, WRF adds a new and necessary intermediate step to the forecasting system that bridges the gap between the 100 km native GFS data and the 1.5-2 km resolution required by disease weather forecasting. WRF still allows the simulations out 7 days which other models (NAM) do not. WRF 36 km can run on a single server (64 bit, dual or quadruple Opteron), and is currently running in the dual Opteron configuration at Fox Weather\Fortuna.