OVERVIEW
OF THE 2000 WINTER STORM RECONNAISSANCE PROGRAM

MEANS:
By taking supplemental adaptive observations over the northeast Pacific ocean

OBSERVING PLATFORMS USED:
15-20 dropsondes per mission released by NOAA G-lV (based in Anchorage, Alaska, 5-6 flights) and USAF C-130 (based in Honolulu, Hawaii, 10 flights) aircraft

DURATION OF PROGRAM:
First possible flight centered around 00Z January 17, 2000; program is expected to end in mid February

OPERATIONAL USE:
All adaptively taken data will be used in operational analysis and forecast products by major NWP centers

EVALUATION OF DATA IMPACT:
By comparing operational analyses/forecasts with those from a parallel analysis/forecast cycle from which all adaptively taken data will be removed

NEAR REAL TIME EVALUATION RESULTS:
Expected to appear on the EMC WSR2000 web page

EXPECTED RESULTS:
On average a 10-20% reduction in largest rms forecast errors for preselected weather events. Errors for individual events can be reduced by as much as 60-80%.

REFERENCE MATERIAL:
See related papers listed in Reference section of EMC Targeted Observations Project web page, and WSR99 web page

CREDITS:
FUNDING PROVIDED BY: NWS/NCEP, NWS/OM and NOAA/OAR; G-lV flight hours provided by the NOAA Aircraft Operations Center and Naomi Surgi.
TARGETING METHOD DEVELOPED BY: C.H.Bishop and S.J.Majumdar of Penn State University, in collaboration with EMC personnel.
 
 

CASE SELECTION

GENERAL CONSIDERATIONS:
Potential societal impact and amount of forecast uncertainty associtated with individual forecast weather events

CASE DEFINITION:
Verification time (yyyymmddhh) and center location (lat/lon) of 1000 km radius verification region for which forecast is to be improved

TIMELINE:
FLIGHT PLANNING. Because for proper aviation planning flight requests have to be issued 24 hours in advance of take-off, flight planning usually takes place 36-48 hours in advance of the actual flights.
OUTLOOK. For general planning purposes, the flight facilities also require a general outlook for the second day (i. e., whether a flight is expected or not). To prepare such an outlook, sensitivity calcualtions need to be run 60-72 hours before flight time.
FORECAST TIME WINDOW. The time elapsed between observation time and verification time.
GEOGRAPHICAL LOCATION. Because it takes more time for the impact of the data to reach the eastern part of the US than the western areas or Alaska, the time window will necessarily be longer for verification regions defined over the eastern US. Given observations over the northeastern Pacific, the time window over the western US and Alaska will typically be between 24 and 48 hours, while for the eastern US it will be between 48 and 96 hours.

FORECAST LEAD TIME:Flight planning/Outlook lead time plus forecast time window. Typically the forecast lead time for case selection will be in the following ranges:
WEST COAST & ALASKA: 60-120 hours.
EAST COAST: 84-144 hours.

NOTE. Most of the time, the same or similar cases considered in the previous day's outlook planning will be selected (then with a 24-hour shorter lead time) next day again, and the sensitivity calculations will be repeated for final flight planning, using new ensemble data.

OBJECTIVE GUIDANCE PRODUCTS:
Beyond general forecast material, the following, ensemble-based objective guidance products can be used for the identification of forecast weather events associated with large uncertainty and large societal impact:
ENSEMBLE MEAN AND SPREAD. For Mean Sea Level Pressure and 250 hPa height fields for the NCEP ensemble:
http://wwwt.emc.ncep.noaa.gov/gmb/targobs/targ/hgtmenu.html
PROBABILISTIC QUANTITATIVE PRECIPITATION FORECASTS. PQPF forecasts of 24-hour accumulated precipitation for different thresholds:
http://wwwt.emc.ncep.noaa.gov/gmb/targobs/prcp/prcphome.html
INTERCOMPARISON OF ENSEMBLE MEANS FROM DIFFERENT CENTERS.

REQUEST FORMAT:
Each selected feature is listed on a separate line in the order of increasing lead time:
ABS. PRIORITY        REL. ORDER      VERIF. TIME       VERIF. REGION      DESCRIPTION
ABSOLUTE PRIORITY (High, Medium or Low, considering severity of event and available observational resources. Not every day are there high or medium priority events.)
RELATIVE ORDER (1 marking first, 2 second, etc. event to be considered that day)
VERIFICATION TIME  (yyyymmddhh)
VERIFICATION REGION (lat/lon for 1000km radius area; if more than one area, listed on separate lines, from west to east)
DESCRIPTION OF WEATHER EVENT/NATURE OF UNCERTAINTY (in few words)

PERSONNEL:
FIELD INPUT. NWS WFO forecasters can provide their input (possibly through their headquaters) to the HPC medium-range forecaster on duty.
CENTRAL COORDINATED LIST. The HPC medium-range forecaster on duty prepares a final prioritized list of the selected cases.

SCHEDULE:
FIRST GUIDANCE. HPC expects to recieve case selection input from the field by 14:30 pm EST. Their prioritized list is prepared by 3 pm EST.
FINAL LIST. Modifications can be suggested by the field next day by 8:30 am EST. HPC prepares an update if necessary by 9 am EST.

CONTACT INFORMATION:
Field offices/headquaters should call the HPC medium-range forecaster on duty at: (301) 763-8146 or (301) 763-8000/ext. 7350
 
 

SENSITIVITY CALCULATIONS

PURPOSE:
To identify areas over the northeast Pacific from where adaptively taken data can have the largest impact on forecast quality in the preselected verification region at the verification time.

METHODOLOGY:
Based on the use of nonlinear ensemble forecasts generated operationally on a daily basis at NCEP and ECMWF. Ensemble members are linearly combined in such a way that their variance is reduced at observation time over the observational area. The same linear combination is used at final time to see where the variance in the transformed ensemble is reduced. All possible predesigned flight tracks are considered and the one where the dropsondes are expected to reduce forecast error variance at verification time within the verification region most is selected.

OUTLOOK:
Beyond preparing flight requests for flights taking place the next day, an outlook for the second day (i. e., whether a flight or no flight is expected with the G-lV and/or C130) also has to be prepared.

PERSONNEL:
2000. EMC personnel who developed the method (in collaboration with Penn State Univ. Scientists) will run the programs and train SDM personnel in its use.
2001. SDM personnel will run the codes with assistance from EMC.
2002. Expected to be run fully operationally by SDM.

SCHEDULE:
Requests for flights centered around 00Z the next day have to be prepared and transmitted to CARCAH by 1 pm EST (18Z the day before flight takes place, more than 24 hours in advance of take-off.) The outlook for the second day have to be transmitted at the same time.

CONTACT INFORMATION:
Zoltan.Toth@noaa.gov, (301) 763-8000/ext. 7268
Istvan.Szunyogh@noaa.gov, (301) 763-8000/ext. 7276
Sdm@noaa.gov, (301) 763-8000/ext. 7361
 
 

AIRCRAFT OPERATIONS

NOAA G-lV:
Out of Anchorage, Alaska, by NOAA/AOC, contact person is Sean White

USAF C130:
Out of Honolulu, Hawaii, by USAF Reserve, contact person is Jon Talbot

CONTACT INFORMATION:
carcah@nhc.noaa.gov, (305) 229-4474
 
 

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