PURPOSE:OVERVIEW
OF THE 2006 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 and USAF C-130
aircraft
DURATION OF PROGRAM:
First possible flight centered around 00Z January 20, 2006; program
is expected to end March 20, 2006. C-130s will be available between 31
Jan - 24 Feb; G-IV will be available between 20 Jan - 20 March
OPERATIONAL USE:
All adaptively taken data will be used in operational analysis and
forecast products by major NWP centers, including NCEP
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 (Currently the model is T126L28, i.e. Triangular truncation 126 on 28 sigma levels).
NEAR REAL TIME EVALUATION
RESULTS:
Expected to appear on the EMC WSR2006
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 and Reference
section
of Global Ensemble Forecasting web
page,
a recent review paper, and
the
WSR99
and WSR00 and the National
Winter Storms Operations Plan web pages
CREDITS:
FUNDING PROVIDED BY: NWS, NOAA/OAR; G-lV flight hours provided
by the NOAA Aircraft Operations Center.
TARGETING METHOD DEVELOPED BY: C.H.Bishop and S.J.Majumdar of
Penn State University and University of Miami, in collaboration with
EMC personnel.
COORDINATION: Naomi Surgi
COLLABORATORS: Mel Shapiro, Marty Ralph
CASE SELECTION
GENERAL CONSIDERATIONS:
Potential societal impact and amount of forecast uncertainty
associtated
with individual forecast weather events (precipitation, wind,
etc)
over the continental US, including Alaska
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
calculations
need to be run 60-72 hours before flight time.
FORECAST TIME WINDOW. The time elapsed between observation time
and verification time. This is equal to the lead time of the forecast
that
the data collected in the future is to improve.
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
REALTIVE MEASURE OF PREDICTABILITY. 500 hPa height
ensemble
mean forecast with a measure of predictability and associated
probabilistic
forecast:
http://wwwt.emc.ncep.noaa.gov/gmb/targobs/yzhu/relpred.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 VERIF.
TIME
VERIF. REGION DESCRIPTION
PRIORITY (High, Medium or Low, considering severity of event
and available observational resources. Not every day are there high or
medium priority events.)
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:
FORECASTER INPUT. WFO offices should contact their focal point
within their region with their request. The focal points from the NWS
Regions
and NCEP Service Centers will then provide their input to the SDM desk
at NCEP/NCO.
CENTRAL COORDINATED LIST. SDM prepares a final prioritized list
of the selected cases.
SCHEDULE:
SDM expects to receive the requests from the Regions and NCEP Service
Centers by 9 am EST.
CONTACT INFORMATION:
Regional focal points and NCEP Service Centers should send an e-mail
with their request to sdm@noaa.gov.
301-763-8298 (or 301-763-8000/ext. 7361)
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 verification
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:
For the request of SDM the IBM opertators release the job to compute
the most sensitive areas/flight tracks corresponding to the requested
forecast
cases. Based on the evaluation of the sensitivity results SDM makes a
decision
whether to fly and if so which flight track(s) to use.
SCHEDULE:
Requests for flights centered around 00Z the next day have to be
prepared
and transmitted to CARCAH by 1:30 pm EST (18:30 Z 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:
Sdm@noaa.gov, 301-763-8298 (or 301-763-8000/ext. 7361)
Zoltan.Toth@noaa.gov, (301) 763-8000/ext. 7596
AIRCRAFT OPERATIONS
NOAA G-lV:
Out of Honolulu, Hawaii, by NOAA/AOC, contact person is Jack Parrish
813 833-3275, jackparrishweather@netscape.net
USAF C130:
Out of Anchorage, Alaska, by USAF Reserve, contact person is Valerie
Hendry
Valerie.Hendry@keesler.af.mil
CONTACT INFORMATION:
carcah@nhc.noaa.gov, (305) 229-4474