Q2 Workshop

William E. LawrenceDevelopment and Operations Hydrologist

Arkansas-Red Basin River Forecast CenterTulsa, OK

June 28, 2005

Multi-sensor QPE:Current Operational Capabilities, Issues

and Perspectives from ABRFC view

ABRFC QPE History

May 1992 – HAS software delivered to ABRFC

March 1993 – Formal HAS operations begin

August 1993 – StageIII software operational, ABRFC switches to using MAPX vs old MAP

June 1994 – Start of ABRFC online archive of QPEs, largest in NWS

June 1996 – ABRFC investigates COE precipitation software, and starts porting code for our use

July 1996 – ABRFC finishes P1 & performs testing

November 1996 – ABRFC switches to using P1 almost exclusively

Why P1?

The P1 code, using a simple scientific algorithm, allowed ABRFC forecasters an easier faster method to come up with reliable QPE’s

Outperformed StageIII both in speed, ease of use, and quality of product

Did not have severe underestimation of rainfall in cooler season months

Had added functionality such as easy ways to “make” snow, remove AP, save changes, etc.

Code and results were forwarded to OHD

LMRFC StageIII Study~ -33% error

•(Stellman, 2000)

ABRFC Process1 Study~ + 2% error

Satellite Data – Do we use it?

ABRFC receives satellite data every hour

Experience has shown its better than nothing, but often misplaced and amounts are unreliable

ABRFC forecaster may use when all else fails, but this occurs only very rarely

P3 has ability to draw in polygon area to swap to satellite data anywhere in basin

Overall, we much prefer radar/gage mix of data

Satellite Data – Do we use it?

Satellite Data – Do we use it?

Gage Data – How do we use it?

Approximately 1200 automated gages in ABRFC area

At any given time, approximately 400 in “bad gage list”

Only ASOS gages are heated, and even they have trouble with frozen precipitation

Oklahoma mesonet data is extremely valuable, well-run mesonet

GOES data also valuable, but maintenance sometimes lacks

Schoolnet, Alert systems least desirable as little maintenance is performed after initial setup.

Overall, gage data is EXTREMELY important to ABRFC in coming up with acceptable QPEs

Gage Data – How do we use it?

ABRFC feels that human interaction is necessary for sufficient QC of gage data. What appears good at first look may turn out to be poor data, ie under-reporting, reporting at wrong hour, etc.

Bad data isn’t always obvious until you start adding up many hours

Gages constantly being moved into and out of “bad gage list”

Most important HAS function at ABRFC is QCing hourly QPEs

Current Issues

Continue to have serious deficiencies/difficulties in producing accurate QPEs in winter events

Continue to have serious deficiencies with radar estimates in mountainous areas; luckily we have few areas like this

Radar estimates of QPE at ranges greater than 75 miles continue to be problematic during cool season

List of problems almost exactly the same as described in ABRFC memo to OHD in 1993

Current Perspective

ABRFC feels that well known issues should be addressed before we dive into probabilistic QPEs.

“If we can’t even produce a good deterministic QPE year round, then why are we attempting to develop a probabilistic QPE?”

Why not MPE?

MPE is great improvement over StageIII

Output is roughly equivalent to P3

Older versions were not user friendly in frozen precipitation events, nor did they remember changes made

Still problems with performance of MPE vs P3

Radar artifacts are still part of MPE

ABRFC continues to work with OHD so that we may adapt using a national software

MPE Artifact

MPE Artifact