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A Quarterly Publication
of the National Weather Service Lower Mississippi River Forecast Center
Slidell, Louisiana
| David Reed, Hydrologist In Charge |
Vol. 1 No. 1, Autumn 1997 |
Suzanne Van Cooten, Editor |
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| During my 2-year tenure as Hydrologist in Charge (HIC),
the Lower Mississippi River Forecast Center (LMRFC) and the National Weather
Service have undergone major changes. Three new hydrologists will join
the LMRFC staff in November, bringing the office to a fully modernized
staffing level of 16. Our technology has changed from making "batch"
forecast runs remotely on a mainframe computer to interactive river forecasting
locally on scientific workstations.
To make optimum use of the additional staffing and new technology, LMRFC
operations and services have changed and will continue to change at a rapid
pace. This winter, LMRFC will implement a second shift and open 16 hours
per day, 7 days a week. With these extended hours, full Hydrometeorological
Analysis and Support (HAS) operations will be
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implemented, forecasts will be updated more frequently,
and LMRFC will be staffed for 24 hour operations more often.
These changes have occurred at such a rapid pace, we could not easily
keep everyone informed of our activities and plans. This newsletter, LMRFC
Crawfish Tales, will be one way we will keep our customers such
as the U.S. Geological Survey (USGS), Army Corps of Engineers (COE), Tennessee
Valley Authority (TVA), and others abreast of changes and events at LMRFC.
The LMRFC Crawfish Tales will be provided to you quarterly
and will contain information on accomplishments and activities planned
for the future at the RFC. We welcome any comments or ideas you may have
to assist the LMRFC in serving you, our public.
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| The LMRFC is staffed weekdays from
6:00 AM to 4:00 PM and from 6:00 AM to 3:00 PM on weekends and holidays.
At 7:00 AM, hydrologists begin preparing daily river forecasts by simulating
runoff using the Sacramento Soil Moisture Accounting
(SAC-SMA) model. The Dynamic Wave Operational (DWOPER)
model and Lag/K routing are used to route water downstream on most rivers.
Across the LMRFC area, a total of 2890 river/ rainfall stations are used
in our modelling efforts. All operations and modelling efforts of the LMRFC
are performed on a computer network consisting of five Hewlett-Packard
(HP) servers.
A total of 18 river forecast products and 18 flash flood guidance products
are issued daily. All river/ flood forecasts contain QPF covering the next
24 hour period, 12 UTC-to 12 UTC. The LMRFC prepares forecasts for 3 days
at 120 locations and 5 days at 25 locations. Weekly 28-day forecasts for
eight locations along the Ohio/ Mississippi are issued each Wednesday.
Upstream RFCs and TVA provide daily flow forecasts to LMRFC at seven
locations: 1) from the North Central RFC for the Mississippi at Chester,
IL, and Big Muddy at Murphysboro, IL; 2) from the Ohio RFC for the Ohio
at Smithland Dam, IL; 3) from the Arkansas Basin RFC for the Arkansas at
Pine Bluff, AR, and Red at Fulton, AR; and 4) from TVA for Barkley Dam
and Kentucky Dam releases. These flow forecasts are used as input to LMRFC
hydrologic models.
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Hydrometeorological Analysis and Support (HAS)
operations started routine shifts in September of 1996. The HAS function
is made up of 3 HAS forecasters working one shift per day, 7 days per week.
RFC hydrologists augment the HAS unit staffing. Ths HAS operation was created
to assist the LMRFC/WFO with hydrometeorological activities which are critical
to flood operations. A major task of HAS personnel is to analyze and quality
control rain gage reports and hourly precipitation estimates from WSR-88D
radars which cover the RFC area . This quality control function includes
Stage III software which allows HAS forecasters to remove erroneous rainfall
estimates due to radar reports of anomalous propagation and/or hail contamination.
The Stage III software combines the estimates from 26 WSR-88D into a mosaic
of radar rainfall estimates for the entire LMRFC. The rainfall mosaic is
used in our local hydrologic models.
The HAS forecaster assesses the hydrometeorological situation over the
LMRFC area and briefs the staff during the day on the latest developments
vital to hydrologic operations. The HAS forecaster assists in coordination
of Quantatative Precipitation Forecast (QPF) from each of the WFO's and
prepares the data for input into the hydrologic models. The forecaster
produces two products, the Hydrometeorological Discussion (HMD) and the
Hydrometeorological Coordination Message (HCM). The HMD consists of information
used for coordination between the LMRFC and the WFO. It includes the flood
potential for the LMRFC area for the next 24 hours. The HCM outlines those
basins which may go into flood based on WFO QPF, allowing offices to determine
if a Flood watch or warning is required. Throughout the day, the HAS forecaster
quality controls hourly observed precipitation reports and maintains proficiency
in hydrologic operations by working hydrologic forecast shifts.
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| A part of the modernization of the
NWS is expanding the staff at RFCs. With this staffing, an RFC will improve
the hydrology of its area and staff the office routinely 16 hours per day,
7 days a week. The LMRFC staffed with 8 people in the early 1990's currently
has 13 people. When three additional people arrive next month, LMRFC will
reach its fully modernized staff level of 16 people.
The mangement staff includes the HIC, Dave Reed, the Development and
Operations Hydrologist (DOH), Bob Stucky, and Administrative Support Assisstant,
Nana Miestchovich.
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Senior hydrologists Marty Pope, Randy
Rieman, Mike Shields and Eric Jones, are technical and operational leaders
in the office.
Hydrologists Angelo Dalessandro, Laurie Hall, Ethan Jolly, Julie Jones,
E.J. Leche, and Janet Spurgeon complete the hydrologic forecast staff.
Jeff Graschel, Senior Hydrometeorological and Analysis Support (HAS) forecaster,
is the technical leader in implementing the HAS functions at the RFC. John
Kuhn and Suzanne Van Cooten serve as HAS forecasters and provide a vital
link between the WFO forecasters and the RFC hydrologists.
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The LMRFC is one of thirteen River Forecast Centers (RFC) spanning the
conterminous States including the Alaska RFC. The LMRFC hydrologic service
are covers approximately 220,000 square miles of drainage and includes
most or parts of twelve different states.
Daily river and flood forecasting responsibility covers the Mississippi River
Basin and all its
tributaries draining below Chester, IL, including 1) the Big Muddy River
in Illinois below Murphysboro, 2) the lower Ohio River and tributaries
at and below Smithland Dam, IL,including the Cumberland River Basin
below Barkley Dam , KY, and the Tennessee River Basin and tributaries
(excluding the mainstem at and above Kentucky Dam, KY), 3) the lower
Red River Basin below Fulton, AR, and 4) all gulf of Mexico drainage
between and including the Pascagoula and Escatawpa basins in Alabama
and Mississippi to the Calcasieu River Basin of southwest Louisiana.
River and flood forecast responsibility for all tributaries of the Tennessee
River rests with LMRFC. All forecasts for the mainstem of the Tennessee
River, at and above Kentucky Dam, KY, are prepared by the Tennessee
River Valley Authority.
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| We here at the LMRFC are going through
some exciting times when it comes to our presence on the World Wide Web.
The LMRFC now provides three forecasts for the lower Mississippi River
along with daily flash flood guidance for our area of responsibility. This
comes under a new and exciting format which uses many of the latest web
tools.
The three Mississippi River forecasts include a daily
five day river height and flood forecast, a weekly
seven day forecast, and a weekly
extended forecast which goes out 28 days in
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the future. The five day forecast
is updated every day by 10:30 AM Central Time with the seven and 28 day
forecasts going out every Wednesday by 2:00 PM and 4:00 PM, respectively.
We are now featuring hourly Stage
III precipitation mosiacs which are quality controlled and
updated several times per day.
Future plans for the home page include daily river forecasts using interactive
river basin maps and technical papers from our staff.
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| Quantatative Precipitation Forecasts
(QPF)s are prepared by 17 Weather Forecast Offices (WFO)s in NWS Southern,
Central and Eastern regions. With each morning forecast package, WFO staffs
prepare 24-hour QPF values from 12 UTC to 12 UTC for each of their hydrologic
basins using WIN QPF software and national QPF guidance. By mapping rainfall
isohytes over these defined basins for four 6-hour intervals, the WFO staff
is able to produce a formatted 24 hour QPF product with the click of a
mouse button. These QPF products are also generated routinely with the
evening forecast packages in the Southern and Central region WFOs for 00
UTC to 00 UTC . Eastern region WFOs issue evening QPF products when hazardous
weather is anticipated or at the request of an RFC.
All LMRFC forecasts include this basin specific QPF for 24 hours into
the future. The HAS forecaster coordinates QPFs among individual
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offices to assure values which are
consistent between neighboring basins and prepares the QPF data for input
into the hydrologic models in the NWSRFS system.
Hydrologic forecasters issue 3 to 5 day stage forecasts based on observed
precipitation and QPFs from the WFOs. Occasionally, a forecast will exceed
flood stage based on WFO QPF but remain below flood stage with zero QPF.
For these situations, the hydrologic forecaster will issue a forecast on
the expected stage and the time the point will go into flood. The HAS forecaster
then issues an HCM outlining the affected Hydrologic Service Area (HSA),
the river system, and the hydrologic forecast point. For these locations,
the WFO with hydrologic forecasting responsibility may issue a Flood Watch
(FFA) or a Flood Warning (FLW) based on this forecast guidance from the
LMRFC.
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