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Public Information Statement 18-01 Updated

National Weather Service Headquarters Silver Spring MD

425 PM EDT Mar 13 2018


To:      Subscribers:

         NOAA Weather Wire Service

         Emergency Managers Weather Information Network


         Other NWS Partners and NWS Employees


From:    Brian Gross, Acting Director

         NCEP/Environmental Modeling Center


Subject: Updated: Soliciting Public Comments on the Proposed

         Upgrade of the NLDAS Operational System through

         April 09, 2018


This Public Information Statement (PNS) was updated to change

the day latency in the North American Land Data Assimilation

System (NLDAS) v2.0 from 4.5 (as noted in the original PNS) to



The Environmental Modeling Center (EMC) is proposing to upgrade

the NLDAS during summer of 2018. The NWS is seeking comments on

this proposed change through April 09, 2018.


On February 01, 2018, EMC began disseminating experimental real-

time NLDAS v2.5 products to users. This was announced in an

evaluation letter that was distributed on February 07, 2018. 

The official evaluation page is located at:


Real-time data:


EMC NLDAS output (NLDAS 2.5):


National Centers for Environmental Prediction (NCEP) Central

Operations (NCO) operational output (NLDAS 2):


Near real-time graphical imagery from the NLDAS v2.0 (NLDAS

drought monitor) is available at:


Real-time graphical imagery from the NLDAS v2.5 (NLDAS drought

monitor) is available at:


Historical data archive:


NLDAS v2.5:


NLDAS v2.0:

EMC LDAS website:


The North American Land Data Assimilation System (NLDAS v2.0) is

being upgraded to real-time NLDAS v2.5. The purpose of NLDAS

v2.5 is to close the 3.5 day latency in NLDAS v2.0. To achieve

this goal, the NLDAS team uses the newly upgraded NAMv4 (North

American Mesoscale forecast system version 4) and its associated

analysis component, which runs at an hourly cadence, as the

meteorological forcing backbone to NLDAS v2.5. The precipitation

data come from global Climate Prediction Center (CPC) gauge-

based daily precipitation, stage II hourly precipitation and

NAMv4 forecast hourly precipitation, respectively. The technical

details can be seen in Section 2.3.1 of NCEP LDAS white paper:


Expected benefits from this upgrade will provide actual real-

time products to governmental agencies, academia and private



The NWS will evaluate all comments to determine whether to

proceed with this upgrade. If approved, an SCN will be issued

giving 30 days notice of the implementation date.


Send comments on this proposal by April 09, 2018 to:

Jack Kain

NCEP/EMC/Model Physics Group, Chief


National Public Information Statements are online at: