The National Blend of Models (or NBM)
is scheduled to be upgraded to version 3.2
in November of 2019.
This upgrade includes the first official probabilistic weather elements,
along with new weather elements for: aviation, fire weather, water resources,
winter weather, tropical weather, and marine applications.
Version 3.2 adds several new model components
and a new forecast domain for Guam.
The most significant change in version 3.2
is the addition of probabilistic weather elements.
These are spread across several service areas and include:
probability of precipitation (or PoPs),
quantitative precipitation forecasts (or QPF),
snow and ice, daily maximum and minimum temperatures,
and standard deviations for
daily maximum and minimum temperatures,
wind speed, and wind gusts.
These elements are bias corrected and forecasts extend out 96 to 264 hours,
depending on the element.
NBM version 3.2 adds several precipitation-related weather elements.
As we previously mentioned,
CONUS receives a full distribution of 6, 12, and 24-hr
probabilistic QPF, along with 1-hr PoPs.
Alaska and Puerto Rico receive 6-hr probabilistic QPF,
along with 6 and 12-hr PoPs.
New winter weather elements include probabilistic snow and ice accumulation,
including both percentiles-for-accumulation and probability-of-exceedance
for several amounts.
NBM version 3.2 adds several weather elements in support of aviation, including:
visibility, ceiling, cloud base, and turbulence elements.
The additions of CAPE and probability-of-thunder support convective forecasts.
New weather elements for marine forecasting include:
water temperature, categorical freezing spray,
12-hour probabilities of both precipitation and thunder over the oceanic domain,
6-hour QPF, and winds at 30 and 80 meters.
Solar radiation and precipitation duration fields
are being added to the blend
to provide more fire weather guidance.
Tropical wind speed and direction over the oceanic domain
now include data from the hurricane WRF, the HMON,
and a gridded version of the official
National Hurricane Center forecast.
New model components in version 3.2 include:
Deterministic and ensemble ECMWF
for all weather elements in the oceanic domain,
and for significant wave height in all domains;
High-resolution American and Canadian short-range
deterministic and probabilistic guidance
for maximum and minimum temperatures;
Global and regional ACCESS models
from the Australian Bureau of Meteorology;
Additional weather elements from the Canadian Regional Ensemble Prediction System
over CONUS and Alaska;
and LAMP core weather elements.
RTMA 2.7 adds significant wave height analyses
in the Alaska, Hawaii, and Puerto Rico domains
so that the NBM model components in these regions
can be bias-corrected.
When RTMA 2.8 is implemented,
significant wave heights in the Great Lakes will be bias corrected
and added to the NBM.
NBM version 3.2 adds Guam
as a new domain with fourteen weather elements
derived from regional and global deterministic
and ensemble model components.
In summary,
the NBM is scheduled to be upgraded to version 3.2
in November 2019.
It includes the first probabilistic blended guidance for
temperature, precipitation, snow, and ice.
There are more blended forecast products for
aviation, marine, water resources,
fire weather, winter weather, and tropical weather.
Version 3.2 uses more model components to improve guidance,
and introduces a new Guam domain.