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Domain 2. Western United States
Algorithms use 1° GFS Model Output


Terrain elevation in meters above sea level. Source: GFS0.25°(NOMADS-NOAA).

ALGORITHM GFS 00Z GFS 12Z
Enhanced GDI and flow - EGDI.CMD
The Enhanced GDI (EGDI) is an enhanced version of the Galvez-Davison Index (GDI) that adds the detrimental effects of low relative humidity in the 300-400 hPa layer, the detrimental effects of upper convergence, the enhancing/detrimental effects of low-level moisture convergence/divergence, and a precipitable water enhancement factor. As the GDI, it is used to identify environments favorable for shallow convection, deep convection or deep convection with the potential for heavy rainfall. Loops include the low-level (1000-850hPa) and upper level (400-200hPa) flow to account for dynamic and orographic forcing, and movement of systems. It also plots low-level moisture convergence/divergence and upper divergence, and GDI advection and flux.
 
 
Potential for severity and hail - GR02T.CMD
GR02T: Risk for Severity. GR02T highlights regions with the potential for severe convection in shades of colors. Gray suggests a risk for strong convection. But green, red and fuscia shades generally relate to marginal/slight, moderate and elevated risk, respectively. The risk increases is boxes appear over color shaded areas. This indicates that deep-layer instability is present, among other potential enhancers.
Specific Risk for Hail: The estimation of the potential for hail was included from GR02 (Galvez and Santayana, 2019), an algorithm specifically designed to detect the potential for hail in mid latitudes of South America. The risk for hail increases when red/fuscia boxes appear encircled by red/fuscia contours, and 500 hPa temperatures < -9°C. If these areas appear over color shaded areas, the risk for hail increases.
 
 

Note: These algorithms are only forecast tools, not official forecasts.

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Page last modified: Thursday, 12-Mar-2020 18:05:24 UTC