Map Overlays for NWS Watches, Warnings, and Advisories Help Page

MesoWest has been designed for use by National Weather Service meteorologists and other professionals for protection of life and property. Comments/suggestions for improvement may be sent to

As mentioned on the Surface Weather Maps Help Page, the Surface Weather Maps allow the user to overlay National Weather Service (NWS) watch, warning, and advisory product layers onto the surface weather map.

To access these layers click "Layer Options" on the left panel of the map interface. See the Surface Weather Map Overlay Help Page for more on how to display these layers.

The NWS layers are generated by the Iowa Environmental Mesonet. They are updated every five minutes.

To interpret the NWS product layers, use the color to determine the significance level and the code to determine the specific phenomena.

Layer Color: The layer color determines the signficance level of the NWS product issued. The colors shown are...
Warning: Warning products are colored red.
Watch: Watch products are colored orange.
Advisory: Advisory products are colored yellow.
Statement: Statement products (e.g. Special Weather Statement) are colored tan.

Product Code: The VTEC Code indicates the type of phenomenon the NWS product is reffering to. The following table contains the codes and their respective phenomena.

Product Code Phenomenon
AF Ashfall
AS Air Stagnation
BS Blowing Snow
BW Brisk Wind
BZ Blizzard
CF Coastal Flood
DS Dust Storm
DU Blowing Dust
EC Extreme Cold
EH Excessive Heat
EW Extreme Wind
FA Areal Flood
FF Flash Flood
FG Dense Fog
FL Flood
FR Frost
FW Fire Weather
FZ Freeze
GL Gale
HF Hurricane Force Wind
HI Inland Hurricane
HS Heavy Snow
HT Heat
HU Hurricane
HW High Wind
HY Hydrologic
HZ Hard Freeze
IP Sleet
IS Ice Storm
LB Lake Effect Snow and Blowing Snow
LE Lake Effect Snow
LO Low Water
LS Lakeshore Flood
LW Lake Wind
MA Marine
RB Small Craft for Rough Bar
SB Snow and Blowing Snow
SC Small Craft
SE Hazardous Seas
SI Small Craft for Winds
SM Dense Smoke
SN Snow
SR Storm
SU High Surf
SV Severe Thunderstorm
SW Small Craft for Hazardous Seas
TI Inland Tropical Storm
TO Tornado
TR Tropical Storm
TS Tsunami
TY Typhoon
UP Ice Accretion
WC Wind Chill
WI Wind
WS Winter Storm
WW Winter Weather
ZF Freezing Fog
ZR Freezing Rain