NOAA National Weather Service Weather Forecast Office

Weather forecasting for aviation is an extremely challenging and important aspect of the NWS mission. Aviation weather forecasts are used in planning and executing over 100,000 flights in the United States every day. The tremendous impact of weather conditions on takeoff and landing operations requires that forecasts always be as specific and timely as possible.

The primary duties of the aviation forecaster at NWS Marquette include:
1) maintaining a continuous weather watch across Michigan's Upper Peninsula
2) issuing regularly scheduled aviation forecasts
3) responding to anticipated changes in meteorological conditions which may impact aviation by amending aviation forecasts.

NWS Marquette issues Terminal Aerodrome Forecasts (TAFs).

Terminal Aerodrome Forecasts

Concept

The NWS aviation terminal aerodrome forecast (TAF) is a concise statement of the expected meteorological conditions significant to aviation to impact an airport during the 24-hour forecast period. An airport is defined as the area within 5 statute miles of the center of an airport's runway complex.

NWS Marquette issues TAFs for the Marquette Sawyer International Airport (SAW) and the Houghton County Memorial Airport (CMX). (The Marquette County Airport (MQT) TAF was discontinued when the airport moved to Sawyer.) The aviation forecaster at NWS Marquette maintains a watch of weather conditions at these locations and issues amended forecasts in addition to the scheduled TAFs when observed or expected conditions meet amendment criteria for the specified forecast elements and are expected to persist, or in the forecaster's judgment, the TAF is unrepresentative of current or expected weather.

Format

The necessary components of a TAF include a location identifier group, a date/time of forecast origin, a valid period date/time group, forecast group(s) for the forecast period, and an end of message designator (=), which trails the last forecast group.

Content  

The forecast elements are entered into the body of the initial forecast period and then are followed by any succeeding time-divider (FM), forecast change (BECMG and TEMPO), and probability forecast (PROB30/PROB40) group(s). The order in which these forecast elements are encoded (if they are necessary) is as follows: wind, visibility, significant weather, cloud (or vertical visibility into a surface-based obscuration), and nonconvective low-level wind shear.

An example of a scheduled TAF:

ETTAA00 KMQT 241730
TAF
KMQT 241730Z 241818 18005KT 5SM HZ BR SCT045
     FM1930 14010KT P6SM VCTS SCT035CB TEMPO 2022 BKN025
     FM2200 16015G25KT P6SM VCTS BKN025CB TEMPO 2202 VRB25G40KT
      1SM +TSRAGR BKN010CB OVC020
     FM0200 30012KT 5SM -SHRA OVC025 WS020/23040KT PROB30 0204
      2SM TSRA BR BKN010CB OVC020
      BECMG 0507 P6SM NSW SCT025
     FM1400 32012G22KT P6SM BKN040=

Examples of unscheduled TAFs:

ETTAA00 KMQT 211125 AAA
TAF AMD
KMQT 211233Z 211312 20010KT 5SM -SN OVC015 TEMPO 1315 P6SM NSW
      SCT015 OVC030
      BECMG 1315 19010KT P6SM NSW BKN015 OVC100 TEMPO 1518 5SM
      -SN
      BECMG 1718 19012KT SCT015 OVC100
     FM0500 22008KT 5SM -SN BR BKN025 OVC040=

NOTE: This is the first amendment to the 211212 TAF issued at 1125Z

ETTAA00 KMQT 162330 CCA
TAF
KCMX 170225Z 170024 36012KT 1 1/2SM -SNPE BR FEW000 OVC003
      WS015/21030KT TEMPO 0003 36012G25KT 1/2SM +PEFZRA FG VV001
     FM0300 34012G25KT 1/4SM +SNFG VV001 TEMPO 0306 1SM SNPE BR
      SCT000 OVC003
     FM0600 33012G25KT 1/2SM SHSN FG VV003
     FM1100 32010G20KT 4SM -SHSN 0VC008
     FM1600 31010KT P6SM VCSH OVC015 PROB40 1620 5SM -SNSH=

NOTE:  This TAF is the first correction to the 170024 forecast issued at 2330Z--the only way you can tell is from the date/time of forecast origin and the contraction CCA.

NWS Marquette issues four scheduled SAW and CMX TAFs valid for 24 hours each day: between 2320-2340Z, 0520-0540Z, 1120- 1140Z, and 1720-1740Z valid 00Z-24Z, 06Z-06Z, 12Z-12Z and 18Z-18Z respectively.