About this tool
helisiapp lite helps you translate reported cloud heights at a nearby weather-reporting station into heights relevant to your facility, which is frequently at a different elevation. Cloud bases in a METAR or TAF are given as height above ground level (AGL) at the reporting station. If your facility sits higher than that station, the same cloud deck is effectively lower above your facility — and vice-versa.
The adjustment applied to every layer is:
adjusted AGL = reported AGL − (facility elevation − station elevation)
For example, facility 8OH9 sits at 937 ft. Its nearest METAR and TAF both happen to be KLUK at 472 ft — 465 ft lower. A reported BKN010 (broken at 1,000 ft) becomes broken at 535 ft when adjusted for 8OH9.
- A ceiling in aviation is the lowest broken (BKN) or overcast (OVC) layer — these are tagged accordingly.
- We also adjust and display the lowest few (FEW) and scattered (SCT) layers, even though they aren't ceilings.
Cloud / ceiling height flags
Every adjusted cloud layer (and the ceiling) is flagged with the blue / red / pink icons based on its height above your facility:
- Blue — adjusted height below 1500 ft. Example:
BKN015 reported at a station 200 ft lower adjusts to 1,300 ft.
- Red — adjusted height below 1000 ft. Example:
BKN010 at KLUK (465 ft lower) adjusts to 535 ft for 8OH9.
- Pink — adjusted height below 500 ft. Example:
OVC008 at a station 400 ft lower adjusts to 400 ft.
The flag is based on the adjusted height, not the reported height, so a layer can change color once corrected for your facility's elevation.
Visibility flags
Prevailing visibility is flagged with the same blue / red / pink icons, on both the METAR and each TAF forecast period:
- Blue — visibility of 5 SM or less. Example:
5SM BR or 4SM -RA.
- Red — visibility less than 3 SM. Example:
2 1/2SM HZ or 1 1/2SM -SN.
- Pink — visibility of 1 SM or less. Example:
1/2SM FG or M1/4SM FG.
Values reported as P6SM ("greater than 6") or metric 9999 are above all thresholds and carry no flag. All forms are parsed — whole miles, fractions (3/4SM), mixed (1 1/2SM), and 4-digit metric.
Thunderstorm & lightning alert ⚡
A yellow lightning-bolt banner appears on the METAR and on any TAF period containing thunderstorm or lightning activity:
- At the station — a thunderstorm group in the body, e.g.
TSRA, +TSRA, TSSN, or bare TS.
- In the vicinity —
VCTS (thunderstorm 5–10 nm out).
- Lightning in remarks — e.g.
OCNL LTGICCG OHD, FRQ LTG VC; distant strikes show as LTG DSNT (10–30 nm) and are labeled distant.
The sensor-inoperative flag TSNO is deliberately ignored — it does not indicate activity.
Icing-potential alert ❄
A blue snowflake banner appears on the METAR only (TAFs carry no temperature) when both conditions are met:
- Temperature is at or below +5°C, read from the report (e.g.
02/00 = +2°C, M03/M05 = −3°C), and
- There is precipitation or water-based visible moisture — rain, snow, drizzle and similar (
RA, SN, DZ, FZRA, -SHRA…) or fog / mist (FG, BR).
Example trigger: 2 1/2SM -SN BR … 02/00 — light snow and mist at +2°C. Dry obscurations such as haze (HZ), smoke (FU) and dust/sand do not trigger it, even when cold.
Wind alert ⚑
A green windsock banner appears on the METAR and on any TAF period when the wind is 20 kt or greater — by either the sustained speed or the gust:
- Sustained — e.g.
24021KT (240° at 21 kt).
- Gusting — e.g.
31015G27KT triggers on the 27 kt gust even though the mean is 15 kt.
- Variable-direction winds (
VRB25G45KT) and metric units (MPS / KMH, converted to knots) are handled.
The banner reads e.g. "Winds 21 kt, gusting 31 kt (240°)". Calm or light winds (under 20 kt) are not flagged.
Facility and station data come from the FAA / aviationweather.gov station database; live METAR and TAF text come from aviationweather.gov. The raw report is always shown alongside the adjusted figures so you can verify the source.
