Section 9: Weather Services — Decoding METARs and TAFs Like They'll Be on the Test (They Will)

REPORTS state now; FORECASTS predict. Both get graded on the same scale: VFR needs ceiling above 3,000 ft AND visibility above 5 SM; Marginal VFR spans 1,000-3,000 ft and 3-5 SM; IFR sits below 1,000 and 3. For a drone pilot bound to 3 SM and cloud clearances, 'the marginal VFR and VFR is what we're going to be looking for.' The classification hinge from last section repeats because the exam leans on it: scattered clouds do NOT make a ceiling - broken, overcast, or vertical visibility only.

His stack: aviationweather.gov first; apps second (Kittyhawk - which doubles for LAANC; AeroWeather free; Hover 'kind of, unfortunately, a dying app'); the Flight Service line 1-800-WX-BRIEF for a live briefer. The three briefing types: STANDARD - the complete picture, 'what you would call in the morning of your flight'; ABBREVIATED - the update after you already had a standard; OUTLOOK - when departure is 6+ hours away. Ground truth comes from AWOS/ASOS automated stations (the difference explicitly not tested) plus human augmentation where staffed.

Hourly, worldwide-standard, with SPECI issues when conditions lurch within 30 minutes. The spine: STATION (4-letter ICAO - K-USA, C-Canada, L-Europe), DATE/TIME as DDHHMM Zulu, WIND as true direction + knots with G-gusts ('20016G22KT' = from 200 at 16 gusting 22), VISIBILITY in SM, SKY as coverage code + hundreds of feet - append two zeros, BKN009 is a 900-ft broken layer - TEMP/DEWPOINT in Celsius with M for minus ('19/M15'), ALTIMETER as four digits reading 30.03.

Then REMARKS, the exam's favorite alley: A01/A02 station types (02 can tell rain from snow); SLP's three digits wanting an inferred leading '10' or '9' by plausibility (103 -> 1013.2; 992 -> a genuinely severe 992); the T-group's tenth-degree temps; PK WND with time; PRESFR = pressure falling rapidly; RAB18 = rain began :18 past; P0018 = 0.18 inches this hour; WSHFT flagging frontal passage; and the $ - the station confessing it needs maintenance: 'I probably shouldn't trust it.'

Intensity: minus = light, nothing = moderate, plus = heavy; VC = vicinity. Descriptors: SH showers, TS thunderstorm, FZ freezing, BL blowing. Precipitation: DZ drizzle, RA rain, SN snow, GR hail (grele), GS snow pellets, PL ice pellets, UP unknown. Obscurations: BR mist (brume), FG fog, FU smoke (fumee), VA volcanic ash, DU dust, SA sand, HZ haze. Storm flags in remarks: CB cumulonimbus and TCU towering cumulus - the two clouds worth fearing. Lightning distance in three tiers: unqualified = within 5 miles, VC = 5-10, DSNT = beyond 10. Beyond this list: AC 00-45H holds the complete decoder ring.

The Terminal Aerodrome Forecast covers bigger airports, 24-30 hours ahead, issued four times daily at 00/06/12/18Z. Same field grammar as the METAR, plus a validity line (issuance time and validity WINDOW are different fields - a tested distinction) and change groups: FM + datetime = a rapid regime change from that moment; TEMPO + window = conditions under an hour at a time; PROB40 = a 40% chance; AMD = an early amendment that shortens the cycle; P6SM = 'plus', better than 6 miles. His demo TAF is the 2018 Boston Marathon day - a masterclass in bad news arriving on schedule.

The practical reading: scan for 'mist, rain, wind, high wind, very low visibility... and I'm seeing what time they're going to happen.' Exam notes: CB is the only cloud type a TAF names, and the FM-group wind extraction is a stock question.