AVIATION METEOROLOGY Initial Forecasters Course AVIATION WEATHER SUMMARY

AVIATION METEOROLOGY Initial Forecasters Course

AVIATION WEATHER SUMMARY CI IFC: Av Wx Smry 2

AVIATION WEATHER SUMMARY Importance § Climatology of a station. § Average weather for the station § Guide to a forecaster in respect of behaviour of each element of weather phenomena not only in terms of frequency of occurrence but also about time. § Major input for a forecaster in his decision tree steps. § Essential input for nowcasting. CI IFC: Av Wx Smry 4

AVIATION WEATHER SUMMARY (Refer: IAP 3202, Ch – XI) General Information § Exist for all IAF flying stations. § Updated every fifth year. § Compiled under the following headings: ü ü ü Preface. & Contents, List of graphs, tables and diagrams/charts. Geographical and Topographical Information. Seasonal Features as a separate chapter for each season. Monthly Statistical Data as a separate chapter for each month of that season. ü Climatological Information, consisting statistical averages & monthly weather statistics and extremes. ü Reference CI IFC: Av Wx Smry 5

GEO & TOPOGRAPHICAL INFO § Detailed information on geography & topography of station is mentioned. § Emphasis on location of sources of pollution like townships, railway yards, industries & significant water bodies in and around airfield which can lead to atmospheric obscurity or low clouds. § Significant topographical details such as hillocks which can influence surface wind/weather is specifically highlighted. CI IFC: Av Wx Smry 6

SEASONAL FEATURES § Season wise pattern of weather for: ü ü Winter (Dec-Mar) Pre-Monsoon (Apr-May) Monsoon (Jun-Sep) and Post-Monsoon (Oct-Nov) § Frequency of adverse weather spells: ü ü Pptn, T'stom, Low Clds. Vis <3000 m & <1000 m. § Seasonal T’ storm characteristics: ü ü Peak period of occurrence, Location of synoptic feature , local parameters and forecasting hints Bar graph for each month. § Wx state for the months of respective season. § Detailed Aviation Wx Hazards CI IFC: Av Wx Smry 7

MONTHLY FEATURES § Broad description of month wise wx features. § Monthly statistical data including tables. § Detailed Aviation Wx Hazards month wise with Frqs, Extremes & SD. § Summary of main aviation wx hazards - month wise. § Monthly wx graphs ( last 10 yrs) § Description of chief adverse weather features (most sig wx hazard) of month. Selection based on Frq & longest mean duration. § Abnormally prolonged spells of adverse wx. § Simultaneity of adverse wx at base and diversion. § PB means (1000’, 2000’, 3000’ 5000’ and 10000’) and monthly wind roses (surface) § Comfort index § Forecasting hints CI IFC: Av Wx Smry 8

CLIMATOLOGICAL INFORMATION § Climatological tables are prepared using data sets of 30 years or more. § Means & extremes of: ü ü ü QFF, Dry & Wet Bulb Temp RH (0300 UTC and 1200 UTC) Max & Min Temp. 24 h rainfall & monthly averages § Temporal Variations: ü Synoptic hour QFE, ü Dry & Wet bulb Temperature ü RH diagram with Isopleths at suitable interval § Pentad Normals : ü Max & Min Temperatures (along with SD) and ü QFF of 03 and 12 UTC CI IFC: Av Wx Smry 9

MONTHLY WEATHER GRAPH § Gives at a glance time distribution of various hazardous wx phenomena & other met info at station as a composite picture. § Comparative study of such graphs highlights important features of the weather over the area such as : ü Intensity, ü Persistence, ü Susceptibility of incidence, ü Preferred hours of occurrence, ü Variations – diurnal, spatial and seasonal, ü Local peculiarities, ü Relationship between weather & synoptic situations ü Simultaneity of occurrence amongst neighbouring airfields. § Provide a much better picture of the overall weather at station than climatological tables and descriptions, and would prove a valuable aid for the realistic planning of terminal operations. CI IFC: Av Wx Smry 10

WIND ROSES CI IFC: Av Wx Smry 11

PLOTTING OF WIND ROSES • Wind roses are prepared for synoptic hours viz: 0230, 0530, 0830, 1130, 1430, 1730, 2030 and 2330 IST • Percentage frequencies reduced to eight point of compass along with total frequency and frequencies of individual speed group for a period of time are to be plotted. • Frequency of calm wind is to be plotted in the centre of circle against total frequency. CI IFC: Av Wx Smry 12

WIND ROSE Station: lat/long Month: Jan Ht: (m) Time: 0530 IST 335 NW 295 W Directions 245 N – 335 -025 NE – 026 -064 E – 065 -115 SW SE – 116 -154 S – 155 -205 SW – 206 -244 W – 245 -295 NW – 296 -334 CI 08 A-05 B-03 04 A-03 B-01 N 10 A-05 B-05 025 03 A-01 B-02 205 03 A-02 B-01 S IFC: Av Wx Smry NE 065 07 A-05 B-02 102/142 0 Most Prevalent Wind 05 A-02 B-03 155 E 115 Speed in kno A – 1 -5 B – 6 -15 C – 16 -30 D – 31 -45 E - >45 CALM SE 2 nd Most Prevalent Wind 13

WIND ROSE Station: lat/long Month: Jan Ht: (m) Time: 0530 IST N 335 NW 295 W NE 7. 04% 5. 63% 2. 81% 245 025 2. 11% 3. 52% 2. 11% 205 S 065 4. 92% 71. 83% 0% SW Most Prevalent Wind 155 E 115 SE 2 nd Most Prevalent Wind In Jan morning hour winds are calm otherwise Nly prevails CI IFC: Av Wx Smry 14

CRITERIA FOR WEATHER SUITABILITY CLASSIFICATION (MSI NO. 01/02) CI IFC: Av Wx Smry 15

INTRODUCTION • Statistics of weather state are valuable for operational planning. • Since fighter and transport operators are governed by different set of weather criteria , it is necessary , that these statistics provide meaningful information for planning both types of operations. • Distinction between rated and unrated weather is of fundamental value for flying activity. • Weather minima for pilots , are with reference to surface visibility and cloud ceiling. CI IFC: Av Wx Smry 16

TIME BLOCKS • Six blocks of 2 hr duration each, starting from 0600 hr to 1800 hr (0600 -0800 hr, 0801 -1000 hr. etc) will be considered individually for classification into Good, Marginal and Bad weather days. • Similarly six blocks starting from 1800 hr will be classified for night. • Classification of period 2200 -0600 hr is optional. CI IFC: Av Wx Smry 17

TIME BLOCKS • Day and Night are divided into six hr each. • Day 0600 -1200 h & 1200 -1800 h • Night 1800 -2400 h & 0000 -0600 h. CI IFC: Av Wx Smry 18

PARTS OF THE DAY CI TIME SPAM (HOUR) PART OF DAY ABBREVIATION 04 -06 EARLY MORNING EM 06 -08 MORNING M 08 -10 LATE MORNING LM 10 -12 EARLY AFTRNOON EAN 12 -14 AFTERNOON AN 14 -16 EVENING EV 16 -18 LATE EVENING LEV 18 -20 EARLY NIGHT EN 20 -22 NIGHT N 22 -24 LATE NIGHT LN IFC: Av Wx Smry 19

CRITERIA FOR WEATHER Bad Weather (B) § Prevalence of or Warning Issued for any of the following will be termed as Bad Weather : Visibility <1 km Ceiling (> 4 Oktas) 300 m or less Weather TS/DS/Heavy Rainfall/ Showers/ Snow/Squall/Gale Optional Surface Winds > 30 kt Surface Temp >40 0 C CI IFC: Av Wx Smry 20

CRITERIA FOR WEATHER Marginal Weather (M) § Prevalence of or warning or CMR issued for anyone or more of following will be termed as marginal weather: Visibility 1 km≤V≤ 3 km Cloud Base 300 m<Base <450 m Weather Light Rain/Drizzle/ Mist/Haze Optional Gusty SW- speed conditions & Temp criterion 400 C or Sub-Zero Temp to be defined locally. Good Weather (G) None of the above. CI IFC: Av Wx Smry 21

CLASSIFICATION OF WEATHER When any of the following criteria has occurred in 2 time blocks out of 3 blocks (each 2 hr duration), it will be classified as : CONDITIONS CI RESULTANT BAD GOOD/MARGINAL WILL BE CALLED BAD M B/G M MARGINAL B/M G G GOOD IFC: Av Wx Smry 22

CLASSIFICATION OF WEATHER If each block is different it will be classified as marginal. CONDITIONS BAD CI MARGINAL RESULT GOOD IFC: Av Wx Smry MARGINAL 23

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