Chapter 13 Meteorology

Tornado forecasting

1884 with Finley using US army signal corps with 950 reporters gathering data, 1886 with program discontinued with tornado banned for fear of public panic, 1940s to 1950s with air force meteorologists fawbush and miller developed method for forecasting tornadoes with tinker air force base with 6 atmospheric conditions that preceded tornado outbreak with reappearing 5 days later and issued 1st tornadoes forecast that were primary issued for military installations, US weather bureau adopted tornado forecasting for public distribution, severe local storm warning center established in OK with 1952 ban on tornado abolished

World meteorological organization (WMO)

founded in 1878 as international meteorological organization (IMO) with headquarters in switzerland the agency of the united nations, wordle weather watch with coordinate efforts of 188 nations and territories in global weather monitoring program, global observing system

Global observing system

more than 20 geostationary and polar orbiting satellites, 11,000 land stations, 4,000 ships at sea, greater than 3,000 reconnaissance and commercial aircraft, radar, 1,300 radiosonde stations, greater than 1,400 drifting and 600 moored buoys, data transmitted to 3 WMO centers where maps/charts created, forecasts, prepared, maps/forecasts sent to regional/national meteorological centers

National center for environmental prediction (NCEP)

responsible for US forecasts

Weather forecasting entails

acquisition of present weather data, graphical depiction of the state of the atmosphere, analysis of data and maps, prediction of the future state of the atmosphere, dissemination of weather information and forecasts to the public

Surface weather observations

thousands of stations across the US monitor surface weather with national weather service, stuff of other government agencies with federal aviation administration and state departments of transportation, private citizens/businesses in businesses in cooperation with the NWS, across the ocean and great lakes with measurements by ships, data gathered for prepping weather maps and forecasts, exchange with other nations, use by aviation and maritime, observations taken same time everywhere to accurately represent state of atmosphere with coordinated universal time, NWS weather forecasts offices at 122 US sites

NWS weather forecast offices at 122 US sites

each has a designated area of forecast and warning responsibility, NWS WSR-88Ds with dual-polarization technology connected to offices, FAA and DOD operate 37 more WSR-88Ds, ASOS, AWOS, NDBC, CoCoRaHS, COOP, USHCN

Automated surface observing system (ASOS)

877 ASOS units in continual operation, reports temperature, pressure, winds, precipitation accumulation, visibility, obstruction to vision, present weather, sky condition

Automated weather observation system (AWOS)

similar to ASOS, about 270 FAA-owned and 1,400 non-federal operating

National data buoy center (NDBC)

operates about 250 automated weather stations, buoys and stations at lighthouses, fishing piers, and offshore oil platforms, important for hurricane warning system

Community collaborative rain, hail, and snow network (CoCORaHS)

volunteers measure/report rain, hail, and snow within areas of US, Canada, Puerto Rico, US Virgin Islands, Bahamas, greater than 20,000 observers

NWS cooperative observer program (COOP)

greater than 8,000 stations through US, operated by volunteers, provide daily precipitation and temperature readings

US historical climatology network (USHCN)

sub-network of COOP network, stations picked based on spatial coverage, record length, data completeness, and historical stability, quantify the national and regional scale temperature changes in the US. data from volunteers networks fed to NWS forecast offices

Radiosondes

radio equipped instrument package carried aloft by a balloon by transmitting to a ground station upper air information with max altitude of about 100,000 ft, winds are computed by tracking balloons drift using GPS, 92 radiosonde observation (RAOB) stations with data measurements from surface to 30 km+, mapped by station model

Isobars

lines of equal air pressure, drawn at 4 mb intervals, analysis reveals locations of anticyclones and cyclones, troughs and ridges, horizontal pressure gradients

Surface weather maps

cyclone centers are indicated by L with closely spaced isobars around cyclone indicate steep pressure gradient and strong winds with front originate at storm centers, anticyclone centers mapped as H with usually relatively weak horizontal pressure gradients shown by the widely spaced isobars resulting in a weak/calm winds, synoptic surface maps drawn every 3 hrs for north america with every 6 hrs for the N hemisphere

Upper-air weather maps

plotted on constant-pressure surfaces, height contours labeled in meters above sea level drawn at 60 intervals, altitude of pressure surface varies because of mean temperature differences with air pressure drops more rapidly in cold air than in warm due to density differences, isotherms plotted as dashed lines with 5 degree intervals, contours with troughs and ridges, wind blow across isotherms produce air advection, NCEP weather prediction center issues upper-air maps 2x each day at 0000 and 1200 UTC, computerized data management systems with being spurred by deluge of real-time weather information, AWIPS

Center of ridge

relatively warm with high height contours, H, linked to a warm-core anticyclone at the surface

Center of trough

relatively cold with low height contours, L, linked to a cold-core extratropical cyclone at the surface

Cold air advection

winds blow from colder to warmer locations

Warm air advection

winds blow from warmer to colder locations

Advanced weather interactive processing system (AWIPS)

receives and organizes ASOS data, analysis and guidance products from NCEP, allows meteorologists to display, process and overlay images, graphics, and other data, used by NWS offices and river forecast centers, AWIPS II is the newest edition

Numerical weather

weather prediction center, climate prediction center, numerical weather forecasting, HRRR, NAM, GFS, GFS, ensemble forecasting, model comparison, work to consolidate mesoscale modeling under NCEP

Weather prediction center

short range with hourly forecasts, medium range with up to a week of extended outlooks

Climate prediction center

long range with multiple day outlook or multi-seasonal outlook

Numerical weather forecasting

computers programmed with numerical model of the atmosphere with equations relating wind, temperature, pressure, water vapor concentration with mutual change with time, current data used to predict atmospheric properties a short time into future with becoming a starting point for yet another short time into the future

High resolution rapid refresh (HRRR)

covers CONUS and alaska, makes forecasts every hour to 18 hrs

North american mesoscale (NAM)

covers north america, makes forecasts every 6 hrs to 3.5 days

Global forecast system (GFS)

covers globe and operates at higher resolution for early and lower resolution for later forecast periods, first 8 days run at 28 km grid-spacing, last 8 days run at 70 km, GFS finite volume cubed sphere dynamical core was launched in 2019

Coupled forecast system (GFS)

covers globe and includes 2 day interaction between GFS and an ocean model, development of a new seasonal forecast system

Ensemble forecasting

conduct many runs of 1 model/different models with each run based on slightly different initial conditions with average of different forecasts is created, GEFS with global forecasts every 6 hrs to 16 days, SREF with out to 3.5 days and SREF replaced by GEFS, HREF with 3 km resolution currently to 36 hrs, NAEFS with collaborative effort between US NWS, meteorological service of canada, national meteorological service of mexio

Model comparison

comparison made among forecasts produced by different models, if agree the forecast issued with a high level of confidence, if inconsistent the forecast is considered unreliable

Mesoscale modeling systems under NCEP

goal is to rapidly-updated with convection-allowing ensemble system using FV3, new high resolution ensemble system would replace the current NREF, HRRR, and NAm model, more sophisticated formulations to capture high-impact weather features with heavy precipitation and severe weather events

Tropical cyclone forecasting

initially US army signal corps in charge of observation/forecasting cyclones, 1874 with first plotted hurricane the 28th of september, 1890 with forecasting moved to civilians with little attention paid to tropical cyclones, 1898 with spanish-american war increasing interest with fear of hurricane destroying US fleet increased weather stations in Caribbean, technological advances, split between NHC and CPHC, SLOSH, tropical cyclone wind probability textual and graphical products, hurricane watch, hurricane warning, watches and warnings also issued for tropical storms, uncertainty in track forecast and considerable tropical cyclone threat required forecasters to over-warn the public, cost of evacuation high but outweighs benefits of being prepared, dramatic decline in hurricane fatalities during 20th century, trend would continue except for few hurricanes with very high fatalities (Katrina and Maria)

Technological advances

invention of radio allowed ship to shore reports, 1930s upper air monitored, 1950s with weather radar at coastal stations, 1960s with remote sensing via satellites began, buoys provide information, aircraft now deploy dropsondes to receive sounding from inside storm

National hurricane center (NHC) and central pacific hurricane center (CPHC)

NHC responsible for issuing statements for tropical cyclones in Atlantic basin and eastern pacific basin to 140 W with watching for development from 15 may to 30 november, SLOSH model, prepared and distributed hurricane watches/warnings for public, conducts research on hurricane forecasting techniques, sponsors public awareness programs, CPHC activated when tropical cyclone develops in central pacific (W of international dateline), predicting track and intensity with every 6 hrs and up to 120 hrs that tracks the forecast based on climatology, numerical models, and experience of forecaster

SLOSH

NOAA uses an ensemble of SLOSH model forecasts to predict storm surge inundation

Hurricane watch

sustained winds of at least 74 mph, associated with tropical, subtropical, or post-tropical cyclone, issued 48 hrs prior to onset of tropical storm force winds

Hurricane warning

hurricane conditions, associated with a tropical, subtropical, or post-tropical cyclone, expected, issued 36 hrs prior to onset of tropical storm force winds

Aviation weather center (AWC)

kansas city MO with issue warnings, forecasts, analysis of weather conditions for aviation interests that supports FAA, flight delays cost both individuals and the economy, forecast for weather conditions that may impact domestic and international airspace during subsequent 24 hrs, analyze weather hazards for aircraft in flight

Example of products for AWC

graphical forecasts for aviation, SIGMETs, AIRMETs, traffic flow management convective forecast

Storm prediction center (SPC)

norman OK, monitors potential development of severe local storms over contiguous US monitoring fire weather, blizzards, and heavy rain, convective outlooks identify areas expected to experience severe and non-severe thunderstorms in 1-7 days with specifying areas of severe thunderstorm risk and issued for tornado, severe hail, and wind, mesoscale discussion issued as threat becomes better defined, issues severe thunderstorm/tornado watches

River forecast centers (RFC)

13 centers located nationwide, greater than 8,000 river gauging stations, primary goal minimizing loss of life and periorty damage caused by floods, provides public with river reservoir, flood forecasts, monitors and forecasts river discharge and stage, national water center

National water center

NOAA-led interagency collaboration, provides new generation of water information and services, foundation is national water model

Marine forecasting with ocean prediction center (OPC)

issues forecasts, warnings, guidance for mariners, fisheries, recreational boaters, analysis and forecasting cover conditions with winds, waves, fog, and ice accretion

space weather forecasting with space weather prediction center (SWPC)

boulder CO, observe and forecast solar geophysical events that impact technological systems that monitors phenomena with aurora, solar wind, and solar cycle, scales rank severity from 1 to 5 by being based on possible effects of current and future space weather conditions on systems with satellite operations and radio communications

Forecast skill

declines rapidly after 48 hrs with minimal beyond 10 days with missing/inaccurate observational data, failure of stations to detect all mesoscale and microscale circulation systems, imprecise equations in numerical models, 1 to 5 day forecasting with slow by steady improvement with better understanding of atmospheric processes and create more realistic models of earth-atmosphere system, larger and faster computers, more reliable and sophisticated observational tools, denser weather observational networks worldwide, computers won’t replace

Computers won’t replace meteorologists

best forecasters rely on knowledge, experience, intuition, good forecaster begins with previous and current observations, analyze and interpret computerized predictions, forecasts adapted to regional and local circumstances with localized lake-effect snow prediction

Long-range forecasting

climate prediction center with climate outlooks map where probability of total precipitation and temperature expected to depart from normal, long range forecasting relies on teleconnections, 30 day outlooks and relies of circulation patterns at mid to upper levels and identifies areas of persistent warm and cold air advection, 90 day outlook relies on long-term trends and recurring events with computer attempts to match past trends with present conditions, 15 month outlooks with 13 forecasts each month with covering a 3 month period beginning 2 weeks from the date of forecasts release with subsequent 3 month overlaps from previous by 2 months

Teleconnections

link between changes in atmospheric circulation occurring in widely separated regions of the globe

Single-station forecasting

short-term weather prediction based on observations at one location, forecasts usually generalized and tentative, fair-weather bias, persistence, climatology

Fair-weather bias

fair-weather days outnumber stormy days almost everywhere, predicting all fair-weather days would be correct more than half the time

Persistence

weather episodes persist for some period of time with if it has been cold and storm for several days it may continue that way for a while

Climatology

forecast prepared based on previous year’s weather

Private sector forecasting

television and radio stations, some newspapers, private forecast services, some private meteorologists tailor forecasts to specific nes to commercial, agricultural, or industrial clients, supplement the efforts of government forecasters

Communication and dissemination

NCEP maps and charts transmitted ot local NWS forecast offices with guide meteorologists in preparing local forecasts, weather information then distributed to the public, outlook, weather watch, weather warning, advisories, tornado warning, winter storm warning for heavy snow, blizzard warning, severe blizzard, ice storm warning, flash flood watch, flash flood warning, urban and small stream flood advisory, public receives weather reports and forecasts via radio, NOAA weather radio, TV, internet, newspaper

Outlook

provided for advanced notice

Weather watch

hazardous weather possible based on current/anticipated conditions

Weather warning

hazardous weather occurring in the region/imminent

Advisories

anticipated weather hazards, less serious then warnings

Tornado warning

detection of a thunderstorm known/likely to include a tornado

Winter storm warning for heavy snow

snowfall of at least 4 to 6 in expected in less than 12 hrs

Blizzard warning

blowing/falling snow with sustained winds of 35 mph+, reducing visibility to less than 1,300 ft

Severe blizzard

produces winds greater than 45 mph, visibility near 0, air temperatures less than 10 degrees, dangerously cold wind-chills

Ice storm warning

potentially dangerous accumulations of freezing rain/sleet

Flash flood watch

flash flooding possible within watch area

Flash flood warning

dangerously rapid rise in river level imminent/occurring

Urban and small stream flood advisory

potential flooding may cause inconvenience but isn’t life threatening

Weather-ready nation

1980-2019 with US experienced 254 weather related disasters in which overall damages reached/exceeded 1 billion with severe storms, tropical cyclones, flooding, droughts, devastating impacted reduced through improved preparedness, building community resilience by improving forecasts and communication fo risk to local authorities, develop mobile-ready emergency response teams, develop better technology, strengthen partnerships

Conclusion

weather forecasting depends on interplay of weather observation and data analysis by meteorologists and computers and rapid communication systems, high level of skill achieved for short-range forecasting, improvement to longer-term forecasting expected with denser surface/upper-air observational networks and more precise modeling and larger and faster computers and more sophisticated remote sensing, international cooperation essential