Figure 5-96. NDFD Wind Speed and Direction Graphic Product Plot Model Wind Speed & Direction Calm 5 knots Example Wind Barb 10 Knots TA 15 Knots Read as:
Horthwest Wind 20 Knots at 25 Knots 50 Knots 65 Knots Points to direction wind is coming from.
Small barbs indicate wind speed.
(1 Knot = 1.15 mph) Figure 5-97. NDFD Surface Wind Gust Graphic-Example tony ind
• 10 г Concor 610 racuse 7o 13 ffalo pittsbur Wind Gust(Kts) Sat Mar 28 2015 8AM EDT (Sat Mar 28 2015 12Z) National Digital Forecast Database 11z issuance Graphic created-Mar 28 7:13AM EDT 5-172
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5.22.2.3 Use.
Perhaps the adage “a picture is worth a thousand words” best describes the NDFD graphical products, which are one of the replacement products for the FA. The NDFD graphical products provide detailed forecasts of sky cover, weather, wind, and several other metrological elements, in a graphical Web-based format. Depending on the website, users can quickly scroll over or animate the products to view any changes in the forecast (e.g., movement, growth, or decay of areas of precipitation).
The NDFD g raphical products complement the Short-Range Surface Prognostic Charts (see paragraph 5.18), which are also based on the NDFD, by providing more detail and add itional weather elements.
The NDFD Sky Cover graphical product is a good situational awareness source for total cloud cover en route as well as at airports without a TAF.
Perhaps the best use of the NDFD Sky Cover graphical product is it provides forecasts of where the cloud cover is minimal, implying that VFR flight conditions are likely (except when smoke and haze exist or are expected). The NDFD Sky Cover graphical product does not provide cloud base height, cloud top height, or information on cloud layers.
The NDFD Weather graphical product is a good situational awareness source for weather (e.g., rain, snow, freezing rain, thunderstorm, fog, and surface wind) en route as well as at airports without a TAF. The NDFD Weather graphical product does not provide visibility forecasts associated with the forecast weather; thus, pilots should use this product in combination with the Low-Level Significant Weather (SIGWX) forecasts, AIRMETs and SIGMETs (including Convective SIGMETs) for possible Marginal Visual Flight Rules (MVFR) or IFR conditions.
Due to the graphical (and colorful) nature of these products, considerations have been made by the NWS for people who cannot distinguish colors.
Despite these efforts, some shades may be somewhat more difficult to distinguish. A color blindness tool, such as the following, may assist in reading the graphics: https://www.ryobi-sol.co.jp/visolve/en/.
5.22.3 Cloud Top Heights Product.
The Cloud Top Heights product provides a detailed set of forecasts of the heights of cloud tops using specified contours.
5.22.3.1 Issuance.
The NWS NCO produces the Cloud Top Heights forecast using the North American Mesoscale (NAM) NWP model.
The Cl oud Top Heights forecast product is available on https://www.aviationweather.gov.
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5.22.3.2 Content.
The Cloud Top Heights product (see Figure 5-98, Cloud Top Heights Product—Example) is a computer model forecast of the height of the tops of the clouds covering the sky valid for the indicated hour. The heights of cloud tops are depicted using color-shaded contours at specific intervals.
Forecasts are provided at select time step intervals.
Additi onal details on the content of this product are provided on https://www.aviationweather.gov.
Figure 5-98. Cloud Top Heights Product—Example
Actual colors and scale may vary depending on upgrades to the product. Refer to the AWC Web page for additional details.
5.22.3.3 Use.
The Cloud Top Heights product is a computer-generated forecast without input from meteorologists. It is the computer’s “best guess” of where clouds will be as well as the height of the cloud tops.
NWP models are much more accurate forecasting winds aloft than they are forecasting cloud tops. Pilots should not expect an equally high degree of
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5.22.4 Cloud Layer Product.
The Cloud Layer product provides a detailed set of forecasts of cloud amount and layers using specified contours.
5.22.4.1 Issuance.
The NWS NCO produces the Cloud Layer forecast using a NWP model.
The Cloud Lay er forecast product is available on https://www.aviationweather.gov.
5.22.4.2 Content.
The Cloud Layer product is a computer model forecast of cloud amount and information on cloud layers, valid for the indicated hour.
Forecasts are provided at select time step intervals.
Additional details on the content of this product are provided on https://www.aviationweather.gov.
5.22.4.3 Use.
The Cloud Layer product is a computer-generated forecast without input from meteorologists. It is the computer’s “best guess” for cloud layers as their details.
NWP models are much more accurate forecasting winds aloft than they are forecasting cloud layers. Pilots should not expect an equally high degree of accuracy with these forecasts.
5.23 Airport Weather Warning (AWW).
The Airport Weather Warning (AWW) addresses weather phenomena that can adversely impact airport ground operations.
Note: The AWW is not to be confused with the SAW, which the NWS refers to as SAW but is also known by AWW on the websites of some weather provider services.
5.23.1 Issuance.
The Airport Weather Warning is issued for select larger airports and is available on NWS WFO websites who have responsibility for issuing the TAFs for that airport. The Airport Weather Warning is not available on https://www.aviationweather.gov.
Issuance criteria are established according to local airport requirements. Some examples of criteria are: strong surface winds, freezing rain, heavy snow, and lightning within 5 miles of the airport.
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5.23.2 Airport Weather Warning (AWW) Format and Example.
The AWW is written in a plain language, free-text format.
WWUS82 KJAX 112212 AWWJAX FLZ025-112315-
AIRPORT WEATHER WARNING FOR JACKSONVILLE INTERNATIONAL AIRPORT
NATIONAL WEATHER SERVICE JACKSONVILLE FL 612 PM EDT WED MAR 11 2015 ...AN AIRPORT WEATHER WARNING HAS BEEN ISSUED FOR JACKSONVILLE
INTERNATIONAL AIRPORT FOR STRONG WINDS AND POSSIBLE WINDSHIFT VALID UNTIL 700 PM...
A CLUSTER OF THUNDERSTORMS WILL MOVE EASTWARD AT 12 KNOTS AND AFFECT JACKSONVILLE INTERNATIONAL AIRPORT BY 620 PM. WIND GUSTS OVER 35 KNOTS ARE LIKELY WITH THESE STORMS...AS WELL AS CLOUD- TO-GROUND LIGHTNING AND REDUCED VISIBILITIES FROM HEAVY RAIN.
WINDSHIFTS ACCOMPANYING THE THUNDERSTORMS MAY ALTER THE RUNWAY LANDING PATTERN WITH SOME STRONG WESTERLY WIND GUSTS.
$$
5.23.3 Use.
Information contained in this product may be useful to airport managers, fixed-based operators, airline ground personnel, and others responsible for the safety of ground operations. Ground decisions supported by the AWW information may include: fueling delays during thunderstorms, de-icing frequency, and other similar ground operations.
AWWs are not intended for use by in-flight operations.
5.24 Space Weather.
The expression Space Weather is used to designate processes occurring on the Sun, in Earth’s magnetosphere, ionosphere, and thermosphere, which have the potential to affect the near-Earth environment.
For aviation users, Space Weather can affect GPS navigation and some communications;
specifically, Space Weather can:
• Increase GPS uncertainty. During a severe space weather event, the ionosphere becomes highly disturbed, and GPS receivers cannot lock on the satellite signal, resulting in inaccurate position information as much as tens of meters or more.
• Result in severe downgrade or loss of high frequency (HF) radio communications, which is a mainstay of aviation, especially on polar and transoceanic routes.
The three primary types of space weather concerns for aviation are solar flares, radiation storms, and geomagnetic storms.
5.24.1 NOAA Space Weather Scales.
The NOAA Space Weather Scales communicate current and future space weather conditions and their possible effects on people and systems. The scales describe the
5-177 environmental disturbances for three event types: geomagnetic storms, solar radiation storms, and radio blackouts. The scales have numbered levels, analogous to hurricanes, tornadoes, and earthquakes that convey severity. Possible effects are provided as well as the average frequency of occurrence. These scales are not aviation specific but do address impacts to aviation systems.
5.24.2 Space Weather Products.
The Space Weather Prediction Center (SWPC) provides a variety of space weather products that describe current and expected space weather activity for a wide range of users (i.e., both aviation and non-aviation).
Information on these products is provided on their Web page (http://www.swpc.noaa.gov/ c ommunities/aviation-communi ty-dashboard), including intended usage, impacts on various systems (e.g., GPS), and details on issuance times and frequency.
5.24.2.1 Space Weather Messages.
SWPC provides non-aviation-specific alerts, watches, and warnings about what to expect from space weather. These products provide levels of severity of the solar activity that can be expected to impact the Earth’s environment.
The products are text based and available on SWPC’s website as well as through a subscription service.
SWPC’s messages and forecasts are modeled after non-aviation services that the NOAA/NWS provide. They are as follows:
• Watch messages are issued with long lead times for the majority of all space weather activity predictions.
• Warning messages are issued when some condition is expected. The messages contain a warning period and other information of interest.
• Alert messages are issued when an event threshold is crossed and contain information that is available at the time of issue.
• Summary messages are issued after the event ends and contains additional information that was not available at the time of issue.
5.24.2.1.1 Formats and Examples of Space Weather Messages.
Refer to NWS’s SWPC website for additional information on these products.
Watch Message Space Weather Message Code: WATA20 Serial Number: 604 Issue Time: 2015 Feb 26 0801 UTC WATCH: Geomagnetic Storm Category G1 Predicted Highest Storm Level Predicted by Day:
5-178 Feb 26: None (Below G1) Feb 27: None (Below G1) Feb 28: G1 (Minor)
THIS SUPERSEDES ANY/ALL PRIOR WATCHES IN EFFECT NOAA Space Weather Scale descriptions can be found at http://www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.
Warning Message Space Weather Message Code: WARK06 Serial Number: 253 Issue Time: 2015 Mar 01 0755 UTC WARNING: Geomagnetic K-Index of 6 expected Valid From: 2015 Mar 01 0755 UTC Valid To: 2015 Mar 01 1300 UTC Warning Condition: Onset NOAA Scale: G2 - Moderate NOAA Space Weather Scale descriptions can be found at http://www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents - Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft - Satellite orientation irregularities may occur;
increased drag on low Earth-orbit satellites is possible.
Radio - HF (high frequency) radio propagation can fade at higher latitudes.
Aurora - Aurora may be seen as low as New York to Wisconsin to Washington state.
Alert Message Space Weather Message Code: ALTK05 Serial Number: 770 Issue Time: 2015 Mar 01 0145 UTC ALERT: Geomagnetic K-index of 5 Threshold Reached: 2015 Mar 01 0145 UTC Synoptic Period: 0000-0300 UTC Active Warning: Yes NOAA Scale: G1 - Minor NOAA Space Weather Scale descriptions can be found at http://www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents - Weak power grid fluctuations can occur.
Spacecraft - Minor impact on satellite operations possible.
5-179 Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.
Summary Messages Space Weather Message Code: SUMXM5 Serial Number: 134 Issue Time: 2015 Mar 03 0158 UTC SUMMARY: X-ray Event exceeded M5 Begin Time: 2015 Mar 03 0125 UTC Maximum Time: 2015 Mar 03 0135 UTC End Time: 2015 Mar 03 0142 UTC X-ray Class: M8.2 Location: N22W94 NOAA Scale: R2 - Moderate Comment: Region 2290, no optical flare reported.
NOAA Space Weather Scale descriptions can be found at http://www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact centered primarily on sub-solar point on the sunlit side of Earth.
Radio - Limited blackout of HF (high frequency) radio communication for tens of minutes.
5.24.2.2 Forecast Discussion.
A plain language technical discussion that details observed data, analysis, and forecast rationale. Issued every 12 hours at 0030 UTC and 1230 UTC (and updated out-of-cycle as conditions warrant). Forecast and observed (summary) criterion is broken down into four sections by phenomenon type and two sub-sections; Summary and Forecast. This product is available on the NWS SWPC’s website.
5.24.2.2.1 Format and Example of Forecast Discussion.
Forecast Discussion Issued: 2015 Mar 11 1230 UTC Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center .24 hr Summary...
Solar activity was at moderate levels during the period as Region 2297 (S16E21, Dkc/beta-gamma-delta) continued its trend of being the only active region on the visible disk. Region 2297 produced three M-class flares during the period, including an M2/Sf at 11/0006 UTC, an M1/1b flare at 11/0718 UTC, and an M2 flare at 11/0757 UTC. The M2/Sf flare that peaked at 11/0006 UTC also had associated Type II (est. shock speed 1512 km/s) and Type IV radio emissions, as well as a 350 sfu Tenflare.
This region also produced over 15 low-level C-class flares over the past 24 hours. Additionally, an approximately 22 degree long solar filament, centered near N16W30, could be seen lifting off the visible disk in SDO/AIA 304 and GONG H-alpha imagery from approximately 11/0625-0815 UTC.
In addition to the three coronal mass ejections (CMEs) mentioned in the previous discussion, available LASCO C2 imagery indicated that two additional CMEs were observed departing the Suns East limb. Both of
5-180 these recent transients appear to be narrow, directed mostly East of the Sun-Earth line, and should not have significant impacts on Earth.
Analysis will be conducted on any additional CMEs observed when LASCO coronagraph imagery becomes available.
.Forecast...
Solar activity is expected to be at low levels with M-class (R1-R2/Minor-Moderate) flare activity likely. A slight chance for X-class (R3 or greater) flare activity remains for the next three days (11-13 Mar) as Region 2297 maintains its size and complex magnetic structure. The forecast remains unchanged for the previously mentioned CMEs as it appears that a combined impact of these transients may occur in the form of a glancing blow, mid to late on day two (12 Mar), with a passage expecting to last 24-36 hours at lower velocities.
Energetic Particle .24 hr Summary...
The greater than 2 MeV electron flux reached high levels this period, peaking at 1,060 pfu. The greater than 10 MeV proton was at background levels throughout the period.
.Forecast...
The greater than 2 MeV electron flux is expected to be at normal to moderate levels with a chance for high levels over the next three days (11-13 Mar). There is a slight chance for S1 (Minor) solar radiation storms over the next three days (11-13 Mar) if Region 2297 produces significant flare activity.
Solar Wind .24 hr Summary...
Solar wind parameters reflected ambient solar wind parameters through 11/0400 UTC. Solar wind velocities were steady near the 380 km/s range, IMF total field values were steady near 6 nT, while Bz varied slightly between +/-5 nT. Shortly after 11/0400 UTC, weak enhancements in the geomagnetic field were observed, likely associated with a transient passing just close enough to Earth to cause the minor disturbances.
Total field increased slightly to 10 nT, Bz saw a maximum southward deflection to near -10 nT, and wind velocities increased slightly to near 430 km/s for a short time. Most parameters have returned to near background levels with EPAM values leveling out as well. The phi angle was mostly positive (away) throughout the period.
.Forecast...
Near ambient conditions are expected to persist for the remainder of day one (11 Mar) through mid-day on day two (12 Mar) when the combined glancing blows from three CMEs are expected to arrive at Earth. Minor velocity and density enhancements are likely, with a greater magnetic response expected to be reflected in enhanced IMF total field and IMF Bz. The greatest response in Bt and subsequent sub-storms are anticipated for the early morning hours of day three (13 March).
Geospace .24 hr Summary...
The geomagnetic field was at mostly quiet levels with an isolated unsettled period during 11/0300-11/0600 UTC.
5-181 .Forecast...
The geomagnetic field is expected to be quiet to unsettled for the remainder of day one (11 Mar) through mid-day on day two (12 Mar).
Unsettled to active levels are forecast for the second half of day two as the combined glancing blows from three CMEs are expected to arrive at Earth. By day three (13 Mar), G1 (minor) geomagnetic storms are likely as the brunt of the CME impacts are expected to begin. A decrease to active levels is expected later in the period as impacts from the CME activity diminish.
Refer to NWS’s SWPC website for additional information on this product.
5.24.2.3 Three-Day Forecast.
A plain language, single-page forecast text product issued every 12 hours, at 0030 and 1230 UTC, with both forecast and observed criterion now broken down for each of the three NOAA Space Weather Scale categories. This product is designed to be a simple look at the observed and forecast of space weather conditions. A brief description of why conditions occurred or are forecast is also included for each category. Users requiring a more detailed explanation of events should refer to the Forecast Discussion. This product is available on the NWS’s SWPC website.
5.24.2.3.1 Format and Example of 3-Day Forecast.
3-Day Forecast Issued: 2015 Mar 11 1230 UTC Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center A. NOAA Geomagnetic Activity Observation and Forecast The greatest observed 3 hr Kp over the past 24 hours was 3 (below NOAA Scale levels).
The greatest expected 3 hr Kp for Mar 11-Mar 13 2015 is 5 (NOAA Scale G1).
NOAA Kp index breakdown Mar 11-Mar 13 2015 Mar 11 Mar 12 Mar 13 00-03UT 1 2 5 (G1) 03-06UT 3 2 5 (G1) 06-09UT 2 2 4 09-12UT 2 2 4 12-15UT 1 4 4 15-18UT 2 4 4 18-21UT 2 4 3 21-00UT 2 4 3 Rationale: G1 (minor) geomagnetic storms are likely on day three (13 Mar) as the brunt of the CME impacts are expected to begin.
B. NOAA Solar Radiation Activity Observation and Forecast Solar radiation, as observed by NOAA GOES-13 over the past 24 hours, was below S-scale storm level thresholds.
5-182 Solar Radiation Storm Forecast for Mar 11-Mar 13 2015 Mar 11 Mar 12 Mar 13 S1 or greater 10% 10% 10% Rationale: There is a slight chance for S1 (Minor) solar radiation storms over the next three days (11-13 Mar) if Region 2297 produces significant flare activity.
C. NOAA Radio Blackout Activity and Forecast Radio blackouts reaching the R1 levels were observed over the past 24 hours. The largest was at Mar 11 2015 0002 UTC Radio Blackout Forecast for Mar 11-Mar 13 2015 Mar 11 Mar 12 Mar 13 R1-R2 60% 60% 60% R3 or greater 10% 10% 10% Rationale: (R1-R2/Minor-Moderate) radio blackouts are likely. A slight chance for (R3 or greater) radio blackouts remains for the next three days (11-13 Mar) as Region 2297 maintains its size and complex magnetic structure.
Refer to NWS’s SWPC website for additional information on this product.
5.24.2.4 Other Space Weather Products.
SWPC provides many products on their website, some of which can be of interest to aviation users. These products and displays will continue to evolve and thus it is not practical to provide all the various product examples along with their description. Instead users should refer to the product descriptions provided on the SWPC website. It is important to state these products are intending for trained users, are not aviation-specific, and subject to change by the NWS.
5.24.3 Use.
At the time of this publication, there are no aviation-specific forecasts or advisory products, such as SIGMETs or AIRMETs, issued for space weather events. Until such time as aviation-specific space weather products are developed, pilots can refer to SWPC’s Web page as well as their space weather alerts, watches, warnings, forecasts and forecast discussions, utilizing the NOAA’s Space Weather Scales, for situational awareness with space weather.
SWPC has a free subscription service that provides a wide range of space weather products, including alerts, warnings, watches, and forecasts that users can receive through email within moments of being issued. Details on this service can be found on SWPC’s website.
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5.25 Soaring Forecast.
5.25.1 Issuance.
Select NWS WFOs issue soaring forecasts. These are automated forecasts primarily derived from the radiosonde observation or model generated soundings (see paragraph 3.6).
5.25.2 Content and Format.
The content and format of soaring forecasts vary with the NWS WFO providing the forecast, based on the needs of their soaring community. It is beyond the scope of this AC to describe all the many variations of soaring forecasts and their content. Soaring pilots should consult with the NWS WFO in their soaring area for more information.
5.25.3 Example.
The following example is Albuquerque, NM:
SOARING FORECAST FOR ABQ DATE... 04/19/15...12Z THERMAL INDEX....MINUS SIGN INDICATES INSTABILITY 5000 FT ASL........-10.0 6000 FT ASL........-9.0 10000 FT ASL........-3.5 15000 FT ASL........0.0 HEIGHT OF THE -3 INDEX....10800 FT ASL TOP OF THE LIFT...........14600 FT ASL ABQ MAX TEMPERATURE.......67 DEGREES F FIRST USABLE LIFT.........59 DEGREES F MAXIMUM LIFT..............509 FT/MIN
UPPER LEVEL WINDS 5000 FT ASL..../// DEGREES AT // KNOTS 10000 FT ASL....330 DEGREES AT 35 KNOTS IT IS EMPHASIZED...THIS SOARING FORECAST INFORMATION IS VALID ONLY FOR THE RAOB SITE AREA AND FREQUENTLY WILL NOT APPLY TO OTHER AREAS IN THE STATE.