PAVE Forecast Support
Code 7646, Middle Atmosphere Dynamics
Naval Research Laboratory: Washington, DC

ARCHIVE OF FORECAST SUMMARIES
(reverse chronological order: note that these archived hyperlinks are stale, superseded by later forecasting)

here....

Forecast Summary for the latest "version a" flight path of Wednesday 9 February (last updated Tuesday 8 February at 18:45 EST):                   archive

Wednesday 9 February: For transit, stratospheric cold pool in +48 hour ECMWF forecasts retreats poleward and eastward from Monday's equatorward excursion. Operational NOGAPS forecasts initialized 7 Feb at 00Z show 60 hour forecast stratospheric temperatures (valid 9 Feb 12Z) increasing at 30 hPa, 50 hPa, and 70 hPa over western CONUS. This warm sector includes western segment of transcontinental flight path (points 2-3) as well as the north-south along-track MLS path (points 3-4), according to preliminary flight plan. +48-hour ECMWF 30 hPa ozone mixing ratio forecasts valid 7 Feb 12Z indicate values increasing steadily westward along east-west portion of planned flight track (points 2-3).        Stratospheric mountain waves are forecast by MWFM at +36 hours to remain intense over the southern tip of Greenland, and with moderate activity spread across the northwest coast of Canada. Big waves are also seen here in the EC divergence fields. Near northwestern Canada there might be light mountain wave turbulence at cruise altitude.

Forecast Summary for the latest "version a" flight path of Wednesday 9 February (last updated Monday 7 February at 17:45 EST):                   archive

Wednesday 9 February: For transit, stratospheric cold pool in +72 hour ECMWF forecasts retreats poleward and eastward from Monday's equatorward excursion. Operational NOGAPS forecasts initialized 7 Feb at 00Z show 60 hour forecast stratospheric temperatures (valid 9 Feb 12Z) increasing at 30 hPa, 50 hPa, and 70 hPa over western CONUS. This warm sector includes western segment of transcontinental flight path (points 2-3) as well as the north-south along-track MLS path (points 3-4), according to preliminary flight plan. +72-hour ECMWF 30 hPa ozone mixing ratio forecasts valid 7 Feb 12Z indicate values increasing steadily westward along east-west portion of planned flight track (points 2-3).        Stratospheric mountain waves are forecast by MWFM at +60 hours to remain intense over the southern tip of Greenland, and with moderate activity spread across the northwest coast of Canada. Near northwestern Canada there might be light mountain wave turbulence at cruise altitude.

Forecast Summary for the latest "version k" flight path of Monday 7 February and into Wednesday (last updated Sunday 6 February at 12:35 EST):                   archive

Monday 7 February: Forecast trends noted at +72 hours persist mostly to +48 hours with the "version K" flight plan for Monday now programmed in. +48 hour ECMWF forecasts continue to show cold stratospheric intravortex temperatures poking well southward, with sub-194Ks reaching as far south as the eastern Canada-US border. We now consider the planned Monday flight legs. On the poleward outbound leg, the along track 12Z (+48 hour) temperature curtains show 194K contours extending down to 50 hPa. On the equatorward inbound leg, the along track 12Z (+48 hour) temperature curtains show similar cold stratospheric temperatures. 12 hours later at 0Z Tuesday (+60 hour forecasts) the cold pool swings eastward: similar but slightly warmer temperature trends are then seen in +60 hour forecast temperature curtains on both the outbound and inbound flight legs.        A region of low total ozone is forecast to develop over the NE US on 7 Feb at 00 Z and moves over Pease AFB by 12 Z, coinciding with forecast ozone mixing ratios < 3 ppmv at 80 hPa that are more typical of lower latitude air masses. This feature appears to be associated with pronounced ridging over the eastern US on the backside of a cutoff low (slow link, be patient) and poleward excursion of low-PV air in the upper troposphere/lower stratosphere (slow link, be patient). Ozone measurements on 7 Feb over Pease may detect ozone-poor air masses originating from lower latitudes.       MWFM +12-30 hour NCEP-initialized mountain wave forecasts continue to show strong stratospheric mountain waves forming over the southern tip of Greenland, with similar trends seen in prognostic ECMWF divergences. Additionally, mountain wave-induced turbulence along the current flight track is forecast by MWFM to be insignificant. Wednesday 9 February: For transit, stratospheric cold pool retreats poleward and eastward from Monday's equatorward excursion. Stratospheric mountain waves are forecast by MWFM to remain intense over the southern tip of Greenland, and with moderate activity spread across the northwest coast of Canada. Near northwestern Canada there might be light mountain wave turbulence at cruise altitude.

Forecast Summary for Saturday 5 February & the latest "version f" flight path for Monday 7 February (last updated Saturday 5 February at 13:25 EST):                   archive

Monday 7 February: Exciting initial +120 hour forecast trends persist largely unchanged to +72 hours with first flight plan for Monday now programmed in! +72 hour ECMWF forecasts continue to show cold stratospheric intravortex temperatures poking well southward, with sub-194Ks reaching as far south as the eastern Canada-US border. We now consider the planned Monday flight legs. On the poleward outbound leg, the along track temperature curtains show but 193K contours extending down to 50 hPa. On the equatorward inbound leg, the along track temperature curtains show similar cold stratospheric temperatures.        A region of low total ozone is forecast to develop over the NE US on 7 Feb at 00 Z and moves over Pease AFB by 12 Z, coinciding with forecast ozone mixing ratios < 3 ppmv at 80 hPa that are more typical of lower latitude air masses. This feature appears to be associated with pronounced ridging over the eastern US on the backside of a cutoff low (slow link, be patient) and poleward excursion of low-PV air in the upper troposphere/lower stratosphere (slow link, be patient). Ozone measurements on 7 Feb over Pease may detect ozone-poor air masses originating from lower latitudes.       MWFM +36-54 hour NCEP-initialized mountain wave forecasts continue to show strong stratospheric mountain waves forming over the southern tip of Greenland. Additionally, mountain wave-induced turbulence along the current flight track is forecast by MWFM to be light-to-absent. Wednesday 9 February: For transit, stratospheric cold pool retreats poleward and eastward from Monday's equatorward excursion. Stratospheric mountain waves are forecast by MWFM to remain intense over the southern tip of Greenland, and with moderate activity spread across the west coast of Canada. Near northwestern Canada there might be light mountain wave turbulence at cruise altitude.

Forecast Summary for the latest "version d" flight path of Saturday 5 February and Monday 7 February (last updated Friday 4 February at 11:55 EST):                   archive

Saturday 5 February: Latest +12-24 hour MWFM forecasts show short-scale stratospheric mountain waves forming over Baffin Island and Greenland near the planned outward flight leg, though wave amplitudes aren't huge. MWFM predicts that the DC-8 may encounter some light-moderate mountain wave-induced turbulence at the northernmost waypoint in and around central Baffin Island and Ellesmere Island. Similar to forecasts 24 hours earlier, long-wavelength gravity wave features remain evident in +48 hour ECMWF divergences, though with activity just to the east of planned flight leg and weakening in successive forecast updates. On zooming in to focus on this outward flight leg, we see from divergence curtains that some weak stratospheric gravity wave activity might be measured by the lidars.        +48 hour ECMWF temperature forecasts show the edge of the vortex cold pool pushing northward out of northern Canada, with planned flight track entering the western edge of the cold pool. As we zoom in on this outward bound leg, we see that the forecast temperature curtains show sub-194K air centered at ~40-50 hPa as the DC-8 approaches "flight d" waypoint #5. On the turnaround and then inbound flight segments (flight d waypoints #5-8), we see forecast temperature curtains maintaining sub-193-194 K values at ~40-40 hPa over ~2000 km of flying distance, before finally giving way to warmer stratospheric temperatures somewhere over the Hudson Bay.        Ozone mixing ratio +48 hour forecasts show a lot of structure at 35 hPa, with a wedge of low ozone over Baffin Island and Greenland between higher values poleward and equatorward, structure that the planned flight leg should cross over and profile fairly effectively. Monday 7 February: Exciting initial +120 hour forecast trends persist as strongly to +96 hours! +96 hour ECMWF forecasts show cold stratospheric intravortex temperatures poking well southward, with sub-194Ks reaching as far south as the eastern Canada-US border. Taking the Friday track through the Monday temperature forecast, for example, then curtains along a similar flight track for Monday suggest NAT could form as far south as the border with 193K contours extending down to 60 hPa. A region of low total ozone is forecast to develop over the NE US on 7 Feb at 00 Z and moves over Pease AFB by 12 Z, coinciding with forecast ozone mixing ratios < 3 ppmv at 80 hPa that are more typical of lower latitude air masses. This feature appears to be associated with pronounced ridging over the eastern US on the backside of a cutoff low (slow link, be patient) and poleward excursion of low-PV air in the upper troposphere/lower stratosphere (slow link, be patient). Ozone measurements on 7 Feb over Pease may detect ozone-poor air masses originating from lower latitudes.       MWFM +60-78 hour NCEP-initialized mountain wave forecasts show strong stratospheric mountain waves forming over the southern tip of Greenland.

Forecast Summary for the latest "version b" flight path of Saturday 5 February and Monday 7 February (last updated Thursday 3 February at 20:05 EST):                   archive

Saturday 5 February: Latest +48-60 hour MWFM forecasts show short-scale stratospheric mountain waves forming over Baffin Island and Greenland near the planned outward flight leg, though wave amplitudes aren't huge. MWFM predicts that the DC-8 may encounter some moderate mountain wave-induced turbulence at the northernmost waypoint in and around Ellesmere Island. Similar long-wavelength gravity wave features are evident in +72 hour ECMWF divergences, though with activity just to the east of planned flight leg and weakening in successive forecast updates. Zooming in to focus on this outward flight leg, we see from divergence curtains that some weak stratospheric gravity wave activity might be measured by the lidars.        +72 hour ECMWF temperature forecasts show the edge of the vortex cold pool pushing northward out of northern Canada, with planned flight track entering the western edge of the cold pool. As we zoom in on this outward bound leg, we see that the forecast temperature curtains show sub-194K air centered at ~40-50 hPa as the DC-8 approaches way point #4. On the turnaround and then inbound flight segments (waypoints 4-6), we see forecast temperature curtains maintaining sub-193-194 K values at ~40-40 hPa over ~2000 km of flying distance, before finally giving way to warmer stratospheric temperatures somewhere over the Hudson Bay.        Ozone mixing ratio +72 hour forecasts show a lot of structure at 35 hPa, with a wedge of low ozone over Baffin Island and Greenland between higher values poleward and equatorward, structure that the planned flight leg should cross over and profile fairly effectively. Monday 7 February: Exciting initial forecast trends! +120 hour ECMWF forecasts show cold stratospheric intravortex temperatures poking well southward, with sub-194Ks reaching as far south to the eastern Canada-US border. Taking the Friday track along the Monday forecast, for example, then curtains along a similar flight track for Monday suggest NAT could form as far south as the border with 193K contours extending down to 60 hPa. A region of low total ozone is forecast to develop over the NE US on 7 Feb at 00 Z and moves over Pease AFB by 12 Z, coinciding with forecast ozone mixing ratios < 3 ppmv at 80 hPa that are more typical of lower latitude air masses. This feature appears to be associated with pronounced ridging over the eastern US on the backside of a cutoff low (slow link, be patient) and poleward excursion of low-PV air in the upper troposphere/lower stratosphere (slow link, be patient). Ozone measurements on 7 Feb over Pease may detect ozone-poor air masses originating from lower latitudes.       MWFM +90-102 hour NCEP-initialized mountain wave forecasts show strong stratospheric mountain waves forming over the southern tip of Greenland.

Forecast Summary for the latest "version j" flight path of 3 February & 5 February (last updated Wednesday 2 February at 16:00 EST):                   archive

Thursday 3 February: Really interesting ECMWF forecast fields developing, showing jet-stream gravity waves, though the planned flight track unfortunately will fly just to the southeast of the most interesting structure. Version f flight track intercepts weak-moderate amplitude gravity waves in the +48 hour ECMWF divergence forecast at the northernmost way point: see flight segment 2 and associated divergence curtain along this segment. Since these divergence waves do not connect with the underlying surface (see here) nor does MWFM predict significant mountain waves here, it seems clear these are obliquely-propagating nonorographic gravity waves, probably generated by the jet stream. It will be very interesting to see whether these oscillations persist in later ECMWF forecasts, and if so, whether they are seen on the DC-8 should the current flight track survive revision. The curtain suggests we may see these jet waves below the aircraft rather than above. Large stratospheric mountain waves persist on the west coast near Vancouver.       Moreover, the +48 hour ECMWF temperature forecasts show these jet-generated gravity waves forming a fairly broad region of sub-193K 30 hPa temperatures over Manitoba, Canada, just to the southwest of Hudson Bay and just to the northwest of the current planned way point, (see corresponding curtain here). These sub-193Ks might be too high in altitude (and hence pressures too low) to form NAT: nonetheless, it raises the intriguing possibility of a nonorographic gravity wave-induced PSC forming over south-central Canada, quite near the current flight track. These jet waves are transient (nonstationary) with time, so flying across forecast wave phases rather than along any forecast cold phases at 12Z would be a wiser flight strategy, since the latter guarantees sampling of both cold and warm phases. +48 hour ECMWF temperature forecasts along the planned flight track to the north show that the DC-8 does not reach the structured edge of the stratospheric cold pool over northern Canada: see sample flight trajectory which is curtained here. The vortex seems to be warming slightly: 188K contours, forecast to be present east of Greenland Wednesday, disappear Thursday and Friday. Saturday 5 February: +96 hour forecasts show the edge of the vortex cold pool pushing northward out of northern Canada. Wave activity weak over the US and northern Canada, with bursts of mountain activity over Baffin Island (near current planned flight track for Saturday), Greenland and west coast of USA/Canada: see here and here. Moderate mountain wave turbulence at flight altitude predicted over Ellesmere Island and central Greenland.

Forecast Summary for the "version f" flight path of 3 February (last updated Tuesday 1 February at 18:45 EST):                   archive

Thursday 3 February: Really interesting ECMWF forecast fields developing, showing jet-stream gravity waves. Version f flight track intercepts weak-moderate amplitude gravity waves in the +72 hour ECMWF divergence forecast at the northernmost way point: see flight segment 2 and associated divergence curtain along this segment. Since these divergence waves do not connect with the underlying surface (see here) nor does MWFM predict significant mountain waves here, it seems clear these are obliquely-propagating nonorographic gravity waves, probably generated by the jet stream. It will be very interesting to see whether these oscillations persist in later ECMWF forecasts, and if so, whether they are seen on the DC-8 should the current flight track survive revision. The curtain suggests we may see these jet waves below the aircraft rather than above. Large stratospheric mountain waves persist on the west coast near Vancouver.       Moreover, the +72 hour ECMWF temperature forecasts show these jet-generated gravity waves forming a fairly broad region of sub-193K 30 hPa temperatures over Manitoba, Canada, just to the southwest of Hudson Bay and just to the northwest of the current planned way point, (see corresponding curtain here). These sub-193Ks might be too high in altitude (and hence pressures too low) to form NAT: nonetheless, it raises the intriguing possibility of a nonorographic gravity wave-induced PSC forming over south-central Canada, quite near the current flight track. These jet waves are transient (nonstationary) with time, so flying across forecast wave phases rather than along any forecast cold phases at 12Z would be a wiser flight strategy, since the latter guarantees sampling of both cold and warm phases. +72 hour ECMWF temperature forecasts along the planned flight track to the north show that the DC-8 does not reach the structured edge of the stratospheric cold pool over northern Canada: see sample flight trajectory which is curtained here. The vortex seems to be warming slightly: 188K contours, forecast to be present east of Greenland Wednesday, disappear Thursday and Friday.

Forecast Summary for the "version f" flight path of 3 February (last updated Monday 31 January at 20:20 EST):                   archive

Thursday 3 February: Version f flight track intercepts weak-moderate amplitude gravity waves in the +96 hour ECMWF divergence forecast at the northernmost way point: see flight segment 2 and associated divergence curtain along this segment. Since these divergence waves do not connect with the underlying surface (see here) nor does MWFM predict significant mountain waves here, it seems clear these are obliquely-propagating nonorographic gravity waves, probably generated by the jet stream. It will be very interesting to see whether these oscillations persist in later ECMWF forecasts, and if so, whether they are seen on the DC-8 should the current flight track survive revision. Large stratospheric mountain waves persist on the west coast near Vancouver.       +96 hour ECMWF temperature forecasts along the planned flight track to the north shows that the DC-8 does not reach the structured edge of the stratospheric cold pool over northern Canada: see sample flight trajectory which is curtained here. The vortex seems to be warming slightly: 188K contours, forecast to be present east of Greenland Wednesday, disappear Thursday and Friday.

Forecast Summary for 31 January version "e" flight & 2 February (last updated Monday 31 January at 10:50 EST):                   archive

Monday 31 January: Latest (+24 hour) forecasts continue to show further elongation of the vortex cold pool downward (equatorward) into Canada (see also here). The latest version "e" flight plan still flies well into the vortex cold pool, and along this poleward leg lidars should sample sub-NAT temperature stratospheric air, potentially down to 190K at the northernmost way point. 6 hourly updated MWFM/NCEP forecasts continue to show stratospheric mountain wave amplitudes weakening in the region and intensifying on the northwest coast of USA and western Canada: see also here. Stratospheric +24 hour ECMWF 35hPa ozone shows gradients with a high-ozone collar over Pease with lower ozone poleward and equatorward. Wednesday 2 February: +72 hour forecasts show vortex cold pool temperatures extending well south into Canada and northern USA, well within flight range of Pease, but retracting more to the east since Monday: see sample flight trajectory which is curtained here. Stratospheric temperatures near the ice frost point (188K) are predicted to return over Greeland within northeast flight range from Pease. Stratospheric mountain waves weaken over eastern Greenland, but continue to intensity with time over western Northern America and western Canada: see here and here. Mountain wave regions within northern flight ranges of Pease are not predicted to be turbulent at DC-8 altitudes. +72 hour ECMWF 35hPa ozone shows high ozone over Pease with sharp gradients poleward and equatorward.

Forecast Summary for 31 January version "e" flight & 2 February (last updated Sunday 30 January at 19:15 EST):                   archive

Monday 31 January: Latest (+48 hour) forecasts continue to show further elongation of the vortex cold pool downward (equatorward) into Canada (see also here). The latest version "e" flight plan still flies well into the vortex cold pool, and along this poleward leg lidars should sample sub-NAT temperature stratospheric air, potentially down to 190K at the northernmost way point. 6 hourly updated MWFM/NCEP forecasts continue to show stratospheric mountain wave amplitudes weakening in the region and intensifying on the northwest coast of USA and western Canada: see also here. Stratospheric +48 hour ECMWF 35hPa ozone shows gradients with a high-ozone collar over Pease with lower ozone poleward and equatorward. Wednesday 2 February: +96 hour forecasts show vortex cold pool temperatures extending well south into Canada and northern USA, well within flight range of Pease: see sample flight trajectory which is curtained here. Stratospheric temperatures near the ice frost point (188K) are predicted to return over Greeland within northeast flight range from Pease. Stratospheric mountain waves weaken over eastern Greenland, but continue to intensity with time over western Northern America and western Canada: see here and here. Mountain wave regions within northern flight ranges of Pease are not predicted to be turbulent at DC-8 altitudes. +96 hour ECMWF 35hPa ozone shows high ozone over Pease with sharp gradients poleward and equatorward.

Forecast Summary for 31 January version "c" flight & 1 February (last updated Saturday 29 January at 20:30 EST):                   archive

Monday 31 January: Latest (+72 hour) forecasts continue to show further elongation of the vortex cold pool downward (equatorward) into Canada (see also here). The version "c" flight plan now flies well into the cold pool, and along this poleward leg lidars should sample sub-NAT temperature stratospheric air, potentially down to 190K at the northernmost way point. 6 hourly updated MWFM/NCEP forecasts continue to show stratospheric mountain wave amplitudes weakening in the region and intensifying on the northwest coast of USA and western Canada: see also here. Stratospheric +72 hour ECMWF 35hPa ozone shows gradients with a high-ozone collar over Pease with lower ozone poleward and equatorward. Tuesday 1 February: +96 hour forecasts show vortex cold pool temperatures extending well south into Canada and northern USA, well within flight range of Pease: see sample flight trajectory which is curtained here. Stratospheric mountain waves remain intense over eastern Greenland and into Scandinavia, but continue to intensity with time over western Northern America and northern Canada: see here and here. These mountain wave regions may be moderately turbulent at DC-8 altitudes, but appear to exist beyond flight range from Pease. +96 hour ECMWF 35hPa ozone shows high-ozone collar over Pease with lower ozone poleward and equatorward, indicative of some

Forecast Summary for 29 January, 31 January & 1 February (last updated Saturday 29 January at 17:45 EST):                   archive

Saturday 29 January: ECMWF +24 hour ozone forecasts suggest strong ozone gradients along flight tracks to north, while corresponding temperature forecasts suggest vortex cold pool elongates, extending sub-NAT temperatures further south into Canada within range of northern flights. The newest version "k" flight path is predicted to intercept cold temperatures at the northernmost way point that occur first at extremely high altitudes, above 20 hPa, then progressively descend to ~30 hPa with values ~193K at the northermost point (see here). Gravity waves along the new (newest version "k") flight track look weak apart from some small-amplitude activity going out of and back in to Pease. Hence mountain wave-induced turbulence at tropopause-region cruise altitudes should be weak or absent. Monday 31 January: Latest (+72 hour) forecasts continue to show further elongation of the vortex cold pool down into Canada (see also here). 6 hourly updated MWFM/NCEP forecasts continue to show stratospheric mountain wave amplitudes weakening in the region and intensifying on the northwest coast of USA and western Canada: see also here. Stratospheric +72 hour ECMWF 35hPa ozone shows gradients with a high-ozone collar over Pease with lower ozone poleward and equatorward. Tuesday 1 February: +96 hour forecasts show vortex cold pool temperatures extending well south into Canada and northern USA, well within flight range of Pease: see sample flight trajectory which is curtained here. Stratospheric mountain waves remain intense over eastern Greenland and into Scandinavia, but continue to intensity with time over western Northern America and northern Canada: see here and here. These mountain wave regions may be moderately turbulent at DC-8 altitudes, but appear to exist beyond flight range from Pease.

Forecast Summary for 29 & 31 January DC-8 flights (last updated Friday 28 January at 21:15 EST):

Saturday 29 January: ECMWF +48 hour ozone forecasts suggest strong ozone gradients along flight tracks to north, while ECMWF temperature forecasts suggest vortex cold pool elongates, extending sub-NAT temperatures further south into Canada within range of northern flights. The newest version "k" flight path is predicted to intercept cold temperatures at the northernmost way point that occur first at extremely high altitudes, above 20 hPa, then progressively descend to ~30 hPa with values ~193K at the northermost point (see here). Gravity waves along the new (newest version "k") flight track look weak apart from some small-amplitude activity going out of and back in to Pease. Hence mountain wave-induced turbulence at tropopause-region cruise altitudes should be weak or absent. Monday 31 January: Later (+120 hour replaced by +96 hour) forecasts continue to show further elongation of the vortex cold pool down into Canada (see also here). 6 hourly updated MWFM/NCEP forecasts continue to show stratospheric mountain wave amplitudes weakening in the region and intensifying on the northwest coast of USA and western Canada: see also here. Stratospheric +96 hour ECMWF 35hPa ozone shows gradients with a high-ozone collar over Pease with lower ozone poleward and equatorward.

Forecast Summary for 29 & 31 January DC-8 flight (last updated Thursday 27 January at 15:05 EST):

Saturday 29 January: ECMWF +72 hour ozone forecasts suggest strong ozone gradients along flight tracks to north, while ECMWF temperature forecasts suggest vortex cold pool elongates, extending sub-NAT temperatures further south into Canada within range of northern flights. Waves remain intense over eastern Greenland, drifting with the vortex, with some evidence of waves near Pease and over northwestern Canada. Mountain wave turbulence is light to absent along the projected flight track. Monday 31 January: Early indications suggest a further elongation of the vortex cold pool down into Canada (see also here). Stratospheric mountain wave amplitudes appear to weaken in the region, intensifying somewhat on the west coast of USA: see also here.

Thursday 27 January: Forecasts for Thursday show intravortex cold pool moving east, with this flight entering the westernmost edge of the cold pool and encountering possible sub-NAT temperatures near the northernmost way points (see here and here). Mountain wave amplitudes and mountain wave-induced turbulence should be minimal along track, although there may be some weak stratospheric wave activity to the north of Pease flying in and out (see, e.g., here and here). ECMWF forecast ozone shows some potentially interesting gradients to the north of Pease along potential flight tracks.

Saturday 29 January: Early forecasts suggest strong ozone gradients along flight tracks to north. +96 hour ECMWF forecasts suggest vortex cold pool elongates, extending sub-NAT temperatures further south into Canada within range of northern flights. Waves remain intense over eastern Greenland, drifting with the vortex, with some evidence of waves near Pease and over northern Canada. Mountain wave turbulence is light to absent.

28 January: Early forecasts suggest similar situation to Wednesday with some drifting of vortex core to the east towards Europe and some reduction in coldest cold pool temperatures. Stratospheric mountain waves continuing to be strong over southern and eastern Greenland and fairly weak over Canada, with little evidence for mountain wave-induced turbulence at flight altitudes. Planned flight to north should encounter sub-NAT stratospheric air at the northernmost waypoint (see here and here). ECMWF forecast ozone shows minimum near Ellesmere Island and higher ozone to the south, hence planned DC-8 flight to north may see sharp ozone gradients at these levels. 

Code 7646: Middle Atmosphere Dynamics

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