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15 January 2009: Lake Champlain Sea Smoke, Steam Devils, and Waterspouts
Exotic Whirls in Arctic Air
Overview | Images | Definitions | Weather Conditions | Historical Arctic Waterspouts
IV. Weather Conditions

This section reviews weather conditions associated with the Lake Champlain waterspouts on 15 January 2009.
graph of temperatures with arctic front An arctic cold front pushed eastward through the North Country during the late evening hours on January 13th and into the early morning hours on January 14th, approximately 30-36 hours prior to the Lake Champlain waterspouts. Temperatures dropped 30oF to 40oF across the area in the hours following the frontal passage (Figure IV-1). By the morning hours on January 15th (the day of the waterspout activity), the arctic boundary had pushed south of New England. The Daily Weather Map for 15/12z (7 am EST) is shown in Figure IV-2.
Figure IV-1. Surface temperature versus time for ASOS stations at Burlington International Airport (BTV), Massena Richards Field (MSS), and the Saranac Lake / Lake Clear Airport (SLK). Time period covers January 13th at 7pm through January 14th at 6am.
surface weather map
Figure IV-2. Daily Weather Map for 12z (7am EST) on 15 January 2009. The dashed-dot line through Vermont and Northern New York represents the 0oF isotherm.
visible satellite image In the visible satellite imagery at 15/16z (11 am EST, Figure IV-3), a wave of low pressure was moving eastward south of New England along the surface boundary. Meanwhile, a strong arctic ridge was centered over the upper Missouri River Valley (maximum pressure around 1049mb). An extension of the surface ridge extended northeast of the Great Lakes region along the international border region between New York and Ontario/Quebec. The presence of this ridge axis to the northwest contributed to a north-northeasterly surface wind flow across Lake Champlain during the early to mid-morning hours on the 15th.
Figure IV-3. Visible satellite imagery at 1601z with sea-level pressure isobars overlaid (blue solid lines, every 4mb) at 16z, on 15 January 2009.
A close inspection of 15/1515z visible satellite imagery (Figure IV-4) with the surface observations at 15/15z (10am EST) shows a line of instability induced cumulus congestus clouds over the broad portion of Lake Champlain from near Colchester Reef (CRF) southward to near the Essex, NY shoreline. The northern portion of the lake was ice covered, especially east of Grand Isle. The surface observations indicated a 15/15z (10 am) temperature of -4oF at BTV, and generally 0 to 5 below in the immediate Champlain Valley. The temperatures at the over-lake stations were -2oF and +1oF at Colchester Reef and Diamond Island, respectively. Winds over land were calm to light from the north-northeast at speeds up to 5 kt.
zoomed visible satellite image The flow was somewhat stronger and more veered over the water; Colchester Reef (KCRF) had winds of 060o/10kts at 1508z (1008 am EDT), while Diamond Island (KDMD) reported 030o/14kt. The northeast flow likely forced the low-level convergence zone over the lake toward the western shoreline (i.e., toward the New York side); a westward displacement of the lake induced cloud band is evident in satellite imagery and in radar reflectivity (discussed below). This may be somewhat atypical, based on the greater occurrence of lake effect snow showers along the southeast rather than the southwest lake short with similar occurrences of north flow over the lake with arctic air.
Figure IV-4. Visible satellite imagery with surface observation over the Champlain Valley and adjacent areas at 15/1515z (1015am EST).
The sequence of KCXX 0.5o radar reflectivity images (Figure IV-5) show a long-lived north to south band of enhanced reflectivity (5 to 15 dBz) over the broad portion of Lake Champlain associated with convective cloudiness and light snowfall. The lake reflectivity band is displaced toward the western half of the lake. The most intense and higher echo tops were located near the southern portion of the lake where residence time of air moving from north to south across the lake was longest. The echo tops in the highest reflectivity region over the southern portion of the lake were generally between 2500 and 3000 feet AGL based on 1.5o reflectivity (not shown). No reflectivity returns were observed during the morning hours above the 1.5o tilt from KCXX.
(a)radar reflectivity image (b)radar reflectivity image
(c)radar reflectivity image (d)radar reflectivity image
Figure IV-5. Base reflectivity (0.5 deg elevation angle) from KCXX for (a) 15/0559z, (b) 15/0854z, (c) 15/1257z, (d) 15/1532z. Reflectivity values low-end color enhanced from -20 dBz to + 20dBz. Radar was in VCP 32 (clear-air mode). Surface observations are also shown.
Fortuitously, an aircraft instrumented with temperature and wind sensing equipment departing Burlington for Chicago passed over the southern end of Lake Champlain around 15/13z (~8am EST). The flight path of the aircraft and associated sounding are shown in figure IV-6.
(a) ACARS sounding (b) ACARS sounding map
Figure IV-6. In (a), ACARS sounding taken during aircraft departure from BTV at 15/1255z (755 am EST). Black circles represent air and water temperatures over Lake Champlain as labeled. In (b) map showing departure route and sounding sample points; the aircraft passed over the southern portion of Lake Champlain during ascent.
At the King Street ferry dock in downtown Burlington, the lake temperature the morning of the 15th was 33oF (0.6C). The air temperature over the southern portion of Lake Champlain was around 0oF (-18C). Thus, the vertical temperature difference in the first few meters above the lake was near 19C. This contributed to the arctic sea smoke or steam fog, and the steam devil activity. Based on the 15/1255z (7:55am EST) ACARS sounding, the lake to 850mb temperature difference was 23C. The 1-h Rapid Update Cycle (RUC) forecast (Figure IV-7) valid at 15/15z indicated a lake-to-850mb temperature difference closer to 25C. The lake to 700mb temperature difference was 32C based on the ACARS profile and around 31C based on the 1-h RUC forecast. This resulted in extremely unstable low-level conditions over the lake. The convective overturning resulted in ascent over the lake, and associated convergence from adjacent land areas to the east and the west. The deeper-layer instability and convective updrafts likely contributed to waterspout formation.
(a) 850mb analysis
(b) 700mb analysis
Figure IV-7. The (a) 850mb and (b) 700mb analysis valid at 15z on 15 January 2009, based on the 1-hr forecast from the Rapid Update Cycle (RUC) model. Analyses from the NCEP/Storm Prediction Center mesoanalysis archive.
The Rapid Update Cycle (RUC) and Global Forecast System (GFS) model vertical profiles (Figure IV-8) showed west-northwesterly winds of 15-30 kts from 2 to 5 kft. Winds below 2 kft were generally less than 10 kts. Assuming lifted parcels over the lake are roughly the average of the lake and near-surface temperature, lake induced convective available potential energy (CAPE) values were around 500 J/kg. The model profiles suggested equilibrium levels between 7000-9000 ft. Because the observed echo tops were only around 2500 ft, it appears this methodology for determining the lifted parcel temperature results in the parcel being too warm compared to reality. The 0h RUC sounding at BTV is also available for viewing here. If we assume a temperature over the lake of 0oF and a dewpoint of -5oF, the lifting condensation level is around 1100 ft. This seems reasonable, and would suggest cloud depths of 1000-1500 ft within the waterspout producing lake cloud band.
(a) RUC model sounding
(b) GFS model sounding
Figure IV-8. The 3-hour (a) RUC and (b) GFS forecast soundings valid at 15z on 15 January 2009 for KBTV. Lake temperature is set at 33oF with lake induced CAPE values of 491 J/kg and 582 J/kg, respectively based on lifted parcel temperature around -8C.
One question is why only two documented cases of winter waterspouts exist over Lake Champlain (see historical section for details on 12 February 1954 case). Typically, arctic frontal passages and northerly winds across the open waters of Lake Champlain will occur several times each winter. While lake effect snow showers or flurries are not uncommon (especially along the southeastern shore of the lake), the occurrence of waterspouts is seemingly far more infrequent. First, it is likely that some events simply go unreported. Also, it could be that some waterspouts and steam devils are obscured by falling lake effect precipitation. The sub-cloud layer was generally free of any significant precipitation in this case, suggesting sub-cloud RH may be important from the standpoint of observing these features. Also, the cloud depths were relatively shallow in this case (probably less than 2000 feet). It is possible that the degree of low-level convergence was enhanced due to northeast flow at the surface across the lake (owing to the position of the surface ridge to the west), while winds at 3000 feet were nearly westerly (per the ACARS and model soundings). This may have enhanced the magnitude of the near-surface convective updrafts compared to other similar events. Because waterspouts are such small features in time and space, it is not possible to measure the presence of cyclonic convergence along the lake convergence zone that is generally necessary in the incipient stages of a waterspout. The strength of the convergence zone along with the extreme instability over the lake due to the arctic air were certainly favorable factors for the development of waterspout activity. However, it appears that it would be difficult to differentiate between similar events with or without waterspout activity on the basis of data that forecasters would typically have available.
Overview | Images | Definitions | Weather Conditions | Historical Arctic Waterspouts
Figure IV-1. Surface temperature versus time for ASOS stations at Burlington International Airport (BTV), Massena Richards Field (MSS), and the Saranac Lake / Lake Clear Airport (SLK). Time period covers January 13th at 7pm through January 14th at 6am.
Figure IV-2. Daily Weather Map for 12z (7am EST) on 15 January 2009. The dashed-dot line through Vermont and Northern New York represents the 0oF isotherm.
Figure IV-3. Visible satellite imagery at 1601z with sea-level pressure isobars overlaid (blue solid lines, every 4mb) at 16z, on 15 January 2009. [Click bottom right of image area to expand to full size]
Figure IV-4. Visible satellite imagery with surface observation over the Champlain Valley and adjacent areas at 15/1515z (1015am EST). [Click bottom right of image area to expand to full size]
Figure IV-5a. Base reflectivity (0.5 deg elevation angle) from KCXX for 15/0559z. [Click bottom right of image area to expand to full size]
Figure IV-5b. Base reflectivity (0.5 deg elevation angle) from KCXX for 15/0854z. [Click bottom right of image area to expand to full size]
Figure IV-5c. Base reflectivity (0.5 deg elevation angle) from KCXX for 15/1257z. [Click bottom right of image area to expand to full size]
Figure IV-5d. Base reflectivity (0.5 deg elevation angle) from KCXX for 15/1532z. [Click bottom right of image area to expand to full size]
Figure IV-6a. ACARS sounding taken during aircraft departure from BTV at 15/1255z (755 am EST). Black circles represent air and water temperatures over Lake Champlain as labeled.
Figure IV-6b. Map showing departure route and sounding sample points; the aircraft passed over the southern portion of Lake Champlain during ascent.
Figure IV-7a. The 850mb analysis valid at 15z on 15 January 2009, based on the 1-hr forecast from the Rapid Update Cycle (RUC) model. Analyses from the NCEP/Storm Prediction Center mesoanalysis archive.
Figure IV-7b. The 700mb analysis valid at 15z on 15 January 2009, based on the 1-hr forecast from the Rapid Update Cycle (RUC) model. Analyses from the NCEP/Storm Prediction Center mesoanalysis archive.
Figure IV-8a. The 3-hour RUC forecast sounding valid at 15z on 15 January 2009 for KBTV. Lake temperature is set at 33oF yielding a lake induced CAPE values of 491 J/kg based on lifted parcel temperature around -8C.
Figure IV-8b. The 3-hour GFS forecast sounding valid at 15z on 15 January 2009 for KBTV. Lake temperature is set at 33oF yielding a lake induced CAPE values of 582 J/kg based on lifted parcel temperature around -8C.


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