Area Forecast Discussion
Issued by NWS Buffalo, NY

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000 FXUS61 KBUF 251101 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 701 AM EDT Sat Mar 25 2017 .SYNOPSIS... A frontal boundary will remain draped across the region today...before slowly lifting back north across the region as a warm front Sunday and Monday. Several disturbances sliding along this boundary will bring frequent bouts of precipitation through the weekend and early next week... with cooler temperatures prevailing north of the boundary and milder temperatures to its south. && .NEAR TERM /THROUGH TONIGHT/...
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At 7 a.m. surface observations showed a frontal boundary dividing temperatures in the 50s from temperatures in the 30s was draped across the Western Southern Tier. Steadier showers were located north of the surface boundary along a sharp mid- level thermal gradient. The boundary will continue to slide slowly south this morning, with periods of rain expected to continue along the I-90 corridor, with lowering chances to the south. There was some thunderstorms last night due to elevated instability, and a few rumbles cannot be ruled out this morning though this instability is limited. Thermal profiles are colder across the Eastern Lake Ontario region, where there will be some mixed precipitation. The temperature of the mid-level warm layer will be marginal (0 to +3C) with snow, sleet, and freezing rain all a possibility. Although any snow or ice accumulation should be light, this may result in some slick spots this morning with a winter weather advisory in place. Temperatures should rise above freezing late this morning. High pressure near the Ontario/Quebec border will expand southward and push the boundary to near the NY/PA state line. Model consensus stalls the front here late this afternoon and evening. The lack of motion should result in diminishing shower activity along the boundary, though a stray shower cannot be ruled out. The front should then lift back northward as the high drifts to the east, with modest mid-level warm air advection increasing chances for some light precipitation late tonight. This should mainly fall in the form of rain, but there is a risk of freezing rain late tonight across the Eastern Lake Ontario region. Confidence in measurable precipitation is low, but this may require another round of headlines for this region. With most of the area on the cool side of the front, temperatures will be much cooler than yesterday. Highs will only be in the upper 30s in many areas, rising to the upper 40s near the Pennsylvania state line. Temperatures will not cool much tonight, before rising late in the night as the frontal boundary lifts back northward into the region. The exception is the North Country where skies should clear out, allowing for some radiational cooling and temperatures to fall into the upper teens to lower 20s. The forecast hedges toward high resolution guidance which is better able to resolve the sharp temperature differences.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... Sunday a band of isentropic lift precipitation will lift across the region, though with neutral temperature advection and ridging aloft rain showers will likely be scattered in nature. Early morning temperatures east of Lake Ontario will likely remain near or below freezing. Expect another period of freezing rain Sunday morning before surface temperatures rise above freezing. A northeast wind through the Saint Lawrence Valley may linger freezing rain chances into the early afternoon. Sunday night an area of low pressure will advance towards Michigan, and bring another increase in moisture across the lower Great Lakes. Increased surface convergence, along with falling heights aloft by a nearing shortwave of low pressure will bring increasing chances for rain showers. Ahead of this surface low will be a fair amount of instability across the Ohio Valley, but waning as it reaches WNY. Still there will be chances for thunder across SW NYS Sunday afternoon and evening. As the upper level shortwave passes Sunday night and into Monday it will carry an area of showers across the region. Through the day Monday and Monday night the surface low will slowly track eastward, just to the north of Lake Ontario. Abundant low level moisture will maintain chances for rain showers through the end of the forecast period. Temperatures Sunday will rise well into the 50s across WNY, though SE and E of Lake Ontario, highs will remain in the 40s. As winds become SW Monday milder air will spread across the entire region, with 50s, and possibly a few Genesee Valley lower 60s for highs. Sunday night will remain mild with the SE winds and thick cloud cover allowing for only a 5 to 10 degree drop in air temperatures. Monday night will remain mild, with overnight lows in the 40s. && .LONG TERM /TUESDAY THROUGH FRIDAY/... The lengthy unsettled period will last into Tuesday as the stalled complex frontal zone remains nearby. Both the GFS and ECMWF based guidance suggest one more wave moving along the frontal zone and passing to our north on Tuesday, producing another round of showers. Temperatures will remain mild given the northerly low track, with highs at least into the 50s and possibly into the 60s for the southern half of the area. Tuesday night and Wednesday a mid level trough will amplify across Quebec and finally drive the frontal zone well south of our area, with moisture and showers diminishing from northwest to southeast. Cold advection associated with the trough will knock temperatures back a few notches, with highs in the 40s Tuesday. A slow warming trend should then ensue for the second half of next week as the trough over Quebec moves offshore of the Canadian Maritimes and height rises/weak warm advection overspread the eastern Great Lakes. Model guidance diverges by next Friday with respect to the track of the next system. The GFS keeps most of the energy and deeper moisture suppressed well to the south across the Ohio Valley and southeast States, while the ECMWF takes a much more northerly track through the Great Lakes and would be a warmer and wetter solution. Given the time range and inherent uncertainty, have just included chance POPS for now. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
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At 11Z a frontal boundary is across the region, with this front across the Western Southern Tier near JHW. A northeasterly flow north of this boundary will advect cooler air which will mix with the moist air in place resulting in low cigs. This pattern is climatologically favorable for IFR or lower cigs at BUF/IAG/ROC/ART and conditions. Expect IFR/LIFR conditions to last through mid-morning before improving a bit. There will also be periods of precipitation and patchy fog, and an isolated thunderstorm cannot be ruled out through mid-morning just north of the boundary due to elevated instability. Precipiation may mix with snow or sleet at ART. Drier air will first build into ART as the boundary pushes further south, with conditions improving this afternoon and evening. Elsewhere, expect a prolonged period of mainly IFR conditions as the northeasterly flow persists. Later tonight, expect IFR/MVFR conditions will continue south of Lake Ontario, with VFR conditions at ART. Outlook... Sunday through Tuesday...MVFR/IFR cigs with rain likely at times. Wednesday...VFR.
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&& .MARINE... A frontal boundary will push further south of Lake Ontario today, briefly pushing south of eastern portions of Lake Erie. A northeasterly flow will develop on the cool side of the front requiring small craft headlines along the south shores of Lake Ontario from late this morning through Sunday evening. Winds and waves will also briefly build on Lake Erie southwest of Dunkirk. Conditions will be marginal, but expect there will be a shorter period which meets small craft criteria late this afternoon and into tonight. After this, expect a benign pattern for the first half of next week resulting in modest winds with any headlines unlikely. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...Winter Weather Advisory until 11 AM EDT this morning for NYZ006>008. MARINE...Small Craft Advisory from 5 PM this afternoon to 2 AM EDT Sunday for LEZ040. Small Craft Advisory from 11 AM this morning to 11 PM EDT Sunday for LOZ042-043. && $$ SYNOPSIS...APFFEL NEAR TERM...APFFEL SHORT TERM...THOMAS LONG TERM...HITCHCOCK AVIATION...APFFEL MARINE...APFFEL

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