Area Forecast Discussion
Issued by NWS Buffalo, NY

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KBUF 290829 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 429 AM EDT THU SEP 29 2016 .SYNOPSIS... An upper level low, cut off from the main jet stream, will meander over the Midwest through week and the weekend while periodically sending rain showers across the region. && .NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
The cut off upper level low that we will be talking about through at least the end of the weekend is now over Indiana and will slowly spiral towards northern Kentucky the next 24 hours. IR satellite imagery displays a wealth of Atlantic moisture stretching from the Carolinas towards the southern Mid-Atlantic region this morning. This moisture will continue to push northward today as the upper level low slowly drops southward. A southeasterly LLJ will transport this moisture northwestward across WNY today, with both early morning isentropic lift, and convergence along the LLJ bringing lift through the deepening moisture to produce rain showers. These rain showers will mainly fall across WNY, with the longest duration over western areas that are closer to the upper level low, and low level jet axis. Tonight moisture will contract to near the upper level low, with rain showers ending from NE to SW across WNY. Lingering showers may clip far western Chautauqua through the night. Rainfall totals today and tonight are expected to range from a few tenths of an inch across Ontario/Wayne/Cayuga to around a half an inch across the Northern Niagara Frontier, to an inch or more across the So. Tier. Though 850 hPa temperatures will be similar today as of Wednesday, the thicker cloud cover will hold afternoon highs 5-10 degrees cooler. Highs today will range through the 60s across WNY, but possibly near 70F east of Lake Ontario where some sunshine this morning is likely. Tonight lows will drop back to around 50F east of Lake Ontario, to the low to mid 50s south of Lake Ontario.
-- End Changed Discussion --
&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
-- Changed Discussion --
On Friday an upper level low is forecast to lift from Kentucky into Indiana, while high pressure retreats into Northern New England. This will result in an increasing southeasterly mid-level flow which will tap into Atlantic moisture. 00Z model consensus is a bit slower, but there is broad model agreement that showers will lift into the Western Southern Tier on Friday. This band should weaken as the upper low stalls across Indiana with showers spreading across the rest of Western New York late Friday. The Eastern Lake Ontario region should remain dry on Friday since is is closer to the departing surface high. After this, the upper low should remain nearly stationary across Indiana through Saturday. This will maintain a moist flow across our region, but showers will be driven by subtle features such as vorticity maxima pivoting around the upper low. These features are difficult to forecast this far out, with this uncertainly reflected by an extended period of mid-range POPs (40 to 60 percent) for Friday night and Saturday. Model consensus lifts the upper low into Eastern Michigan Saturday night. This will shift the diffluent flow aloft northward into the Eastern Lake Ontario region with more spotty showers elsewhere. Although there is a persistent chance for showers, expect periods of dry weather too between disturbances. Rainfall amounts should average between a quarter and half inch across the Western Southern Tier on Friday. After this, consensus QPF is on the light side with less than a quarter inch expected in most locations during the Friday night through Saturday night period. Due to the cloud cover temperatures should have a narrow diurnal range with highs in the 60s and overnight lows in the 50s. This is near to slightly above normal for this time of year.
-- End Changed Discussion --
&& .LONG TERM /SUNDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
The cut-off upper level low is expected to begin tracking from Michigan eastward across Lake Ontario through Sunday. This track will continue the threat for some showers across western and north- central NY as lift produced by the low continues to interact with Atlantic moisture wrapping into and around the circulation. Model consensus finally transitions the closed low to an open wave on Monday. The axis of this trough will cross our forecast area from northwest to southeast along with residual moisture to continue chances of scattered showers to start of the work week. During this 48-hour period we are not expecting any significant rainfall accumulations due to the scattered nature of the showers. Model consensus QPF during this time is around a quarter inch. A return to drier weather is then expected by Monday night through Wednesday as the remnants of the upper low shift off the coast of southern New England and an amplified 500mb ridge builds over the eastern States all in response to a deep trough pushing across the western states. Subsidence beneath this ridge will help scatter out much of the lingering moisture leading to partly to mainly sunny skies. Temperatures through the entire long term period will top out in the mid 60s to low 70s during the day and upper 40s to low 50s each night.
-- End Changed Discussion --
&& .AVIATION /09Z THURSDAY THROUGH MONDAY/... A southeast flow aloft, and surface easterly flow will spread deeper Atlantic moisture over the region and bring an area of showers over the western three TAF sites. The region remains VFR (So. Tier MVFR) to start the 06Z TAFS, but we should see additional low clouds within the MVFR flight range (So. Tier IFR) spread northward through the night with the deepening Atlantic moisture. In addition to lowering cloud bases, we should also see an increase in shower activity from the So. Tier at 06Z to near KROC around 07Z and then KBUF/KIAG between 10Z and 14Z. With the upper level low remaining to our west over the TAF cycle, the bulk of the showers will fall along and west Finger Lakes region. Greatest duration of shower chances will be across KJHW, with lower duration across KROC. KART airfield shall remain dry and VFR through the TAF cycle. Moisture will retreat westward tonight, with shower activity focusing more upon KJHW for the overnight period. Tonight will mainly be VFR, with perhaps some MVFR over KJHW and vicinity in lingering deeper moisture. Outlook... Friday...Areas of MVFR with periods of showers. Saturday through Monday...VFR/MVFR with scattered showers. && .MARINE...
-- Changed Discussion --
High pressure over eastern Quebec this early morning will push westward towards New England, strengthening a pressure gradient over the Eastern Great Lakes region between a surface/upper level low to our west. This will continue a strong easterly flow over the Lakes today, with small craft advisories continuing for the western half of Lake Ontario. There will be enough of a NE component to the wind on Lake Erie that we could see winds in excess of 20 knots along the southern shoreline today. Will therefore issue a SCA for Lake Erie today and into the evening hours. This northeast flow through the SLV may also top 15 knots on the river today, and though low confidence, will issue a SCA for the St. Lawrence River today. SCA will persist the longest on Lake Ontario where easterly winds may exceed SCA through Friday night.
-- End Changed Discussion --
&& .BUF WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
NY...None. MARINE...Small Craft Advisory until 2 AM EDT Friday for LEZ040-041. Small Craft Advisory until 2 AM EDT Saturday for LOZ042-043. Small Craft Advisory from 11 AM this morning to 11 PM EDT this evening for SLZ022-024.
-- End Changed Discussion --
&& $$ SYNOPSIS...THOMAS NEAR TERM...THOMAS SHORT TERM...APFFEL LONG TERM...APFFEL/SMITH AVIATION...THOMAS MARINE...THOMAS

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.