204 FXUS61 KBGM 041141 AFDBGM AREA FORECAST DISCUSSION National Weather Service Binghamton NY 641 AM EST Mon Feb 4 2019 .SYNOPSIS... Warm and mainly dry weather today will be replaced by a frontal system bringing rain showers Monday night into Tuesday. Unsettled weather, with up and down temperatures, will continue through the week. There is a good chance for a wintry mix late Wednesday through Friday. && .NEAR TERM /THROUGH TONIGHT/... 640 AM Update...Subtle changes were made to forecast high temperatures today, leaning closer to the warmest MAV guidance since we've remained a few degrees milder than expected overnight and have a head start to climb above blended guidance. No other significant changes as clouds have one final west-east push in the next few hours before retreating northward. Highs now well into the 50s in the Finger Lakes and NEPA with upper 40s-lower 50s elsewhere. 245 AM Update...Lower clouds early this morning have been keeping temperatures up a bit higher than expected across much of CNY, except for areas where it cleared out last evening. This included areas from the central Southern Tier to the Catskills and much of NEPA where temperatures dipped to near freezing. Elsewhere, low to mid 40s were the norm under the clouds. As southerly flow increases ahead of next frontal system, clouds should slowly erode from south to north during the day. Temperatures will likely be warmer than Sunday, reaching the lower 50s in many areas. A cold front approaching from the Great Lakes tonight will bring a period of showers during the overnight hours. This front will have minimal moisture, and be disassociated from strong forcing to the north...thus rainfall amounts are expected to range from around one third of an inch in northern areas to less than a tenth of an inch in NEPA. Precip tonight should be mainly rain with only slight cooling of overnight lows into the upper 30s and lower 40s. Some of the locations furthest SE in our area may hit freezing early under mainly clear skies...but should rebound before any precipitation reaches that area late. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... 245 AM Update...The cold front will sweep through the area early Tuesday with cold advection increasing as the day wears on. Looking at morning highs for most places in NY and early afternoon highs in NEPA before cooling during the late afternoon. The Wyoming and Delaware valleys in NEPA are likely to see another fairly mild day before temperatures drop later on. The front washes out with limited moisture as it settles through the zonal upper flow and any lingering rain showers will change to snow showers downwind of Lake Ontario as the colder air filters in. High pressure builds overhead Tuesday night with skies becoming partly cloudy allowing temperatures to drop back closer to normal overnight lows with readings in the teens and 20s. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... 340 AM Update... Main concern in the long term period will be prospects for freezing rain midday Wednesday through early Thursday morning, before warm air fully dislodges the near-surface cool air by mid morning Thursday. It will be one of those very touchy situations where temperatures being up or down just a couple degrees will make the difference between just isolated to more widespread ice accretion. One trend in the models is for initial light precipitation to develop a bit earlier, from midday west to across the rest of the region in the afternoon. This poses a better potential for wetbulbing. GFS-ECMWF then have main slug of precipitation with a wave late Wednesday afternoon through evening, before somewhat diminishing late Wednesday night, though the Canadian model persists it longer into Thursday morning. Total precipitation amounts appear to range from one or two tenths of an inch northwest, to more like several tenths southeast. Multi-model temperature blends have much of the area in the 33-36 degree range Wednesday afternoon through night, yet raw NAM numbers are cooler and this model usually performs well thermally for handling wintry mix/ice scenarios. The NAM like other models is quite warm aloft, yet has a shallow steep inversion around 925mb with near-to-slightly-below freezing temperatures underneath. One thing we also look for in terms of freezing rain potential, is for high pressure anchored over New England to cause cold air damming. The high is not ideally placed - more into Central to Northern Quebec - but a fairly solid ridge at least extends across New England into the Atlantic. This may promote a light southeasterly feed of cool air near the surface, underneath the warm air just a few thousand feet up, as the NAM suggests. Overall, this tilts the scenario towards an increasing likelihood of light ice accretion for much of the area, but especially in higher terrain; east of I-81 in particular where there are signals for ice amounts to perhaps exceed a tenth of an inch. Things will be much more iffy in the valleys/lower elevations from the Finger Lakes and Twin Tiers southward. Continue to monitor the forecast as details become clearer the next couple days. Previous discussion... Operational models continue to slowly converge on a solution for the system at the end of the week, but with the Euro still forecasting a deeper, more wound up system with stronger warm air advection ahead. The GFS keeps a weaker, faster moving storm with less warm air over the area. In either case, forecast is for any mixed precipitation becoming all rain later Thursday and Friday, before a strong cold front passes and brings much colder air and snow showers for the weekend. Cold front charges through on Friday with strong cold advection and perhaps a brief period of snow, followed by diminishing snow showers into Saturday. Continued to use the blended guidance for temperatures including non diurnal periods, for P-type and hourlys. Pops blended as well, and coming sharper into focus as the models slowly begin to agree. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... Low to mid level ceilings will gradually erode from south to north today. Pockets of early morning light fog will burn off by 14Z. A corridor of MVFR will linger this morning between KSYR-KRME, otherwise VFR for most of today and this evening. A cold front will approach tonight with lowering ceilings and showers developing after 04Z, primarily for areas north of (and including KITH-KBGM. A period of post frontal MVFR is likely in the colder air Tuesday. Winds variable to SW under 10 knots today, increasing 10-15 kts tonight. Outlook... Tuesday...Restrictions return from rain showers. Rain mixing with snow showers Tuesday afternoon. Tuesday night through midday Wednesday...Primarily VFR. Late Wednesday through Thursday...Restrictions as wintry mix develops, changing to rain by Thursday afternoon. Friday...Additional restrictions likely as the rain changes back to snow later in the day. && .HYDROLOGY... Periods of milder weather are expected for the upcoming week. Rainfall amounts look to be minimal (1.5" or less) over the course of the week, and will be interspersed with mixed and frozen precipitation at times. The existing snow pack is very cold and needs an abundance of energy to melt significantly. Some melting and runoff is expected, but the chance for flooding is low. What will need to be monitored by State and local emergency management, and other agencies, is the potential for ice breakup and jams. Any ice problems in CNY and NEPA will be localized and should be generally rare for much of the region. Typical problem areas should be watched closely. Confidence in the occurrence of ice jams and associated flooding is low- medium. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...None. NY...None. && $$ SYNOPSIS...JAB NEAR TERM...JAB SHORT TERM...JAB LONG TERM...DGM/MDP AVIATION...JAB HYDROLOGY...