Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/24/17

Area Forecast Discussion
National Weather Service Burlington VT
1042 PM EST Mon Jan 23 2017 .SYNOPSIS... A wintry mix of precipitation will overspread the North Country after midnight tonight and become heavy at times during the Tuesday Morning commute. An extremely hazardous Tuesday Morning commute is anticipated with the icy roads and poor visibilities. A plowable snow and sleet accumulation is likely...along with some ice. Improving weather with above normal temperatures return by Wednesday. && .NEAR TERM /THROUGH TUESDAY NIGHT/... As of 1033 PM EST Monday...Latest trends across e-central NY and s-central VT show sleet as the predominant precipitation type. With slow-moving closed mid-level circulation across the mid- atlantic states, getting plenty of atlantic moisture and above freezing temps aloft moving in on ely 850mb flow of 50-55kts per RAP at 03Z across central New England. The 00Z NAM is in line with observational trends, showing predominantly sleet across much of our region as precipitation develops and intensifies during the pre- dawn hours. It`s rare to get a predominantly "sleet storm", but that appears to be the case given expected thermal profiles, along with pockets of freezing rain during Tuesday morning (especially central/ern VT). Impacts on the morning commute will likely be significant, with moderate to heavy sleet, with pockets of freezing rain expected resulting in icy and hazardous roadways and sidewalks. All in all, no significant changes needed to the forecast attm. Have adjusted onset timing to be a bit quicker, with precipitation (predominantly sleet) underway at SLK/RUT/LEB/VSF and spreading nwd at 0330Z. Anticipate sleet into BTV by 05Z. Heaviest mixed precipitation rates generally 08-14Z most locations. Previous discussion...A complex and extremely difficult forecast with regards to thermal profiles and associated precip types. Complex thermal profiles have started with Whiteface down to 19F and Mansfield at 21F...while BTV is 36F. We have taken a conservative approach in the snow accumulation department...with a general 2 to 6 inches of snow/sleet expected...along with some ice accumulation...especially eastern/central VT...including the Northeast Kingdom. We also have to watch low level cold air bleeding down the CPV on north winds...resulting in more freezing rain. Our thinking is generally between one and two tenths of an inch of ice...with some isolated higher amounts in central/eastern VT. Winter weather advisory continues from 7 PM tonight until 10 PM Tuesday for our entire forecast area. The most intense part of the storm with the highest precip rates will occur right during the Tuesday Morning commute (4 AM to 9 AM)...making for an extremely hazardous morning commute. Water vapor shows well defined closed cyclonic circulation over central NC...with a tremendous feed of deep Atlantic moisture advecting into the NE CONUS/Mid Atlantic. IR sat pic shows a classic mature cyclone with well defined warm conveyor and strong upper level divergence pattern with embedded dry slot over eastern NC. This circulation will slowly move northeast with surface low pres tracking from eastern NC to Cape Cod by 00z Weds. Overall models in excellent agreement with tracking of surface low pres...along with showing deeply negative mid/upper level trof lifting northeast...but weakening through time. This weakening mid/upper level feature...along with limited low level cold air advection will minimize backside bonus snow potential on Tuesday Night. NAM/GFS show band of very strong lift/fgen forcing with strong 700 to 500mb vorticity advection lifting from south to north across our cwa between 2 AM and 10 AM tuesday. Helping to enhance deep layer lift and low level moisture advection will be nose of 45 to 55 knot easterly 850mb jet and anticyclonic curved 250mb jet over eastern Canada. Big question does this strong lift/upper vertical velocities cool the column just enough to support snow or does the low level easterly jet advect warm nose of 4 to 6C air into our region and support a mix of sleet and freezing rain. Still plenty of uncertainty with regards to low level thermal profiles with latest 12z GFS supporting a mostly snow event...while NAM/ECMWF is a mix of sleet/freezing rain...while GEM is in the middle. For example the NAM Bufkit at BTV at 10z shows 5C at 5000 feet associated with southeast wind of 40 knots....while temps at 2000 feet are -6C with low level north/northeast winds draining down the CPV. Meanwhile...same time period GFS shows isothermal layer near 0C from 4500 to 7500 feet with -6C between 1500 and 3500 feet...supporting more snow. Based on complexity of thermal profiles and uncertainty...have gone conservative with snow and utilized a model blend of NAM/BTV4km/GFS/ECWMF to determine precip type and associated snow/ice amounts. This supports a mix of snow/sleet with areas of freezing rain...thinking during the heaviest precip rates mostly snow will occur...with some sleet. As warm layer becomes better established on Tuesday and low level cold air bleeds down the CPV/CT River Valley profiles support more of a freezing rain threat...with more snow/sleet across Northern NY where warm nose is limited. However...boundary layer temps are just marginally cold ice accumulation is uncertain at this time...especially CPV where temps today are in the mid/upper 30s. Given downslope easterly flow...would not be surprised if temps warm into the mid/upper 30s from Mt Holly to East Middlebury to Underhill to support some rain on Tuesday Afternoon. Expecting a break in the heavier precip by mid-morning into early afternoon...before next round of light to moderate mix rain/sleet and freezing rain develops on late Tues Afternoon/ closed system lifts northeast. Timing of this secondary surge of precip could impact the evening commute with another round of light wintry mix slowly changing back to snow showers from west to east toward profiles cool. Bottom line for snow/sleet accumulation is generally 2 to 6 inches with some higher amounts possible Dacks/SLV and parts of the southeast upslope region of the Green Mountains. Ice accumulations of a trace to 0.10 of an inch CPV...with 1 to 2 tenths of an inch possible across central/eastern VT...including the Northeast Kingdom. The heavy wet snow/low ratios and freezing rain will probably lead to some power outages. Overall storm total qpf will range between 0.50 and 1.0 with highest values along the se upslope regions of the Green Mountains from Ludlow to Mansfield and another stripe along the eastern Dacks. Expect some shadowing along the western slopes from near Rutland/Danby to North Underhill and over the Northeast Kingdom. Given winds expect terrain to impact qpf amounts for this system. Qpf ranges from 0.25 to 0.75 across the western dacks/ moisture depth is less. Wind threat is minimal and relatively small area along the western slopes from Danby/Rutland to East Middlebury...with isolated gusts to 30/35 mph possible. Mixing is limited as strongest winds occur when precip rates are the strongest. Temps cool into the mid/upper 20s to lower 30s tonight and warm upper 20s to mid 30s...warmest along the western slopes. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... As of 332 PM EST Monday...By Wednesday morning aforementioned low pressure will be over the Gulf of Maine and Nova Scotia, with deep layer moisture rapidly shifting northeast of the BTV CWA through the day. Could see some lingering snow showers across the high peaks in the morning, but by mid-day weak mid/upper level ridging briefly builds in so expect to see some afternoon sun, especially across central and southern areas. Highs will continue to run well above normal in the 30s. Break in active weather is very short as another deep mid/upper level trough over the central CONUS begins to shift eastward Wednesday night, with surface low pressure over the Great Lakes Wednesday shifting northeast in the Ottawa/St. Lawrence Valley. Favorable southwesterly flow combined with increasing low/mid level moisture will enhance precipitation potential downwind of Lake Ontario and points northeastward into northern New York, the northern Champlain Valley and north-central Vermont through the night with boundary layer temps supporting mainly snow except a rain/snow mix across southern portions of St. Lawrence county. As the boundary layer warms further Thursday, precipitation becomes more mixed area-wide until the low pulls east of the area Thursday afternoon and cold air advection develops on increasingly northwest flow. Overall not looking for a lot of QPF through the period, so snow amounts will generally be a dusting to perhaps 2 inches, and locally up to 2-4" across the high peaks. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... As of 332 PM EST Monday...Long term period for Thursday night through the weekend highlights a broad upper trough across the majority of the CONUS with no big systems on the horizon, rather daily chances for light precipitation especially across the high peaks. Temperatures return to more seasonal values though still slightly above normal with highs mainly in the 20s and lows in the teens which supports mainly snow as the dominant ptype for anything that does fall. Best chances look to be Thursday night through Sunday as we remain under cyclonic northwesterly flow with light snow accumulating along the higher peaks, followed by drier conditions for Sunday into Monday. && .AVIATION /04Z Tuesday THROUGH Saturday/... Through 00z Wednesday..VFR overall to start the period with KRUT being the exception with MVFR ceilings. Conditions will deteriorate rapidly to a mix of low MVFR/IFR as wintry precip moves in overnight after 07Z. The forecast trend continues to show the precip moving in late overnight between 03-06z in southern Vermont and between 09-12z across central and northern Vermont and across Northern New York. Expect a variety of precip types with a mix of rain/snow/sleet and freezing rain possible. Additionally with the icing layers just off the surface conditions could be dicey with icing in the low levels of the atmosphere. An easterly low level jet is expected to create gusty winds at RUT and also cause issues with low level turbulence and wind shear due to the speed differences from the ground to 2500-3000 feet agl. Winds overall will also be northeasterly at 05-10 knots for most of the period. Outlook 00z Wednesday through Saturday... 00z Wednesday - 12z Wednesday: MVFR/IFR trending towards VFR/MVFR as the wintry precip tapers off Tuesday evening. 12z Wednesday - 12z Thursday: VFR with skies becoming cloudy late. 12z Thursday onwards: Generally VFR with on and off chances of MVFR in periods of rain and snow showers. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...Winter Weather Advisory until 10 PM EST Tuesday for VTZ001>012- 016>019. NY...Winter Weather Advisory until 10 PM EST Tuesday for NYZ026>031- 034-035-087. && $$ SYNOPSIS...Taber NEAR TERM...Banacos/Taber SHORT TERM...Lahiff LONG TERM...Lahiff AVIATION...Deal/MV
Area Forecast Discussion
National Weather Service Buffalo NY
1026 PM EST Mon Jan 23 2017 .SYNOPSIS... Strong low pressure off the Mid Atlantic will move northeast along the east coast into Tuesday bringing widespread precipitation to the region. Rain will spread northward across the entire area before mixing with and then changing over to snow overnight with portions of central and north central New York receiving significant snow accumulations. Weak high pressure will then cross the region Tuesday night into the first part of Wednesday before low pressure slides north of the region Wednesday night into Thursday dragging a cold front through the area. Colder air behind the front will slowly filter into the region into this weekend with lake effect snows increasing east of the Lower Great Lakes. && .NEAR TERM /THROUGH TUESDAY/... ...Accumulating wet snow to impact a portion of western and north central New York through Tuesday... Latest water vapor imagery showing a large storm system over eastern North Carolina. This feature will slowly churn northward along the Mid Atlantic coast tonight, while a highly anomalous easterly flow in the low levels will pump a wealth of Atlantic moisture back across our region. The moisture will be lifted by a combination of divergent upper level flow, significant height falls and some weak H925-70 frontogenetic forcing. While this will virtually guarantee that all areas will pick up some precipitation, the challenging portion of the forecast will deal with both precipitation type and overall QPF. Latest regional radar imagery showing the leading edge of precipitation has finally worked its way into the Southern Tier and nearing the Finger lakes. Precipitation type so far across the western Southern Tier still rain, with a mix developing east across the Elmira/Ithaca/Binghamton area. Colder air will continue to feed in from the northeast and a gradual transition over to snow/sleet is still expected. Latest HRRR seems to have a decent handle on current trends. It is not overly impressive across the western half of the area tonight, suggesting a gradual diminishing trend to the precipitation and showing a greater precipitation focus up across eastern portions of the area. Will maintain current headlines as we have in place and continue to monitor trends. Latest HRRR continuing to suggest the potential for decent snows of upwards of 6 inches across the Finger Lakes into the North Country, but probably falling shy of this west of the Finger Lakes. On Tuesday...the vertically stacked storm will be nearly stationary off the New Jersey coast. Winds aloft will back in the process...and this will encourage stronger cold advection that will send the whole column to below freezing. Any mixed precipitation in the morning will then change to just snow. The most significant accumulating snow will be during the early morning...then as we work through the midday and afternoon...substantially weaker forcing and gradual drying in the mid levels will lead to a tapering off of the snowfall from west to east. Additional snowfall on Tuesday will range from an inch or so over the far western counties to about three inches across the North Country. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... The middle portion of the week will be the transition period back to a more typical winter pattern. Low pressure in the Gulf of Maine Tuesday night will gradually giveway to a ridge of high pressure which will extend from the Southeastern states into Western New York. There may be some lingering snow showers across eastern portions of the cwa from the departing low with little if any accumulation. Otherwise, it will be dry with lows ranging from the mid 20s to lower 30s. Wednesday will start with a narrow ridge across the region and low pressure developing near Lake Michigan. 12Z model consensus is slower with this system, with precipitation expected to mainly hold off until Wednesday afternoon. The southerly flow will warm areas south of Lake Ontario into the lower to mid 40s resulting in mostly rain showers. It will be cooler east of Lake Ontario where some snow is possible even though any accumulations will be light. The surface low is forecast to track into Southern Ontario Wednesday night, with an increasing southwesterly flow. Late Wednesday night and early Thursday morning it will be windy northeast of the lakes. The track of the low is favorable for strong winds, however the system is weakening as it passes by suggesting wind gusts in the 45 mph ballpark. Otherwise, the system will bring several rounds of precipitation to the area, with the surface low, upper level trough, and enhanced by upsloping as the flow becomes WSW on Thursday. Precipitation amounts should generally be light Wednesday night into Thursday, with the greatest amounts east of the lakes. Temperatures will gradually cool with the passage of the mid-level trough, with higher elevations changing to snow late Wednesday night, and a mix of rain and snow during the day Thursday. Modest accumulations of a few inches are possible on the Tug Hill and across higher terrain in the Western Southern Tier. Amounts should be held down due to the marginally cold enough temperatures aloft. By Thursday evening, consensus 850mb temperatures are about -8C, which is cold enough for all precipitation to change to snow. Temperatures aloft Thursday night will result in only marginal lake induced instability, but the flow will be quite moist with upstream lakes providing some extra moisture. Also, the westerly flow is favorable for banding and upsloping. Off Lake Ontario, expect lake snows to focus on the Tug Hill or just south into Northern Cayuga and Wayne county. Off Lake Erie, suspect that the Chautauqua ridge will funnel winds with a WSW flow at times. Lake snows should focus on the Western Southern Tier and may extend into the Boston Hills. Expect the lower resolution model guidance available during this timeframe does not resolve this funneling and is too far south with its QPF. Moderate snow accumulations are possible off both lakes on Thursday night. This is the start of what looks to be an active period for lake effect snow, potentially requiring lake effect headlines as forecast confidence increases. && .LONG TERM /FRIDAY THROUGH MONDAY/... A return to winter this period as the upper air pattern becomes amplified...allowing for cold air that has been building across the arctic to be tapped into and drawn southward across the Great Lakes region. This cold air will not be extreme, but will be cold enough to yield a lake response off the Eastern Great Lakes. The current storm system over the eastern US will linger over eastern Canada next week, this in response to a building surface ridge near Greenland. Meanwhile an upper level ridge will also build across western NOAM and this will result in northwest flow across central Canada and down across the Great Lakes region this forecast period. For the Friday through Monday time period our region will remain active, with several shortwave troughs refreshing a cold airmass over the airmass that will become cold enough to support lake effect snow. The shortwaves will alter the low level wind field through the period, allowing the lake effect bands to oscillate...but a general northwest flow will make the Southern Tier/Ski Country as well as SE and E of Lake Ontario prime real estate for accumulating lake snows...that could become significant. Temperatures at 850 hPa will average -10 to -13C below zero Friday through Sunday supporting lake effect snow off lakes that are around +2C (Erie) and +5-6C (Ontario). Lake induced equilibrium levels will rise to around 10K feet and with the shortwaves bringing increased synoptic moisture lake effect snow bands could become fairly strong. By Monday temperatures will drop to around -13 to -16C over the region, bringing perhaps the chilliest day this period. An upper level ridge will near the region Monday night, and this feature will likely end the lake effect snow through Monday night. Air temperatures just above normal Friday, will fall to near normal Saturday-Sunday and then below normal Monday. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... A storm system moving up the east coast will bring a period of rain, changing over to snow tonight into Tuesday. Some sleet and freezing rain is likely during the transition to snow. After the precipitation transitions over to snow overnight expect IFR/LIFR conditions at all terminals through Tuesday afternoon. The exception may be at KJHW, where vsby may come up as snow tapers off very late in the period, however IFR/LIFR cigs will hang in. The heaviest snow will fall across central and north central NY, where vsbys down to a mile and possibly lower can be expected. Outlook... Tuesday night...Areas of MVFR/IFR with wet snow. Wednesday and Thursday...VFR/MVFR with a chance of rain and snow. Friday...VFR/MVFR with a chance of snow showers. Saturday...VFR/MVFR with a chance of snow showers. && .MARINE... A deep storm system off the Mid Atlantic coast will combine with high pressure over northern Quebec to produce a fairly strong east to northeast flow across Lake Ontario overnight into Tuesday. This will make it quite choppy for the nearshore waters west of Mexico Bay, so a small craft advisory will remain in effect for those areas. A small craft advisory also remains in effect tonight for the Lower Niagara River. A weaker surface pressure gradient will be found over Lake Erie. The aforementioned storm system will push north along the New England coast later Tuesday and Tuesday night, while a ridge will advance from the Upper Great Lakes. This will promote relatively light winds and negligible waves on the Lower Great Lakes through the middle of the week. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...Winter Weather Advisory until 7 PM EST Tuesday for NYZ007. Winter Storm Warning until 7 PM EST Tuesday for NYZ005-006-008. Winter Storm Warning until 10 AM EST Tuesday for NYZ004-013- 014-021. Winter Weather Advisory until 10 AM EST Tuesday for NYZ003-011- 012-020. MARINE...Small Craft Advisory until 3 AM EST Tuesday for LOZ030. Small Craft Advisory until 1 PM EST Tuesday for LOZ042-043. Small Craft Advisory from 4 AM to 1 PM EST Tuesday for LOZ044. && $$ SYNOPSIS...JM/TMA NEAR TERM...RSH/TMA SHORT TERM...APFFEL LONG TERM...THOMAS AVIATION...JM/TMA MARINE...APFFEL/TMA
Area Forecast Discussion
National Weather Service Cleveland OH
916 PM EST Mon Jan 23 2017 .SYNOPSIS... Low pressure near the North Carolina coast will move off shore this evening and then track northeast along the coastline through Tuesday night. To our west, high pressure in the central plains will briefly ridge into the region on Tuesday. The next storm system will move into the Central Great Lakes from the Plains on Wednesday. A cold front will move through late Wednesday and usher in colder air Thursday through the weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Water vapor imagery shows bands of moisture rotating away from the upper low along the coast. Have noted an uptick in rain in northwest Ohio as one of these bands seems to be interacting with the deformation axis. Although rain will be light, raised pops in northwest Ohio. This band is expected to weaken with time but also shift eastward overnight. Will continue with a mention of light rain and drizzle for most of the area overnight. Have also extended the chance of snow westward to include Ashtabula/Trumbull/Mahoning Counties overnight with thermal profiles that are marginal to support snow. Better chances are over the higher terrain of NW PA but little to no accumulation expected. Previous discussion...Satellite shows breaks in the clouds near KERI and across the eastern third of the lake but this should fill in over the next several hours. Otherwise clouds will continue through the night. Follow the HRRR forecast reflectivity trends into the night showing the best rain chances remaining east third as flow around the east coast low rotates moisture back into the area. Will however continue with chance pops west half into the night. Pops decrease overnight west to east as moisture finally begins to pull out. There is some question as to ptype overnight. The NAM continues to bring 850mb temps down to -1 to -2C late this evening and then temps rise to 0 to -1C by morning. The GFS drops just below 0C after 06z. Dont really think this is low enough to put a lot of snow in the forecast so aside from a possible early morning mix far NERN OH and NWRN PA probably in the higher terrain...kept precip all rain. Low temps in the 30s. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY NIGHT/... Surface low should be off the New Jersey coast Tuesday morning with a surface trough hanging west across the area. Moisture will still be over the area but much of the forcing should be east. Will begin with chance pops east as well as chance pops into the area from the northwest along the trough axis. For the afternoon expect mostly dry conditions under cloudy skies as the ridge builds in from the west. The next storm system will move through the central plains to the central Great Lakes Wednesday. There is a very small chance that precip ahead of the associated warm front moves into the western counties before dawn. Will have a slight chance pop for the far west late Tuesday night. Otherwise rain chances increase through the morning as a warm front/cold front combination move across the area from the west. Will have chance pops continuing through the afternoon. Any precip with the cold front should move east of the area Wednesday evening however more moisture moves in from the west overnight so will have chance to likely pops. Thursday will continue chance pops most places and likely pops in the snowbelt as lake enhancement likely occurs with 850mb temps down to -7C. Temps mild through Wednesday then they drop back to near normal. && .LONG TERM /FRIDAY THROUGH MONDAY/... Winter will have returned by friday with the airmass likely to slowly get colder each day thru sunday. Lake effect snow showers should occur each day but look to try and come to an end by monday evening. Weak upper systems rotating se thru the area may also lead to a little snow shower activity for other areas also. No one day appears to have real heavy snowfall but in a cumulative sense, areas in the snowbelt will likely start to see some significant total accumulations by monday. Temps look to be about normal friday then trend to be a little below normal for sunday and monday. && .AVIATION /00Z Tuesday THROUGH Saturday/... Widespread IFR/LIFR conditions will spread over entire forecast area and linger through the overnight as low the SE coast...moves north. conditions will slowly improve from the west Tuesday afternoon as high pressure moves across the upper Ohio Valley. OUTLOOK...Non-VFR Wednesday into Friday. Rain on Wednesday will give way to snow Wednesday night. The synoptic snow will end from the west Thursday afternoon. Then...lake effect snow will develop in the snowbelt east of Cleveland and continue into Friday. && .MARINE... NE winds with marginal sca conditions for the middle of the lake will settle down later tonight into tue as a ridge of high pressure shifts east across the lake. A strong low will move ne across mi pulling a strong cold front across lake erie wednesday. South winds should increase to 15 to 25 knots ahead of the cold front shifting to wsw then west with frontal passage wed and increasing to 30 knots with a possibility of 35 knot gales. Winds and waves should gradually diminish some thu into fri as the strong low shifts further ne away from the lakes. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...TK NEAR TERM...KEC/TK SHORT TERM...TK LONG TERM...Adams AVIATION...DJB MARINE...Adams
Area Forecast Discussion
National Weather Service GLASGOW MT
815 PM MST Mon Jan 23 2017 .SHORT TERM...for northeast Montana...tonight through Wed... Update: The going forecast is in good shape. The only tweak made was to end the freezing rain advisory for Dawson, Prairie, and Wibaux counties. Radar returns there are tapering off, a development which is in good agreement with the HRRR forecast model. The MDT road report also shows only minimal impacts from any freezing rain that did fall. The remainder of the forecast was left alone, as on and off light snow will be commonplace through the overnight hours. Gilchrist Previous discussion: Small mesoscale system moved east across mainly the central zones this afternoon with snow spreading east into Roosevelt county. further south, precipitation fell as Freezing Drizzle from north of Circle to Sidney. This area was moving south and models have been consistent on keeping it going for a few hours in Dawson, Prairie and Wibaux counties. Accumulations should be about .01-.03, enough to make untreated roads and sidewalks slippery. A Freezing Rain Advisory is in effect until 8 pm. Elsewhere, system exits into North Dakota this evening. Cold Air Advection takes places as cold air mass moves in from Alberta/Sask. A couple of upper low, one over central Canada, the second one is moving through the western states. Both upper lows will merge Wednesday with the upper flow over northeast Montana becoming northerly then. Another batch of moisture in this flow will move through Wednesday with temperature profiles showing all snow. Little if any accumulation is expected, so chance pops look good for now. Temperatures will cool for the central and eastern zones to slightly below normal levels. TFJ .LONG TERM...Wed night through Mon... The long term forecast remains in excellent shape as described below. Upper ridging will provide mainly dry weather conditions for the end of the week and starting off the weekend before a Pacific shortwave knocks down the ridge late in the weekend into early next week with a return to colder temperatures to follow that system. Maliawco Previous Long Term Discussion... Canadian high pressure moves across the region on Thursday with midweek snow shower ending and cooler temperatures. Upper ridge then pushes over the Rockies for drier weather through the end of the week. As a Pacific shortwave pushes into the top of the ridge over the weekend, with warm Alberta chinook will spread south into Montana. By early next week, cooler temperatures and the chance for snow will return with a cold front as the Pacific shortwave slides into the prairies. Ebert && .AVIATION... MVFR CIGS and VFR VSBYS will prevail tonight for most locations while LIFR ceilings linger longer over KGDV as the snowfall gradually ends from north to south through the overnight hours. Amendments may be needed from time to time. BMickelson && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$
Area Forecast Discussion
National Weather Service Pocatello ID
212 PM MST Mon Jan 23 2017 .SHORT TERM...Tonight through Wednesday. Complicated system overhead currently. As indicated by models and satellite imagery, broad upper trough remains in place over western US. Main circulation over Pacific Ocean appears to be filling in while circulation over OR/CA/NV has strengthened. Expect the upper low center to reform over ID this afternoon and evening. In addition, surface low currently located over Great Salt Lake expected to gradually shift E/NE. Combination of these features puts much of SE ID in cross hairs for elevated snow through tonight. Accumulations this morning were higher than originally expected, with snowfall rates meeting or exceeding inch/hour. Short range models, particularly HRRR and RAP continue to show redevelopment of moderate to heavy band of snow this evening into the overnight. The difference between the two is where the band will be located. Both favor orographic enhancement along the I-86 corridor between Pocatello and Burley, but RAP slightly further west than HRRR. Regardless, model spread including GFS, NAM, NAM experimental, NSSL-WRF, etc all favor higher snow amounts through tonight with 8-16 inch totals somewhere between Pocatello and Burley with a slightly smaller bullseye between Idaho Falls and the INL. Operational NAM and GFS slightly lower in the 6-10 inch range, and have tempered forecast snow amounts with those values. The positioning of the low is likely to have the greatest impact with respect to direction of the winds and orographic forcing. Have upgraded all advisories to warnings for tonight especially regarding potential impact for evening and morning commutes regardless of snow amounts. Confidence remains relatively high for timing of the bands but moderate on placement and amounts. Complicating factor is strengthening of the winds in the Burley/Oakley area, and in the north along the MT border. Have left blowing snow in the forecast overnight for these areas where winds are expected to gust over 20kts. Upper low shifts into Plains states during the day Tuesday. Remaining pattern Tuesday through Wednesday includes northerly flow stacking moisture into SE highlands. Gradually cooling temperatures increase snow ratios but deep moisture shifts east with the low. Have kept chance precip most higher elevations near the WY and UT borders, otherwise chances decrease toward the NW central mountains. Increasing snow ratios will complicate matters, but QPF amounts decrease so each 24 hour period should have relatively low snow amounts. DMH .LONG TERM...Wednesday night through next Monday. Development of upper ridge is consistent in long-term models through much of the period. We will have enough upslope component in the 850-700mb layer to trigger some light snowfall over the Caribou Highlands and Upper Snake Highlands. An east-west oriented trough will slide down out of Canada on Friday, cutting off the upslope component and producing some drying. Thus will keep PoPs low Friday through Monday. With the passage of the upper trough, and a northerly flow in its wake, expect to see temperatures coming below normal. Hinsberger && .AVIATION...Pessimistic TAFs for the 18Z package for most of the terminals. Radar trends show two distinct areas of snow in play for southeast Idaho. The first is currently over KPIH and dropping visibility as low as 1/2 mile. The second is still over KBOI and models show this area surging eastward this evening. NAM and BUFKIT soundings suggest heavy and prolonged QPF associated with the second wave lasting through 18Z. Snow could become heavy enough to temporarily drop KBYI, KPIH, and KIDA below minimums. Additionally, winds are expected to increase this afternoon/evening as the second band of snow approaches southeast Idaho. Hinsberger && .HYDROLOGY...After discussion with Custer Emergency Management, the areal flood advisory will be continued for one more day. There has been some improvement in conditions, but concerns have shifted to future snow melt. Therefore it has been advised that we allow the advisory to expire tomorrow. DMH && .PIH WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 6 AM MST Tuesday for IDZ017-020>025. && $$
Area Forecast Discussion
National Weather Service Phoenix AZ
855 PM MST Mon Jan 23 2017 .SYNOPSIS... The last in the recent series of Pacific storm systems will move through the area tonight and Tuesday. The threat for rain and mountain snow showers are forecast to linger over central and eastern Arizona through late tonight, otherwise clearing from the west to east is expected. A much colder and drier air-mass is forecast to settle over the region Tuesday through Thursday, resulting in some of the coldest low temperatures of the season Wednesday and Thursday mornings. Mostly clear skies and slightly warmer temperatures will return next Friday and the weekend. && .DISCUSSION... As expected, the colder front that brought locally heavy rain to parts of SE CA as now moving across South-Central AZ at this hour. Light to moderate shower activity ahead of the front has dropped up to 1/3 inch of rain over much of lower elevation areas of northern Maricopa County, with up to 0.75 of an inch falling over the higher terrain north and east of Phoenix. A final push of shower activity is now moving through the region as the sfc cold front moves through. Perhaps another 0.05 to 0.20 inch of rain could fall over the lower deserts of south-central AZ before the rain ends for good later this evening, as indicated on latest HRRR and 3km NAM model output. Rain and snow showers will likely linger into Tuesday morning over southern Gila County and the higher terrain of extreme northern and eastern Maricopa County. A few inches of snow is still expected above 6000 feet tonight and early Tuesday, with flakes falling as low as 4000 feet. As far as the short-term forecast is concerned, other than some adjustments to the hourly temp/dewpoint/wind grids to better reflect current trends, inherited forecasts are still looking good. .PREVIOUS DISCUSSION... Later Tonight... Clearing skies are expected tonight, but with lingering showers forecast over the higher mountains east of Phoenix on Tuesday, namely southern Gila County zone 24. Tuesday through Thursday... A much colder and drier airmass is forecast to settle over the region Tuesday through Thursday following Mondays cold front. This incoming airmass is the coldest so far this season, and although not extremely cold, will be enough to drop minimum temperatures on the lower deserts into the low to mid 30s, possibly 28 degrees both Wednesday and Thursday mornings. Mostly clear skies area also forecast, again with the exception of a few lingering snow showers over the mountains east of Phoenix Tuesday afternoon. Friday through Monday... Dry northerly flow aloft will continue to keep temperatures below normal through the period. With mostly clear skies, night-time temperatures on the deserts will also remain below normal, from the middle 30s to middle 40s. && .AVIATION... South-Central Arizona including KPHX, KIWA,and KSDL: Modest cold front moving through metro Phoenix as of 21Z with isolated to scattered showers and variable ceilings ranging from 4- 7 kft MSL. Higher mountains obscured. Anticipate higher ceilings and a temporary cessation of shower activity roughly between 22Z-02Z over the lower elevations (no break for higher terrain). Then, scattered to numerous light showers redevelop for a few hours (bases 5-7 kft MSL) followed by clearing after 06Z-07Z (lingering until about 10Z over higher terrain). Surface winds will favor westerly directions through about 10Z before trending southeast. Southeast California/Southwest Arizona including KIPL and KBLH: Isolated showers will continue through 03Z with areas of ceilings 6- 8 kft MSL and localized 5-7 kft MSL before clearing. Southwest and west winds with gusts to 30 kts will continue until about 02Z-03Z before weakening. Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Wednesday through Sunday: Weakened but broad and dry troughing will settle over the west Wednesday keeping flow aloft westerly with low level winds north to northwesterly but rather light. Quasi-zonal flow will develop into the region as high pressure attempts to build into the west and various shortwave systems ride over the ridge flow. Temperatures initially will be well below normal but will gradually warm during the five day period, becoming near seasonal seasonal normal by Sunday. Humidity values will start highly elevated with minimum RH values 30-45 percent, gradually drying during the week and lowering into the mid to upper teens by the weekend. One stronger storm system passing through the Four Corners during the late week/early weekend will produce enhanced easterly surface flow over the Mogollon Rim and northerly flow down the Colorado River Valley, introducing breeziness and periodic gustiness from the north and northeast for the districts. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...Winter Weather Advisory above 6000 feet until 5 AM MST Tuesday for AZZ024. CA...None. && $$ Visit us on Facebook...Twitter...and at DISCUSSION...Percha/Vasquez AVIATION...AJ FIRE WEATHER...Nolte/CB
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
755 PM EST Mon Jan 23 2017 .UPDATE... 01z water vapor and H4 RAP analysis show the deep/sharp trough the moved through the southeastern states Sunday and Sunday night pivoting up the eastern seaboard...and driving a strong nor`easter low pressure system across the mid- atlantic/Northeastern states overnight. In the wake of this system...heights are quickly rising over the Florida peninsula and eastern Gulf of Mexico as we transition quickly to upper level ridging that will control our weather through the middle of the week. 00Z KTBW sounding profile shows the atmosphere over our heads has dried out considerably during the past 12-18 hours...with a PW value down down to around 0.7". A sharp subsidence inversion is located around 850mb...with very dry air/large dewpoint depression through the remainder of the column. Still seeing some lower level moisture trapped below this level arriving with the strong NW winds off the Gulf of Mexico...but this moisture will also be drying out overnight and Tuesday morning. At the surface...The pressure gradient is still quite tight across the region between the aforementioned low along the eastern seaboard and high pressure over the western Gulf. However this gradient across the peninsula and eastern Gulf will be weakening steadily overnight...dropping from about 9mb roughly 4mb by daybreak. This drop in gradient and loss of any CAA will really allow winds to diminish and become less gusty during the next 12 hours. We had seen some passing showers through the afternoon hours driven by the CAA over the gulf...coupled with the very impressive vorticity aloft associated with the passing trough. Our area is now under a region of strong NVA...and shallower moisture...which as cut off the shower development over the eastern Gulf. Our forecast for the remainder of the overnight and into Tuesday is now a dry one. With the inclement weather and windy conditions exiting the forecast...we can settle in for a much quieter day Tuesday...highlighted by lighter winds...plenty of sunshine...and seasonable temperatures. Have a great Monday night everyone! && .AVIATION (24/00 through 25/00Z)... A breezy day has turned into a breezy evening. However...winds will be subsiding for all terminals through the overnight and becoming less gusty. More typical 8-12kt winds can be expected for much of the day Tuesday. Generally VFR conditions this evening with a few patches of MVFR stratocu moving in from the Gulf. The BKN stratocu should end by 06Z...with prevailing VFR for the remainder of the TAF period as skies clear during the late night and morning hours Tuesday. && .MARINE... Conditions still quite rough across the eastern Gulf this evening. The Gale watch has expired...however high end small craft advisory conditions are still exist. Wind and waves will gradually be subsiding through the overnight hours. Residual wave action may however take until later Tuesday morning to fall below advisory levels. Winds and wave will continue to subside Tuesday afternoon into Tuesday night as high pressure builds over the region. && .Prev Discussion... /issued 247 PM EST Mon Jan 23 2017/ SHORT TERM (Tonight-Tuesday)... A strong low pressure system will move off the mid Atlantic coast tonight and south of New England on Tuesday. The associated cold front has moved well east of the Florida peninsula with strong west to northwest winds in its wake across west central and southwest Florida with gradient winds gusting 40 to 50 mph. The gradient will begin to relax late this afternoon and tonight as the low pulls away from the region. Cold air advection across the coastal waters is creating low level instability over the eastern Gulf, and combined with U/L forcing from an approaching 50H trough...scattered low top showers have been developing over the coastal waters and advecting onshore. As the U/L trough pushes east of the forecast area this evening, large scale subsidence will move over the eastern Gulf and Florida tonight bringing an end to the shower activity with skies becoming mostly clear. On Tuesday, high pressure surface and aloft will build over west central and southwest Florida with mostly clear skies and temperatures near climatic normals. Potential will likely remain for high surf and strong rip currents at area beaches on Tuesday as it will take time for seas to subside. LONG TERM (Tuesday Night - Monday)... Models remain in good agreement with overall synoptic scale features during this time frame so a blend will be used. At the start of the period mid level and surface ridging will be building over the area with pleasant dry weather and much lighter winds expected through Wednesday. By late Wednesday the high will shift east into the Atlantic as another upper level trough and cold front approach from the west. Sufficient moisture return ahead of this next front should support a slight chance of showers (Pops 20 percent) across the Nature Coast by late Wednesday night, with the showers then spreading south into the central and southern portions of the forecast area during Thursday and Thursday night as the front moves south through the region. On Friday and continuing into the first part of the upcoming weekend cooler and drier air will advect into the region in the wake of the front with cool dry weather with below normal temperatures expected as surface high pressure noses in from the northwest. During the latter part of the weekend and into early next week embedded shortwaves moving east across the Gulf within a very strong (140+ knot) jet aloft aligned west to east across the southeastern states and northern Gulf coast region combined with sufficient low level moisture and additional upper level energy moving through the base of the eastern U.S. upper trough over the southeastern states will likely support a good deal of clouds and chances (Pops 30 to 40 percent) for showers across the region through the period. Slightly above normal temperatures Wednesday into early Thursday will fall back to below normal Friday through Monday as cooler air overspreads the region. && .Preliminary Point Temps/PoPs... TPA 57 71 56 74 / 0 0 0 0 FMY 58 77 56 77 / 0 0 0 0 GIF 51 73 51 78 / 0 0 0 0 SRQ 60 71 54 75 / 0 0 0 0 BKV 50 69 46 77 / 0 0 0 0 SPG 59 71 59 74 / 0 0 0 0 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...Beach Hazards Statement until 10 PM EST this evening for Coastal Manatee-Coastal Sarasota. High Surf Advisory until 1 PM EST Tuesday for Coastal Charlotte-Coastal Hillsborough-Coastal Lee-Coastal Manatee-Coastal Sarasota-Pinellas. High Rip Current Risk through Tuesday evening for Coastal Charlotte-Coastal Hillsborough-Coastal Lee-Coastal Manatee-Coastal Sarasota-Pinellas. Gulf waters...Small Craft Advisory until 4 AM EST Tuesday for Charlotte Harbor and Pine Island Sound-Coastal waters from Bonita Beach to Englewood FL out 20 NM-Coastal waters from Englewood to Tarpon Springs FL out 20 NM-Coastal waters from Tarpon Springs to Suwannee River FL out 20 NM-Tampa Bay waters-Waters from Bonita Beach to Englewood FL out 20 to 60 NM-Waters from Englewood to Tarpon Springs FL out 20 to 60 NM-Waters from Tarpon Springs to Suwannee River FL out 20 to 60 NM. && $$ UPDATE/AVIATION/MARINE...Mroczka PREVIOUS DISCUSSION...OGLESBY
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
647 PM MST Mon Jan 23 2017 .UPDATE... Issued at 640 PM MST Mon Jan 23 2017 00z KUNR sounding showed decent support for ST running up the Black Hills and creating areas of fog, some FZFG. Support for FZDZ is weak, but recent looks outside suggest there might be a bit starting to fall with KUDX scans showing some shallow returns. Have added FZFG/FZDZ to forecast along the eastern slopes of the Black Hills and adjacent plains. Upstream system looks quite vigorous on water vapour and should provide excellent lift and kill FZDZ potential overnight as -SN overspreads CWA. 00z RAP showing impressive totals by 19z Tuesday along the WY/SD/NE border. Will continue to reassess and collaborate with our friends at CYS. && .SHORT TERM...(This Evening Through Tuesday Night) Issued at 154 PM MST Mon Jan 23 2017 Vigorous impulse and associated jet streak will shift quickly east toward the region and support strong cyclogenesis over the Plains tonight into Tuesday. FGEN/WAA response will support widespread snow later tonight with periods of heavy snow across the SE third Tues. Sfc pressure falls will support a tightening pressure gradient in a CAA regime with increasing ll flow, esp in the lee of the Black Hills where winds are expected to be sustained at 25 to 30 with gusts to around 45 mph Tues. This will support areas of blowing and drifting snow across much of the SD plains. LL easterly flow will support fog through much of the evening over western SD, esp in the foothills region of the Black Hills. UVM and WAA/FGEN will spread NE and support developing snow over the far SW this evening, spread NE through the night. Long period overlap of pos theta-e adv at the base of steep mid level lapse rates centered in the DGZ will support a period of moderate to heavy snowfall rates across scentral SD Tues, esp with a brief mid level closed circulation. Potential CSI banding will also be an issue over scentral SD further enhancing snowfall. Hence, this is where the heaviest snowfall is expected with 6-10 inches likely, some places could see around a foot easily, esp from Wanblee to Winner. Snowfall amounts will drop to the west with adv criteria, save for the northern Black Hills where some weak upslope enhancement will support slightly higher totals around warning criteria. Winds will be of concern on the SD plains, esp east and south of the Black Hills where blowing and drifting snow will be a concern. Given snow amounts and winds, have decided to upgrade areas to a warning and issue an adv elsewhere. Snow will quickly tapper off Tues eve from west to east, although blowing snow will be an issue through much of the night, thus the reason for the longer duration of the warning/adv through Tue night on the SD plains. .LONG TERM...(Wednesday Through Monday) Issued at 154 PM MST Mon Jan 23 2017 Low pressure moves quickly away from the region by Wednesday morning. However, the broad upper trough will remain across the region Wednesday, with a chance for mostly upslope snow showers over far northeast WY and the northern Black Hills area through Wednesday into Thursday as upper level energy slides through the area. Temperatures will be below average Wednesday and Thursday. The upper trough will move out of the area toward the end of the week with a ridge building over the western CONUS. Some moderation to temperatures is expected through the weekend along with dry weather. && .AVIATION...(For the 00Z TAFS Through 00Z Tuesday Evening) Issued At 413 PM MST Mon Jan 23 2017 Deck of IFR ST from far southeast MT to eastern slopes of the Black Hills to central SD will sink south/southwest tonight creating areas LIFR ST/FG. A storm system over UT will spread deteriorating conditions across the rest of the CWA tonight with -SN developing late evening and continuing through the period as it spreads east. Widespread IFR conditions with areas LIFR expected Tuesday due to SN. Gusty winds on the SD plains will produce areas BLSN. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...Winter Storm Warning from 11 PM this evening to 11 PM MST Tuesday for SDZ024. Winter Storm Warning from 2 AM MST /3 AM CST/ Tuesday to 5 AM MST /6 AM CST/ Wednesday for SDZ032-043-044-046-047-049. Winter Storm Warning from 11 PM this evening to 5 AM MST Wednesday for SDZ027-030-031-041-042-073. Winter Weather Advisory from 11 PM this evening to 11 PM MST Tuesday for SDZ029. Winter Weather Advisory from 2 AM Tuesday to 5 AM MST Wednesday for SDZ012>014. Winter Weather Advisory from 11 PM this evening to 5 AM MST Wednesday for SDZ025-026-028-072-074. WY...Winter Storm Warning from 11 PM this evening to 11 PM MST Tuesday for WYZ057. Winter Weather Advisory from 11 PM this evening to 11 PM MST Tuesday for WYZ055-056-058. Winter Weather Advisory from 2 AM Tuesday to 5 AM MST Wednesday for WYZ071. && $$ Update...Helgeson SHORT TERM...JC LONG TERM...13 AVIATION...Helgeson
Area Forecast Discussion
National Weather Service Las Vegas NV
238 PM PST Mon Jan 23 2017 .SYNOPSIS...Scattered to numerous rain showers and snow showers will dissipate overnight Isolated snow showers are possible over the higher terrain Tuesday. Drier, cool and locally breezy conditions are then in store for Wednesday and beyond. && .SHORT TERM...Through Tuesday night... Plan is to let the current Winter Weather, Wind and Flood products run there course through 4 pm. Looking at snow rates and wind speeds diminishing quickly this evening. Instability showers along with a few embedded thunderstorms under cold air aloft will last into the evening before dissipating overnight. Current radar data shows a broken line of showers from SW Utah west toward Beatty. 18z guidance and latest 20Z HRRR still insisting this broken line of showers will move southeast out of Lincoln/Nye Counties across Clark/northern Mohave Counties this evening and into the overnight hours. Region will lie under a broad cyclonic flow on Tuesday with isolated instability showers developing primarily over the higher terrain of Mohave, Clark, Lincoln Counties as well as the Southern Sierra. .LONG TERM...Wednesday through Monday. Looks like an essentially dry forecast through the period except for slight chances of showers on the higher terrain along the northern fringes of our CWA Thursday afternoon and Thursday night. The main concern looks like strong north winds down the Colorado River Valley Friday through Sunday. A trough digging down the east side of the West Coast ridge is forecast to swing southward through our area Friday, with a strong surface high pressure system building over the Great Basin in its wake. This will increase surface pressure gradients to 10-14 mb from Ely to Needles, suggesting strong northerly winds down the Colorado River Valley at least Friday and Saturday, and perhaps beyond. Otherwise, temperatures should remain below normal areawide at least through Saturday, with models disagreeing whether or not to warm things up Sunday or Monday. && .AVIATION...For McCarran...Showers look like they will stay confined to the higher terrain west of the valley which will obscure the higher terrain. There are indications of a line of showers moving from north to south across the valley between 7 pm this evening and 2 am Tuesday morning. Moderate confidence in that occurring so mentioning VCSH during that time. Cigs should remain above 6 kft this afternoon and overnight but could lower to 4 kft if showers materialize. Southwest winds around 20 knots and gusting 30 knots into early evening before speeds start decreasing. Wind direction could swing to a northwest direction with any showers this evening and hold from the northwest through Tuesday. For the rest of southern Nevada...northwest Arizona...and southeast California...Scattered to numerous showers are expected today into this evening mainly over Mohave County and southeast California with mountains frequently obscured. Cigs 4-6 kft will be common dropping to 2-3 kft at times. Southwest winds 15-25 knots gusting 30- 45 knots decreasing this evening and becoming west to northwest overnight through Tuesday. Any residual shower activity on Tuesday will be confined to the higher terrain of southern Nevada, northwest Arizona and the southern Sierra. && .Climate... Bishop, CA has so far (including today) received 5.23 inches of rain. The normal yearly total is 5.18 inches. This marks the first climate station in the United States that has surpassed their entire annual precipitation total. This is also the second wettest January on record behind the 8.93 inches that fell in January 1969. Bishop has also recorded more rainfall this year then the yearly totals in: 2011...3.19" 2012...3.48" 2013...1.33" 2014...3.23" 2015...3.37" 2016...3.43" && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report rain or snow amounts through this evening as a storm moves through the region. && $$ Short Term/Aviation...Pierce Long Term...Morgan Climate...Gorelow For more forecast information...see us on our webpage: or follow us on Facebook and Twitter