Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/02/18

Area Forecast Discussion
National Weather Service Binghamton NY
908 PM EST Thu Mar 1 2018 .SYNOPSIS... A complex storm system will approach the area from the Ohio valley today. This storm will bring rain to the area later this afternoon through evening, changing to accumulating snow as we head into Friday, possibly heavy at times. Cold weather with snow showers will start off the weekend. && .NEAR TERM /THROUGH FRIDAY NIGHT/... 9 pm update... A very complex scenario continues to unfold tonight. Strong forced ascent, via excellent and coupled upper jet dynamics, and the approach of a negative-tilt upper-level trough, has caused steadier precipitation to overspread most of CNY/NEPA this evening. As for precipitation type, a transition to mostly snow seems evident at this time, as per MRMS/KBGM radar imagery, spotter reports, surface observations, and web cams, across the western Finger Lakes region. In fact, a recent spotter report has revealed heavy snow and already around 6" of accumulation at the higher elevations of Steuben county as of this writing. Meanwhile, valley locations in this same general area continue to see rain, or a rain/snow mix. Elsewhere across CNY/NEPA, just rain is being observed at this juncture. The HRRR model seems to have the best handle on low-level temperatures so far this evening, so we`ve heavily blended its temperature values into the forecast. It also gives credence to our thinking that dynamic cooling will result in a change over to snow, both from north-south, and from higher terrain down to the valleys with time, during the night. By daybreak, most of the forecast area should be snow, except perhaps for the Wyoming and Lackawanna Valleys in NEPA. As mid to upper-level portions of the storm rapidly intensify overnight and Friday morning from southern PA towards the NJ coast, strong lift should bring a period of heavy snowfall. We still think the most intense snowfall should take place from overnight towards the midday hours from about the I-81 corridor westward in CNY/NEPA, and from Friday morning into the early afternoon east of the I-81 corridor. This is when snowfall rates of 1-2"/hour and locally higher will be common. No significant changes were made to snowfall totals at this particular time. We`ll obviously continue to monitor this evolving situation overnight and on Friday. Previous discussion below: * High Impact Winter Storm to Impact the Region tonight through Friday* Summary: Low pressure over the Great Lakes tonight will transfer offshore to our south early tomorrow. Moisture influx into the region from the south coupled with lift along the track of the low will result in the continued development of widespread precipitation. Precipitation will mainly start as rain and gradually change to snow overnight into the morning hours Friday with higher elevations changing over first. Western portions of the area and higher elevations will see several inches of snow by sunrise. As the low shifts offshore the precipitation will become more focused east of I-81 including the Catskills during the day Friday. Moisture will continue to influx into the region but change directions to the north and east. The moisture will be enhanced by the higher terrain along and east of I-81 Friday, increasing the snowfall rates for those locations. The mechanisms that will lead to heavier precipitation will become more localized on Friday. Exact locations that see the heaviest precipitation during the day are still uncertain with variations of several inches expected over small areas. Winds will increase as well with indications of 30-50 mph wind gusts on Friday afternoon. A look at the CIPS analog package shows few matches close to this event which doesn`t the uncertainty. Precipitation should diminish to flurries and snow showers later tomorrow afternoon and night. Temperatures will start in the 30`s and 40`s late this afternoon but then fall into the morning hours Friday before becoming steady at or just a few degrees below freezing. Current temperatures are several degrees cooler than most model guidance across western portions of the area which will allow for a fairly quick changeover late this afternoon and evening northwest of Elmira in the higher elevations. Impacts: - Snow will accumulate with 6-12 inches (locally up to 24 in the highest elevations in eastern portions of the region). Snow will make both the morning and evening commutes Friday difficult with slick and snow covered roads. Snowfall rates may reach 1-2 inches per hour in spots. - By Friday afternoon and night, blowing snow will start to occur with the increase in wind gusts over 30 mph, perhaps as 50 mph in the highest elevations. - Heavy wet snow will cause stress to trees and power lines likely resulting in some downed trees and power lines along with scattered power outages. Headlines and Uncertainties: A winter storm warning is in effect for our region. The highest uncertainty is across the Poconos where the precipitation will take longer to changeover to snow Friday morning. Totals will elevation dependent for the entire region. Uncertainty is also present with where the localized ingredients for the heavier snowfall (banding) will be located. Right now Otsego, Delaware and Sullivan counties have the best chance to be targeted for the highest totals. NAM/RGEM utilized for the local banding locations. Model Analysis: General trends with the NAM/ECMWF being on the colder end and the GFS being too warm. The RGEM also trended warmer. Our forecast approach was between these two extremes. The HRRR was incorporated for pops over the next few hours. Temperatures were used for precipitation type a blend of the NAM/GFS and our previous forecast. Model data was also blended for the winds with bufkit analysis incorporated on the gusts, expected winds look about the same from the previous update. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... Major winter storm will be situated well off the east coast by Saturday morning but wrap around moisture will still bring a chance for snow showers and flurries especially across central New York. Boundary layer temperatures warm enough by afternoon for mixed rain/snow showers. High will range in the middle to upper 30s. Saturday night/Sunday... Saturday night, scattered flurries still possible across central New York primarily west of I81 with some moisture enhancement from Lake Ontario. Otherwise a dry period with high pressure in the western Great Lakes building into the region. Lows will range in the mid to upper 20s with highs Sunday in the mid to upper 30s. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... Medium range models are in fair agreement through the early part of the forecast then diverge with the next system that comes out of the mid west. Sunday night through Monday night will be dry with seasonable temperatures as an upper level ridge builds across the northeast and surface high pressure noses down from eastern Canada. Tuesday through Thursday will carry chance pops as low pressure lifts into the eastern Great Lakes with a coastal system developing near Delmarva along the triple point then tracking northeast along the coast. Highs temperatures will gradually cool down through the period but during the daylight hours especially the precipitation will be a rain/snow mix. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... The front edge of rainfall is spreading across the terminals this evening and pushing ceilings down into MVFR territory. Flight conditions will degrade as moisture thickens, with visibilities progressively falling to around 2SM-4SM in rain. The rain will mix with and change over to snow from north-to- south, beginning early Friday morning near RME/SYR/ITH and eventually making its way to AVP after sunrise. Visibilities in snow will fall to between 1/4SM and 1SM, with ceilings hanging between 300 and 1200 feet. Winds will gust at 25 to 35 knots at times through the afternoon hours, further degrading visibilities in blowing snow. Outlook... Friday night...Gradual improvement. Snow diminishing to snow showers. Windy with some BLSN. Saturday...VFR/MVFR in Scattered snow showers. Sunday through Tuesday...VFR, though rain/mix and associated incoming restrictions possible late Tuesday-Tuesday night. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...Winter Storm Warning until 1 AM EST Saturday for PAZ039-040- 048-072. Winter Storm Warning from 2 AM Friday to 1 AM EST Saturday for PAZ038-043-044-047. NY...Winter Storm Warning until 1 AM EST Saturday for NYZ009-018- 036-037-044>046-055>057-062. Winter Storm Warning until 1 AM EST Saturday for NYZ015>017- 022>025. && $$ SYNOPSIS...MWG NEAR TERM...MLJ/MWG SHORT TERM...RRM LONG TERM...RRM AVIATION...DJP
Area Forecast Discussion
National Weather Service Birmingham AL
514 PM CST Thu Mar 1 2018 .UPDATE... For 00Z Aviation. && .SHORT TERM... Today and Tonight. Mild conditions persist across Central Alabama at this hour with southwest winds around 10-15 mph. The quasi-stationary front that was across our northern counties earlier tonight has begun to lift just north of our area as a warm front, as winds have shifted at Haleyville and Cullman with an increase in dew points. This is ahead of a weak wave of low pressure over northeast MS. This boundary then extends further west towards another weak area of low pressure near Shreveport LA, taking on characteristics of a cold front. Meanwhile a stronger cold front associated with a northern stream system and surface low near St. Louis is about to move into northwest Arkansas. The southern stream lows will strengthen/consolidate into one low that moves into GA/the Carolinas this afternoon, while the northern stream low will also strengthen as it moves through Ohio. These systems will eventually phase into a strong nor`easter off the New England coast in Miller B- like fashion, while cold fronts associated with each of the lows move through Central Alabama. Main area of rain is located just to the northwest of the forecast area on the cool side of the front, but some showers are beginning to develop over our northwest counties as the LLJ strengthens ahead of the northeast MS meso-low. Meanwhile a few isolated showers are also located over our southeast counties in a low-level moisture axis extending off the Gulf. Further to the west, a pre-frontal QLCS has formed over over SW AR/NW LA/east TX. The area of rain located just northwest of the forecast area should continue to sag southeast into our northern counties this morning. The HRRR is indicating the possibility of a few embedded convective cells in this activity during the early morning hours. These will need to be monitored for any rotation given the enhanced low-level shear/SRH in the presence of the boundary. However, instability during the early morning hours will be very limited, and low-level flow remains veered/uni-directional, minimizing hodograph curvature. So while a brief tornado can`t be completely ruled out across the north this morning, the potential remains much too low to mention in the HWO at this time. The main focus for convection the rest of the day will be the QLCS that will continue to develop and push eastward and then southeastward during the day ahead of a potent but positively tilted southern stream shortwave. Strong westerly mid-level winds will give 0- 6km and 0-3km bulk shear vectors a component perpendicular to the line, giving it some momentum, but low-level flow will be oriented parallel to the line. Warm air aloft will limit updraft intensity along the line, with CAMs indicating a thin convective line with reflectivities struggling to reach 50 dBZ, and this activity may struggle to produce much lightning. Main threat with the QLCS will be gusty winds due to downward momentum transport, as the setup does not appear very favorable for mesovortices based on low-level flow orientation and limited stretching potential. Most winds should remain below severe limits. SPC has dropped the marginal risk of damaging winds for our eastern counties at this time, but prefer to keep a marginal damaging wind threat in our forecast in our east-central counties for now to avoid flip-flopping. This is where the best instability will be due to daytime heating ahead of the QLCS, and there is some DCAPE present as well, so feel that there is still at least a low-end risk of damaging winds. Further south, there will be more instability, but the QLCS will be weaker there due to weaker forcing and the LLJ lifting out. Speaking of winds, 925 mb winds will be around 35-40 kts ahead of the QLCS with decent low-level lapse rates and a well-defined surface pressure trough. High-res guidance indicates good potential for gradient winds to mix down and gust to around 35 mph ahead of the line, so a wind advisory has been issued for areas along and south of I-20. Gradient winds will weaken behind the QLCS, so the advisory was split into 2 segments to account for an earlier ending time along the I-20 corridor. Focusing on impacts, there will probably be some sporadic tree branches/weak trees down across the area, whether the winds are from thunderstorms or gradient winds, and whether or not they are technically "severe" or not. Rainfall amounts will range from a half inch to an inch north, to a quarter inch or less south, so not expecting flooding issues. Behind the QLCS, light to moderate rain should linger for much of the day due to frontogenesis and moisture aloft ahead of the shortwave trough. A couple showers could also develop along the northern stream cold front as it moves in late in the afternoon. Conditions should dry out from north to south during the later afternoon and evening hours, with cooler temperatures moving in. 32/Davis .LONG TERM... Friday through Wednesday Friday brings a pattern change as upper level ridging builds northward from the southwestern Gulf of Mexico into Central Canada. Surface high pressure strengthens as it moves into the Midwest and extends southward to the Gulf coast. This will bring dry and cooler conditions to Central Alabama through the end of the week. Locations across the northern tier of the area, generally near and north of the Highway 278 corridor, will flirt with low temperatures near freezing both Saturday and Sunday mornings. Elsewhere, lows will be in the mid to upper 30s. The upper level ridge axis shifts eastward late Sunday in response to a shortwave moving into the Central Plains. A weak impulse ahead of the shortwave will move across the region, bringing an initial pull of moisture back northward, and isolated showers to west Central Alabama Sunday night. The shortwave will cross the Midwest, dragging a front through the area in the Tuesday/Wednesday timeframe. Unfortunately, there is quite a spread in timing of the front and best rain chances. Will keep pops conservative for now. Near normal temperatures expected for the remainder of the extended with highs in the 60s and lows in the 40s. 14 && .AVIATION... 00Z TAF Discussion. Overall, VFR conds expected thru most of the period. A rain cooled outflow boundary has pushed southward and out of Alabama. North of the the boundary, patchy light rain will continue for areas south of I-20 thru 03z, but intensities not enough to reduce vsbys blo 5 miles. The actual cold front was across extreme nw Alabama and will reach the I-59 corridor by 03z. West winds 3-6 knots ahead of the cold front will become northwest 10-15 knots after fropa. There will likely be some MVFR cig associated with the cold front as it passes thru the northern TAF sites, and included TEMPO cigs arnd 2000 feet agl for a few hours. After 06z VFR conds will prevail with skies becoming clear by 09z at most locations. 58/rose && .FIRE WEATHER... A line of showers and some embedded thunderstorms will move through today. Drier and cooler weather will move in Friday and continue into the weekend. RH values may drop to around 25 percent in portions of East Alabama Saturday afternoon, but 20ft winds will remain light. There are no fire weather concerns. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 40 59 33 61 34 / 20 0 0 0 0 Anniston 40 61 34 62 35 / 20 0 0 0 0 Birmingham 41 61 36 63 37 / 20 0 0 0 0 Tuscaloosa 42 63 36 65 38 / 20 0 0 0 0 Calera 42 62 37 64 38 / 30 0 0 0 0 Auburn 44 63 38 64 39 / 30 0 0 0 0 Montgomery 46 66 38 67 38 / 30 0 0 0 0 Troy 46 66 38 67 38 / 30 0 0 0 0 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$
Area Forecast Discussion
National Weather Service Billings MT
252 PM MST Thu Mar 1 2018 .SHORT TERM...valid for Fri and Sat... Satellite imagery shows upper ridge axis over the high plains with a deep Pacific low off the coast. SW flow aloft has brought an increase in high clouds over our cwa today. Pressure falls to our west has allowed for winds to shift to the east across most of the area. This includes the Livingston airport, while Livingston DOT stations remain gusty out of the south. Orientation of gradient and mid level flow suggest the winds in the city of Livingston itself will be stronger than at the airport, and could see gusts to 50 mph. Latest ob at Wicked Creek Raws in the Absarokas shows gusts to 41 mph, so will have to keep watch of the DOT sites. Otherwise weather tonight will be quiet as we await the Pacific trof. Could see some valley fog across our east late tonight into Friday morning. There will be some low level moisture advection as winds increase a bit out of the SE, and cannot ignore the component of boundary layer moisture provided by some melting snow. HRRR beginning to show patches of fog across our east beginning around 06z. Initial shortwave rotating around the Pacific coast low will lift thru the western half of MT tomorrow. This will bring some western mountain snow but little else in our cwa. Temps should be similar to today most locations, and somewhat warmer in our southeast where 850mb temps will rise to +4C to +6C within surface trof. This should yield highs well into 40s in the SE corner of MT. Push of pressure rises from the southwest behind aforementioned shortwave will bring a period of increases SW winds along our western foothills including Livingston tomorrow afternoon and evening. Could see more gusts to 50 mph. Saturday will be slightly cooler (highs in 30s) as we see weak cool advection behind shortwave lifting to our north. Things get more interesting late Saturday and Saturday night as Pacific low moves inland bringing moist and diffluent southerly flow into our region, as surface and mid level winds are upsloping. Expect snow to develop during this time period across much of our cwa. Model spread begins to increase and this will affect who sees how much snow with this system through the weekend. Heads up for anyone traveling. JKL .LONG TERM...valid for Sun...Mon...Tue...Wed...Thu... Complex and highly uncertain weather pattern is anticipated for the end of the weekend and beginning of the work week. The main theme will be chances for accumulating snow Sunday and early Monday along with colder temperatures. Conditions improve through the week with generally dry conditions anticipated Tuesday through Thursday. Please continually monitor the forecast through the weekend. Initial wave of low pressure that passed through the area Saturday will retreat into western Alberta Saturday night as another area of low pressure rotates around a broad trough in place across the western United States. There is large uncertainty in the going forecast due to this second area of low pressure. As it rotates east around the bottom of the trough, if will then move northeast into the forecast area Sunday night. Ahead of the feature strong diffluent flow, and lift, will bring widespread snow across the region Sunday into Monday. At this time, there is high confidence that nearly everyone in the southern and eastern half of Montana will receive some amount of accumulating snow with this system. The high uncertainty revolves around where the heaviest amounts of snow will fall. The GFS kept the higher amounts generally south of the I-94 corridor while the latest EC guidance kept the higher amounts north of the I-94 corridor. The Canadian solution was a healthy balance between these two ends of the spectrum with higher amounts of snow extending along and to the north and south of the I-90 corridor. At this point, still leaned closer to the GFS/Canadian solutions as these have been the more consistent solutions recently but future forecast updates will need to be watched closely as forecast amounts will likely change in this complex pattern and could shift further north (as has been the slow trend in the GFS solution the last 24 hours). For the locations in the heavier bands we`re looking at 3 to 6 inches of new snow possible Saturday night through Monday afternoon. Elsewhere, north of the I-90 corridor and in zones west of Billings/Roundup we`re looking at 1 to 3 inches of new snow. As this area of low pressure wraps up Sunday evening into Monday morning and moves into the Dakotas, northwest winds will quickly increase early Monday. Currently have 30 to 40 mph wind gusts east of Forsyth and Lame Deer. When combined with the new snow this will increase the blowing snow threat with limited visibilities and drifting snow possible along area roadways in eastern Montana. If the GFS solution verifies this winds are anticipated to be less of a problem as the GFS clears this system out of the region quickly Monday morning. As stressed earlier, this weekend is not a good time to take a break from the good habit of checking the weather forecast. Expect changes to these forecasts over the next 48 hours as details become more clear. Conditions become quieter across the region Tuesday afternoon through Thursday as a ridge of high pressure takes over the weather pattern in the region with no snow expected these days as of this update. Dobbs && .AVIATION... VFR condtiions will prevail through the TAF period everywhere except eastern Montana at KMLS/KBHK where patchy fog could develop after 09z this evening and last through 15/18z Friday. Expect LIFR conditions in any fog that develops across eastern Montana. Regionwide, light easterly and southeast winds will affect all terminals except KLVM where gap winds will occasionally break through the east winds and bring 25 to 35 kt gusts from the southwest. Mountain obscurations expected through the night at KLVM. Dobbs && .PRELIMINARY POINT TEMP/POPS... Fri Sat Sun Mon Tue Wed Thu ----------------------------------------------------------- BIL 018/038 020/036 017/028 013/035 016/037 017/037 021/039 01/E 12/S 56/S 32/J 11/B 10/B 11/B LVM 023/043 017/036 013/027 013/035 016/038 019/038 022/039 13/W 22/S 56/S 32/J 11/B 11/B 11/N HDN 013/039 017/036 016/027 012/032 012/034 014/035 017/038 01/B 12/S 56/S 42/J 21/B 10/B 11/B MLS 010/030 015/033 015/025 009/022 003/024 004/030 011/030 00/B 01/E 46/S 52/J 21/B 00/B 01/B 4BQ 017/043 019/035 018/027 011/028 009/029 010/034 016/036 00/B 01/B 56/S 53/J 31/B 00/B 11/B BHK 014/039 017/035 017/027 010/020 002/022 002/029 008/031 00/B 00/B 46/S 53/J 22/J 00/B 11/B SHR 014/046 021/036 017/026 011/032 012/035 014/039 019/040 00/U 02/S 56/S 32/J 11/B 10/U 11/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$
Area Forecast Discussion
National Weather Service Gray ME
1034 PM EST Thu Mar 1 2018 .SYNOPSIS... Low pressure will quickly intensify as it moves off the mid atlantic coast south of New England tonight through Friday. The center of low pressure will gradually move southeast Saturday through Sunday. High pressure will build in from the west Monday through Tuesday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... 1020 PM...For the most part overnight forecast on track, although did shift arrival of precip back by an hour or so in srn zones. For the most part the p-type should be rain in the srn half of NH and SW ME, although some of the higher elevations in the Monadnocks NE to the Belknap Mtns will see precip as snow when it begins. Any area of higher elevations NE of here are unlikely to see precip overnight. A quick early look at 00Z NAM shows it being drier across the CWA and more in line with 12Z Euro. Also, 02Z HRRR shows a somewhat drier look, with precip shield not extending quite as far north other models, at least thru 20Z. 720 PM...Update to slow arrival of precip by a bit, which should mean a mainly dry evening across almost all of the CWA. Some light precip is possible before midnight in SW NH, but for the most part precip should begin after midnight from SW-NE, and should into most of NH and western ME by sunrise. A few tweaks to T/Td were made based on current obs. Previously...Despite all the action expected Fri...tonight is actually quite the tricky forecast. Mostly clear conditions S of the mtns will gradually give way to increasing low level clouds thru the late evening. As weak lift arrives this should produce some light precip. With no cloud ice expected...we could see areas of drizzle...especially across parts of Wrn ME. With some areas already at or below freezing...some light freezing drizzle is possible. Given all the other preference was to avoid a winter wx advisory for this lower confidence forecast. Given high and mid clouds streaming N ahead of our next system...some seeder-feeder may also lead to very light snow vs. drizzle. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... ***MAJOR COASTAL STORM EXPECTED FRIDAY*** A complex storm is taking shape across the OH Valley this afternoon. A primary 998 mb low pressure is headed towards central PA...while surface pressures are already falling off the Mid Atlantic coast signaling secondary development is underway. It is this secondary low pressure that is expected to rapidly intensify Fri...expanding the precip shield and bringing rain and snow to much of the Srn half of the forecast area. Model guidance continues to come into better agreement about placement of important features. There is broad consensus in rapidly deepening mid level low centers S of Srn New England midday Fri. That being said the ECMWF continues to drift these features SE faster than the American models. So there is still enough uncertainty about temps and duration of precip to leave the winter storm watch in place. Strong Ely inflow N of the deepening low will focus a band of precip across much of Srn NH and adjacent SWrn ME. Boundary layer is expected to be warm enough for rain in most locations early mild air today has little room to wet bulb cool with dewpoints only now falling into the upper 20s. The cooling of the column will come from intense lift aloft washing out warm layers aloft and gradually working down towards the surface. It really looks like between 18z and 21z Fri afternoon the column will cool enough aloft...despite surface temps in the mid 30s...for ptype to flip to snow. When it does so it may flip to heavy snow at that. For some areas there may only be a couple hours of precip a couple inches is possible. The ECMWF shuts precip down quickly...but based on forcing aloft and RH thru the column I think it may be under selling QPF a bit on the N side. But for parts of SWrn NH precip will linger to around 00z Sat...and significant snowfall is possible. For now the high terrain of the Monadnock region into Sullivan and far Wrn Merrimack County have 6 to 12 inches of snow in the forecast. A slight cooling of the boundary layer could lead to some of these snow totals occurring in the valleys as well. Strong 90 knot H9 jet will form N of the surface low...and roughly parallel the ME coastline. This will focus the strongest winds along coastal York and Rockingham Counties...where 60 mph wind gusts are possible Fri. A high wind warning is in effect for those zones. NEwd along the coast the islands and necks will see wind gusts generally in the 40 to 50 mph range...and I have issued a wind advisory for those areas. Coastal flooding and marine impacts are included in their own sections below. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Broad cyclonic flow will continue over the area Saturday and Saturday night as the center of low pressure continues to slowly drift off to the southeast. The strong north to northeast winds will slowly diminish Saturday and Saturday night. Some residual moisture at times will rotate around the large cyclonic flow bringing bouts of cloud cover at times while other times conditions will become partly cloudy to mostly clear. High temperatures on Saturday will be close to normal in most areas ranging from the mid 30s in the mountains to mid 40s south. Lows Saturday night will be in the mid 20s to lower 30s. Sunday we continue under the cyclonic flow from the departing low well out to seas but drier air will be entrained into the flow as high pressure builds to the west. Considerable more sun can be expected. Sunday will be another day of near normal temps. A large Blocking pattern will dominate weather in the northeast for Monday and Tuesday as an upper level ridge progresses east. Looking for mostly sunny skies both days. Temps will be near seasonal levels. Midweek another system digs southeast toward the mid atlantic coast but models differ considerable on handling of this system. It will be something to watch in the coming days but for now will go with a hedge of a chance of precipitation in the Wednesday time frame. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... Short Term...VFR conditions this evening will begin to deteriorate after 03z as deep...onshore flow develops. I expect conditions to drop to MVFR briefly before IFR in low CIGs. I expect precip to begin as -RA across all NH terminals after 09z. Between 12z and 15z...LLWS conditions will overspread all terminals except for HIE...AUG...and RKD. By 18z LLWS is expected at AUG and RKD. -RA is possible at Wrn ME terminals between 12z and 18z...spreading from S to N. Between 18z and 00z Sat...Srn NH terminals may flip to SN. This is a low confidence forecast...but the transition may happen very quickly...especially around MHT and CON...and accumulation several inches. By late Fri evening/early Sat morning CIGs will be improving...though gusty winds are expected to continue right thru Sat. Long Term...Mainly VFR conditions. && .MARINE... Short Term...Have upgraded all waters to storm warnings...though lower gusts are expected in the bays than on the outer waters. Closer to 25 nm from shore a few wind gusts approaching hurricane force are possible. In addition...large...long period swell will build thru the day Fri. By Fri night into Sat significant seas in excess of 25 ft are expected outside the bays. Strong Ely winds are expected to continue into Sat...and it is possible storm warnings may need to be extended outside of the bays. Long Term... Gales likely on Saturday....diminishing to SCA`s on Sunday and continuing Monday. Winds finally become light and seas subside by Tuesday. && .TIDES/COASTAL FLOODING... Coastal flood warnings have been issued for Portland on S thru high tide Sat morning. To the N high tides combined with wave action will result in coastal flood advisories thru Sat morning. Though Portland itself is more uncertain about reaching moderate flood stage for all 3 tide cycles...wave action will contribute to significant enough impacts to include in the warnings farther S. Across the NH Seacoast strong Ely winds will help keep winds piled into Great Bay...and water levels may not come down much between high tides. Prolonged NEly flow and large...building seas will likely lead to storm surge values up to 2.5 ft. This may lead to pockets of major flooding in NH. Fri night and even into Sat noon high tides will be significant as well. The surge may actually be higher then with continued Ely flow and building seas. We have continued with storm surge 2 to 3 feet along the coast. Long period swell will continue into the weekend across several tide cycles. There will likely be significant splash-over and coastal erosion even after the main system moves out to sea. Expect total water levels to be higher then the models forecast as long as the swell continues. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Wind Advisory from 9 AM Friday to midnight EST Friday night for MEZ024>028. Coastal Flood Advisory from 9 AM Friday to 2 PM EST Saturday for MEZ025>028. Coastal Flood Warning from 9 AM Friday to 2 PM EST Saturday for MEZ023-024. High Wind Warning from 9 AM Friday to midnight EST Friday night for MEZ023. NH...Winter Storm Watch from 7 AM EST Friday through Friday evening for NHZ007-011-015. Coastal Flood Warning from 9 AM Friday to 2 PM EST Saturday for NHZ014. High Wind Warning from 9 AM Friday to midnight EST Friday night for NHZ014. MARINE...Storm Warning from 7 AM to 7 PM EST Friday for ANZ151-153. Storm Warning from 7 AM Friday to 1 AM EST Saturday for ANZ150- 152-154. && $$ SYNOPSIS... NEAR TERM...Cempa/Legro SHORT TERM...Legro LONG TERM...Marine AVIATION... MARINE... TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Huntsville AL
850 PM CST Thu Mar 1 2018 .NEAR TERM...(Tonight) Issued at 850 PM CST Thu Mar 1 2018 After a few very wet days over and around the Tennessee Valley, a drier and cooler airmass following a cold front passage late this afternoon, had brought an end to the rain. The back edge of the rain close to our region was well south of the I-20 corridor of AL/GA. Another area of light precipitation moving SE across Ohio should remain well to the east of this forecast area. Rainfall totals across the region ranged from less than one well south of the Tennessee River, to over 3 inches over far northern Alabama and southern middle Tennessee. Runoff from this rainfall has resulted in rises areas streams and rivers. While some of the smaller rivers/creeks levels are receding, the larger ones, and especially the Tennessee River will overall be running higher than normal, with some points nearing or exceeding flood stage. Please consult our latest statements and/or warnings on this. The Nighttime Microphysics and 10.3-3.9 micron Fog/Low Cloud product indicated more lower altitude clouds headed this way from central Kentucky and Middle Tennessee. The cloud bases in most of TN were VFR (above 3000 ft AGL), but observations at Fayetteville and Tullahoma were becoming MVFR ceilings (2000-3000 ft AGL). We earlier had these lower clouds affecting the northern Alabama airports later this evening till a few hours after midnight. The southward progression of them, as well along with newer output from the HRRR/RAP indicated these clouds should fade shortly after midnight. The drier, cooler air will result in night time lows falling into the upper 30s - close to seasonable norms. Winds should stay up in the 4-8 mph range most places overnight. This will help keep the formation of fog minimized. .SHORT TERM...(Friday through Saturday night) Issued at 130 PM CST Thu Mar 1 2018 A welcome period of dry weather will then begin Friday as a large upper ridge axis in the Plains migrates east into the MS Valley by Saturday morning. The surface/850 mb ridges will also be highly amplified from Ontario through the Gulf of Mexico. We should see highs in the upper 50s to around 60 Saturday afternoon, and in the lower to middle 60s Sunday. Morning lows will dip to around freezing both Saturday and Sunday mornings. .LONG TERM...(Sunday through Wednesday) Issued at 130 PM CST Thu Mar 1 2018 Deep layer ridging pattern will continue into the end of the weekend, helping to maintain benign, dry, and rather pleasant conditions. The main focus of the long term period will be a developing cyclone coming out of the Plains states and dragging a cold front across the area by Tuesday. Ahead of the front, on Monday, expect moisture to surge southwest to northeast across the region. Rain chances will gradually increase throughout the day on Monday and persist through Tuesday afternoon. Model soundings are showing a nose of warm air, likely associated with a warm surface boundary ahead of the cold front, appearing to set up an inversion from 850-700 hPa which persists through early Tuesday. This scenario, along with weak lapse rates, will limit the instability along and head of the approaching front. Shear wise, it is definitely worth mentioning the GFS and Euro model soundings are showing 0-3k SRH over 400 m2/s2. The instability trend bears worth watching over the next few days, but for now, have omitted thunderstorm mention in the forecast for this system. Rainfall associated with this system is not expected to be as abundant as the previous system, with QPF values around half an inch to an inch Monday-Tuesday. With the front passing on Tuesday, cooler air will filter over the region for the tailend of the long term period. We could see some very light rain on the backside of the front, mainly in S. Middle TN and NE AL, but dry air will be quick to advect into the region, especially through the mid/upper levels. Temps Wednesday morning will approach freezing in parts of TN and NE AL, but with lingering cloud cover and a light breeze, not expecting much in the way of frost at the moment. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 603 PM CST Thu Mar 1 2018 At the present, a cold front was moving across the Tennessee Valley. The passage of this front, and drier/cooler air filtering in will help bring an end to the showery weather. Very isolated lingering showers just ahead of the front were noted from south of Chattanooga to SW of Cullman. Those showers were diminishing in coverage as they advanced further to the SE. The RAP and NAM do show MVFR (2000-2500 ft AGL) CIGs during the mid/late evening, as a surge of lower altitude moisture moves across the region. Those clouds should scatter out during the late night, with VFR weather on Friday. NW winds 5-10 kt this evening, should be reduced to near 4-5kt at daybreak. This brings a slight risk of fog formation (especially if winds decrease to light/variable) due to high amounts of residual ground moisture. Winds should become NE 5-10kt in the later morning through the afternoon. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...RSB SHORT TERM...17 LONG TERM...Barron AVIATION...RSB For more information please visit our website at
Area Forecast Discussion
National Weather Service Lincoln IL
844 PM CST Thu Mar 1 2018 .UPDATE... Issued at 844 PM CST Thu Mar 1 2018 High pressure building into the upper Midwest has brought a rapid decrease in wind speeds from this afternoon as pressure gradients relax across the area. In addition, skies have cleared throughout central and southeast Illinois. Enough wind...4-7 mph...should continue to prevent any fog, while a relatively dry air mass pushing in from the northwest will help as well. Lows ranging from 25 in Galesburg to 33 in Lawrenceville look on target. Have made minor updates to decrease wind speeds overnight given a quicker decrease than previously anticipated. && .SHORT TERM...(This evening through Friday) ISSUED AT 213 PM CST Thu Mar 1 2018 Storm system that brought widespread showers and a few thunderstorms to central Illinois last night is well to the east over Ohio...while high pressure over the Plains is building slowly eastward. Showers have come to an end across the NE KILX CWA early this afternoon: however, skies remain overcast. Satellite trends over the past few hours have shown additional diurnal clouds developing on the back edge of the main cloud shield, thus slowing the eastward progression of the clearing. 20z/2pm visible satellite imagery indicates partial clearing along/west of the Illinois River...with clear skies noted west of the Mississippi River. Once the sun begins to set, diurnal clouds will dissipate and clearing line will accelerate eastward late this afternoon into the early evening. Based on latest HRRR forecast, it appears the entire CWA will be mostly clear by around 02z/8pm. Winds will initially be strong/gusty late this afternoon, but will then decrease to less than 10mph later this evening through the overnight hours. Thanks to clear skies, lighter winds, and dry advection from the northwest...overnight low temperatures will drop into the middle to upper 20s along/west of I-55...with readings in the lower 30s close to the Indiana border. Aside from a few high/thin clouds, abundant sunshine will prevail on Friday as high pressure moves across the region. High temperatures will climb into the middle to upper 40s. .LONG TERM...(Friday night through Thursday) ISSUED AT 213 PM CST Thu Mar 1 2018 A mild and dry weekend is on tap across central upper ridging builds across the Great Lakes/Midwest. Mostly sunny skies combined with S/SE winds will boost highs well into the 50s both Saturday and Sunday. The next system slated to impact the region will arrive early next week...with the 12z Mar 1 models all in excellent agreement on its initial timing. All models show low pressure developing in the lee of the Rockies across eastern Colorado Saturday night into Sunday, then tracking northeastward into the Upper Midwest on Monday. While the airmass will initially be quite dry, a band of showers ahead of the low and its associated cold front will push into central Illinois from the west late Sunday night. Model trends have been slightly slower with precip onset...with latest suite suggesting east-central Illinois will remain dry until Monday morning. Best rain chances will arrive on Monday as the boundary nears. Forecast soundings are sufficiently moist to support likely to categorical PoPs...and would not be surprised to see isolated thunder as well, although current GFS MUCAPE values do not support this. After that, model solutions diverge as an upper low cuts off somewhere over the Midwest. The GFS is the furthest south model, featuring the upper low over central Illinois by 12z Tue. Meanwhile, the ECMWF/GEM are both considerably further north over Minnesota/Wisconsin. Given the significant model spread, forecast confidence beyond Monday is below average. If the GFS verifies, showers will persist Monday night through Wednesday as the low meanders through the area. If however the GEM is correct, any rain/snow showers associated with the low will remain north of central Illinois across the Upper Midwest into the Great Lakes. At this point, will take a middle-of-the-road approach...featuring low chance PoPs mainly Tuesday into Tuesday night. This will likely be adjusted as better model consistency is achieved over the next few runs. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 519 PM CST Thu Mar 1 2018 VFR conditions expected the next 24 hours as high pressure moves into the region. NW winds gusting up to 15-20 kts to start the forecast period, then decreasing rapidly overnight. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...37 SHORT TERM...Barnes LONG TERM...Barnes AVIATION...37
National Weather Service Jackson KY
1103 PM EST Thu Mar 1 2018 .UPDATE... Issued at 1102 PM EST THU MAR 1 2018 Showers have redeveloped as colder air arrives and low level lapse rates steepen. Based on HRRR and radar trends, have used a brief period of likely POP over the central and southeast part of the forecast area late tonight. Can`t rule out wintery precip before dawn at the highest elevations in the southeast part of the area. It`s questionable if moisture will reach -10c for ice production once the surface temps are cold enough, but a mention of snow was included on the tallest ridges. UPDATE Issued at 743 PM EST THU MAR 1 2018 Showers have diminished faster than was forecast. Some limited redevelopment may occur for a brief time this evening, with the NAM showing an increase in shallow convection as colder air arrives and low level lapse rates steepen. Have reduced the POP, but held onto the possibility of some light showers this evening. Winds are slowly diminishing after getting quite gusty. Most places gusted 30-40 mph, with a few locations in open terrain or on ridges peaking with gusts of 40-50 mph. Will let the Lake Wind Advisory ride for a while longer, but it may be able to be cancelled before its scheduled 03Z expiration. && .SHORT TERM...(This evening through Friday night) Issued at 351 PM EST THU MAR 1 2018 The latest surface map features deepening low pressure moving across Ohio, with a cold front aligned southwest, currently moving into eastern Kentucky. Aloft, a southern stream short wave trough is moving across the Ohio and Tennessee valleys, and a northern stream short wave is following quickly on its heels, moving across the Midwest region. Showers and windy conditions will occur across eastern Kentucky through this evening as the front continues marching east across the Commonwealth. Have seen wind gusts as high as 51 mph, as reported by one of the Mesonets out in north central Kentucky. The best pressure gradient looks to remain just to our north, so will continue with the Lake Wind Advisory and Special Weather Statement as is for now. The surface low will continue to deepen as it heads east tonight, with colder northwest flow bringing temperatures down into the low to mid 30s across the area. Showers will gradually scatter out through tonight behind the front, with even a few flakes possible on the higher terrain across the southeast. Clouds will likely linger across the east into early Friday morning, before scattering out during the day as high pressure builds in throughout the column. Highs will be in the 45 to 50 degree range, slightly below normal readings for early March. Clear skies into Friday night will set the stage for lows in the 20s for most locations. .LONG TERM...(Saturday through Thursday) Issued at 405 PM EST THU MAR 1 2018 A very broad area of high pressure will move into place for the weekend, along with robust upper level ridging. This ridging is expected to amplify throughout the weekend across our region as it becomes blocked between 2 strengthening upper level over the mid Atlantic, and one over the northwest Conus. The pattern will start progressing again Sunday night, with deep upper level troughing moving across much of the western conus, developing into a secondary upper level low across the northern Plains by Monday morning. From this point forward, the models still have good agreement on the features and timing, but their locations and strength are very much out of agreement, which could play into uncertainty for weather impacts across the Ohio Valley in the upcoming days. By Monday night, for instance, the ECMWF 500mb height is about 9 dam lower than the GFS and located about a state farther NW (southern Minnesota) than the GFS (located over western Illinois). Both shift southeast into the Ohio Valley Tuesday into Wednesday, with the ECMWF maintaining its more stronger and more northerly track. The system, regardless of solution, should exit east of the area by Thursday afternoon, with rising heights expected into next weekend. As for sensible weather, both Saturday and Sunday will be dry and sunny with deep northerly flow in place. This will keep temperatures just below seasonal normals for Saturday with highs in the upper 40s, with a slight rise into the low to mid 50s by Sunday. Did add in some ridge/valley temperature splits for overnight Saturday night and Sunday night with such strong subsidence in place, despite the northerly flow. Return flow on the backside of the departing surface high pressure system will increase throughout the day Monday, as an area of low pressure moves northeast into the Iowa by the afternoon. This boost of southerly flow will result in warmer temps for Monday afternoon, with highs in the low 60s in most locations. The low will quickly track eastward Monday night into Tuesday, dragging a fairly strong cold front across the state during the day Tuesday. As noted above, the upper level pattern by this point is pretty out of sync, so the exact timing of the frontal passage and more so the extent/timing/amount of the associated precip is still somewhat uncertain. Stuck with the given blend of models given the uncertainty. This would place pops in our SW counties starting Monday afternoon after 18Z, with likely pops across the entire CWA by Monday night, continuing through Tuesday morning (and Tuesday afternoon in the east). Slight chance to chance pops will then remain in place for the rest of the period due to wrap around moisture and the proximity of the low pressure systems to the state. With northwest flow expected on the backside of this system, colder temps will advect into the region, which may result in overnight lows below freezing, and the potential for a rain/snow mix across much of eastern KY Tuesday night. However, the pops are fairly low, the QPF is very light, and there is very high uncertainty in the placement of this system this far out, so not putting too much stock in at this point. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) ISSUED AT 743 PM EST THU MAR 1 2018 A mix of MVFR and low end VFR conditions prevailed at the start of the period, with the restrictions being due to ceilings. Winds were brisk out of the northwest with sustained speeds of mostly 10-20 kts and gusts of 20-30 kts. The winds will diminish tonight, but clouds will hold on. In fact, ceilings are expected to come down a bit, with most places ending up with MVFR ceilings before clouds eventually start to clear out. The ceilings should scatter out from west to east late tonight and Friday morning, leaving VFR at all locations by the end of the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...GEOGERIAN LONG TERM...JMW AVIATION...HAL
Area Forecast Discussion
National Weather Service Melbourne FL
813 PM EST Thu Mar 1 2018 .UPDATE... ...Turning Much Cooler Starting Friday Night with Building Seas and Surf Through This Weekend... Tonight...Isolated pre-frontal showers north of our area quickly diminished with loss of surface heating. There has been a little more coverage of showers right along the front, which was currently dropping through the panhandle. We have small PoPs after midnight across our north half as the front drops down the peninsula. The HRRR forecasts a smattering of low dBZ returns there, so will maintain our 20 percent chances, though any showers would be light. The HRRR shows a chance for fog in the far south but boundary layer winds 10-15 knots suggest low stratus, and if any low visibility occurs, it will be short-lived. We`ll have one more night of above normal temperatures, with lows in the lower-mid 60s. Don`t plan much change to the previous forecast. && .AVIATION... VFR through 06Z or so then MVFR CIGs should develop first across northern terminals (LEE/DAB/SFB/MCO) as a cold front pushes into the area, then overspread remaining terminals around or shortly after sunrise. Ceilings should break up or lift to VFR by late morning. North winds on Friday behind the initial frontal passage look to be about 10 knots or less except 10-15 knots at the coastal terminals. && .MARINE... Tonight/Fri...The pressure gradient will support 15-20 knot winds ahead of the cold front tonight, mainly from the southwest/west. The models show winds turning more northerly late tonight across the northern waters behind the front, then spreading into the southern waters Fri. The current forecast which has an exercise caution statement in the offshore waters looks good. Of course, mariners probably already know that quite hazardous boating conditions are on tap for the weekend. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ FORECASTS...Lascody IMPACT WX...Combs
Area Forecast Discussion
National Weather Service Marquette MI
703 PM EST Thu Mar 1 2018 .SHORT TERM...(This evening through Friday) Issued at 419 PM EST THU MAR 1 2018 Water vapor imagery and RAP analysis show a shortwave trof moving into the western Great Lakes. Trof aided an area of shsn that moved across northern WI. These shsn brushed portions of interior western Upper MI, roughly in the area btwn KIWD and KIMT. Webcams showed fairly decent snow intensity around Watersmeet, and Paulding reported 1.5in of snow. Over the last few hrs, there has been an increase in sunshine noted across much of the area. Short term period will feature quiet weather. In the wake of the shortwave moving across the western Great Lakes, heights will steadily rise thru Fri as mid-level ridge shifts toward the Upper Mississippi Valley. Initially, exiting deep layer forcing associated with departing shortwave may support some flurries or isold -shsn over the far e this evening. Otherwise, with 850mb temps only down to -9C, perhaps -10C, air mass won`t be cold enough to support LES tonight. With much of the lower clouds clearing out this aftn, trended fcst toward a little less cloud cover over the w half tonight. Global canadian bias corrected, which is often a superior performer on radiational cooling nights, has temps falling to near 0F over the interior w tonight. If sky ends up mostly clear, that`s probably quite reasonable. For now, trended temps down toward 10F. Temps will range up into the 20s where clouds are more prevalent. Sfc high pres ridge will move into the Upper Lakes on Fri. Clouds off Lake Superior into the eastern fcst area will probably expand for a time in the morning/early aftn as daytime heating works on moisture off the lake. Should see a trend toward more sun as the day wears on. Sunshine working on the lower albedo forested terrain should support temps rising into at least the lower 40s well inland over the w half. Expect 30s closer to Lake Superior and over the e. .LONG TERM...(Friday night through Thursday) Issued at 432 PM EST THU MAR 1 2018 Warmer temperatures through the weekend with dry weather. Potential system expected for early to mid week. Friday night into Sunday night, Mid to upper-level ridging and a surface high will build strongly into the Upper Great Lakes by Friday and then remain the dominant feature into Sunday before slowly shifting eastward Sunday night. This will keep mainly dry conditions in place across the U.P. through this time period. Temperatures will moderate through the weekend as winds become south to southeasterly across the area. Look for high temperatures to remain above normal through the weekend with higs in the upper 30s to low 40s with lows mainly in the 20s. Monday into Tuesday evening: A low pressure system is still on track to slide to the south of the U.P. during this time period; however, models continue to differ on both the surface low track and the mid to upper level low track. The GFS is much farther south with the wave and surface low, taking it across central Illinois. The NH GEM takes takes these features much farther north, bringing them directly across Upper Michigan as shown by previous model runs. The EC takes these features directly between the GEM and GFS. Current thinking with each of the models is that there would at least be a period of mixed precipitation before transitioning to snow. The exact track will determine how much snow/mixed precip the Upper Peninsula will end up seeing. The GFS would bring very light precip to the area, especially with a drier east wind, while the EC/GEM wouild bring light to moderate widespread snow to the area. This system is not currently being sampled with the densely populated observation network, so we can expect better agreement over the next few days. Will be worth keeping an eye on, especailly the mixed precipitation potential. Rest of the extended: As previous shift mentioned, the amount of cold air advection on the back side of the system depends on both the strength and final track the low takes. If the colder solutions are correct, then this would lead to lake effect snow off Lake Superiod Wednesday into Thursday. Specifics will have to be ironed out as we get closer to the event; however, will stick with a consensus of the models for this time period, bringing chance of lake effect snow or rain and snow mix at times. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 702 PM EST THU MAR 1 2018 VFR conditions are expected through the TAF period, but it is possible that some 1,000-2,000 ft CIGs could move over KCMX briefly this evening and early tonight. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 419 PM EST THU MAR 1 2018 Winds across Lake Superior tonight thru Fri will be mostly at or blo 15kt. Winds will increase some over the weekend and will be up to 20- 30kt Mon/Tue as low pres approaches the western Great Lakes. Depending on the strength of the low, winds could reach gale force. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...KEC AVIATION...Titus MARINE...Rolfson
Area Forecast Discussion
National Weather Service Nashville TN
622 PM CST Thu Mar 1 2018 .UPDATE... FOR 00Z AVIATION DISCUSSION. && .DISCUSSION... Current radar imagery is virtually precip free at this time. The frontal boundary is just now pushing across our Plateau. Broken low level cloudiness, though partial in places, still extends north and west across much of KY and western TN. Hrrr still shows a few very light returns into early evening. Will go ahead and update the forecast within the next half hour or so and remove the late afternoon wording. Will adjust wx grids to include a chance of a sprinkle for our Plateau until around 3z. Will update again once the sprinkle threat terminates. && .AVIATION... 00Z TAF DISCUSSION. CKV/BNA/MQY/CSV...Low level VFR ceiling erosion may not take place until 02/07Z W to 02/11Z E per examining current sfc obs, satellite imagery, and consensus of short range model runs forecast/guidance projections. Sfc pressure gradient influences should weaken as forecast valid period progresses as ridging influences become more established. Although substantial low level moisture and clring skies, NW sustained sfc winds around 10kts with occasionally higher gusts should preclude any fog formation development thru 02/14Z. These building sfc ridging influences sfc/aloft will also result in mostly SKC conditions 02/14Z-02/24Z. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......19 AVIATION........31
Area Forecast Discussion...UPDATED
National Weather Service Spokane WA
703 PM PST Thu Mar 1 2018 .SYNOPSIS... Cool and unsettled weather continues into Friday. This includes heavy snow across north central Washington, with periods of rain and snow for the Panhandle and eastern third of Washington. A limited risk for snow showers continues into early next week, especially around the mountains. Temperatures are expected to remain cooler than normal. && .DISCUSSION... Update this evening was to increase chance of precipitation across portions of eastern WA. The heavier band of precip has set up a bit further east that what models were advertising, and therefore made adjustments. Currently the heavier rain/snow is stretched from Pomeroy to LaCrosse towards Davenport to Keller and Republic. After 10 or 11 pm tonight the HRRR shows the precip confined to north WA and the ID Panhandle and exiting towards 4am. The next wave will move into Central WA towards Wenatchee, the Waterville Plateau and east slopes between 4 and 6 am. We have received reports today of 1 to 2 feet of snow across portions of Okanogan and Ferry county. This has been heavy wet snow. This is a good reminder to all northern counties of WA and ID that if you live in locations that have a lot of snow on their roofs (especially flat roofs) to be aware of snow loading problems. Every situation is different, but it may be a good idea to research if snow loading is something to be concerned about where you are. /Nisbet && .AVIATION... 00Z TAFS: Another wave is moving through central Washington in southerly flow and is responsible for low elevation rain and mountain snow. At the time none of this is hitting any of the TAF sites but this band of moisture should track slowly east and bring a chance for rain to KLWS/KPUW and snow or rain/snow mix to KGEG/KSFF/KCOE between 03-09z. This will drop conditions down to MVFR/IFR cigs/vsby. Another wave is expected between 12-15z so there will not be much of break for the eastern TAF sites and the TAFs only show minor improvement before deteriorating again. Further to the west the precipitation has moved east of KEAT/KMWH for VFR/MVFR conditions. Expect moisture and the chance for snow to increase after 12-13z with cigs/vsby dropping down to MVFR/IFR. Tobin && .PRELIMINARY POINT TEMPS/POPS... Spokane 30 37 25 39 25 38 / 90 80 30 10 10 20 Coeur d`Alene 30 37 23 41 23 39 / 70 80 30 10 10 30 Pullman 30 37 25 39 24 38 / 60 80 10 20 10 20 Lewiston 34 44 29 44 29 44 / 40 70 10 10 30 10 Colville 34 37 26 42 23 41 / 100 80 30 10 10 20 Sandpoint 29 34 25 39 23 37 / 70 80 30 10 10 30 Kellogg 29 34 23 37 21 35 / 80 70 30 20 20 40 Moses Lake 34 46 27 45 25 46 / 50 50 10 10 10 10 Wenatchee 33 44 28 43 24 45 / 40 80 10 10 10 10 Omak 33 38 29 40 23 40 / 100 70 40 10 10 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...Winter Storm Warning until 4 AM PST Friday for Okanogan Highlands. Winter Storm Warning until 10 PM PST this evening for East Slopes Northern Cascades. Winter Storm Warning until 4 AM PST Friday above 2500 feet for Northeast Mountains. && $$
Area Forecast Discussion
National Weather Service Charleston WV
1026 PM EST Thu Mar 1 2018 .SYNOPSIS... Continued windy overnight through Friday in the wake of a cold front, with deepening east coast low. High pressure Saturday and Sunday. Another cold front Monday night/Tuesday. && .NEAR TERM /THROUGH FRIDAY/... As of 1025 PM Thursday... Updated temperatures and dew points overnight into Friday to better account for the ongoing cold/dry advection and near term guidance. As of 1010 PM Thursday... Allowed portions of the wind advisory over the middle Ohio Valley to expire, while extending areas farther north further into the night. As of 835 PM Thursday... Updated to expand wind advisory for the reminder of the mountains, along with areas just west of the mountains, for tonight. Got widespread reports of trees and power lines down farther west, on gusts of 50 to 55 mph with the front. VAD briefly peaked at 55 KTS at 5kft. As of 710 PM Thursday... Forecast on track. Latest guidance and momentum mixing suggests 40 KT plus gusts will be contained within the advisory area, However, wind gusts of 30 to 35 KTS with the front is resulting in numerous reports of trees down and power outages in the WV lowlands outside the advisory area As of 120 PM Thursday... Lots of issues to keep an eye on through the near term. Have leaned fairly heavily on the HRRR and NAMNest for many aspects of the forcast, including POPs, temperatures and winds. For this afternoon, have an area of isolated to scattered showers across the SW forecast area, gradually shifting eastward. Then have 90-100 POPs entering from the west ahead of a cold front. Have the highest POPs crossing from west to east ahead of the front into this evening. Winds off the surface really pick up late this afternoon, with 40-50kts at 850mb. Not a lot of instability out there to help mix this down, but in the heavier showers still expect some 30-40 mph wind gusts. Behind the front, in the cold air advection, models showing a period this evening into tonight where these will could downglide to near the surface -- in fact the HRRR shows a decent area of 40kt plus surface gusts in the middle Ohio River Valley this evening and then across far northern CWA tonight. It is rather borderline, but opted to post a wind advisory for the area that the HRRR is hitting the hardest. Thought about extending this all the way across the forecast area, however it looks like the strongest winds across southern WV and southwestern VA will be tied more closely to the line of showers so a shorter fused product like the SPS may be a better way to handle these. Across the highest elevations, have upgraded the high wind watch to a high wind warning. Have decent coverage of 50kt+ gusts along the higher ridges. No changes made to the wind advisory for the rest of the mountainous zones. Attention then turns to cold air rushing in, changing the rain over to snow. Could see some flakes mixing in across most of the forecast area, however accumulations should be very elevation dependent. Only made some minor changes to snowfall amounts through tomorrow. Did decide to expand winter weather advisory into the higher elevation zone of Nicholas County where the forecast bumped up to right at 3 inches which is advisory criteria. Add in the gusty winds creating blowing snow and it seemed prudent to make this change. Could argue that the blowing snow may be enough for a winter weather advisory through the southern mountain high elevations zones as well, but with amounts quite a bit less there held off for now. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... As of 130 PM Thursday... Still looking at strong wind gusts lingering across the higher terrain Friday night, with a decrease in winds across western zones, although still gusty at times Friday night and Saturday, as surface high pressure tries to nudge in. Otherwise, some lingering light snow showers across the northern mountains Friday night, with little to no additional accumulations expected. High pressure finally takes a firm hold over the weekend, with dry, and gradually warming conditions through the weekend, as heights build and high gradually slides off to the east. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 130 PM Thursday... Active weather returns Monday night/Tuesday as the next system moves into the region, spreading mainly rain across the area to start, although a brief period of snow is possible across the higher terrain, but gradually transitioning to snow area wide by Tuesday night/early Wednesday, as colder takes hold across the region. && .AVIATION /04Z FRIDAY THROUGH TUESDAY/... As of 710 PM Thursday... Main impact this period is strong west winds becoming northwest. Wind gusts to 40 KTS were accompanying the front, which crossed the Ohio River just before 00Z, and will cross WW lowlands by 01Z and the mountains by 02Z. Strong northwest winds behind the front will continue gusting to 35 to 40 kts north overnight and into Friday in the northern mountains, before diminishing to 20 to 25 KTS northern lowlands and 30 to 35 KTS in the mountains. Farther south, gusts will be in the 30 to 35 KT range overnight, diminishing to 20 to 25 KTS by Friday afternoon. Moderate to strong southwest winds aloft quickly switch to northwest by 03Z tonight, and then remain moderate to strong northwest through Friday. Brief IFR is still possible in rain showers east of the Ohio River through about 02Z, and in the mountains in snow showers overnight, otherwise MVFR stratocu through Friday morning will mix up and out Friday afternoon. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SATURDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing of category changes with showers and then change over to snow may vary. Strong, gusty winds will tend to vary. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE FRI 03/02/18 UTC 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14 EST 1HRLY 22 23 00 01 02 03 04 05 06 07 08 09 CRW CONSISTENCY H H H H H H H H H H H M HTS CONSISTENCY H H H H H H M H H H H M BKW CONSISTENCY M L L L M L M H H M H L EKN CONSISTENCY L L L L L L L L L L M M PKB CONSISTENCY H M M M H H H H H H M M CKB CONSISTENCY M M M M M M M L H L M M AFTER 06Z SATURDAY... After a break in the weather this weekend, IFR is possible in rain Monday night into Tuesday. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Wind Advisory until 5 PM EST Friday for WVZ516-518-520-522-524- 525. High Wind Warning until 1 AM EST Saturday for WVZ523-526. Winter Weather Advisory until 5 PM EST Friday for WVZ520-522- 523-526. Wind Advisory until 4 AM EST Friday for WVZ009>011-019-020- 027>034-039-040-515-517-519-521. Wind Advisory until 1 AM EST Friday for WVZ017. OH...Wind Advisory until 4 AM EST Friday for OHZ066-067-075-076. Wind Advisory until 1 AM EST Friday for OHZ084-085. KY...None. VA...Wind Advisory until 4 AM EST Friday for VAZ003-004. && $$ SYNOPSIS...TRM/MZ/SL NEAR TERM...TRM/MZ SHORT TERM...SL LONG TERM...SL AVIATION...TRM