Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/02/17

Area Forecast Discussion
National Weather Service Columbia SC
959 PM EST Sun Jan 1 2017 .SYNOPSIS... Widespread rain is expected through Monday as a warm front advances northward into the region. After a cool start to the week, well above normal temperatures are expected by mid week. Another cool down will develop late in the week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Upper level ridging over the southeastern states will continue. Southwest flow aloft will allow continued deep moisture and weak short waves to cross the region. Isentropic lift will hold rain across much of the area through tonight. Latest SPC HRRR indicating the heaviest precipitation overnight may stay just west of a line from Waynesboro to Columbia to Cheraw, but all parts of the CWA will see rain. Continued categorical pops through the overnight especially west of the abovementioned line, and likely pops east of the line. A warm front stretching from central GA into the southern Midlands will continue to slowly lift northward overnight. In-situ wedge is forecast to hold across the northern Midlands and Piedmont. Temperatures should hold steady or rise slightly overnight as the warm front moves north. Models focus heaviest rain from from the Central Midlands and CSRA to the Upstate. QPF amounts for the entire short term period are forecast around 1 to 1 1/2 inches with the highest amounts in the western portions of the CWA. Piedmont and CSRA are in a marginal risk of excessive rainfall. Cannot rule out isolated thunder towards daybreak in some locations but no severe weather is expected. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/... Monday...Subtropical ridge off the southeast coast will promote southwesterly flow aloft. A stalled frontal boundary is expected to be across the forecast area on Monday. The models may be trying to push the front northward too quickly given the ongoing rain that is expected. Deep moisture will continue across the area Monday with precipitable water values peaking around 1.6 inches which is around 250 percent of normal. Continued to indicate categorical pops. Rain may be heavy at times and may be enhanced along the boundary. The area remains in the SPC general thunderstorm category which appears reasonable so continued to indicate a slight chance of thunder. Temperatures are a challenge given the tight gradient expected near the front. Blended in output from the local wedge tool to arrive at temperatures north of the front`s expected location. Forecasting 50s north of the warm front and lower 70s south of the front although confidence is low. Tuesday...A robust shortwave trough will move through the area Tuesday morning. This should enhance the precipitation, so have increased QPF during the 06 to 12Z time frame. The warm front is expected to lift northward across the northern portion of the area early Tuesday ahead of an approaching cold front. The area remains in the SPC general thunder category. A high shear low CAPE scenario is possible. NAM bufkit sounding for CAE shows relatively strong 0-6km shear at around 40 knots at 09Z. Severe potential will continue to be monitored. The cold front is expected to push east Tuesday afternoon. Scattered lingering showers early Tuesday with decreasing pops by early afternoon. Some clearing is expected with drier air moving into the area. Precipitable water values will decrease to below an inch by Tuesday evening. It will be breezy on Tuesday and a lake wind advisory may be needed. Drying and downslope flow will promote above normal temperatures in the 70s. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... A broad upper trough over the north central CONUS on Wednesday will dig southeastward across the Carolinas late Thursday/Friday. A dry reinforcing cold front will move through the area on Wednesday. Surface high pressure will build into the area from the west Thursday and Friday and move over the forecast area Saturday. Above normal high temperatures expected on Wednesday with below normal temps for the remainder of the long term period. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Restrictions to dominate the TAF period. Widespread IFR/LIFR conditions expected through the TAF period. A warm front extending across central GA into the southern tip of SC will lift northward cross the Midlands overnight. Abundant low level moisture coupled with weak upper disturbances will hold widespread rain across the region. Light easterly winds ahead of the front will become south to southwest around 5 knots behind the front on Monday morning, and then variable or northwest on Monday afternoon. EXTENDED AVIATION OUTLOOK...High confidence in restrictions continuing through midday Tuesday as a frontal boundary stalls over the region. Restrictions again possible Thursday. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$ SYNOPSIS...99 NEAR TERM...99 SHORT TERM...99 LONG TERM...99 AVIATION...99
Area Forecast Discussion
National Weather Service Charleston SC
1013 PM EST Sun Jan 1 2017 .SYNOPSIS... A warm front will lift north across the area into Monday. A cold front will push through Tuesday, followed by a second cold front Wednesday. High pressure will then build in late in the week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... The forecast philosophy overnight remains generally unchanged and on track. A quasi-stationary front across the southern half of SC is expect to lift north as a warm front overnight. Upper forcing, deepest moisture, and a more pronounced series of weak waves embedded in sw flow aloft are expected to remain over the northern half of GA and across the central/western half of SC. Periods of lighter rains and scattered showers will traverse over our inland zones overnight, while coastal areas south of Savannah probably be mainly dry for most of the night. The risk of thunder over inland zones is non-zero but not significant enough to attempt to forecast in both space and time the next 6-8 hours. Forecast problems overnight will probably end up being related to fog development and pinning down where any stratus develops then builds down. We expanded patchy fog mentions over more inland areas bordering the CSRA and Midlands and over inland GA zones where locations such as Statesboro and Claxton were already reporting some fog at 03Z. Along the immediate coast, everything rides and the development and expansion of sea fog and stratus. Latest vsby progs from the RAP13 and HRRR suggest some fog is possible along the Charleston County coast overnight but hints that the better chances of sea fog will hold off until we near daybreak off the GA and the southern SC coasts. We will continue to monitor overnight with web cams and coastal observations. Temps will remain extremely mild for this time of year with prevailing readings in the 60s across the forecast area. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... Monday: The day starts with considerable low stratus and patchy to perhaps areas of fog, most especially over the coastal corridor where sea fog is possible. However, strong boundary layer mixing will allow for these conditions to gradually improve by late morning, as the sea fog pulls off the coast and the stratus layer lifts. Sub-tropical ridging off the southeast coast will produce a deep SW flow throughout the atmosphere, which allows for a short wave found over the Lower Mississippi Valley from Sunday to traverse the region in the afternoon. This feature has plentiful moisture to work with, with PWat more typical of June than January. the combination of the moisture transport, the forcing for ascent due to the energy aloft and a nearby warm front (maybe transitioning into more of a stationary front) will provide us with scattered to likely showers. The greatest coverage will be located from Allendale County to Tattnall County, where the lowest condensation pressure deficits coincide with some stronger wind fields aloft in closer proximity to the short wave. There is some destabilization that occurs with the aforementioned short wave, and with at least some CAPE and instability, we have maintained mention of isolated t-storms in the forecast. There is little to no risk of severe weather however due to poor lapse rates and the lack of any appreciable thermodynamics, but with modest 0-6 km shear of 35-45 kt the severe potential is certainly non-zero. Due to the strength of the warm advection, where 925 mb temps are as warm as 16-18C, or more common in May or June, and provided the warm front lifts completely north of the region, max temps will reach the lower and middle 70s. Even a few upper 70s will occur from Savannah south. Not quite records, but within a few degrees of such. The beaches will be quite a bit cooler, especially over South Carolina due to the lingering sea fog and onshore fetch over the cooler waters. Monday Night and Tuesday: The stalled out warm front is lifted further to the north, as low pressure treks NE from the lower Mississippi Valley through the Tennessee valley Monday Night, then toward the Delmarva by late Tuesday. A trailing cold front from that low moves into and through our area around 2-6 pm Tuesday. A de- amplifying but negatively tilted short wave swings through the local zones between about 09Z-15Z Tuesday, before lifting off to the NE thereafter. A strengthening low level jet in advance of this feature will continue to pull considerable sub-tropical moisture out of the Gulf of Mexico, which will enhance the potential for showers. So we a solid 60-80% PoP Monday Night, before PoP diminishes during the day Tuesday, as subsidence follows the short wave, along with boundary layer warming and drying. Although there is increased CINH during this time, there remains enough QG forcing, ample shear and upper level difluence for at least a slight chance of thunderstorms into Tuesday morning. The period from 06-15Z is when we have some of the highest QPF of the short term period, where many locations could get a good 1/2 inch or so. Sea fog and low stratus will impact at least the coastal corridor Monday Night and linger into early Tuesday, before a strengthening SW flow develops as we tap into 30- 40 kt of wind within the boundary layer. This produces a breezy day on Tuesday, with highest wind gusts of 20 to perhaps 30 mph at times. Continued warm advection Monday Night and sufficient mixing will prevent temps from dropping any more than about 10-12F from the daytime, and we could establish possible record high minimums for the date. Compressional heating in advance of the cold front and 925 mb temps of 16-18C Tuesday, plus the warm start, will allow for max temps close to records (See CLIMATE section below below). But if you`re on the coast of South carolina, the onshore fetch will hold temps down in the mid or upper 60s. Wednesday: A quasi-zonal flow aloft gives way to a developing low amplitude but broad mid and upper trough that covers much the eastern and central states. The dry westerly flow aloft and the lack of convergence with a secondary cold front that arrives by late in the day, prevents not only any rain chances, but also allows for temps to again achieve highs far above normal. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... The models continue to flip flop in the long term. Given the continued variations in models and to match with out neighbors, we opted to go dry Wednesday Night into Thursday and then have slight chance POPs on Friday and Saturday. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Forecast uncertainties increasing overnight as low cloud build- down potential increases, especially closer to the warm front which is closer to KCHS. Given timing concerns and various forecast soundings seen on higher resolution model guidance, we have not introduced any IFR conditions but have MVFR at KCHS. There is some low level direction shear overnight but not enough in the way of speed shear for low level wind shear mentions. The potential for significant fog is possible near the warm front and cooler shelf waters, but we will wait until trends become better defined with sea fog/stratus impacting near- coastal locations. Chance are good for VFR on Monday afternoon, but showers are possible. Extended Aviation Outlook: Flight restrictions expected Monday evening through Tuesday morning, with low stratus, showers, potential fog and a low end chance of TSRA. Gusty SW winds on Tuesday. && .MARINE... Overnight: Winds to veer to the south and increase only slightly with the warm front gradually moving north. Main concern will be the likely development of sea fog as warmer and moister air moves in from the south, mainly starting over the Georgia nearshore waters, then advecting north into the South Carolina waters. Any sea fog that develops will likely be dense at times and a Marine Dense Fog Advisory may eventually be needed. Monday and Monday Night: the coastal waters will lie near the western periphery of sub-tropical Atlantic ridging, as low pressure travels NE through the lower Mississippi Valley toward the Ohio Valley. While there are no concerns in regards to winds and seas, which remain well below any advisory thresholds, there is a continued chance of sea fog. While at times the fetch may be a little too much SE, and there is a chance of showers and possible t- storms, much of the time the fetch is more favorable from the S to SW. That occurs with elevated temps and dew points that are higher than the cooler shelf waters and those of the Charleston Harbor and the mouth of the Savannah River. This will lead to at least areas of sea fog, possibly dense at times, and the chance of Dense Fog Advisories. Tuesday: Sea fog in the morning will gradually diminish in coverage as a stronger SW flow develops in advance of our next cold front. Warm advection will limit some of the mixing potential, especially over the coolest shelf waters, but with geostrophic winds of 30-35 kt it looks like we`ll be close to advisory conditions on AMZ350 and AMZ374, as well as in Charleston Harbor. It`s too early to issue any SCA at this point, but they could be required at a later time. Wednesday through Friday: Continental high pressure will build behind a secondary cold front that moves through late Wednesday. Cool advection behind that front will allow for elevated winds and seas, but most likely not quite to SCA levels. Also, mariners will be pleased to know that sea fog is no longer a concern with a dry and offshore flow to prevail. && .CLIMATE... Record Max Temps January 2... KCHS...80 set in 2015 KCXM...77 set in 1955 and previous KSAV...79 set in 1952 Record Max Temps January 3... KCHS...79 set in 1998 and previous KCXM...79 set in 1952 KSAV...79 in 1952 Record High Min Temps January 2... KCHS...60 set in 1985 KCXM...63 set in 1985 KSAV...64 set in 1985 && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE... CLIMATE...
Area Forecast Discussion
National Weather Service State College PA
932 PM EST Sun Jan 1 2017 .SYNOPSIS... Low pressure will slide slowly into the area from the southwest early this week. This will lead to a few cloudy and unsettled days. The cold front associated with this low pressure area will cross Pennsylvania on Tuesday or Tuesday night. Temperatures on Wednesday into next weekend will be below, to much below normal. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Mid and high level clouds continue to spread steadily NE and thicken-up across the region this evening. Hourly sfc obs indicate that temps are on track with fcst values and expected overnight mins (that will range from the L20s across the NE, to the L30s across the Southern Tier and Laurel Highlands). The wind will be calm or, at most, light and variable this evening. This, combined with thin patches in the cirrus deck, should allow for a continued slow temp drop via radiational cooling. temps across all of the area will dip to or go below freezing. Only perhaps the higher elevation of the SW and the very tightest slice of land along the Mason-Dixon line stay above fzg tonight - mainly due to the fact that they were pretty mild during the afternoon hours this Sunday. Light precip was seen expanding slowly NE across the SW half of VA attm (along with the SE portion of WVA). A blend of the 01Z HRRR and RAP and the 00Z NAM indicates light freezing rain developing across the south between 06-09Z...and across the northeast half of the CWA after 09Z. Temps will certainly be cold enough for light FZRA when it does arrive. Expect the current radar coverage of the light precip to our south to slowly expand as the developing upslope llvl serly flow combines with increasing uvvel beneath the right entrance region of a 125 kt 300 HPA jetlet lifting NE across the commonwealth during the mid to late morning hours Monday. Collaborated with WFO PHI to exapnd the ZR advy to include Lancaster County. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Low level cold air damming lets go only slowly, but most areas will be above freezing by late Monday morning. The NE mtns should stay coldest the longest - with pockets of slightly sub-freezing temps lingering into the midday hours. Maxes on Monday look a little cooler than prev fcsts, but I only knocked a deg or two off in most places, since they were already set up well. Easterly flow and thick low clouds will put a damper on the Federal Holiday festivities...if there are any. Very light rain and/or drizzle is possible all day and into Mon night before the next good surge of moisture and forcing approaches from the W/SW. Limited diurnal range on Monday and temps will either stay steady or even rise a tiny bit Mon night. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Mild air over my far western zones will return as the next in the low pressure systems to track west of PA occurs again Tuesday. This will bring a southerly flow and high PoPs for Tuesday into Wednesday. Cold frontal boundary will push across the state on Wednesday with scattered snow showers and flurries...especially over lake effect areas. Long range models indicate an area of disturbed weather possibly affecting the mid-Atlantic on Friday. A clipper like system moving into the Ohio valley. Otherwise normal to below normal temps are expected through this extended period. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... VFR conditions prevail over Central Pennsylvania airfields this evening. Light winds will turn to the east later tonight as sfc high will be to our northeast. Warm advection clouds move back in from the south and west later tonight. Before that happens, however, radiational cooling in the will allow temperatures to go below freezing at all terminals, except perhaps JST where higher elev and earlier cloud arrival may keep them just above freezing. Moisture and warmer air flowing northward will ride over the cold air trapped in the mountains, leading to some freezing rain. With marginal temperatures at KLNS, KMDT and KJST, have included only a brief period of freezing rain, with a longer period at the other airfields. The increasing moisture and RA/FZRA will bring lowering conditions, with widespread IFR/LIFR over much of the region by Monday morning, continuing through the day. The entire area should warm above freezing Monday morning, and the patchy showers left after the first surge of moisture late tonight will be plain rain. Restrictions will likely linger for the next 24 hours or so until a cold front moves through on Tuesday or early Tuesday night. Outlook... Tues...Scattered rain showers with areas IFR and MVFR. Wed-Thu...Breezy with scattered snow showers North and West. Fri...Light SN/MVFR poss - mainly NW. && .CTP WATCHES/WARNINGS/ADVISORIES... Freezing Rain Advisory from 5 AM to 1 PM EST Monday for PAZ037- 041-042. Freezing Rain Advisory from 4 AM to 10 AM EST Monday for PAZ005-006-010>012-017>019-026>028-045-046-049>053-058. Freezing Rain Advisory from 1 AM to 7 AM EST Monday for PAZ024- 025-033>036-056-057-059-063>066. && $$ SYNOPSIS...Dangelo/Lambert NEAR TERM...Dangelo/Lambert SHORT TERM...Dangelo/Lambert LONG TERM...Martin/Tyburski AVIATION...Jung/Dangelo
Area Forecast Discussion
National Weather Service Grand Junction CO
439 PM MST Sun Jan 1 2017 .SHORT TERM...(Tonight through Monday night) Issued at 132 PM MST Sun Jan 1 2017 One system travels south of the area this evening while westerly flow and the polar jet and approaching cold front consolidate over the northern half of the area through the next 48 hours. These two features area working together to draw moisture and lower clouds into the area late this afternoon and will continue to do so tonight. Very light snow has fallen a Canyonlands airport and in the Grand Junction vicinity. Have increased the chance of snow across the forecast area this evening though believe it will be light with no real accumulations at lower elevations. The main forecast concern through the next 36 hours will be the situation over the northern half of the area. The cold front that will stretch across the area tonight should remain stalled there through Monday night. Models differ with snow solutions, the HRRR being more optimistic with snowfall while the NAM12 turns it into more of an orographic event with snow hugging the west-facing slopes in northern and central CO and northern UT. Have decided to lean toward the HRRR which has had a good track record the last few weeks and increased the areal coverage and snowfall amounts from the Bookcliffs north. The eastern Uinta Mountains will border on snow advisory criteria and will stand watching, though the general westerly flow at mountaintop level is a better snow producer over the higher western Uinta mountains than over the eastern part of the range. .LONG TERM...(Tuesday through Sunday) Issued at 132 PM MST Sun Jan 1 2017 The Tuesday to Thursday night timeframe may produce persistent, mainly orographic, snowfall on northwest-facing slopes, with steady snow accumulations in the mountains throughout. The front will remain draped across extreme northern CO and UT Tuesday with a 140 kt jet overhead. Windy conditions are likely over much of the area north of the Bookcliffs and Roan Plateau with breezy conditions further south. The flow remains relatively moist Tue as the front is projected to begin waving to the north in response to a ridge building over the Western Great Basin and a closed low plunging south along the west coast. Winds aloft shift to a more northwesterly direction. This should push much of the moisture and precipitation out of SE UT and SW CO...leaving mountain snowfall induced by northwesterly orographics. This pattern will continue Wed and Thu night with moisture increasing as well. By Friday the Great Basin ridge should strengthen and begin cutting off the moist NW flow aloft. Then widespread precipitation may start again Sat and Sun as the ridge pushes east and the flow turns to the SW aloft, opening up the area to another possible warmer push of precipitation. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 434 PM MST Sun Jan 1 2017 Ceilings are the main challenge this forecast period. There will be periods of ceilings near or below ILS breakpoints and snow showers in the vicinity, especially in the mountains and KDRO. Mountains will remain obscured. Also with winds increasing aloft, occasional LLWS is possible at KASE...KMTJ and areas in the lee of the Flat Top Mtns. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...CC LONG TERM...CC AVIATION...BEN
Area Forecast Discussion
National Weather Service Goodland KS
833 PM MST Sun Jan 1 2017 .UPDATE... Issued at 833 PM MST Sun Jan 1 2017 After collaboration with neighbors, decided to issue a Dense Fog Advisory for late tonight to mid-morning Monday. Did 2 segments to begin the advisory and end it later for Red Willow, Decatur, Norton, Sheridan, Graham, Gove counties. These locations should see fog earliest and be the last to observe it`s dissipation. Moisture flux into the region in terms of increasing mixing ratios is ongoing. In addition, light winds, clear skies and falling temperatures should set the stage for widespread freezing fog development. Dense fog is expected with visibilities less than 1/4 mile likely. Slick surfaces are also possible as temperatures will be below freezing and there is a risk of some patchy freezing drizzle. Plan to issue an SPS for the risk of slick surfaces as well. Forecast and associated products have been issued/updated. && .SHORT TERM...(This evening through Monday) Issued at 223 PM MST Sun Jan 1 2017 Low level moisture return and light upslope winds will result in areas of fog and low clouds moving from east to west tonight, getting somewhere close to the Colorado border by 12z before halting due to westerly winds behind a retreating surface trough. Followed latest HRRR timing which usually performs best in these situations. Temperatures will drop below freezing in most if not all locations so freezing fog and maybe some freezing drizzle will develop. Visibilities will likely drop below one mile with dense fog also possible. Best chance for freezing drizzle will be in the northeast area around McCook to Norton. Conditions will slowly improve Monday morning. Assuming that happens, may be able to warm into the middle to upper 40s ahead of the front which sweeps through in the late afternoon and drops temperatures. .LONG TERM...(Monday night through Sunday) Issued at 235 PM MST Sun Jan 1 2017 Main forecast concern for the period will center around temperatures and the magnitude of cold air set to impact the Tri State Area through the upcoming week. Canadian and ECMWF are much more aggressive with the colder temperatures in the middle of the week although latest ECMWF starting to back off a bit with coldest temperatures lingering into the next weekend. While GEFS suggests that operational GFS is on the warm fringe of solutions...colder ECMWF and Canadian solutions also appear to be a bit closer to mean values. Overall, weighted blends have temps in the upper teens to low 20s with overnight lows in the single digits. With ensemble spreads of 40-50 degrees, difficult to get to committed to one solution or the other at this point while weight of data would have me lean a bit more to the colder solutions at this point. Bottom line, the biggest impacts through next weekend will be potential cold air mass and associated problems a period of well below normal temps may cause. For precipitation, short wave trough will quickly sweep across the area on Wednesday Night and Thursday. While liquid equivalents do not look all that high...profiles look favorable for high snow to liquid ratios/dry fluffy snow. Overall do not expect significant snow amounts as this system passes. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 440 PM MST Sun Jan 1 2017 Widespread poor conditions anticipated east of the Colorado border tonight into tomorrow morning. Due to moisture flux, cool temperatures, healthy radiational cooling, and a strong nocturnal inversion, anticipate LIFR fog/stratus to develop this evening after 03z. Worst conditions should be observed from 08z through at least 15z. Areas east of a surface trough should experience poor conditions. KGLD appears to be on the fringe so confidence is lower for this TAF. Same can not be said for KMCK as they appear solidly in line for LIFR cigs/vis. Freezing fog is main concern but could see freezing drizzle where moisture is deepest. Light winds expected tonight with north winds expected behind a incoming cold front Monday afternoon. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...Dense Fog Advisory until 10 AM CST Monday for KSZ003-004-015-016- 029. Dense Fog Advisory from 2 AM to 9 AM CST Monday for KSZ001-002- 014-028. CO...NONE. NE...Dense Fog Advisory until 10 AM CST Monday for NEZ081. Dense Fog Advisory from 1 AM MST /2 AM CST/ to 8 AM MST /9 AM CST/ Monday for NEZ079-080. && $$ UPDATE...RRH SHORT TERM...024 LONG TERM...JRM AVIATION...RRH
Area Forecast Discussion
National Weather Service Green Bay WI
636 PM CST Sun Jan 1 2017 Updated aviation portion for 00Z TAF issuance .SHORT TERM...Tonight and Monday Issued at 233 PM CST Sun Jan 1 2017 The latest rap analysis and satellite/radar imagery show a shallow front dropping into northern Wisconsin early this afternoon. Scattered to broken mvfr cigs have made little progress to the southeast of a Wausau to Iron Mountain line so far today. These clouds should retreat a bit northward into early this evening. Looking upstream, high clouds are already pushing into southwest Wisconsin ahead of a shortwave trough moving northeast across the central Plains. As this shortwave and additional impulses move towards the region, precip chances and types are the main forecast concerns in the short term. Tonight...The weak, shallow cold front will remain nearly stationary during the evening, before slowly returning north overnight. Since clouds look rather solid over northwest WI and the Upper Peninsula, think the low stratus will likely stick around through the night north of RHI, though central WI should have better luck. Regardless of low clouds, a shortwave will be lifting northeast from the central Plains and into the western Great Lakes tonight. It will spread a thick layer of mid and high clouds overnight, making it a rather cloudy night. A dry air wedge between 900 and 700mb should prevent precip from reaching the ground though. Lows wont fall off much with the cloud cover, and temps should only fall into the upper teens in the far north to the mid 20s in the southern Fox Valley. Monday...Southerly to southwesterly flow will increase as additional shortwave impulses lift into the northern Mississippi Valley. With mid and high clouds streaming from the southwest, partly sunny to mostly cloudy conditions should remain present through early in the afternoon. Then from about mid-afternoon onward, will see a push of higher mid-level dewpoints arrive from the south, which should lead to light precip moving into the area. Through early in the evening, precip should be mainly snow over central and north-central WI where temps should be in the lower 30s. Snow accumulations could reach around a half inch to an inch through the evening commute, highest over Wood/western Marathon/Lincoln counties. Over eastern WI, temps will be a little warmer, which should yield a wintry mix of rain/snow/sleet. Highs in the low to mid 30s. .LONG TERM...Monday Night Through Sunday Issued at 233 PM CST Sun Jan 1 2017 WAA/Isent lift and upper forcing from a jet streak will generate precipitation across the region Monday night. Precipitation type will be complicated by surface temperatures near freezing, a warm layer aloft and variations in the availability of ice crystals in the saturated layer. The area of least concern appears to be from Wautoma to the Fox Valley and lakeshore areas, where outside of a brief period of mixed precipitation early, rain is expected due to warming surface temperatures. Farther northwest, colder temperatures and a weak warm layer aloft will lead to a wintry mix of precipitation in the evening, with mainly snow over north central and far northeast WI. A dry slot will arrive after midnight, which will cause all precipitation to change over to freezing drizzle or drizzle. Overall, expecting 1 to 3 inches of snow and some minor icing over north central and far northeast WI, and ice accumulations of less than a tenth of an inch over central and northeast WI (northwest of the Fox Valley/lakeshore areas). Will issue a Winter Weather Advisory to highlight the expected hazardous travel conditions. Will have an expiration time of 8 am Tuesday, as models show just enough low-level moisture to keep some freezing drzzile going until then. Colder arctic air will flood into the region as the system exits on Tuesday and Tuesday night, and will remain over the region through the extended period. Precipitation chances will be focused on the Lake Superior snowbelt, where periods of light lake-effect snow showers will affect mainly Vilas county. Of greater concern is the potential for wind chill advisories west of a line from Wisconsin Rapids to Iron Mountain on Wed ngt, Thu ngt and possibly Fri ngt. Wind chills should generally be in the -20 to -30 F range. && .AVIATION...for 00Z TAF Issuance Issued at 636 PM CST Sun Jan 1 2017 MVFR cigs were persistent along and near a west to east surface front stretching over northern Wisconsin, or north of a AUW to MNM line. Mainly vfr conditions south of this line overnight, until MVFR cigs develop southward on Monday as snow spreads into the state from the west. && .GRB WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 3 PM Monday to 8 AM CST Tuesday for WIZ005-010>013-018>021-030-031-035>037-073-074. && $$ SHORT TERM.....MPC LONG TERM......Kieckbusch AVIATION.......TDH
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1054 PM EST Sun Jan 1 2017 .SYNOPSIS... Waves of moisture will spread atop a cool wedge of high pressure through Monday night. Milder air and lingering showers should be seen on Tuesday before a cold frontal passage Tuesday night. && .NEAR TERM /THROUGH MONDAY/... As of 10:45pm Sunday: Some light to moderate showers have begun to spread into the CWA from the south and west with more on the way. Showers will reach all areas over the next few hours. Some thunder has also been seen in the heaviest showers 3 counties south of the CWA in GA. There is some chance for a little thunder in southern parts of the CWA where some MUCAPE is analyzed to 50 to 100 j/kg. Forecast soundings for Monday maintain cool surface temperatures and no surface-based instability, but lapse rates are steep enough for some elevated instability. Saturated soundings throughout the day on Monday suggest that rain will be the main result, but some thunder is possible as well, especially in Piedmont areas of SC where the limited elevated instability is strongest. Surface high over New England is generating some weak CAD northeasterly surface flow which will likely continue through the day on Monday. Resulting entrenched cool surface air is aiding isentropic upglide for moist southwesterly flow at 850mb and aloft. This will combine with an approaching 500mb vort max currently over West TX, and a moist air mass to generate good amounts of rain overnight and on Monday, with 1 to 2.5 inches anticipated through Tuesday, with the heaviest amounts over Piedmont areas. Current forecast sticks with the WPC guidance on rainfall amounts; however, convective nature of the heaviest rain means that some areas will get quite a bit more than others. The latest HRRR has the heaviest precip. over the Piedmont, with relatively light amounts over the mountains. With rain and thick cloud cover, temperatures on Monday will have a small diurnal range of less than 10 degrees. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... As of 210 PM Sunday: Deep layer forcing will increase Mon night, as a potent, albeit de-amplifying southern stream short wave trough and attendant frontal zone sweep across the Southeast. Pops therefore increase once again Monday evening, becoming categorical in all locations by around midnight. While most locations should see rain during this time, there is uncertainty on just how much will fall. This is primarily due to the potential for organized convection developing across the Gulf Coast states Mon afternoon/evening to disrupt moisture transport into the area. Indeed, the pattern is conducive to such a scenario, with a progressive/fast moving causative system, and more than ample buoyancy forecast across the GC states on Monday. We could easily see a scenario in which the most significant rainfall occurs along the wedge boundary/coastal front (in the vicinity of the lower SC Piedmont) and points south. As such, we have generally undercut QPF from numerical guidance, siding closely with the stingier WPC QPF from this morning. Increasing elevated instability may support thunder across the area Tue morning, and there remains some potential that surface-based buoyancy could develop across far southern parts of the forecast area ahead of the front early Tue. However, while forecast low level shear is adequate for organized convection, it does leave something to be desired considering the weak nature of the buoyancy. Thus, while a high shear/low CAPE severe convective threat is non-0, it doesn`t appear to be particularly high. The initial frontal wind shift pushes through the area throughout Tue morning, with mid/upper level drying and subsidence bringing an end to precip chances for most areas (the exception being the western NC mtns). However with heights falling to our west, winds will be slow to veer, and low level dry/low thickness air will lag behind the wind shift by a considerable distance. Considering that a robust downslope flow will not develop across the area until late Tue, if not Tue night, there is some doubt as to when cold air damming will completely drain. Thus, huge temperature bust potential exists for Tue, as areas that do break out of the goo will likely see maxes 10-15 degrees above climo. The real push of colder air holds off until Wed, when temps are expected to fall or remain steady in most areas throughout the afternoon. Some NW flow showers will be possible early Tue along the TN border, but any snow potential would be confined to the higher elevations before the moisture dries up during the afternoon. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 230 PM EST Sunday...The last couple of runs of the medium range guidance have been a bit more consistent. But the deterministic 12z ECMWF and GFS still have some disagreements on our sensibile weather for Thursday thru Saturday. This is due to a large blocking upper high over the Gulf of Alaska, with short wave energy ejecting out from under it and interacting with a persistent Great Lakes upper trough. The GFS phases the energy and brings a vigorous vort lobe across the CWFA on Thursday. This energy squeezes out a brief shot of moisture and with very cold low-level thicknesses, would support nearly all snow across the CWFA (but mainly in the mountains). Meanwhile, the ECMWF shears out the energy and keeps a much flatter upper flow across the eastern CONUS, gradually digging a long wave trough across the central and then eastern CONUS Friday thru Saturday. The previous run of the ECMWF had a very wet storm system associated with this trough for Friday and Saturday, but the 12z run keeps most of the moisture across the Gulf of Mexico and up along the Carolina coast. The ECWMF would still suggest a dry day on Thurday and cloud with a chance of precip Friday night thru Saturday. So with all that said above, the WPC preference and this forecast went close to the consensus of the GFS/EC/NAEFS ensemble means. This still gives a nod to the quick shot of moisture Thursday, then trends drier for the rest of the forecast. And this looks good given the new ECMWF trending drier. Any snow accums should be confined to the NC mountains, unless the trough ends up deeper and the precip falls during the overnight when temps will be cooler. Cold high pressure is expected to build in behind that system, with temps about 5 to 10 degrees below normal thru next weekend. && .AVIATION /04Z MONDAY THROUGH FRIDAY/... At KCLT and elsewhere: A wet system will impact the area tonight and tomorrow with widespread LIFR CIGS through the day on Monday and VIS down to a mile or less at times with periods of heavy rain. Visibility will have some large fluctuations, with periods of improved visibility, though CIGs will remain low. Period of heavy rain is beginning currently out west and will spread eastward over all by very early Monday morning. Winds are expected to be light and northeasterly with a blocking surface flow pattern. Some improvement is anticipated Monday afternoon, but CIGs may remain at LIFR levels. Outlook: Unsettled and moist conditions will continue in the CAD regime Monday night, with a cold frontal passage expected on Tuesday. A passing upper disturbance may bring light precip and a period of restrictions again Thu. Confidence Table... 04-10Z 10-16Z 16-22Z 22-00Z KCLT High 100% High 87% High 82% Med 60% KGSP High 84% High 82% Med 75% High 97% KAVL High 82% Med 75% Med 70% High 94% KHKY Med 66% Med 75% Med 70% High 86% KGMU High 97% High 80% Med 75% High 97% KAND High 86% High 87% High 90% High 91% The percentage reflects the number of guidance members agreeing with the scheduled TAF issuance flight rule category. Complete hourly experimental aviation forecast consistency tables and ensemble forecasts are available at the following link: && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...CSH NEAR TERM...WJM SHORT TERM...JDL LONG TERM...ARK AVIATION...WJM
Area Forecast Discussion
National Weather Service Houston/Galveston TX
957 PM CST Sun Jan 1 2017 .UPDATE... Area of storms moving across W Texas at 9:30 PM were associated with a strong upper level shortwave trough. The main items of concern continue to be the impact of the upper level shortwave across SE Texas overnight tonight and Monday morning. Patchy fog over the inland areas and sea fog along the coast are other concerns. The latest Texas Tech WRF had a decent handle on the location of the storms at 9 PM. The model shows development ahead of the system beginning between 3 and 6 AM. There were also indications that showers and isolated thunderstorms will develop over the coastal waters and coastal counties after midnight. The HRRR picked up on this development as well with showers moving inland after midnight. A slight risk for severe storms continues as can be seen on the 00Z CRP and LCH soundings where the MU Cape values ranged from 1600 to near 2300. Forecast helicity values reach 260 ahead of the main line of storms, also. Regarding fog--the high res models showed the potential for patchy fog development overnight as well. The current forecast continues on track. 40 && .PREV DISCUSSION... /ISSUED 549 PM CST Sun Jan 1 2017/ AVIATION.../00Z TAF/ Surface analysis at 23Z has low pressure in west Texas in response to an advancing short wave trough over the southern Rockies on water vapor imagery. Light southerly winds tonight should increase tonight. Hi-res mesoscale models have strong/severe convection forming in central Texas and then pushing east rapidly through the morning hours into SE Texas. Ahead of the line expect patchy fog and IFR ceilings. Look for a transition from VFR/MVFR to IFR from 04Z to 06Z tonight with IFR through about 15-16Z when convection pushes through. TAFs will keep mention of VCTS and tempo TSRA for morning hours of 12-16Z since this looks like the time frame in which a line of storms will push through the area. Hi-res models and NAM keep strongest convection north of KCLL/KUTS while the GFS consistently hits all of SE Texas hard with convection. Upper level support will be strongest north of the area and based on model soundings weak capping may be an issue as boundary layer flow veers from SE at the surface to SW at 850MB. Will need to watch Hi-res model trends the next few hours to see if any changes need to be made to timing and intensity of convection. Overpeck PREV DISCUSSION... /ISSUED 354 PM CST Sun Jan 1 2017/ DISCUSSION... The main highlights for the upcoming forecast will be a messy entrance into January for Southeast Texas as a thunderstorm complex moves across the region overnight, warm (and possibly near record temperatures) behind this complex on Monday, and a return of colder temperatures as Arctic air spills into the region mid to late week. Visible satellite imagery this afternoon shows that drier mid- level air working its way into the region has thinned cloud cover across the central and northern counties. This has allowed for enough insolation for a few showers to pop up along the Interstate 10 corridor; have extended mention of isolated showers through 6 PM tonight as a result, but anticipate all activity to dissipate with loss of heating later this afternoon. A dry evening is expected across the region, but the approach of a shortwave trough from the west will quickly herald in an unsettled period of weather by early Monday morning. Located over southern Arizona/New Mexico on afternoon water vapor imagery, this compact disturbance will continue to translate east across Texas tonight. Height falls associated with this feature will result in scattered thunderstorms developing across West and West Central Texas tonight, with upscale growth into a thunderstorm complex expected after midnight tonight. This thunderstorm complex will continue to propagate eastward across Texas, aided by its parent shortwave, reaching the western counties of Southeast Texas after 5-6 AM CST on Monday morning. Ahead of this complex, an intensifying 40-50 knot low level jet after 4 AM and increasing mid/upper level lift overspreading the region may also result in the development of isolated showers and thunderstorms. High resolution guidance continues to waffle between whether or not this pre-thunderstorm complex activity will develop and what the intensity of this activity would be, likely owing to the presence of a weak capping inversion present around 900 MB on area soundings. Regardless, environmental conditions continue to remain favorable for the development of severe weather both ahead of and with the main thunderstorm complex. The intensifying low level jet will contribute to increasingly curved hodographs and 0-1 KM storm relative helicity values in excess of 150 J/kg across much of the region, representing the presence of at least an isolated tornado threat. This threat would likely materialize with any of the discrete thunderstorms that develop ahead of the main thunderstorm complex approaching from the west. Even if thunderstorms are not able to develop owing to the weak cap in place, any shower that develops ahead of the complex will be able to transport at least some of the strong winds above the surface to the ground. The somewhat negative tilt to the shortwave trough will also encourage steep mid-level lapse rates (around 7-8 C/km) to spread across much of the region, resulting in the risk for large hail as well as damaging winds as the main thunderstorm complex moves across the region. Expect the main thunderstorm complex to clear the region by 12 PM CST on Monday. Behind the complex, clearing skies and deep westerly flow spreading across the region will result in temperatures rising rapidly into the mid 70s to near 80 degrees on Monday afternoon. Have continued to trend warmer than model guidance for this time period given the depth of the westerly flow. These temperatures may even warm enough to result records being tied or broken. For reference, Galveston`s record high on January 2 is 78. This would also be the record warmest temperature for the month of January. The next cold front approaches the region on Tuesday, clearing Southeast Texas by Tuesday night. With limited moisture recovery in the wake of Monday`s system, have continued with a dry forecast for the mid-week portion of the forecast. Modified Arctic air spilling into the region behind the front looks to drop temperatures back down near (to below) seasonal normals, with highs in the 50s to near 60 and lows in the upper 30s to 40s. A reinforcing cold front reaches the region late in the week (with considerable medium range differences persisting on timing) and this will keep temperatures below seasonal normals through the end of the week. Have continued to utilize a blend of model guidance for the weekend portion of the forecast, with the deterministic GFS attempting to develop a coastal trough and return Southeast Texas to a rainy pattern and the European maintaining offshore flow and a drier solution. Huffman MARINE... Sea fog (some dense) will continue to be possible until a line of showers and thunderstorms moves through the area during the day on Monday. South winds are expected to strengthen tonight ahead of the storms, and small craft advisories might be needed for the winds as well as building seas. Winds will shift to the west and weaken in the late morning through afternoon hours after the storms move through. A couple of cold fronts during the week will bring north to northeast winds to the area with both winds and seas possibly reaching advisory levels. 42 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 63 75 49 72 42 / 60 70 0 0 0 Houston (IAH) 68 77 52 74 46 / 40 80 0 0 0 Galveston (GLS) 67 79 60 72 52 / 30 70 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT SHOULD EXERCISE CAUTION through Monday morning for the following zones: Coastal waters from Freeport to the Matagorda Ship Channel out 20 NM...Coastal waters from High Island to Freeport out 20 NM...Galveston Bay...Matagorda Bay. Small Craft Advisory until noon CST Monday for the following zones: Waters from Freeport to the Matagorda Ship Channel from 20 to 60 NM...Waters from High Island to Freeport from 20 to 60 NM. && $$ Discussion...40 Aviation/Marine...39
Area Forecast Discussion
National Weather Service Wilmington NC
937 PM EST Sun Jan 1 2017 .SYNOPSIS... Moisture streaming up the coast will ramp up rain chances through Monday and Tuesday. A cold front will usher in some cooler and drier air Wednesday night. The cooling trend may last through the weekend. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... As of 930 PM Sunday...The coastal front is moving into the coastal waters. Based on buoy data from the CORMP network it appears the boundary is within about 15-20 miles of Cape Fear. Charleston, SC wind observations show the front is already onshore there, so extrapolation back toward Cape Fear suggests the boundary could be as close as 5-10 miles from Winyah Bay. A rather impressive shift from NE to SE winds occurs right along the boundary along with a good increase in surface temperatures and dewpoints. Although the HRRR and RAP have an excellent depiction of the current location of the front, they appear to have been 2-3 hours too fast moving the boundary westward all this evening. For this reason, I am using their wind forecasts but time- shifting it to show a slower movement onshore. We`re already at our lows tonight, and temperatures should begin to increase at the coast, reaching the lower 60s before daybreak. Farther inland look for steady-state temperatures for the next several hours, followed by a slow rise through the 50s late. Radar composites show light, spotty rainfall across the area now. A more substantial area of rain across central South Carolina is associated with a series of weak upper level disturbances moving through the western Carolinas. PoPs have been ramped up to 100 percent along and west of the I-95 corridor, but remain in the 50-70 percent range along the coast. We`ll continue to watch for the potential of upright convection developing near the front late tonight, as this could spread some heavier showers across the coastal waters or perhaps near the Cape Fear coast late. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...Primary weather headline this period is "Wet and Mild, Drying late Tuesday". Additionally we will feel exceptionally mild daytime temperatures Monday and Tuesday to accompany the bouts of rainfall, 14-17 degrees above normal for very early January. We potentially could receive a good rain event, as QPF totals tonight through Tuesday point to 1-1.25 inches near the coast and averages around 1.5 inches over interior SE NC and the I-95 corridor. There is enough CAPE to warrant slight chance TSTMS, but at this time am not expecting an enhanced risk, as the flow remains unidirectional. Near the coastal trough low-level helicity could increase briefly. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 300 PM Sunday...Forecast confidence is far from spectacular regarding the long term as model solutions vary considerably. Wednesday will offer unseasonably mild temperatures ahead of a cold front later in the day or at night (though the 12z Canadian is much, much faster). The pattern aloft should be of fairly low amplitude implying that gradual cold advection is slated for the several days that follow and that subsequent cold fronts (re-enforcing cold shots following the Wednesday FROPA) should be moisture-deprived and the next real chance for rain comes over the weekend possibly due to offshore cyclogenesis. Not to be ignored however is the GFS which amplifies the pattern and has a more solid push of modified Arctic air plunging 850mb temps to almost -15C by Thursday night. Even more distressing is the healthy vort center moving through the trough dynamically squeezing out what would be some wintry precipitation. Kept more in line with previous forecast which is more in line with the former models but did add a slight chc for rain/snow over northern zones Thursday night in deference to the GFS. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... As of 00Z...Complex weather scenario for the next TAF cycle as deeper moisture will continue to stream in from the southwest. Isentropic lift will continue to tap into this moisture and light rain will become widespread over the entire area for the next 12-18 hours. We continue to trend down to IFR conditions at all terminals within the next few hours. There is a front in the area and wind directions will be challenging inland. However wind speeds will remain muted for a mid winter system. Finally, there are indications of a lull later MOnday afternoon extending into Tuesday evening as winds in the 290-300K layer veer somewhat. I did show a slight improvement in conditions due to this agreement. Extended outlook...IFR conditions tonight will continue off and on through Tuesday. && .MARINE... NEAR TERM /UNTIL 6 AM MONDAY MORNING/... As of 930 PM Sunday...The coastal front is moving westward and should be approaching the coastline over the next 3-4 hours. According to data from NWS and CORMP networks it appears the front is within 15-20 miles of Cape Fear, and perhaps as close as 5-10 miles from Winyah Bay. NE winds should turn southeasterly as the front pushes by, with an increase in wind speeds to near 15 knots away from the coast late. Showers remain possible, particularly across the Cape Fear waters overnight. SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...Not ideal conditions on the waters, Exercise Caution conditions Monday potentially could worsen to Advisory conditions Tuesday as strong low pressure west of the waters turns northward. The pressure gradient will produce SW gusts to 25 KT and 4-7 foot seas Tuesday. Isolated TSTMS will pose an additional hazard. The S waves of 4-7 feet every 6-7 seconds will produce steep wave faces capped with wind-whipped chop. Winds will ease and go west Tuesday night as the low lifts north of the region. LONG TERM /WEDNESDAY THROUGH FRIDAY/... As of 300 PM Sunday...Offshore flow on Wednesday ahead of a cold front though how much north of west will be up for debate, depending on the approach speed of said front. Current forecast thinking is that is moves though Wednesday night and that northerly flow sets up by Thursday. Unless the GFS is correct and this turns out to be a modified Arctic blast the wind speeds will not pick up much as we are in for a more gradual and tempered cold advection pattern. Seas will tend to stay in the 2 to 4 ft range. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...MBB NEAR TERM...TRA SHORT TERM...MJC LONG TERM...MBB AVIATION...SHK
Area Forecast Discussion
National Weather Service Wilmington OH
954 PM EST Sun Jan 1 2017 .SYNOPSIS... A weak disturbance will lift north across the area tonight as high pressure moves east. Low pressure approaching from the southwest will bring widespread showers, especially Monday night. Weak disturbances following the low will allow shower chances to continue through Tuesday. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Weak showers have formed across our southeastern zones this evening as isentropic lift commences with condensation pressure deficits approaching zero. Looks like the greatest lift will continue across the eastern zones. Have adjusted PoPs based off the latest RAP/ HRRR TL. GFS/ NAM forecast soundings also show dry air moving in around 800 mb with soundings supporting drizzle Monday morning. Temperatures will also hold steady and slowly rise across our northern zones Monday morning as a warm front slowly washes north. Prev Discussion -> Surface analysis has high pressure receding toward New England, while a broad area of low pressure develops well to the west. Models indicate that a disturbance will form in the vicinity of a warm front developing ahead of the low. As the disturbance moves north across Ohio, a few showers could deliver minor amounts of rainfall mainly to eastern locations later tonight. Evidence of light precip over southern Kentucky adds confidence to this scenario. All locations will see increasing clouds as per satellite imagery that shows cloud cover advancing from the south. Overnight lows ranging from the low 30s north up to the low 40s south will be influenced by the increasing cloud cover and warm advection. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... Monday should start with little to no precip as the initial disturbance lifts northeast, leaving the environment relatively dry and weakly forced for a few hours. That will change by later Monday when low pressure moves to Missouri, bringing increasing moisture and lift, leading to a good chance of showers by Monday evening. Showers will become widespread Monday night as the low travels to northwest Ohio. A rather impressive plume of moisture advected on a southerly low level jet may result in a half inch to one inch of rainfall, with southern locations likely to receive more precip. Bulk of moisture will lift northeast with the low by Tuesday morning. A couple of disturbances aloft may then trigger a few more showers in shallower residual moisture behind the low. For Tuesday night, snow may mix in as colder air filters in on the trailing edge of precip. Much above normal temperatures will result from strong warm advection, with highs reaching the 50s most locations. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Fcst period dominated by arctic push with only minor snow chances. Cold air settles in on Wednesday with departing front. With northwest trajectory have included possibility of flurries/scattered snow showers with low pops for mainly afternoon and evening period. Another chance of snow showers comes into play Thursday afternoon and evening with second surge of cold air with a little better moisture available. Again not significant accumulation but half inch or less looks reasonably promising with any heavier snow showers. Coldest of air for Friday into Saturday. Temps into single digits for lows in some locations looks likely. Highs only near 20 to 25 most areas. Cold air retreats a bit by Sunday but still below normal. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... VFR/ MVFR conditions across the TAF sites this evening as widespread cloud cover towards the south pushes northeast into the region. This is thanks to high pressure pulling east with low level moisture returning from the south. As this occurs a weak warm front will push over the area with overrunning occurring. Forecast soundings are showing saturation up to about 700 mb with PWATs only rising to around 0.85". High res models only show light showers advancing through the southern TAF sites starting around 3z and then moving through the northeastern TAF sites by 6z. These isolated showers will then clear the TAF sites by 12z. The main impact will be a lowering of CIGS as moisture rich low level air moves across the region. Due to the above IFR/ MVFR conditions will be slow to improve Monday. GFS/ NAM forecast soundings support LIFR/ IFR cigs starting Monday morning through the end of the issuance. Looking at high res guidance think this is to pessimistic. Have trended the IFR cigs recovering to MVFR later Monday afternoon though. Monday evening into Tuesday morning a surface low will approach the area bringing rain to all TAF sites with widespread IFR/ MVFR cigs. OUTLOOK...MVFR/IFR ceilings and MVFR visibilities will continue at times through Tuesday night. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Coniglio/Haines NEAR TERM...Coniglio/Haines SHORT TERM...Coniglio LONG TERM...Padgett AVIATION...Haines
Area Forecast Discussion
National Weather Service Lincoln IL
857 PM CST Sun Jan 1 2017 .UPDATE... Issued at 857 PM CST Sun Jan 1 2017 Fog formation overnight could become problematic for southeast Illinois, as low levels become saturated after midnight. HRRR and RAP guidance are pointing toward dense fog developing in southern IL and expanding northward into our forecast area. A dense fog advisory seems in order for at least our far southeast 3 counties along Highway 50 for now, with a possibility that it may need to be expanded northward later tonight. The dense fog advisory will run from midnight to 9 am. In addition to the fog formation, low level lift will turn the saturation into areas of drizzle. Forecast soundings indicate no ice crystals will be present to fall into the low level saturated layer tonight, so any precip will likely be drizzle instead of rain. As the moisture levels deepen toward the colder mid level temperatures, precip should include more rain showers tomorrow. Updated forecast info is already available. && .SHORT TERM...(This evening through Monday) ISSUED AT 300 PM CST Sun Jan 1 2017 This afternoon, the high pressure ridge responsible for the quiet weather is moving out to the east coast...and clouds are moving into the Midwest in advance of the next storm system. A couple of waves within the general trof over the southwest will drive the forecast through the next 24 hours. The first wave that moves through the region is relatively weak, but drops very low clouds into place and whereas the models persist on developing some weak is scattered and inconsistent. With the dry air aloft in the column and the thicker stratus so close to the ground... going to keep in a drizzle mention for before 12z. Later in the morning, the second wave starts to drive the weather across the region. More moisture accompanying this stronger wave...but before 00z, the precip is still expected to remain somewhat showery. Weak instability and afternoon development of the stronger wave will increase chances for thunder. Have pulled the threat slightly further west, and SPC has put all of Central IL in a general thunder category. Southerly flow ahead of the approaching waves will keep the temps above normal for the first of the year. .LONG TERM...(Monday night through Sunday) ISSUED AT 300 PM CST Sun Jan 1 2017 The weather system will be moving east of the area Monday night, and when and where precip will end is still dependent on which model you look at. Consensus says likely pops still needed in the evening in the east and southeast parts of the CWA, while chance pops still warrantied in the central and eastern parts of the CWA. Then with the way the whole system seems to evolve beyond Monday night, chance pops still needed for Tuesday morning across most of the area and then in the east for Tue afternoon. Models also keep some instability in the east and southeast Mon evening, so will continue the chance of thunder in those areas during that time frame and then just have rain for after midnight. Some precip could be in the form of drizzle, but keeping it simple for now and will fine tune things tonight or tomorrow. Tue afternoon, as the precip ends from west to east and the colder air begins to advect into the area, some of the precip could become mixed with snow or change to all snow while its ending. It will be in the gridded forecast that way, but may not show up in the worded forecast. Temp will remain warm Tuesday, but mostly in the central, east and southeast. Colder air will already begin to advect into the CWA during the morning, so high temperatures for the day will likely be in the morning and then remain steady or slowly fall during the afternoon...then get much colder Tue night. Beyond this system, dry weather is expected through the rest of the week and into the weekend. A jet streak brings some clouds and possible flurries/light snow for Thursday over part of the CWA, but ECMWF is the only model that still has this feature/possibility. Blend of slight chance pops for this time period still looks ok for now since any precip that does occur should be very minor. Temps will be quite cold with highs staying below freezing through the period. There is a little hint of temps getting to near freezing by Sunday, but that is 7 days from now. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 553 PM CST Sun Jan 1 2017 Low pressure will take aim on Illinois over the next 24 hours, producing IFR vis and LIFR ceilings later tonight. Conditions will deteriorate from south to north as the low reaches into central Kansas by 12z/6am tomorrow. Continued southeasterly flow of moisture and warmer air on Monday will support a saturated boundary layer with at prevailing LIFR for a majority of the day tomorrow. Drizzle may transition to rain showers at times as lift periodically increases and moisture depth increases. Wind directions should be easterly at less than 10 kts tonight, then become southeast tomorrow at 10kt or less. && .ILX WATCHES/WARNINGS/ADVISORIES... Dense Fog Advisory from midnight tonight to 9 AM CST Monday for ILZ071>073. && $$ UPDATE...Shimon SHORT TERM...HJS LONG TERM...Auten AVIATION...Shimon
National Weather Service Jackson KY
1049 PM EST Sun Jan 1 2017 .UPDATE... Issued at 1049 PM EST SUN JAN 1 2017 Hourly grids have been fined tuned a bit to better align with recent radar trends and observations. This led to raising pops to closer to 50 percent from Johnson County to near JKL to Whitely County and east for the rest of the evening and into the overnight hours. Several showers moving across that region are producing measurable rainfall. Otherwise, winds have been increased a bit into the 10 to 15 mph with gusts up to 25 mph for the overnight in the higher elevations above 2000 feet per recent observations and model forecasts supporting winds of these magnitudes in those areas for about the next 6 hours. UPDATE Issued at 710 PM EST SUN JAN 1 2017 Hourly grids have been updated based on recent observations and radar trends. Isolated to scattered showers or patchy light rain and drizzle continues to lift north across the area. Additional light returns were moving across Middle and Eastern Tn and moving northeast in a warm air advection/isentropic lift scenario in advance of low pressure over the Southern Plains and a warm front extending east across the Gulf Coast states to the Carolinas. Short term models generally indicate the current light precipitation across the area will lift north and east as an initial weak disturbance departs. As the next weak disturbance in SW flow approaches, additional isolated to scattered showers are expected to moving across mainly the southeastern counties nearer to VA toward midnight and after. Hourly pops as well as temperatures and dewpoints were freshened up based on the recent trends and then blended into the previous forecast for the overnight hours. Those grids already accounted for the threat of showers toward midnight and after nearer to the VA border. && .SHORT TERM...(This evening through Monday night) Issued at 325 PM EST SUN JAN 1 2017 19z sfc analysis shows high pressure to the north and northeast of the CWA with a developing and somewhat inverted trough located over the deep south arcing into south central Kentucky. The low clouds remain across the area along with some patchy drizzle while the earlier fog has lifted and dissipated. Under overcast skies temperatures are generally in the upper 40s and lower 50s with dewpoints holding in the low to mid 40s. Meanwhile, winds are mostly light and variable throughout the area this afternoon. The models continue to be in good agreement aloft through the short term portion of the forecast. They all depict increasing southwest flow at mid levels between ridging over Florida and a strengthening southern stream trough rolling into the Big Bend area of Texas early Monday. Weak bits of energy will continue to move through the area ahead of this trough. The trough and its core energy will push just south of Kentucky Monday night with some height falls for our portion of the state. With the good model agreement have favored a blended solution along with a solid lean toward the HRRR and NAM12. Sensible weather will feature cloudy and damp conditions through the evening and overnight. Passing light showers and pockets of drizzle/sprinkles will be around through the night along with area of fog - potentially dense on the ridges. The high moisture content will keep conditions mild with lows only a few degrees below what temperatures are currently. There appears to be a lull in pcpn setting up for the bulk of the day Monday as the first sfc wave moves off to the east and the next one will not move in until the upper trough approaches late in the day. The sfc low for this latter one deepens and rides northeast into the western Ohio Valley Monday night with a sfc trough lifting into eastern Kentucky towards midnight with the best chances for widespread - soaking showers and a potential for thunderstorms - though instability looks to be limited north of the Tennessee border. Again started with the CONSShort and ShortBlend for most of the wx elements with only minor adjustments in the near term for current conditions and then to raise lows a notch on Monday night. Did also tighten up the PoPs as they come in on Monday evening/night. .LONG TERM...(Tuesday through Sunday) Issued at 325 PM EST SUN JAN 1 2017 The long term period will be met with the surface low moving right across eastern KY. There is good agreement between the model suites and ensembles for this to pull NE through the day. On the tail of this will be another cold front that will usher in cold air by Wednesday. That said, afternoon highs top out in the lower 60s Tuesday, and then we will be looking at a 20 degree drop by Wednesday behind the front. After this the models begin to diverge leading to big differences in regards to the synoptic scale pattern. All in all the blend of models does trend quite cold to end the period and this seems reasonable. The first issue will be later Thursday when the ECMWF and Canadian indicate a semi zonal pattern at the 500mb level, while the GFS has a positively tilted trough axis across the Ohio Valley. Therefore the ECMWF and Canadian allow some perturbations to ride through the flow and lead to precip. Given the uncertainty kept with the blend of models which would keep best chances in the far SE toward the VA border, however only going with chance at this stage. Also the WPC Day 5 probs keep a 10 percent in the far east as well. There could be some measurable snow with this system if QPF pans out, as a result will keep the mention in the HWO for now The previously mentioned trough that is reflected the GFS would also bring 850mb temps in the -15 to -20 range. Meanwhile the ECMWF is slower bringing this deeper trough and will hold the coldest air at 850mb (although not as cold) off till Saturday morning. Overall to end the period would expect high pressure to generally dominate. Typically this would lead to more confidence in ridge/valley splits, however the guidance remains too convoluted to be able to nail down any sort of crest for the surface highs. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) ISSUED AT 725 PM EST SUN JAN 1 2017 Isolated to scattered light rain showers or sprinkles will affect mainly JKL, SYM, and SJS early in the period. These should bring CIGS down into the MVFR range. Otherwise, MVFR should linger at LOZ and SME. With some limited cooling tonight, stratus build down may bring some MVFR vis in fog to the ridges and a gradual lowering of CIGS to IFR for all but SJS. After the disturbance leading to the current light precipitation passes late tonight or early Monday, JKL and SJS should improve to VFR by 18Z to 0Z and SYM, LOZ, and SME could also do the same. Winds will be light through the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...GREIF LONG TERM...DJ AVIATION...JP
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
532 PM CST Sun Jan 1 2017 .SYNOPSIS... Issued at 325 PM CST Sun Jan 1 2017 An active H5 pattern continued across the western half of the CONUS this morning. A deep area of low pressure was located over western portions of Hudson Bay. Southwest of the low, a tandem of strong shortwaves were noted. the first over the Idaho Panhandle and the second over northern portions of Baja California. With respect to the shortwave over the Idaho Panhandle, ht. falls of 150 to 250 meters were noted over Washington state and northern Oregon. Across the intermountain west and plains, shortwaves were noted over western Colorado, as well as over western Kansas and along the Oklahoma/Texas border. East of these features, low amplitude ridging extended from the lower Ohio Valley north into the arrowhead of Minnesota. Ht. rises of up to 150 meters were noted at Green Bay Wisconsin this morning. South of the ridge, High pressure was anchored across the western Caribbean in the vicinity of Cuba and Jamaica. At the surface, abundant cloud cover in association with the disturbance over western Kansas, has pushed into the forecast area. Radar returns across the forecast area are decent, but given the dry boundary layer, almost all of the returns are not even reaching the surface. Under partly cloudy skies in the west and mostly cloudy skies in the east, 3 PM CST temperatures ranged from 33 at Valentine to 41 at Imperial. && .SHORT TERM...(This evening through Monday) Issued at 325 PM CST Sun Jan 1 2017 Tonight into the Monday Morning Commute...The main concern tonight will be for areas of fog and freezing drizzle after midnight. Another short wave will move into the plains, bringing with it another push of low level moisture. However, there is not much moisture aloft so the depth of the saturated layer is rather shallow. This will limit the amount of moisture that transitions out of fog and into the drizzle category, making our chances for glaze due to freezing drizzle marginal at best but worthy of a mention given the impact that ice has, especially given its timing during the Monday morning commute. Fog is looking more likely tonight given the clearing at the mid levels, light winds, and the healthy moisture advection at the surface. We should have no problem becoming saturated and seeing some locally dense fog between midnight and noon. Monday Afternoon...A cold front begins to drop down from the northwest. There will not be much moisture with this front given its paltry arctic origins. Its primary impact will be much colder temperatures and a wind shift to the northwest with increasing wind speeds. Temperatures will rise into the upper 30s ahead of the front, in the areas that are at most risk for freezing drizzle tonight, so any ice that would accumulate will likely melt quickly in the afternoon. .LONG TERM...(Monday night through Sunday) Issued at 325 PM CST Sun Jan 1 2017 Monday night through Wednesday: In the mid range, temperatures and the threat for light snow Tuesday Night into Wednesday are the main forecast challenges. Bitterly cold air will push into western and north central Nebraska Monday night with cold air advection continuing through 12z Tuesday. This will allow northwesterly and northerly winds to stay in the 10 to 20 MPH range overnight. The combination of wind and temperatures around zero, will lead to wind chills approaching -20 in far northern Nebraska Monday night. Cold air advection will become neutral on Tuesday with H85 temps remaining unchanged through Tuesday Night. Highs on Tuesday will struggle to reach 5 above in the far northwest, while readings in the teens to near 20 along and south of the interstate are expected. Temperatures for Tuesday night will actually be colder than Monday night`s as a surface high noses into northwestern Nebraska. Lows will bottom out in the zero to -10 degree range. However, winds will be lighter, so wind chills of zero to 20 below will be common. Some wind chills may reach -25 in the Pine Ridge where snowcover is the deepest. On Wednesday, a secondary shot of arctic air will push into north central and eastern Nebraska. Highs will be in the single digits north to around 20 in the south. In addition to arctic air, there will be a small threat for light snow in the west on Wednesday as the cold arctic air is forced west and some limited upslope occurs. The latest ECMWF and Canadian models develop a weak fronto band of precipitation across Western portions of the forecast area Wednesday afternoon into Wednesday night. The NAM solution and GFS solution are much drier in comparison. The blender solution painted low pops across the entire forecast area Wednesday, and trimmed this to the western forecast area to better reflect the ECMWF and Canadian solutions. Any accumulations will be very light as only couple hundredths of an inch of QPF is expected. Wednesday night through Sunday: The threat for light snow will linger into Wednesday night across the west and southwest as cold air advection forces the arctic front even further south into the Texas panhandle and Oklahoma. At the same time, mid level frontogenesis will increase north of the surface front over Kansas Thursday into Thursday night. This will lead to dry, but bitterly cold conditions continuing into Thursday night. By Friday, ridging will try to build into the western CONUS. This will force the coldest arctic air east of the area into the upper midwest. However, even with the slight warming of H85 temps, highs Friday will struggle to get out of the 20s. By the weekend, highs will reach the freezing mark, then the lower 40s. Confidence in temperatures next weekend is strongly lacking attm as the latest MEN ensemble guidance indicates a wide spread in temperatures this weekend. For now was conservative with highs, and leaned toward the cold side of the ensemble members. This favored the latest ECMWF solution, which does not totally scour out all of the arctic air next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 532 PM CST Sun Jan 1 2017 All models show LIFR in fog and low cigs developing along and east of highway 83 09z-15z. The forecast uses the 15z SREF which does not show these features reaching KVTN with 100 percent probability like KLBF. The SREF and GFS would suggest flight conditions would improve to MVFR by 18z while the RAP and NAM do not until the arctic front reaches the area 21z-00z. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Buttler SHORT TERM...Allen LONG TERM...Buttler AVIATION...CDC
Area Forecast Discussion
National Weather Service Marquette MI
625 PM EST Sun Jan 1 2017 .SHORT TERM...(This evening through Monday) Issued at 330 PM EST SUN JAN 1 2017 WV imagery and RAP analysis indicated a mid/upper level low over Hudson bay with the polar branch jet through nrn Ontario. A southern branch shortwave trough over the cntrl plains was lifting to the northeast toward the Upper MS valley. At the surface a trough extended from James Bay to central Upper Michigan while a ridge prevailed from MN/WI to OH/PA. Radar and sfc obs indicated that any leftover LES had diminished to a few flurries as drier air filters into the area. Tonight, models suggest that the cntrl plains shortwave and associated 285k-290k isentropic lift will bring some light snow into wrn Lake Superior that may also brush mainly the west from IWD to the Keweenaw. Little or no snow accumulation is expected. Otherwise, with the developing WAA suporting mostly cloudy skies, temps will drop into the upper teens to lower 20s. With incrasing low level moisture and lower cigs late, especially where upslope erly flow prevails, cannot rule out some -fzdz but expect enough dry layer below the clouds to minimize potential. Monday, The WAA pattern is expected to strengthen further as a stronger shortwave trough lifts into the nrn plains and an inverted trough develops toward the upper MS valley. Deeper layer 285k-295k isentropic lift will bring an area of snow toward the wrn cwa. However, the onset may be slowed by the antecdent dry airmass as the NAM/GFS show a persistent 900-800 mb dry layer. By late in the afternoon the lift/advection should be strong enough for snow into the west with some light accumulations less than an inch. .LONG TERM...(Monday night through Sunday) Issued at 235 PM EST SUN JAN 1 2017 Nam shows a closed 500 mb low in the Pacific NW 00z Tue with a shortwave in the northern plains. This shortwave heads east with a closed 500 mb low in the upper Great Lakes 00z Wed and moves to near James Bay by 00z Thu. Nam brings in some deeper moisture and 850-500 mb q-vector convergence 00z Tue into the cwa and both move out 12z Tue. GFS shows about the same thing as well. One thing both models did was cool things down slightly aloft and this would mean less freezing rain and sleet now. QPF amounts also fell a bit as well and this will also lower snow totals a bit. Looks like there might need to be advisories posted at best in the keweenaw for now, but confidence is still low enough due to model differences still to not hoist anything yet. Will highlight mixed pcpn and uncertainty in a special weather statement product for now. Otherwise, did not make too many change to the going forecast. In the extended, GFS and ECMWF differ with intensity of the 500 mb trough over the area with the GFS deeper and further east 12z Thu with the trough axis over the lower Great Lakes and the ECMWF trough axis is over the northern plains into the northern Rockies at that time which is a big difference. The ECWMF has its trough axis over the upper Great Lakes 12z Thu while the GFS is still ahead with its trough axis into the mid atlantic seaboard states 12z Fri. More troughing remains over the area with the ECMWF 12z Sat with colder air than the GFS has. ECMWF shows the 500 mb trough axis over the lower Great Lakes 12z Sun with the GFS having a shortwave entering into the upper Great Lakes at that time. Confidence is low due to two very different solutions and about the only thing to be confident in is that lake effect snow showers and below normal temperatures will continue this forecast period. ECMWF would have colder temperatures than the GFS does. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 624 PM EST SUN JAN 1 2017 Expect MVFR cigs at all the TAF sites through Mon aftn. Could see cigs lift to VFR briefly overnight at CMX and also at SAW. Also could see cigs lower to IFR later Mon aftn at SAW with upslope ESE winds. Some light snow may also be possible later tonight into Monday morning over the west but should have little impact on vsby. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 330 PM EST SUN JAN 1 2017 East winds of 15 to 25 knots Monday night will give way to w winds to 30 knots Tuesday as low pressure moves through Lake Superior. Winds are then expected to strengthen to nw gales to 35 knots possible Tuesday night into Wed morning as the deepening low moves away to the east. Northwest to west winds to around 30 knots will then linger from Wednesday afternoon into Thu with potential for heavy freezing spray as Arctic air moves over the area. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...07 AVIATION...JLA MARINE...JLB
Area Forecast Discussion
National Weather Service Omaha/Valley NE
543 PM CST Sun Jan 1 2017 .SHORT TERM...(tonight through Wednesday) Issued at 303 PM CST Sun Jan 1 2017 Patchy light mixed precipitation chances will continue tonight into Monday. Latest water vapor imagery shows a weakening shortwave trough in broad southwesterly flow moving through eastern Nebraska and into northwest Iowa. Latest radar mosaics show patchy echoes but compared to surface observations, most of the radar returns are aloft with dry layer below 9K feet. Upstream, another shortwave trough was rounding the AZ/Mexico border with a lead shortwave out ahead of it over northeastern New Mexico. This lead shortwave will swing northeast toward the area in broad southwesterly flow while the primary shortwave remains across the Southern Plains. The other feature of note in satellite imagery is the deeper shortwave trough over the Pacific Northwest. This feature will be sending a cold front into our area late Monday. In the meantime, isentropic upglide in low level warm air advection regime will increase this evening. Point forecast soundings continue to show saturation near the surface with drying in the mid levels indicating drizzle type pattern. The above mentioned lead shortwave from the desert southwest will approach the area around midnight and the latest runs of the HRRR do indicate a few hours of heavier qpf drifting northeast through northeast Nebraska. Based on moisture and temperatures profiles, a very light freezing drizzle mix is expected across much of northeast Nebraska where surface temperatures are slightly below freezing. The southeast two-thirds of our CWA should likely see all liquid with possibly a light mix not out of the question. QPF values overall are less than 0.04". Low level warm air advection will continue into Monday. Despite cloudy/foggy conditions, we should be able warm with highs in the mid to upper 30s across northeast NE and the upper 40s across our southeastern counties. Areas of drizzle/fog will continue through Monday until the above mentioned cold front associated with the Pacific Northwest shortwave slides into the region and dries out the low levels. Temperatures will drop significantly into Tuesday morning with highs only a couple degrees warmer than the overnight lows. Strong cold air advection will continue into late week. .LONG TERM...(Wednesday night through Sunday) Issued at 303 PM CST Sun Jan 1 2017 The ECMWF continues to indicate some light snow across our southern tier of counties late Wednesday into Thursday while the GFS remains dry. With such strong sfc high pressure building south, it is possible that a few flurries could be around during this time frame. Overall temps Wednesday night through at least Friday will range from lows in the single digits to highs in the teens to possibly low 20s. Otherwise, return flow will increase across the region next weekend with a slight rebound in temperatures. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 543 PM CST Sun Jan 1 2017 Difficult TAF period with several concerns through the period. Initially VFR conditions will become MVFR by late this evening. We will likely see a band of light precipitation develop late this evening and may affect all 3 TAF sites. This is most likely to be light rain at KLNK/KOMA, but may be some light freezing rain for a couple of hours at KOFK. Thereafter increasing moisture from the south will bring IFR and eventually LIFR cigs and IFR visby to all TAF sites by Monday morning. There may be a couple of periods during the day on Monday we see some drizzle, especially at KLNK/KOMA but will leave out for now and concentrate on the cigs and visby restrictions through the day. Finally late in the period a cold front will move southeast across the TAF sites, which will switch the winds to northwest, but may also bring another period of light precip to all TAF sites to end the period. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Kern LONG TERM...Kern AVIATION...
Area Forecast Discussion
National Weather Service Norman OK
732 PM CST Sun Jan 1 2017 .UPDATE... && .DISCUSSION... The forecast remains on track with only minor adjustments needed. Latest water vapor imagery shows a fairly pronounced shortwave trough moving rather quickly through New Mexico. Convection has increased in southeast New Mexico and will continue to move east across West Texas through the evening. We added more temporal detail with precipitation probabilities based on the latest short term guidance. The aforementioned line of convection should reach our western north Texas counties around midnight and then progress across the southern portion of the area. Latest RAP and NAM forecast soundings show modest instability from elevated parcels which should be sufficient to maintain at least weak convective intensity. Any severe thunderstorms should be marginal given the weak instability limiting hail growth and stable boundary limiting the wind threat. Latest 11-3.9 satellite imagery shows stratus/fog advancing westward as southeasterly winds bring substantial low level moisture. So far obs have been as low as a half mile and briefly a quarter mile at Ada and Durant. We will watch trends and issue a Dense Fog Advisory if necessary based on trends in the observations. Model forecast soundings suggest around 2,000 ft deep saturated layer sufficient for drizzle, and the ob at Ada has indicated drizzle. Furthermore, mesonet sites in southeast Oklahoma have measured a hundreth in the last few hours. We have added drizzle for portions of south central and southeast Oklahoma where it appears low level saturation will remain deep enough for drizzle through the evening and overnight. BRB && .PREV DISCUSSION... /issued 525 PM CST Sun Jan 1 2017/ AVIATION... Low clouds and fog will develop back north and west this evening. Have some lower MVFR visibilities and even some mention of IFR ceilings along I-35 corridor. Meanwhile, a line of showers and thunderstorms are expected to move west to east across much of the area overnight into early Monday morning. Latest HRRR would suggest approaching southwest OK and north TX around midnight, into I-35 corridor around 11Z and exiting southeast OK by late morning. Have included a 2 to 3 hour window with TEMPO/PROB at all sites except GAG/WWR. VFR conditions expected to return to most sites by midday. 30 PREV DISCUSSION... /ISSUED 321 PM CST Sun Jan 1 2017/ DISCUSSION... Stratus and fog have dissipated over all but the eastern sections today. But expected stratus and fog redevelopment again overnight as the upper 50s to lower 60s dewpoints lurking just to the southeast advect up into the area. Meanwhile, the upper wave near the Arizona-Sonora border will lift northeast approaching the area tonight with scattered convection. There is enough MUCAPE to support some thunderstorms and even the potential of some hail in the south where SPC has highlighted the marginal risk of severe weather. This system moves to the east during the day on Monday and very warm temperatures are expected with the clearing and a downslope component to the surface wind. The first cold front moves through Monday night bringing noticeably cooler temperatures. Mid-week will be cold as the Canadian surface high moves down the high plains. There is still some significant disagreement with how the upper-level pattern will evolve mid-to- late week and therefore how quickly the Canadian airmass will move out, so confidence is not too high toward the end of the week. Canadian and ECMWF would says that the cold air will stick around for awhile, but the GFS and DGEX (and the vast majority of GFS ensemble members) would suggest the surface ridge moving on quickly with associated temperature recovery late in the week. Leaned slightly toward the colder solution, but confidence is not high given the varied upper-level patterns. && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 56 48 67 35 / 10 50 20 10 Hobart OK 56 46 65 33 / 10 80 0 10 Wichita Falls TX 64 50 69 37 / 30 80 10 10 Gage OK 57 41 65 25 / 10 20 0 10 Ponca City OK 52 44 63 32 / 10 30 30 10 Durant OK 61 55 69 44 / 50 80 80 10 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...None. TX...None. && $$ 12/30
Area Forecast Discussion
National Weather Service Reno NV
656 PM PST Sun Jan 1 2017 .UPDATE... Wind prone areas east of the Sierra are still likely to see gusts greater than 50 mph for a few more hours...but most gusts in the Reno/Carson City area have decreased. We will let that advisory expire along with the Wind Advisory for the Tahoe Basin. Snow is developing in the Tahoe basin and a Winter Weather Advisory is now in effect along with the advisory for northeast California. Latest HRRR and NAM guidance shows less chance of snow making it into the Yerington/Hawthorne region late tonight...and a much smaller chance of any getting as far south and east as Fallon. Have delayed the onset of snow for the Reno/Carson City and lowered chances quite a bit for Fallon/Yerington. It is still not out of the question that banded snow will develop in some of these areas...but the best forcing appears to be north of those locations. The Tahoe Basin is likely to see moderate to heavy snow later tonight. That is also the case for parts of western Lassen and central Plumas counties above 5500 feet. The HRRR still shows a band from around Doyle to north of Lovelock after midnight. 20 && .PREVIOUS DISCUSSION... /Issued 605 PM PST Sun Jan 1 2017/ UPDATE... Winds on Pyramid Lake are decreasing a bit this evening as they are across the Tahoe Basin and far western Nevada. We will allow the advisory for Pyramid to expire while keeping the Wind Advisories for Tahoe and the Sierra Front up through 7 pm. Some wind prone locations are seeing gusts in excess of 45 mph...but most of these areas are gusting no more than 40 mph now. Farther south...gusty winds continue for the typical windier areas of Mono County. This advisory will remain in place through at least 10 pm. Light snow is spreading into the western edge of the Tahoe Basin now and is becoming a bit more widespread across parts of Lassen and Plumas counties and northeast into Surprise Valley and far northern Washoe County. We still expect a band of moderate to heavy snow to develop later tonight from northeast California into northwest Nevada with upslope precipitation spreading through northeast California and the Tahoe Basin by early Monday morning. The latest HRRR shows the most likely location for the band tonight running from about Doyle to just north of Lovelock and persisting for about 5 hours. Wherever this band develops there could a localized amounts of 2-3 inches of snow with little or no snow 5-10 miles either side of the band. We will be looking at this closer for possible updates through the evening. 20 PREVIOUS DISCUSSION... /Issued 351 PM PST Sun Jan 1 2017/ SYNOPSIS... A strong cold front will bring gusty winds today and Monday. Snow showers will develop in the Sierra and for portions of western Nevada. Light to moderate accumulations are possible tonight through Monday night, mainly in the northern Sierra and north of Highway 50. A stronger storm arriving Tuesday night and Wednesday could bring heavier snow, or a rain-snow mix in lower elevations. SHORT TERM... A strong cold front is slowly dropping south through northeast California and western Nevada this afternoon. Winds ahead of the front are gusting between 35-45 mph this afternoon, with a few spots in wind prone-areas reaching close 45-55 mph. With this in mind, the wind advisories for Tahoe, the Reno-Carson City- Minden area, and Mono County look good for the next few hours. As far as snow, that should begin to break out in the next couple/few hours in the northern Sierra and northern Nevada as deeper cold air and moisture slowly drops south. For most of western Nevada tonight, the best chance of seeing snow showers will be a short few hour window after the front moves through later this evening. Across western Nevada this means only about a trace to at most an inch roughly between Hwy 50 & I-80, with more in the 1-3 inch range from about Pyramid Lake and Lovelock northward. Locally higher amounts are possible across northern Pershing and Washoe County as moisture and instability are expected to be deeper there. Monday should feature mainly periodic light snow showers as models don`t depict much in the way of spillover except across far northern Washoe and Pershing Counties. Elsewhere across western Nevada, the best chance for more than sporadic snow showers and accumulations will be to the east of Lake Tahoe and Pyramid Lake where lake enhanced snow showers will be possible. Profiles have plenty of temperature difference from 700 mb to the surface with the cold air intrusion and flow is unidirectional. The only holdup for Tahoe will be moisture as simulations only show saturation up to around 650 mb. Pyramid Lake may have a bit better chance to get the lake effect machine going as moisture will be deeper there. For the northern Sierra and northeast California Monday and Monday night, efficient upslope along with an unstable, moist atmosphere will combine with an upper wave moving around the base of the trough positioned near the Pacific Northwest coast to bring continued light to moderate snow. With this in mind, our snow totals may be a bit low for Tahoe northward through Lassen County, especially near the crest, and will have to be re-examined by the next shift. By later Monday night and Tuesday, snow showers are expected to wane considerably (especially east of the Sierra) after the upper wave moves off to the east. However, the break will be short-lived as the next disturbance approaches the region. Simulations are still at odds regarding key details that will affect how much snow falls in northeast CA, the Sierra, and western NV Tuesday night and Wednesday. The key appears to be how close to the coast an upper low is as deeper moisture is tapped, which will affect the degree of amplification of a ridge and potential warm air advection over the interior West. The 12z GFS remains more amplified and brings warm air advection (and heavier precipitation) more into northern CA and extreme northwest Nevada. Meanwhile, the 00Z/12Z EC and most of its 00Z ensemble runs have a flatter flow with the heavier precipitation farther south, which would hit western NV and the Tahoe area. The 18Z GFS has come in a bit flatter so the potential remains for a period of heavier snow with at least several inches for western Nevada Tuesday night into Wednesday. Stay tuned as we begin to iron out the details...hopefully the models will consolidate soon! Regarding snow levels, they do not look to be an issue through Tuesday night with all snow expected. However, on Wednesday uncertainty increases as the more amplified ridge in the GFS allows much warmer air to creep into the region behind the the warm air advection while the EC`s flatter flow holds down snow levels considerably...and even brings in colder air late Wednesday. In any case, the wet pattern continues with most models showing significant additional precipitation for the Sierra and western NV. Snyder LONG TERM...Wednesday night through Sunday... A complex weather pattern persists into next weekend with wide contrasts in medium range guidance especially from Thursday through Friday. Because of these model fluctuations and disagreements with the large scale weather pattern, there is not a particularly high level of confidence for the specific weather, especially in the lower elevations and urban areas. Highlights of our updates to the extended forecast are as follows. - Widespread moisture Wednesday night into Thursday, then decreasing precip chances (but not going fully dry) for Friday. Next weekend we bring back high precip chances, with potential for large amounts of rain and snow, as guidance is in relatively good agreement with bringing a moderate-strong atmospheric river across the Sierra and western NV. - Temperatures were pushed upward a few more degrees from Thursday- Friday with milder temps at night. Some of the scenarios favored a more amplified ridge with temps rising several degrees above average, but we are currently taking a middle ground approach with temperatures and snow levels. - We have abandoned the idea of min temps dropping below 20 degrees thru the extended period, as only a handful of the latest guidance still indicates this colder scenario. Even if precip diminishes toward the end of the week, widespread cloud cover is more likely to limit radiational cooling at night. - Most scenarios keep all snow in the Sierra above 7000 feet, with the potential for a few feet of snowfall between Thursday-Sunday with the majority occurring next weekend. Below 7000 feet, the high level of varied scenarios make snow amount projections very challenging at this time. We are including the possibility of a rain- snow mix up to near lake level in the Tahoe basin from Wednesday night into next weekend. At the same time, some of the colder scenarios would keep mostly snow even down to western NV valleys, so we will mention both rain and snow throughout the extended forecast at all elevations below 7000 feet. Bottom line...if you have travel plans later this week into next weekend, be sure to check the latest forecasts and always be ready for winter weather in such an active pattern. Friday may provide a small window of opportunity for fewer travel impacts, but it is possible for winter travel conditions to be nearly continuous over the Sierra passes, with more significant impacts possible next weekend. MJD AVIATION... Gusty winds will continue through this evening with peak gusts 35-45 kt for the main terminals and Sierra ridge gusts up to 80 kt. Even overnight into Monday, only a slight drop off in winds is expected. Turbulent conditions with mountain wave activity will continue to be an issue through Monday evening, followed by lighter surface winds through Tuesday which may lead to LLWS as ridge level winds are not expected to decrease very much through Tuesday. Periods of snow showers will bring MVFR/IFR conditions at times this evening and continue thru Monday night from I-80 northward, especially for KTVL/KTRK. A few inches of snow accumulation are likely on the pavement at KTVL/KTRK each forecast period from tonight to Monday night, with only minimal snow amounts (most of the snow that falls will blow around rather than accumulate) for western NV terminals southward to KMMH. A more potent storm system is likely to bring more significant snow amounts for all Sierra terminals, and possibly in lower elevations from Tuesday afternoon through Wednesday night. MJD && .REV Watches/Warnings/Advisories... NV...Winter Weather Advisory until 10 AM PST Tuesday NVZ002. Lake Wind Advisory from 7 AM to 7 PM PST Monday for Pyramid Lake in NVZ004. CA...Winter Weather Advisory until 10 AM PST Tuesday CAZ071. Wind Advisory until 10 PM PST this evening CAZ073. Winter Weather Advisory until 10 AM PST Tuesday CAZ072. && $$ For more information from the National Weather Service visit...
Area Forecast Discussion
National Weather Service Blacksburg VA
623 PM EST Sun Jan 1 2017 .SYNOPSIS... Several waves of low pressure will affect the area over the next several days with periods of rainfall likely. A strong cold front will approach late Tuesday into Wednesday. && .NEAR TERM /THROUGH MONDAY/... As of 610 PM EST Sunday... Batch of light to moderate rain moving across the NC piedmont/foothills northeast to southside VA. Bumped pops up here while lowering in the northwest. Appears HRRR through the evening keeps most of the rain along/east of the Blue Ridge with possible another stripe of rain northeast to southwest along I-81 corridor around midnight. Otherwise little change to the previous forecast, though added some fog in the south as well. Previous afternoon discussion... Complex weather scenario unfolding in the near term as amplifying western trough acts to pump up ridging over the southeastern U.S. opening the door for plenty of moisture to be drawn northward toward the southern Appalachian region. This in combination with a surface high over New England which will slowly drift northeast maintaining cool air damming and east to northeast flow at the surface through the period. Meanwhile low pressure moving slowly through the southern Mississippi Valley will be contributing to a possible severe weather and heavy rainfall event over the LA/MS/AL area tomorrow. Do not expect severe weather parameters to approach anything of concern this far north although general thunder extends north into the central portions of the CWA in the Day 2 SPC outlook. Rainfall will be moderate to possibly heavy in the next 24 hours, mainly from late tonight until around midday tomorrow. Models and WPC are showing a tight gradient in QPF from northwest to southeast and ranging from perhaps less than 0.50 inches to up to 1.5 inches in the far southeast (see Hydro section below for details). It will be generally mild through the period with temps well above normal although heavy clouds will keep it from getting too out of hand. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... As of 250 PM EST Sunday... At the start of the short term period our area will be between systems, with a sfc wedge of high pressure firmly in place. Low level winds back in response to an approaching negatively-tilted shortwave ushering in higher theta-e air, especially to the southeast portion of the forecast area where PWAT values are forecast to be 200%+ of normal by early Tuesday morning. With the strong moisture advection and good qg forcing late Monday night into early Tuesday, ramped up POPS to categorical for this timeframe, while lowering pops at the start of the short term period. Cannot rule out isolated thunderstorms on the edge of the low level wedge in the far southeast late Monday night/early Tuesday, but considering the time of day precipitation will be falling, kept precip as showers. Medium range models are less aggressive with the erosion of the low level wedge on Tuesday after the upper wave passes by late morning/early afternoon. As a result, tried to show a broader range in temps from the Alleghany Highlands/LYH area (cooler) to the NC Piedmont. A strong cold front moves through late Tuesday night/early Wednesday. While the forecast 850mb winds are only 35-40 knots, impressive height rises and strong CAA will push gusts potentially over 40 MPH in higher elevations. Continued the trend of increasing wind speeds for this time period. Temps could fall during the day on Wednesday and tried to reflect that trend in the hourly grids. Otherwise, leaned toward the cooler guidance in the west, but expect temps to climb into the 50s in the east before dropping late in the afternoon. Upslope precipitation will continue for most of Wednesday with rain changing to snow or a rain/snow mix across Greenbrier County, but any accumulations should be very light. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 315 PM EST Sunday... After the long range models showed some modest agreement with the upper air pattern yesterday, significant differences returned today leading to greater the normal uncertainty in the forecast for this period. The 00z/01 ECMWF returned to the idea of phasing Pacific energy with northern stream wave, with a secondary surface low spinning up in the southeast and moving along the carolina coast for Friday-early Saturday. On the opposite end of the spectrum, the 12z/01 GFS forecasts a dominate northern stream trof over the eastern U.S. Thursday-Friday keeping drier and much colder temperatures in place for our area. Interestingly, the 12Z Canadian model is more similar to the 00z/01 ECMWF with a less amplified eastern trof and a weaker secondary sfc low developing in the southeast, spreading lighter precipitation into our area Friday night-early Saturday. A quick look at the 12z/01 ECMWF now forecasts a deeper eastern U.S. trof keeping most significant precip to our south, but still producing light precip associated with a weak upper wave Late Thursday. For Saturday night and Sunday there is good agreement for below normal temperatures and dry weather. && .AVIATION /23Z SUNDAY THROUGH FRIDAY/... As of 615 PM EST Sunday... Aviation conditions will start to deteriorate this evening as rain and lower clouds move in, first over southside VA and DAN and elsewhere after midnight, though the mountains of WV seems to be away from the main axis of moisture convergence, should see less rain and possibly more drizzle/fog. Nonetheless cigs/vsbys will fluctuate between MVFR to as low as IFR at times through about 12-14z Monday, then some slight improvement though still MVFR at best, with still best location of rain east of a ROA/BCB line. This will persist through the end of taf period. Extended aviation discussion... Potential for an extended period of sub-VFR ceilings continues into Tuesday. A weak warm front sets up to our to south and impulses along it that will brings rain Monday night. A much stronger area of low pressure passes to the west Tuesday, likely allowing for a much more widespread rain event with potential IFR cigs and MVFR to IFR vsbys on Tuesday. A sharp cold frontal passage should see ceilings/visbys improve to VFR areawide (except sub-VFR at BLF/LWB) through Tuesday night but also a likely gusty increase in northwest winds. VFR most TAFs Wednesday but with MVFR/brief IFR upslope snow showers possible for LWB/BLF. Gusty northwest winds will hinder aviation operations Wednesday. Thursday-Friday looks mainly dry and cold, but still will have to watch model trends as earlier they advertised potential snow Thu- Fri time frame. Right now should be VFR for those 2 days. && .HYDROLOGY... As of 300 PM EST Sunday... With the latest models converging somewhat on QPF with amounts ranging from less than a half-inch across the upper James and Greenbrier river basins and up to about 1.5 inches over the lower Dan and Roanoke basins in the next 24 to 48 hours. We may see substantial runoff for the first time in while as SERFC forecast for the Dan shows a rise to near Action Stage by late Tuesday night and several runs from the GEFS/NAEFS hydrologic ensembles show minor flooding at South Boston. There is a very tight gradient in the QPF fields with the highest amounts south and east of the WFO RNK hydrologic service area. A northward shift in the band of highest rainfall could bring a higher chance for minor flooding on the Dan River, while a southward shift would reduce the chances. For the most part however a moderate to even heavy rain event would be beneficial to the persistent dry and moderate drought conditions which have been around for several months now. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...KK/SK NEAR TERM...KK/PC/WP SHORT TERM...PH LONG TERM...PH AVIATION...KK/PC/WP HYDROLOGY...PC
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
809 PM MST Sun Jan 1 2017 .UPDATE... Issued at 808 PM MST Sun Jan 1 2017 KUDX WSR-88D, surface observations, and webcams continued to show -FZDZ near the Black Hills, mainly from the north through eastern slopes. Light icing developing and expanding, so have hoisted advisory for the overnight hours. UPDATE Issued at 459 PM MST Sun Jan 1 2017 Over the past hour, KUDX radar starting to show a distinct FZDZ signature on the plains adjacent to the Black Hills. Looking outs the window, on area web cams, and at road reports, looks like icy spots developing as the sun sets. Have added -FZDZ for these areas through most of the night as the latest RAP showing -SN coming more slowly and further north. && .SHORT TERM...(This Evening Through Monday Night) Issued at 142 PM MST Sun Jan 1 2017 Pattern change underway as another round of arctic air begins to advect into the region and a blocking pattern develops holding cold air in the region for most if not all of this week. PAC NW upper trough will eject a impulse toward the region, which is currently in progress. Associated jet streak and reflected ll flow will support increasing chances for snow from west to east Monday morning. This will be the main impact from this system. However, a secondary impact from this system will be chances for freezing drizzle across the far NE through east. Forecast models have generally opted for a faster jet streak induced system which should limit the amount of WAA and pos theta-e adv across eastern areas. However, a backdoor cold front has brought a saturated ll cold layer into the northern half, which will further cool and saturate tonight. Weak impulse now advecting across ND looks to support enough wind shear/lift to support areas of freezing drizzle in the aforementioned areas this evening given thermal profiles indicated in NAM/HRRR. Snow will then overspread the area Monday morning with snow ending in the early to mid afternoon west to east. Any ZL should end Monday morning. Current progs suggest 1 to 2 inches of snow across the NW 2/3 with up to 3 inches across the far NE. Winds will pick late Monday morning, esp across NW SD, which will support patchy blowing and drifting snow on the SD plains, esp NW SD. Winds will begin to decrease some Monday evening. Given the combination of freezing drizzle, snow, and patchy blowing snow, have decide to issue a winter wx adv for the far NW SD zones. .LONG TERM...(Tuesday Through Sunday) Issued at 142 PM MST Sun Jan 1 2017 Arctic air will settle into the region with temps struggling above zero Tues and possible Wed. A clipper type wave will advect through the region Wed-Wed night, maybe supporting snow light snow across the area, esp the southern third and the northern Black Hills. Otherwise, dry wx is forecast through the remainder of the long term. Forecast models do begin to break down the blocking pattern late next weekend, which would support more zonal flow and a temporary retreat of the arctic air. Currently have a warming trend in the forecast for then. && .AVIATION...(For the 00Z TAFS Through 00Z Monday Evening) Issued At 436 PM MST Sun Jan 1 2017 Stratus and fog will push southwest tonight bringing widespread IFR conditions due to ST/FZFG with local LIFR conditions near the higher terrain of the Black Hills. Patchy FZDZ is possible on the SD plains. -SN will develop over northeast WY overnight and spread into western SD by Monday morning. IFR/LIFR conditions will persist through Monday in the -SN. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...Winter Weather Advisory until 5 AM MST Monday for SDZ012-013- 024>026-028-030-031-072>074. Winter Weather Advisory until 11 PM MST Monday for SDZ001-002- 014. WY...Winter Weather Advisory until 5 AM MST Monday for WYZ071. && $$ Update...Helgeson SHORT TERM...JC LONG TERM...JC AVIATION...Helgeson