Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/28/16


Area Forecast Discussion
National Weather Service Bismarck ND
940 PM CST Sun Nov 27 2016 .UPDATE... Issued at 933 PM CST Sun Nov 27 2016 No significant changes with this update. Based upon trends in the 12-00 UTC global suites and the high resolution iterations through 02 UTC, have increased the wording to isolated areas of 15 inches of storm total snowfall by Wednesday evening. This is in line with the WPC afternoon forecast. Through 0330 UTC precipitation per reports and webcams is transitioning from rain through sleet and now snow in Glen Ullin, New Salem and Bismarck. This is generally on time with the previous forecast thinking of change over. UPDATE Issued at 647 PM CST Sun Nov 27 2016 As of 0045 UTC...rain is the predominant precipitation type across south central North Dakota. Road temperatures are holding in the 34-36 degree range. Thus, at the time the freezing rain potential seems somewhat lower given the road temperatures expected take a few more hours at least to cool to freezing. However, by that time across the south central, the 22-23 UTC RAP and HRRR suggest precipitation is expected to begin its transition to mostly snow in the 04-06 UTC timeframe. A mix is favored through the night and and through much of Monday across the James River Valley. Given a slightly quicker onset of precipitation, did adjust the Winter Storm Warning start time to 01 UTC for south central North Dakota. && .SHORT TERM...(This evening through Monday Morning) Issued at 236 PM CST Sun Nov 27 2016 A major winter storm will impact western and central North Dakota beginning tonight. A negatively tilted upper level trough will swing into the Northern Plains tonight. This will induce rapid cyclogenesis over the central and northern plains with a 975-980MB surface low situated somewhere near the ND/SD/MN border by 6 AM Monday. Ahead of this, abundant moisture will stream into the eastern Dakotas, with strong forcing from the leading shortwave inducing precipitation over the James River Valley as early as this evening, but certainly by midnight tonight. As the system deepens and becomes stacked tonight, a well defined trowal develops, spreading precipitation westward into central and eventually western ND by Monday morning. Models continue to indicate a brief period of warmer temperatures aloft and the potential for freezing rain and sleet over portions of the James River Valley this evening. Temperatures will remain near the critical freezing threshold for much of the overnight and daytime hours of Monday across the James Vally. Eventually colder air will advect in and change the rain/freezing rain to all snow by Monday night. For these areas a Winter Weather Advisory has been issued to highlight the potential for freezing rain tonight and accumulating snow tomorrow through Wednesday. Due to the delay in switching over to snow, portions of Foster, Stutsman, LaMoure and Dickey Counties will see less snow than locations further west. .LONG TERM...(Monday through Saturday) Issued at 236 PM CST Sun Nov 27 2016 Deterministic and ensemble model guidance have come into pretty good agreement in the evolution of this storm. The deep low near the ND/SD/MN border Monday morning moves very little through Tuesday morning. The stacked system moves slowly east across Minnesota through Wednesday morning, and finally lifts into the Great Lakes region by Thursday. With such a deep and slow moving system there is the potential for significant snowfall across most of western and central ND Sunday night through Wednesday night. The brunt of the snowfall is expected from late Sunday night through Tuesday morning as the warm moist air continues to feed into western and central ND via the TROWAL. Winds with this strong system will increase over western ND on Monday and spread into central ND Monday night and Tuesday. At this time it looks the snow will be wet enough and winds will be low enough to keep Blizzard conditions from forming, but this could change if temperatures are little cooler and winds a little higher. Regardless winds around 30 mph will cause some blowing and drifting of snow, limiting visibility and making travel hazardous. Therefore, a Winter Storm Warning has been issued for all of western and most of central North Dakota. The heaviest snow is expected across central North Dakota where 6 to 12 inches could accumulate by Wednesday. The TROWAL begins to break down Tuesday evening, but synoptic forcing will remain sufficient to produce light snow through Wednesday night. Accumulations will become much lighter during this period, but winds will remain strong through Tuesday evening. There are still some uncertainties with this storm system. The biggest being snowfall accumulations, and the potential for blowing and drifting snow. Due to our very warm November, soil temperatures remain in the mid 30s to lower 40s. Road surface temperatures will also be warm during the beginning portions of this storm. A heavy wet snow is expected initially with a reduced threat of widespread blowing snow. This combination may initially limit the severity of impacts, but later as temperatures drop and surfaces freeze widespread travel impacts are expected. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 933 PM CST Sun Nov 27 2016 A winter storm will impact all of western and central North Dakota tonight through Wednesday. Significant hazards to aviation are expected. Flight categories will to fall to LIFR for all terminals. && .BIS WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 6 PM CST /5 PM MST/ Wednesday for NDZ019>023-034>036-042-045>047-050. Winter Storm Warning until 6 PM CST /5 PM MST/ Wednesday for NDZ001>005-009>013-017-018-031>033-040-041-043-044. Winter Weather Advisory until 6 PM CST Wednesday for NDZ025-037- 048-051. && $$ UPDATE...AYD SHORT TERM...AJ LONG TERM...AJ AVIATION...AYD
Area Forecast Discussion
National Weather Service State College PA
958 PM EST Sun Nov 27 2016 .SYNOPSIS... A narrow north to south ridge of high pressure will slide east across Pennsylvania tonight and Monday, accompanied by dry weather with light wind. A frontal system will develop over the plains states and push a cold front through PA on Tuesday. A second storm will follow shortly after. It will be mild and wet in the middle of the week, with cooler air and lake effect snow showers returning for the end of the week. && .NEAR TERM /UNTIL 8 AM MONDAY MORNING/... A NNW-SSE stripe of stratocu clouds will exit our far eastern zones by 05Z followed by just a brief hour or two period of mainly clear skies...that will allow temps to dip several degrees or more and into the 20s. Patchy dense valley ground has formed in this ribbon of clearing across the NW mtns where moist ground from snowmelt has added the necessary near sfc moisture. Last few HRRR runs captures this fog formation best via its sfc RH field and near 100 percent values across the nrn mtns. This area of high RH advects steadily to the east and out of the northcentral mtns by 08Z, as a cirrus/cs shield overspreads the region and a light serly breeze develops. The high cloud shield will also help to level off temps late. Min temps look rather seasonable in the mid 20s to around 30F. && .SHORT TERM /8 AM MONDAY MORNING THROUGH 6 PM MONDAY/... 8H temps rise early in the day, and Monday seems like the best day for quite a few. High clouds will thicken-up from the west, but it should remain dry until the evening. A sprinkle may occur over the nrn mtns late in the day as moisture associated with warm advection from the next system spills over the migratory upper ridge. Maxes will get 5 to 10F above normal (m40s-l50s) thanks to the light southerly wind and despite the meager mixing which limits our tap into 9H temps of +2 to 5C. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... Storm system centered over Minnesota will bring unsettled/stormy weather through midweek. Models agree with an occluded front swinging through the area Mon night/Tuesday accompanied by an area of widespread light to occasionally moderate rain. Behind that on Tue night, a brief period of relative drying out as shortwave ridge slides through. Some minor differences in detail arise thereafter, but models showing another significant wave forming on the trailing front and spreading another slug of rain up over the area by early Wednesday. Heaviest rain looks to be over the SE in highest PWAT air, where a period of moderate rain is likely. By late week, the upper low morphs eastward across southern Canada, ushering in a prolonged period of cold NW flow aloft and breezy conditions at the surface. The airmass doesn`t look especially frigid, but it should be cold enough to provide an extended period of widespread cloudiness and frequent lake effect snow showers over the the NW mountains down into the Laurel Highlands, possibly lasting all weekend long. Temps become mild Tue/Wed with highs back up into the 50s/lower 60s. Thu will be a transition day back to colder temps with late week/weekend just a shade below normal. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Main concern this evening is at KBFD, where clearing skies have resulted in dense fog. 00Z obs reporting 1/4SM visibility, but based on surrounding obs and satellite view, it appears to be an isolated pocket of fog. Difficult to determine how long the dense fog will persist, as a developing southerly breeze and increasing high clouds could lead to improving conditions later this evening. For now will go with the idea of improvement later this evening, but there is a lot of uncertainty and low vsbys could potentially persist well into the night. Elsewhere across Central Pa, high pressure building into the region will bring clearing skies and light wind overnight. Will have to watch for the possibility of some patchy valley fog around dawn at KIPT. However, GLMP MELD suggests the odds are fairly low. Any early fog should lift shortly after 12Z, then model data supports a high confidence of widespread VFR conditions the rest of the day, as high clouds overspread the state in advance of an approaching storm system. Outlook... Tue...Low cigs/rain, mainly in the morning. Wed...Rain/low cigs possible. Thu-Fri...Restrictions possible KBFD/KJST in scattered snow showers. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert NEAR TERM...Lambert SHORT TERM...Dangelo LONG TERM...La Corte/RXR AVIATION...Fitzgerald
Area Forecast Discussion
National Weather Service Hastings NE
543 PM CST Sun Nov 27 2016 .SHORT TERM...(This evening through Monday) Issued at 318 PM CST Sun Nov 27 2016 Current radar has showers and maybe an isolated thunderstorm moving through the central to northeast part of the forecast area. Satellite shows clearing in or near the southwest portion of the area this afternoon. Surface analysis still has the low pressure system near the Nebraska/Kansas/Colorado borders. The main question for the remainder of the afternoon and into the evening is if there will be enough instability near the clearing line to start a few thunderstorms. The HRRR has been consistent with having some convection that starts in the north central Kansas counties and moves to the northeast from there. There is also a small area that starts up in the west before moving to the northeast. The best timing for the thunderstorms will be from about 3pm to 6pm. There is still a question as to how much instability there will be. The RAP brings a small area of 500 to 1000 j/kg into the southwest and pushes it across as it weakens. Once the sun goes down this evening, that should effectively cut off chances for thunder. The precipitation should move off to the northeast of the forecast area during the evening hours and there should be some clearing behind the precipitation. As the surface low moves to the east/northeast into this evening. The winds should turn to the west and bring in drier air to the area during the evening hours. The clearing skies and drier air should allow temperatures to fall off into the mid 30s. A little wrap around moisture will bring some clouds back to the area for a time on Monday, but the clouds will move out during the afternoon. Temperatures will warm back into the lower 50s during the afternoon. .LONG TERM...(Monday night through Sunday) Issued at 318 PM CST Sun Nov 27 2016 There will be mostly northwest flow across the area through this period. There are a few waves that move through the area. Have kept the forecast dry through the period, but each of the waves brings an increase in cloud cover and a weak cold front. The first wave moves through Monday night. Temperatures will be cooler Tuesday and there will be a few more clouds around. Temperatures will remain cooler than normal with in and out clouds Wednesday through Friday. A surface high moves through the area on Friday and when it moves to the southeast Friday night, winds will turn back to the south and temperatures will start a slow increase back to near normal for the weekend. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday evening) Issued at 539 PM CST Sun Nov 27 2016 The main issue with this forecast is low-level wind shear this evening and into the early overnight. Most showers/thunderstorms have moved off to the east and we should be dealing with VFR conditions. Wind speeds will initially be quite gusty, but should let up somewhat as the cold front approaches. Wind speeds will pick back up again behind the cold front later on tonight and into Monday. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ SHORT TERM...JCB LONG TERM...JCB AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Lincoln IL
902 PM CST Sun Nov 27 2016 .UPDATE... Issued at 902 PM CST Sun Nov 27 2016 Initial wave of rain has progressed eastward slightly ahead of model projections, and there appears to be a back edge of the rain approaching from across Missouri ahead of previous forecasts as well. The faster pace may be partly due to the intense low and mid level winds out of the southwest that have developed this evening. Winds 1-2K ft above the ground are up to 40-50kts based on VWP plots from the ILX radar. Surface winds have sustained up around 20 mph with gusts over 30 mph at times. HRRR and RAP updates are showing the faster progression of the first wave of rain, so we have followed suit in the PoP and weather grids for the next 12-18 hours. Thunder has not materialized in Illinois, nor Missouri for that matter, so we removed any mention of storms from the rest of the night. Low temps will be help warmer due to blanket of clouds, periodic rains, and strong ground level winds. Forecast lows are not much below current air temps, so expect relatively steady temps overnight. Updated forecast info is already available. && .SHORT TERM...(This evening through Monday) ISSUED AT 230 PM CST Sun Nov 27 2016 Early afternoon surface map shows surface low organizing across northwest Kansas, as the upper low takes shape over eastern parts of Montana and Wyoming. The earlier stratus continues to lift northeastward and the southern half of the forecast area is mainly seeing mid and high level clouds at this point. A few showers have grazed the western CWA as of late, but the more organized precipitation is steadily advancing across southern Iowa and northern Missouri and should reach the middle Illinois River Valley by late afternoon. Morning model suite continues to indicate a rapid intensification of the surface low as it lifts into eastern South Dakota this evening, before it begins to occlude later Monday over eastern North Dakota. Showers will continue to steadily advance across the forecast area this evening and have gone with categorical PoP`s at most locations tonight. Have added some isolated thunder mention as well. The initial dry slot behind this band of showers will spread across the western CWA late tonight, and rain chances will be somewhat minimal for a time over a large area west of I-55 early Monday. The higher PoP`s for the afternoon still look good though, as a wave ejects northeast out of the Desert Southwest and sends another surge of moisture northward ahead of the cold front. Precipitable water values approach 1.1-1.2 inches south of I-70, which will help with some healthy rain totals near an inch during the daytime. The mild temperatures -- lows in the lower 40s and highs in the lower 50s -- will be offset by wind gusts of 30-35 mph at times over central Illinois overnight and Monday. .LONG TERM...(Monday night through Sunday) ISSUED AT 230 PM CST Sun Nov 27 2016 The main cold front associated with the weather system moving through the area, will quickly move through the remainder of the CWA Monday evening. As it does, most areas will see an end to the precip by midnight, with just a chance of precip in the eastern parts of the CWA. Dry weather is then expected behind this front. However, central IL will remain in a cyclonic flow pattern through most of the week, with the associated surface low slowly moving east northeast across the Great Lakes region. The models do develop a secondary surface low that moves across northern IL; but, since there will also be another weather system in the southern Miss valley at the same time, moisture will be limited for the northern system in our area. So, for Tue night, when this moves through, dry weather is still expected over most of the CWA, with a slight chance of precip in southeast IL from the southern system. The upper level low will finally move into eastern Canada toward the end of the week, bringing a change in the pattern for the weekend. The resulting pattern seems to be one with a split flow as an upper level low sets up in the southwest US and a northwest flow pattern sets up over the norther US and Great Lakes region. This should keep things somewhat quite over the area, but the ECMWF brings a weather system across Illinois for Sunday. Since this is the first run with that and the GFS is dry, pops for Sunday will only be slight chance for now. Colder air will lag behind the weather system Mon night so high temps Tuesday will still be above normal, reaching the 55 to 60 degree range. Given the pattern, the colder air does not really make into the CWA until Wed night. So, Wed highs will be slightly above normal for end of November. Normal to slightly below normal temps can then be expected Thur through next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 603 PM CST Sun Nov 27 2016 Rain has already reached SPI and PIA and will overspread the remainder of the TAF sites by 03z. VFR clouds ahead of the rain will drop to MVFR a couple of hours after rain onset. Periods of light to moderate rain are expected this evening. Radar images upstream indicate we will see breaks in the rain after the first 2-3 hours of steady rain at the onset. A warm front will lift northeast through Illinois later this evening, prompting a lowering of ceilings to IFR and possible MVFR fog development at all terminals tomorrow morning. Cloud heights and visibility in fog are projected to drop even further tomorrow afternoon, with 1-2SM BR and OVC004 become widespread. South winds will increase this evening and remain strong the remainder of this TAF period, in response to a tightening pressure gradient and LLJ winds mixing to the surface. We are expecting sustained winds of 18-20kt with gusts over 30kt at times. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Shimon SHORT TERM...Geelhart LONG TERM...Auten AVIATION...Shimon
Area Forecast Discussion
National Weather Service Marquette MI
640 PM EST Sun Nov 27 2016 .SHORT TERM...(This evening through Monday) Issued at 356 PM EST SUN NOV 27 2016 WV imagery and RAP analysis indicated a mid/upper level trough over much of the wrn CONUS, from the Rockies into the wrn plains. A vigorous lead shortwave was lifting northeast into wrn IA. At the surface, se winds were increasing between a 989 mb low over sw Nebraska and a ridge from Quebec into the ern Great Lakes. With daytime warming, low level moisture trapped below a 1k-2k ft inversion has lifted to a low stratus deck over most of the cwa except over portions of the west where downslope se flow was strongest. The short range models were in good agreement with the progression/onset of the rain ahead of the IA shrtwv and surge of 295k-305k isentropic lift. Expect the rain developing from sw to ne between 06z-12z to taper off during the morning after the initial band moves through. Although the mid level moisture will depart during the day, continued low level isentropic lift will maintain some light rain or drizzle through most of the day, with lower amounts and coverage near Lake Superior where the strongest downslope wind prevails. Fog may thicken again tonight with the loss of sfc heating but with the rain moving in, should not be as dense into Monday as it was this morning. Temps will remain steady or slowly rise tonight and then climb just a few degrees to the lower to mid 40s Monday. .LONG TERM...(Monday night through Sunday) Issued at 405 PM EST SUN NOV 27 2016 Positive height anomalies currently dominating much of the east half of Canada will expand across most of Canada by midweek, then diminish in magnitude/coverage next weekend. To the s, energy flowing off the ne Pacific will carve out the long advertised central CONUS trof over the next few days. This trof will then evolve to a positive tilt from se Canada/New England to the sw CONUS by late week. Next weekend, lower amplitude flow looks to develop briefly across the northern CONUS/southern Canada prior to trof development in the vcnty of far western N America in the 8-10day period. This trof development will herald a potential pattern change across N America heading into mid Dec that will initially lead to advection/build up of arctic air into western Canada. Ahead of the developing central CONUS trof in the shorter term, southerly flow will push temps well above normal across the area over the next couple of days. While temps will fall back closer to normal later in the week as the trof axis drifts e, readings should remain a little above normal as the positive height anomalies across Canada prevent any arctic air from developing or dropping s thru Canada and into the CONUS. As for pcpn over the next 7 days, the developing central CONUS trof will bring a wet period into early Tue with all of the pcpn in the form of rain. Pcpn will then transition to ocnl lighter snow mid and late week with troffing over the area, though there will be potential of lake enhanced snow that may provide some accumulations. Looking farther ahead beyond this 7 day fcst, CPC/NAEFS outlooks in the 8-14 day period, out to Dec 11, now show diminishing probabilities of above normal temps as the start of the potential pattern change moves into that time period. Farther out, CFSv2 runs continue to show the pattern change toward colder weather heading into mid Dec as positive height anomalies that have dominated Canada for many weeks give way to negative height anomalies. The changes shown are consistent with GFS/ECMWF trends for early next week which show western N America trof development initially which leads to advection/build up of arctic air in western Canada. Could be an active period of weather as this cold air shifts farther e and se. However, it is noted that the majority of Canadian ensembles valid Dec 13 have a mild look for the Upper Lakes. Beginning Mon night/Tue, the second of 3 significant pieces of energy moving thru the central CONUS trof will lift into the Great Lakes. This second wave will have stronger jet dynamics/upper diffluence and stronger deep layer forcing compared to the first wave that generates pcpn tonight/Mon. Result will be heavier rainfall affecting the fcst area Mon night into early Tue morning, especially across the central and eastern fcst area. Potential is there for 1+ inch of rainfall over roughly the e half where stronger forcing better overlaps warm conveyor belt deep moisture ribbon which has precipitable water around 0.80 inches/250pct of normal. Passage of occluded front to the n and ne Tue morning will then bring an end to the steadier/heavier rain. Models have been trending more toward a dry period following fropa under mid level drying. Fcst will follow suit, but will retain a schc mention over the far w Tue aftn, closer to mid level low center over MN. Expect low temps Mon night in the upper 30s/lwr 40s. High temps on Tue may reach 50F over the e, especially if clouds break, while low/mid 40s will be the rule w. It now appears that the 3rd piece of significant energy moving thru the central CONUS trof will probably have a track far enough w to spread deep layer forcing and deep moisture back into Upper MI on Wed, especially across the e. Given multi-model trends, fcst will show chc pops spreading across the e and much of the central fcst area on Wed. Wetbulb zero heights support only rain as ptype. Over the far w, deep moisture in the vcnty of the decaying mid level low may support some -shra, perhaps mixed with snow. Thu into Fri, fcst area will be under the influence of the gradually weakening mid/upper level trof that will extend from se Canada to the sw CONUS at the end of the week and the associated sfc trof. With deep moisture and 850mb temps gradually falling to -5 to -8C, expect some -shsn/-shra transitioning to mainly -shsn across the area. There is the potential of lake enhanced snow off Lake Superior, dependent on location/movement of the sfc trof across the Upper Lakes. ECMWF is much sharper with this trof, offering potentially mdt snow accumulations in the Lake Superior snow belts Wed night/Thu. Not a lot of consistency run-to-run and btwn models with the details, but this will be a time period to monitor for some snow accumulations in the Lake Superior snow belts, especially across the higher terrain of western Upper MI and then e toward Marquette. Light LES will then continue into Fri. Model trends are quicker toward a transition to a lower amplitude more zonally oriented flow over the weekend. There will likely be a shortwave passing during this transition period, but any pcpn that might occur should be light. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 639 PM EST SUN NOV 27 2016 Continuing moist SE flow ahead of the approaching sfc low will keep ceilings low across the three TAF sites overnight an into Monday. SE flow favors keeping ceilings LIFR/IFR at KSAW and IFR at KCMX. KIWD to see low end MVFR/IFR as SE flow is downslope there. Ceilings do improve to MVFR late in the forecast at KIWD and KCMX but KSAW will remain IFR/LIFR. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 356 PM EST SUN NOV 27 2016 High pressure over the ern Great Lakes will shift to the east tonight as low pressure deepens across the northern plains into the upper midwest. This will result in a tight pressure gradient developing across the northern Great Lakes creating gales overnight. Gales to 40kt are expected across all of Lake Superior spreading west to east, but the gradient will slacken earliest across the far west. Further east the gradient will remain tight, with gales lingering through Mon night. The low pressure system will linger over the upper midwest Tuesday into Wednesday. However the pressure gradient is not expected to be as tight and allow winds to diminish below 25kt by Tuesday evening. Northerly winds to around 25 knots may develop Thursday as the slow moving low moves to the east of Lake Superior into Quebec. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Warning from midnight tonight to 10 AM EST Tuesday for LSZ249>251-266-267. Gale Warning from midnight EST /11 PM CST/ tonight to 10 AM EST /9 AM CST/ Monday for LSZ162. Gale Warning from midnight tonight to 4 AM EST Tuesday for LSZ243-244-264. Gale Warning from midnight EST /11 PM CST/ tonight to midnight EST /11 PM CST/ Monday night for LSZ240>242-245>248-263-265. Lake Michigan... Gale Warning from 4 AM Monday to 4 AM EST Tuesday for LMZ221-248- 250. && $$ SHORT TERM...JLB LONG TERM...Rolfson AVIATION...RJT MARINE...JLB
Area Forecast Discussion
National Weather Service Norman OK
909 PM CST Sun Nov 27 2016 .DISCUSSION... Recent runs of the HRRR develop convection southwest of Wichita Falls between 1 and 2 am with further develop to the north and east through 7 am. However, some weak returns around Big Springs and Synder may indicate storms may form before midnight. Regardless, it appears south central and southeast Oklahoma will have a good opportunity for showers and storms tonight with strong winds and hail possible with the strongest storms. Storms will move very quickly and storm tops should be below 30k feet. && .PREV DISCUSSION... /issued 244 PM CST Sun Nov 27 2016/ DISCUSSION... Latest water vapor satellite imagery reveals one lead shortwave trough emerging from the Central Rockies onto the Central High Plains, and another moving through Nevada. The first shortwave trough has resulted in strong surface pressure falls in the lee of the Rockies and latest surface analysis shows a 988 mb surface low in far northwest Kansas. Strong winds have resulted across Oklahoma and western north Texas. Maximum gusts have been around 40 mph across northwest Oklahoma. The stronger winds have been confined to the Oklahoma and Texas panhandles where deeper mixing is occurring and gusts over 50 mph have been common. The strongest winds in our area through sunset will be where partial clearing and deeper mixing has occurred across far northwest Oklahoma. As a Pacific cold front moves east and winds veer, gusts approaching 50 mph may be possible across this area until mixing subsides early this evening. Otherwise, low stratus has been persistent across the entire area all day and this will continue into the night with gradual clearing from the west. Short term model guidance continues to show a low-level theta-e corridor ahead of the front slowly moving eastward. As aforementioned lead shortwave lifts northeast the front/moisture axis will linger and slowly move eastward. Cooling aloft/ascent ahead of the next shortwave trough (now over Nevada and moving quickly east) will overspread this moist axis and should result in isolated/scattered convection developing late this evening and continuing into the night. Low level moist advection beneath steepening mid level lapse rates should contribute to at least 500 J/kg to perhaps 1,000 J/kg MUCAPE from parcels that should originate just above the surface. This combined with strong deep layer shear in excess of 60 knots should lead to organized/intense thunderstorms and a few may be marginally severe. Marginally severe hail is the most likely severe threat given somewhat stable boundary layer limiting the wind/tornado threat. Having said that, given the very strong momentum aloft, a few severe wind events are possible. Spatial details of convection are not quite clear but it does appear the potential exists further northwest than originally thought, possible as far northwest as north- central Oklahoma, by late evening. Convection will probably expand in coverage toward the south and east and be most numerous later in the night across south-central and especially southeast Oklahoma. Rain chances will end early tomorrow as the second shortwave trough departs. A period of mean westerly/downsloping flow should result in slightly above normal temperatures tomorrow. The combination of a drier air mass and breezy conditions may lead to elevated to near critical fire weather conditions across western portions of our area (see Fire Weather Discussion below). The weather will be uneventful through Thursday with the only notable change being a cold front forced by head another shortwave trough rotating around large/deep Midwest closed low. This cold front will arrive on Tuesday and keep temperatures from warming nearly as much as is anticipated tomorrow. Highs in the 50s will be common in all but the southern portion of the area where the front will arrive later. Even colder temperatures are expected Wednesday as northerly flow and cold advection keep temperatures in the 40s across the northern portion of the area. Low amplitude ridging aloft will bring moderating temperatures (to near late November normals) on Thursday. A complicated scenario develops by Friday and especially this weekend. Inconsistencies and disagreements among medium range guidance leads to a low confidence forecast. Beginning late Friday and persisting through the night, most of the deterministic and ensemble guidance shows a broad/weak isentropic ascent scenario with sufficient moistening for precipitation. This occurs ahead of a deepening increasingly closed off mid-upper low that will be positioned to our west. Variances in the synoptic scale details with the pattern across the Midwest into the Northeast have implications for precipitation type for us. Some solutions are more robust with a cold surge into our area early on that would be sufficient for snow across at least the northern portion of the area. However, the GEFS mean and ECMWF deterministic have trended less anomalously negative with 500 mb heights across the northeast indicated that the first cool surge may be less significant and confined to just the northern portion of the area. The new 12z ECMWF is the most concerning for our area with regards to cold/snow and potential winter weather impacts. It shows the Southwest closed low phasing with northern stream wave and accelerating east, passing to our south. This scenario would bring a second more defined cold surge southward coincident with large scale ascent spreading over the area. The GFS and its ensembles as well as the Canadian are more closed off with this system and have it out of phase with this northern stream wave, however. If medium range guidance trends toward the latest ECMWF, this would necessitate higher precipitation probabilities for Saturday and more potential for snow. BRB FIRE WEATHER... Mimimum relative humidity values are expected to fall to between 20 and 25 percent across much of western north Texas and perhaps far southwest Oklahoma tomorrow afternoon. This may be somewhat mismatched with when the highest winds are expected (earlier in the day) thus limiting the fire weather concern. Still, 15 to 20 mph sustained 20 foot winds will lead to elevated to near critical fire weather conditions across this area. BRB && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 50 66 40 56 / 30 10 0 0 Hobart OK 45 66 38 56 / 20 10 0 0 Wichita Falls TX 52 70 45 64 / 30 10 0 0 Gage OK 37 63 32 51 / 10 0 0 0 Ponca City OK 48 64 36 54 / 40 10 0 0 Durant OK 59 70 46 65 / 80 40 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...None. TX...None. && $$
Area Forecast Discussion
National Weather Service Bismarck ND
1250 AM CST Mon Nov 28 2016 .UPDATE... Issued at 1250 AM CST Mon Nov 28 2016 Inherited forecast is mainly on track. I did increase winds Monday night into Tuesday. We start to see pressure rises develop west into central Monday night along with an increase in gradient forcing, which continues Tuesday. 1000-850mb geostrophic winds range from 50-60KTs as well during this time frame. UPDATE Issued at 933 PM CST Sun Nov 27 2016 No significant changes with this update. Based upon trends in the 12-00 UTC global suites and the high resolution iterations through 02 UTC, have increased the wording to isolated areas of 15 inches of storm total snowfall by Wednesday evening. This is in line with the WPC afternoon forecast. Through 0330 UTC precipitation per reports and webcams is transitioning from rain through sleet and now snow in Glen Ullin, New Salem and Bismarck. This is generally on time with the previous forecast thinking of change over. UPDATE Issued at 647 PM CST Sun Nov 27 2016 As of 0045 UTC...rain is the predominant precipitation type across south central North Dakota. Road temperatures are holding in the 34-36 degree range. Thus, at the time the freezing rain potential seems somewhat lower given the road temperatures expected take a few more hours at least to cool to freezing. However, by that time across the south central, the 22-23 UTC RAP and HRRR suggest precipitation is expected to begin its transition to mostly snow in the 04-06 UTC timeframe. A mix is favored through the night and and through much of Monday across the James River Valley. Given a slightly quicker onset of precipitation, did adjust the Winter Storm Warning start time to 01 UTC for south central North Dakota. && .SHORT TERM...(This evening through Monday Morning) Issued at 236 PM CST Sun Nov 27 2016 A major winter storm will impact western and central North Dakota beginning tonight. A negatively tilted upper level trough will swing into the Northern Plains tonight. This will induce rapid cyclogenesis over the central and northern plains with a 975-980MB surface low situated somewhere near the ND/SD/MN border by 6 AM Monday. Ahead of this, abundant moisture will stream into the eastern Dakotas, with strong forcing from the leading shortwave inducing precipitation over the James River Valley as early as this evening, but certainly by midnight tonight. As the system deepens and becomes stacked tonight, a well defined trowal develops, spreading precipitation westward into central and eventually western ND by Monday morning. Models continue to indicate a brief period of warmer temperatures aloft and the potential for freezing rain and sleet over portions of the James River Valley this evening. Temperatures will remain near the critical freezing threshold for much of the overnight and daytime hours of Monday across the James Vally. Eventually colder air will advect in and change the rain/freezing rain to all snow by Monday night. For these areas a Winter Weather Advisory has been issued to highlight the potential for freezing rain tonight and accumulating snow tomorrow through Wednesday. Due to the delay in switching over to snow, portions of Foster, Stutsman, LaMoure and Dickey Counties will see less snow than locations further west. .LONG TERM...(Monday through Saturday) Issued at 236 PM CST Sun Nov 27 2016 Deterministic and ensemble model guidance have come into pretty good agreement in the evolution of this storm. The deep low near the ND/SD/MN border Monday morning moves very little through Tuesday morning. The stacked system moves slowly east across Minnesota through Wednesday morning, and finally lifts into the Great Lakes region by Thursday. With such a deep and slow moving system there is the potential for significant snowfall across most of western and central ND Sunday night through Wednesday night. The brunt of the snowfall is expected from late Sunday night through Tuesday morning as the warm moist air continues to feed into western and central ND via the TROWAL. Winds with this strong system will increase over western ND on Monday and spread into central ND Monday night and Tuesday. At this time it looks the snow will be wet enough and winds will be low enough to keep Blizzard conditions from forming, but this could change if temperatures are little cooler and winds a little higher. Regardless winds around 30 mph will cause some blowing and drifting of snow, limiting visibility and making travel hazardous. Therefore, a Winter Storm Warning has been issued for all of western and most of central North Dakota. The heaviest snow is expected across central North Dakota where 6 to 12 inches could accumulate by Wednesday. The TROWAL begins to break down Tuesday evening, but synoptic forcing will remain sufficient to produce light snow through Wednesday night. Accumulations will become much lighter during this period, but winds will remain strong through Tuesday evening. There are still some uncertainties with this storm system. The biggest being snowfall accumulations, and the potential for blowing and drifting snow. Due to our very warm November, soil temperatures remain in the mid 30s to lower 40s. Road surface temperatures will also be warm during the beginning portions of this storm. A heavy wet snow is expected initially with a reduced threat of widespread blowing snow. This combination may initially limit the severity of impacts, but later as temperatures drop and surfaces freeze widespread travel impacts are expected. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 1250 AM CST Mon Nov 28 2016 A winter storm will impact all of western and central North Dakota through Wednesday. Significant hazards to aviation can be expected. Flight categories will fall to IFR-LIFR all terminals. && .BIS WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 6 PM CST /5 PM MST/ Wednesday for NDZ001>005-009>013-017>023-031>036-040>047-050. Winter Weather Advisory until 6 PM CST Wednesday for NDZ025-037- 048-051. && $$ UPDATE...NH SHORT TERM...AJ LONG TERM...AJ AVIATION...NH
Area Forecast Discussion
National Weather Service Lincoln IL
330 AM CST Mon Nov 28 2016 .SHORT TERM...(Today and tonight) ISSUED AT 328 AM CST Mon Nov 28 2016 A large and slow moving storm system will continue to impact central and southeast Illinois through the period and beyond. The deep 976 mb surface low is currently centered over eastern South Dakota and will move little over the next 24 hours. A tight pressure gradient to the east of this system is providing gusty southerly winds across the area, and these should persist through the period, with gusts to 40 mph possible at times. While showers are moving out of the forecast area early this morning, the break in the rainfall will be short lived. A second strong short wave will help produce another round of showers from midday today into this evening. The short wave that brought us rainfall late yesterday to now tracked west of the forecast area, while today`s wave is progged to track directly across the forecast area. This track is supportive of better dynamics locally, as well as steeper lapse rates. These factors favor including a mention of thunder with today`s rainfall. The track of the wave will also provide more of a gradient of QPF, with the eastern half of the forecast area receiving more significant rainfall totals than the west. Southeast Illinois is likely to see rainfall totals in excess of 1 inch before the rain ends later tonight. Much like in the past 24 hours, the next 24 hours will see relatively small diurnal temperature ranges due to the clouds and rainfall. Expect highs today in the lower 50s and lows tonight in the 40s, both of which are well above normal for late November. && .LONG TERM...(Tuesday through Sunday) ISSUED AT 328 AM CST Mon Nov 28 2016 The 00Z forecast models continue to show a fairly nice late fall day on Tuesday over central and southeast IL, as a partly to mostly sunny day unfolds. Breezy southerly winds bringing milder highs in the upper 50s and lower 60s. MET guidance even as warm as 65F at Jacksonville and Lawrenceville and if we get enough sunshine, that could be achievable. Large low pressure system over the upper MS river valley Tuesday will pivot a short wave trof and cold front eastward across IL Tuesday night. The 00Z NAM model continues to have some light qpf over areas along and north of a Rushville to Bloomington line, where SPC day2 again shows general risk of thunderstorms. Plume of steep mid level lapse rates will advect over central IL Tue evening and be over a somewhat unstable air mass with MUCAPES of several hundred J/kg. Have added slight chance of showers/thunderstorms to northern CWA Tue evening. Large upper level low/trof tracks east across the northern Great Lakes Wed and Wed night and into southern Quebec and northern New England on Thursday. This will bring more low clouds (especially north of I-70) and cooler temperatures. Brunt of light rain/snow showers, should mostly stay north of central IL, but get closest to far northern counties Wed afternoon and early Wed evening. Highs Wed range from mid 40s over IL river valley, to lower 50s in southeast IL. Highs Thu in the lower 40s, with Lawrenceville near 45F. About 2 degrees cooler on Friday with highs in the upper 30s from I-74 north and lower 40s south. Seasonably cool temperatures to continue Friday and this weekend with dry weather Friday and Saturday. Some big differences continue between the ECMWF and GFS model solutions on Sunday, with ECMWF showing large area of qpf lifting northward over IL while GFS model is dry and colder over IL. Made no changes to the blended model guidance due to lack of confidence in forecast that far out. Have slight chances of light rain/snow over southeast IL overnight Sat night and across most of area on Sunday. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 1147 PM CST Sun Nov 27 2016 Despite steady rains all evening, cloud heights remained VFR. A warm frontal boundary along the Illinois Missouri border is poised to lift northeast through our forecast area the rest of the night. Behind the front, ceilings drop to MVFR, as rainfall coverage decreases significantly. Have introduced an extended period of VCSH at all terminals starting at 07z for SPI and eventually reaching CMI around 10z. HRRR and RAP show spotty showers still possible during that time due to continued synoptic lift in the warm sector. However, a band of dry mid-level air should limit precip development until the next main push of moisture and forcing for precip Monday afternoon. Have continued a downward trend in ceilings and visibility with the onset of steady rains Monday afternoon, with IFR and possibly LIFR ceilings and visibility becoming widespread. Precipitation is projected to quickly come to an end from SW to NE Monday evening, as VFR conditions return. Strong south winds will continue through Monday afternoon, with 20G30kt common. Winds will shift to the southwest Monday evening with diminishing gusts somewhat, but we still expect sustained winds of 15-19kt. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Bak LONG TERM...07 AVIATION...Shimon
Area Forecast Discussion
National Weather Service Miami FL
448 AM EST Mon Nov 28 2016 .DISCUSSION... At 430 AM, doppler radar continued to show scattered light showers avecting slowly westward from the Atlantic waters towards portions of the east coast metro. However, little in the way of accumulation is expected with this activity. The latest HRRR and WRF model runs generate spotty light showers through the remainder of this morning and into the afternoon across the CWA. Have included a slight chance pops over nearly the whole CWA to account for this. Surface high pressure will continue to build across the western mid Atlantic waters today. This will help to maintain breezy east southeast winds, especially along the east coast metro, where gusts would reach around 15-20 mph. Temperatures this afternoon should remain mild with highs in the the upper 70s to around 80 degrees along the immediate east coast to lower 80s further the west. Tuesday through Wednesday, high pressure will maintain the east southeast flow. Dry weather should prevail during this timeframe, with the exception of a few brief light showers over the Atlantic waters and east coast metro. Expect a slight warming trend with maximum temperatures Wednesday and Thursday forecast to range from the low to mid 80s across the entire region, around 5 degrees warmer than normal for this time of year. Thursday into Friday, both the GFS and ECMWF push yet another cold frontal boundary southwards across the region. Ahead of this feature, low level moisture and instability appear sufficient enough to include a slight chance of scattered showers. Late this weekend, models diverge with the GFS maintaining zonal flow and the ECMWF developing a long wave trough and wetter pattern over south Florida. Will a keep a slight chance of pops in the forecast for Sunday, but confidence remains low. && .MARINE... Winds will shift to the east southeast today as high pressure builds to the north of the region. Small craft advisories are in effect for the Atlantic waters outside Biscayne Bay through this evening for winds 15 to 25 KT and seas 5-7 feet, highest in the Gulf Stream. && .AVIATION... VFR conditons through the TAF period. High pressure, currently to the north, will slide to the east for the next several days. This will cause the wind to turn more to the southeast on Monday. Also, the wind will increase to around 15kts, and may have gusts to around 25kts for a good part of the day. The wind is forecast to subside in the evening hours. In the easterly flow, some brief isolated showers may impact the TAF sites along the Atlantic coast. However, they should have little impact on flight conditions. && .BEACH FORECAST... There will be a high risk for rip currents through Tuesday morning along the east coast beaches, due to the increasing onshore flow. The risk may drop to moderate by midweek with weakening easterly winds. && .PRELIMINARY POINT TEMPS/POPS... West Palm Beach 81 72 83 74 / 20 20 10 10 Fort Lauderdale 80 73 81 75 / 20 20 10 10 Miami 81 72 83 73 / 20 20 10 10 Naples 83 66 85 68 / 10 10 10 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk through Tuesday morning for FLZ168-172-173. AM...Small Craft Advisory until 1 PM EST this afternoon for AMZ651- 671. Small Craft Advisory until 7 PM EST this evening for AMZ650-670. GM...None. && DISCUSSION...27/JT MARINE...27/JT AVIATION...13 BEACH FORECAST...27/JT
Area Forecast Discussion
National Weather Service Marquette MI
424 AM EST Mon Nov 28 2016 .SHORT TERM...(This evening through Monday) Issued at 356 PM EST SUN NOV 27 2016 WV imagery and RAP analysis indicated a mid/upper level trough over much of the wrn CONUS, from the Rockies into the wrn plains. A vigorous lead shortwave was lifting northeast into wrn IA. At the surface, se winds were increasing between a 989 mb low over sw Nebraska and a ridge from Quebec into the ern Great Lakes. With daytime warming, low level moisture trapped below a 1k-2k ft inversion has lifted to a low stratus deck over most of the cwa except over portions of the west where downslope se flow was strongest. The short range models were in good agreement with the progression/onset of the rain ahead of the IA shrtwv and surge of 295k-305k isentropic lift. Expect the rain developing from sw to ne between 06z-12z to taper off during the morning after the initial band moves through. Although the mid level moisture will depart during the day, continued low level isentropic lift will maintain some light rain or drizzle through most of the day, with lower amounts and coverage near Lake Superior where the strongest downslope wind prevails. Fog may thicken again tonight with the loss of sfc heating but with the rain moving in, should not be as dense into Monday as it was this morning. Temps will remain steady or slowly rise tonight and then climb just a few degrees to the lower to mid 40s Monday. .LONG TERM...(Tuesday through Sunday) Issued at 424 AM EST MON NOV 28 2016 Tuesday: The most significant issue Tuesday morning will be a reinforcing shot of energy that will slide north and eastward from northern Lower Michigan into southern Ontario. This wave of energy will drag an associated surface lobe of low pressure across the same area. The occluded front, stretching between the aforementioned feature and the vertically stacked low over MN, will slide from southwest to northeast, clearing the area between 15Z/29 18Z/29. The better forcing will be will be over the east half and Lake Superior before 15Z and then quickly slide out of the area with the aforemention features. At this point, not expect more than an additional 0.1 to 0.2 inches of additional rainfall over the east half and the Keweenaw through the morning hours. The deep layer moisture exits the area with the occluded front through the afternoon, which should make for a dry afternoon with some breaks in the clouds expected, especially across the south central and east. Highs will be well above normal over the east half with most locations expected to be in the upper 40s to around 50, while the west half stays mainly in the low to mid 40s. Tuesday night into Wednesday night: As the occluded front continues to slowly slide north and east, the area should continue to remain dry Tuesday night with increasing cloud cover once again ahead of the next system. The next shot of energy is progged to slide near the eastern U.P. late Tuesday night through Wednesday evening.Theadded deeper moisture along with increased forcing, will allow for another chance of showers moving through the area. Additionally, the aforementioned occluded low will begin to slide across the western U.P. by Wednesday afternoon, which will begin to introduce precip chances over the far west once again. By that time, cooler air will begin to move in aloft which may allow some snow to mix in with the rain at times over the far west late Wednesday afternoon into Wednesday night. Thursday through the extended: The closed low will slowly meander through the Upper Great Lakes region through Friday morning before sliding out of the area Friday night into the weekend. As this happens, colder air will begin to filter into the region, at the surface and aloft, allowing the rain to transition to snow. Currently it looks like the north to northwest wind favored snowbelts would be most likely to see the best chances for precipitation. It does look like temperatures overall will trend colder during this time period and 850mb temperatures are progged to cool to the -6C to -8C range. Models begin to differ beyond Friday afternoon, with the EC placing a ridge over the area while the GFS has a trough over the area Saturday into Sunday, before both aligning with a slight troughing pattern form Monday. At this point will stick with a consensus of the models for the late part of the extended. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 1235 AM EST MON NOV 28 2016 IFR/low-end MVFR conditions to prevail at KSAW and KCMX through the forecast with KSAW and KIWD experiencing some LIFR ceilings at times during the daylight hours, but especially once the sun sets Monday evening. Areas of rain continues to spread toward the region and will persist through Monday evening as a very moist SE flow continues. Winds to be gusty through the daylight hours with the highest gusts reaching near 28 knots at KCMX due to channelized flow there. Gusts to reach into the 20-25 knot range at KSAW and KIWD during the day before diminishing in the late afternoon. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 356 PM EST SUN NOV 27 2016 High pressure over the ern Great Lakes will shift to the east tonight as low pressure deepens across the northern plains into the upper midwest. This will result in a tight pressure gradient developing across the northern Great Lakes creating gales overnight. Gales to 40kt are expected across all of Lake Superior spreading west to east, but the gradient will slacken earliest across the far west. Further east the gradient will remain tight, with gales lingering through Mon night. The low pressure system will linger over the upper midwest Tuesday into Wednesday. However the pressure gradient is not expected to be as tight and allow winds to diminish below 25kt by Tuesday evening. Northerly winds to around 25 knots may develop Thursday as the slow moving low moves to the east of Lake Superior into Quebec. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Warning until 10 AM EST Tuesday for LSZ249>251-266-267. Gale Warning until 8 AM EST /7 AM CST/ this morning for LSZ162. Gale Warning until 4 AM EST Tuesday for LSZ243-244-264. Gale Warning until midnight EST /11 PM CST/ tonight for LSZ240>242-245>248-263-265. Lake Michigan... Gale Warning until 4 AM EST Tuesday for LMZ221-248-250. && $$ SHORT TERM...JLB LONG TERM...KEC AVIATION...RJT MARINE...JLB
Area Forecast Discussion
National Weather Service Pocatello ID
212 AM MST Mon Nov 28 2016 .SHORT TERM...Today through Tuesday night. The story the day for many will be snow and wind. The focus for snow continues to be across portions of the central mountains, eastern and southern highlands plus along the interstate corridor from Idaho Falls through Burley. The main band will swing through during the early to mid morning hours, with winds either staying pretty gusty or increasing along/behind it depending on location. While there may not be a lot of snow with this band, the wind and timing during the morning drive will make it a bit tricky in many locations. By late morning and afternoon, many areas will see a decrease in widespread snow and things becoming more showery. The EXCEPTION will be across the southern/southeastern highlands and along the interstate corridor from Idaho Falls to Coldwater. Snow will continue across those highlands areas especially where upslope is favored in northwest flow. The higher resolution models like the NAM and HRRR indicate a convergence band combined with upslope will keep some snow going across portions of the Snake Plain. The strongest winds still look to be from Pocatello westward and south into the south central highlands. Winds in these areas will peak between 25-35mph sustained with gusts of 40+mph. They will be higher off the valley floor south of the Snake River, with some places briefly exceeding 60mph based on the latest forecast. Headlines will remain in place although we may be able to adjust some timing during the day based on how things progress. Based on how much snow falls across the Magic Valley, blowing snow may not be an issue and the impacts end up being purely based on wind and not blowing snow. Snow amounts will generally be 1-2 inches for the Upper Snake Highlands and central mountains. For the Snake Plain, expect up to 2 inches along the travel corridor with locally higher amounts on the benches. For the southern and eastern highlands, look for 1-3 inches down low and 3-6 inches at mid and upper slopes. Locally higher amounts are possible. Tonight, some showers will continue especially across the southeast highlands. Through this evening, the models still point to lingering snow from around Blackfoot to Coldwater associated with the dying convergence band and upslope. Winds will die down but still remain a bit gusty coming across portions of the central mountains and the south central highlands. Conditions will dry out more on Tuesday ahead of the next storm. It will remain cold as we stay in northwest flow. Tuesday night, it looks like we could see some fog and light snow/flurries across portions of the Upper Snake Plain and Highlands. Keyes .LONG TERM...Wednesday through Monday. Models in much better agreement tonight. Upper ridge still expected to fold across the region Wednesday though weak upslope could keep precip going in northeast corner. Stronger shortwave drops through PacNW states into Idaho Wednesday night into Thursday with snow spreading across the region. Low appears to close off somewhere over Idaho Thursday though there are still minor differences in location. Low drops through four corners area Friday with next ridge folding over Idaho. Moist northwest flow sets up with Friday night through Sunday though models keep moisture spread through panhandle into MT. Have kept weak pops over northern zones and across eastern highlands. Stronger feature drops into Idaho Monday with ECMWF stronger than GFS and further south with precipitation. Opted for blend with increased precip chances most areas. DMH && .AVIATION...Precipitation gradually filling in across the region this morning though northwest flow aloft keeping most portions of Snake Plain dry so far. Expect cigs/vis to lower to MVFR as snow begins with occasional IFR in heaviest bands. Conditions improve to mainly scattered MVFR snow showers this afternoon. Winds remain strong through the day with Snake Plain terminals KPIH/KBYI sustained around 25kts. Depending on how much snow accumulates early, this could limit visibilities this afternoon in BLSN. Gradient turns north late today with winds decreasing during the evening. Isolated showers could continue overnight at terminals but overall conditions should improve to VFR with occasional MVFR. DMH && .PIH WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 6 PM MST this evening for IDZ017- 020>025. && $$
Area Forecast Discussion
National Weather Service Portland Oregon
903 PM PST Sun Nov 27 2016 .SYNOPSIS...A strong cold front moved onshore from the northwest into southwest Washington and northwest Oregon late this afternoon and evening and will move out of the forecast area overnight tonight. Gusty winds and fairly heavy rains with snow in the mountains accompany this strong cold front. Northwest onshore flow behind the front will spread plenty of showers through the area later tonight and on Monday, with heavy snow continuing in the Cascades. High pressure will bring a short break from the wet weather later Monday night and Tuesday, though some locally dense fog may form in the valleys. The next system is likely to bring more valley rain and mountain snow to the forecast area later Tuesday night and Wednesday. && .SHORT TERM...Tonight through Wednesday...After getting some snow in the Cascades Saturday night with 6-7 inches reported at Willamette Pass, another strong cold front was moving across southwest Washington and northwest Oregon this evening, being pushed along by a strong northwest jet up around 150 kt. The front began moving onshore near Astoria around 5-6 pm and near Newport around 715 pm. Winds have approached warning criteria at a couple of headland locations, with widespread 40 to 50 mph gusts elsewhere along the coast. We are also seeing some gusts to 35 mph in the Willamette Valley south of Portland. The front will be through the Portland area around or just after 8 pm, and past Eugene by around 9 pm. The front has some heavy rain with it as it moves through, which will translate to heavy snow in the Cascades, which combined with the wind will lead to areas of blowing and drifting of snow, translating to difficult travel conditions. Moist northwest onshore flow will spread in behind the front, with breezy conditions continuing, especially along the coast and in the higher terrain. This will lead to showers over the area that will continue through Monday and perhaps into early Monday evening, with heavy orographic snows continuing in the Cascades. The current Winter Storm Warning still seems reasonable with 1 to 2 foot accumulations, the passes on the lower end of the range. An upper ridge will bring drying to the forecast area going through Monday night and Tuesday, though the models suggest a few residual showers are possible Monday night and Tuesday. The building ridge could lead to some areas of fog later Monday night and Tuesday morning. The next decent front spreads more rain onto the coast Tuesday evening with valley rain and Cascade snow over the inland areas during the second half of Tuesday night. Plenty of showers will continue during the day Wednesday with snow continuing in the Cascades. Snow amounts could reach the 4 to 8 inch range Tuesday night and Wednesday, though a brief bump up in the snow level at the beginning of this event might lower those numbers a touch. Tolleson .LONG TERM...No Changes. Previous discussion follows... Wednesday night through Sunday...Shower chances - in the form of valley rain and Cascade snow, with snow levels remaining around 3,000 feet - continue Wednesday night through early Thursday. Heights then begin to rise later Thursday as an upper ridge builds into the Pacific NW. Some model differences remain for late Thursday and early Friday with both the position of the ridge and the strength of a system riding over the top of the ridge, but regardless, generally drier conditions can be expected in between systems. Maintained slight chance PoPs for the northern and northwestern portions of the forecast area through this time. Flow aloft begins to become zonal by early in the weekend as the next disturbance approaches the area, but still some uncertainty as to where this will track across the region. Expect showers to then persist through Sunday, when a stronger front will push into the Pacific NW by late in the day, bringing sharply lowering snow levels and another round of more significant and widespread precipitation. && .AVIATION...Cold front will likely have worked across the taf terminals by the time 06z arrives. Cigs around 015 only lasting a short time behind the front with a fairly rapid improvement to VFR thereafter. A showery pattern will continue into Mon, but expect conditions will remain VFR during most of this time. Strong westerly flow into the Cascades will bring heavier showers and keep the mountains mostly obscured through Mon. KPDX AND APPROACHES...VFR cigs will return shortly as the trailing edge of the cold frontal rains move east. Showers under westerly flow will likely prevail for the period. JBonk/Pyle && .MARINE...Cold front crossed earlier this evening bringing a solid period of gales. Trailing northwesterly winds are somewhat disappointing at 20-25kt with gusts around 30 kt. Was tempted to drop the gale warning but winds at buoy 36 have stayed around 30 kt with frequent gusts around 40 kt. Additionally, the HRRR and other convective allowing short term models allude convective gusts will also remain around 40 kt for at least the next several hours. So, will leave the gale warning in place as planned for the time being. Winds remain breezy early Mon, but will gradually subside through the day. Weak high pres will build over the waters later Mon and Tue, bringing winds below 15 kt. Another front will move through the waters Tue night. The fcst models suggest solid or high end small craft advisory winds are likely with this front, with an outside chance at gales. Weak high pres will bring more benign conditions for the second half of the week. Seas continue to run around 12-14 feet and didn`t see an appreciable increase with the frontal passage. Have seen plenty of indications seas will build as the dynamic fetch from a strong low in the northern Gulf of Alaska sends a large swell train towards our waters on a parallel track to the BC coast. Seas will gradually build through the day. Buoy 46004, well offshore the southern tip of Haida Gwaii, saw seas peak at 32 feet/14 seconds earlier this evening. The standard wave decay model would bring seas near 22 feet/16 seconds to the area Monday evening. This is a couple feet above the 18z WW3 guidance. Have increase our NW swell by a couple feet covering Monday afternoon with a gradual decay through Tuesday afternoon. Would expect little overall impact on the High Surf Advisory. /JBonk && .PQR WATCHES/WARNINGS/ADVISORIES... OR...High Surf Advisory from noon Monday to 1 AM PST Tuesday for Central Oregon Coast-North Oregon Coast. Winter Storm Warning until 6 PM PST Monday for Cascades in Lane County-Northern Oregon Cascades. WA...High Surf Advisory from noon Monday to 1 AM PST Tuesday for South Washington Coast. Winter Storm Warning until 6 PM PST Monday for South Washington Cascades. PZ...Gale Warning until 7 AM PST Monday for Coastal Waters from Cape Shoalwater WA to Florence OR out 60 nm. Small Craft Advisory for Rough Columbia River Bar until 10 AM PST Tuesday. && $$ Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland This discussion is for Northwest Oregon and Southwest Washington from the Cascade crest to 60 nautical miles offshore. The area is commonly referred to as the forecast area.
Area Forecast Discussion...Corrected
National Weather Service Tampa Bay Ruskin FL
301 AM EST Mon Nov 28 2016 .SYNOPSIS... 08Z water vapor and H4 RAP analysis showing a complex upper level pattern over North America early this morning. Simplifying the longwave pattern shows strong jet energy arriving over the Oregon/northern California coast into the backside/base of troughing covering the inter-mountain west and mid-section of the country. Southern stream energy is also lifting across northern Mexico into the base of this trough and then advancing into the TN valley over-top weak longwave ridging that is providing generally fair and warm conditions to the Florida peninsula. This ridge will be the dominant force in our weather for the next 24-48 hours. At the surface...1020+mb ridge centered over the mid-atlantic states will shift eastward today and tonight over the Atlantic as a cold front shift eastward from the central plains states toward the Appalachians. Our local winds will veer from east to southeast and eventually south by later tonight in response to these mass-field changes. Conditions are benign and seasonable across the region early this morning...with temperatures generally in the 50s to lower 60s. A few normally cooler spots north of the I-4 corridor may briefly dip into the upper 40s by dawn...but readings this low will not be widespread. && .SHORT TERM (Today through Tuesday)... Upper ridging holds position over the FL peninsula today. Weak large scale subsidence under the ridge above 700mb keeps the majority of the troposphere dry. Below 700mb...things are a bit more complex. Veering low level winds to the southeast will introduce a swath of WAA and weak isentropic upglide along the 295-305K surfaces beginning this morning and lingering into the afternoon hours. While shallow...RUC/NAM/GFS all show a gradual southeast to northwest moistening of the lowest 10KFT of the trop due to this upglide. So...would at the very least anticipate the development of a BKN cu/statocu deck as we advance into the late morning and especially afternoon hours. Would also anticipate some sct sprinkles to be around this afternoon...moving quickly south to north. Once again...the moisture is relatively shallow...and so sprinkles/light showers are all we are going to see. However...it is worth mentioning that a few raindrops can not be ruled out. Would say..most spots do not even measure...but a few hundredths would not surprise me in spots either. Have a swath of low 20-30% Pops with very low QPF this afternoon to account for this potential. Otherwise...partly to mostly cloudy skies by this afternoon with highs in the mid/upper 70s north and around 80 central and southern zones. Few sprinkles fade away this evening as the overall WAA/upglide shifts northward and we loose diurnal heating. The overnight forecast will feature partly cloudy skies...a light southeast to south breeze...and warm temperatures for the the end of November. Most spots tonight are unlikely to drop out of the 60s. SREF and statistical guidance suggesting some fog potential late at night...most likely in response to the boundary layer moisture and ridging aloft. However...gradient may stay just tight enough to keep boundary layer at least partially mixed and prevent significant areas of fog. Will add patchy fog to the grids after 06Z tonight...but allow day shift time to re-evaluate before going to aggressive on the low visibility. Tuesday shaping up to be a rather warm and seasonably humid day. Warm low levels (14-15C at 850mb) and decent gradient to support diurnal mixing should allow temps to easily reach the lower 80s for a large portion of the region. Some spots reaching the middle 80s certainly possible from the I-4 corridor southward if we can get sufficient insolation. Southerly flow may even shift southwest at the coast for a time in response to the strong terrestrial heating. This onshore component off the relatively "cooler" shelf waters of the eastern Gulf should limit the diurnal heating at the immediate coast...and hold beach temps in the 70s. The WAA/upglide component we have today is not forecast to be repeated tomorrow...and will keep all shower/sprinkle mention out of the forecast for this cycle. && .LONG TERM (Wednesday through next Monday)... A highly amplified pattern continues over the CONUS. A strong upper level low sits over the Midwestern states with a positively tilted trough extending southwest through New Mexico. This is supporting a major storm system moving through the Great Lakes region and the eastern half of the U.S. Upper level ridging extends northeast over the western Atlantic from an upper high located over Cuba. This ridge will prevent any significant movement of the upper trough through mid week. The trough will slowly progress eastward on Thursday as the ridging weakens and moves east of the Bahamas. By the end of the week and into next weekend, a more zonal pattern sets up over the southeast U.S. On the surface, the high pressure that had been sitting over the eastern U.S. has slipped eastward and it now located near Bermuda. This will keep dry conditions and a southeast wind flow over the area through mid week. Over the central U.S., the upper parent low pressure system is located over Minnesota with another low pressure center developing over Lake Superior. The associated frontal boundary extends south along the Appalachian Mountain chain. The low will be located over Nova Scotia by Wednesday morning with the front extending along the eastern seaboard. Another low pressure system develops over Mississippi and extends a cold front into the Gulf of Mexico. This is the system that will give us our highest rain chances through the period. This system moves rapidly to the northeast and will trail a cold front across the area beginning late Wednesday. The front will push completely south of the area by early Friday morning. In the wake of this front, cooler and drier air will filter into the area through next weekend as high pressure builds to the north. By late Sunday next week, models are hinting at another low developing along the northern Gulf and moving eastward. As for weather during the period, dry conditions can be expected through mid week. The frontal boundary moving through the area late Wednesday into Thursday will bring us our highest chances of rain in the period with 40-50 POPs over the northern coastal waters/Nature Coast and 20-30 POPs from Tampa Bay southward. The front exits the area by early Friday morning with clearing conditions expected through the weekend. Late Sunday into Monday, the developing low over the northern Gulf will bring us a second round of rainfall with 30-40 POPs region wide. Daytime highs will be at or above normal through Thursday, then dropping down 3-5 degrees below normal on Friday and Saturday, then warming back up once again to average on Sunday and into early next week. && .AVIATION (28/09 through 29/06Z)... No significant aviation concerns expected across west-central and southwest Florida through the TAF period. Potential for brief MVFR patchy fog toward dawn at KLAL/KPGD...otherwise VFR prevailing through Monday with a sct-bkn cumulus field (bases at or above 4KFT). Widely sct light and brief showers/sprinkles possible after 18Z...but no associated restrictions. light east winds becoming moderate southeast (9-12kts...gusts 15-18kts) by late morning. && .MARINE... High pressure over the eastern states shifts into the Atlantic through Tuesday as a cold front advances eastward through the Appalachians. In response...winds over the eastern Gulf of Mexico will shift from east to southeast and then south through Tuesday. Periods of cautionary level winds between 15 and 20 knots can be expected away from the coast through tonight. Another period of cautionary winds is forecast for Tuesday night into Wednesday away from the coast. && .FIRE WEATHER... No significant fire weather concerns expected through the middle of the week across west-central and southwest Florida. Low level moisture will be on a steady increase into Tuesday...preventing any areas of critical low relative humidity. Wind profiles will support elevated dispersion indices Today and Tuesday. Widely scattered sprinkles/light showers are expected across the region this afternoon...however the potential for a wetting rainfall is low for most areas. && .Preliminary Point Temps/PoPs... TPA 79 66 81 69 / 30 20 0 10 FMY 81 65 83 67 / 30 20 10 10 GIF 79 63 83 66 / 30 20 10 10 SRQ 79 66 78 67 / 20 10 10 10 BKV 80 63 82 63 / 30 20 0 10 SPG 77 66 79 68 / 20 10 0 10 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...Beach Hazards Statement through this evening for Coastal Sarasota. Gulf waters...None. && $$ SYNOPSIS/SHORT TERM/AVIATION/MARINE/FIRE WX..Mroczka MID TERM/LONG TERM/DECISION SUPPORT...Wynn
Area Forecast Discussion
National Weather Service Albany NY
547 PM EST Mon Nov 28 2016 .SYNOPSIS... An active period of weather for the region as a couple of storms are set to impact the region. While most of the precipitation will fall as rain, a period of wintry type weather is possible across the Adirondack Region and Southern Vermont overnight into early Tuesday morning. In the wake of these storm systems, brisk and cooler weather is expected for the end of this week. && .NEAR TERM /THROUGH TUESDAY/... As of 545 PM EST...Skies remain mainly clear across the eastern half of the forecast area with high clouds starting to stream in across western areas. Temperatures have fallen quickly early this evening with the lack of cloud cover and should continue to fall quickly for the next few hours before leveling off. A deep cyclone over the center of the nation remains quasi- stationary with an impressive plume of moisture racing from Baja California into the mid and lower Mississippi River Valley. The low level jet increases quickly toward sunrise close to 50kts with strong isentropic lift and impressive omega signatures. Question is just how low temperatures will get before the cloud coverage arrives and temperatures slowly moderate as the precipitation arrives. At this time, low level ageostrophic flow per the latest RAP remains and increases in magnitudes from the northeast. This would place portions of the Adirondacks, Lake George Region and southern Vermont (mainly eastern Windham County) under the threat of keeping the low level sub-freezing temperatures in place for a period of time as strong warm advection is underway. Per collaboration with other WFOS, we will withhold any headlines as the period of wintry type precipitation should be less than 3 hours which we can issue a SPS. Otherwise, clouds increase and PoPs increase from southwest to northeast well after midnight with overnight lows mainly into the 30s with 20s to the north of I90. Those temperatures slowly rise after 09z toward sunrise as strength of low level warm advection increases. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... Impressive low level jet along with warm/moist advection will be across the region through most of the day. So a rainy and breezy day (mainly across the terrain) setting up across the region. As is the case in these low level jet warm advection regimes, its difficult to mix down the higher momentum air aloft. A possible exception would be portions of the Taconics, Berkshires and Catskills. Winds may back just enough to result in a bit more magnitudes for these areas as we will continue to watch if those backing of the winds materializes. South to southeast winds of 10 to 20 mph with some gusts in the 30-40 mph are possible. The 12Z GEFS remains with southerly wind anomalies /+v-component/ of 1 to 3 standard deviations above normal with PWAT anomalies a couple standard deviations above normal in the late morning into the early pm. In addition, did include the slight chance mention of thunder along the I84 corridor which is in coordination from SPC and OKX. The showalter values drop close to +1C and per lightning activity upstream, showalter values of +2C and lower is where lightning activity was most prevalent. Highs Tuesday climb mainly into the 40s with some lower 50s south of the Capital District. Tuesday Night...A lull in the action is expected as a micro- ridge or bubble-sfc high, but it will be short-lived as another short-wave will be ejecting along the E/SE flank of the H500 positively tilted long-wave trough from the Southeast and TN Valley. As a few breaks in the clouds are expected and very moist low levels, fog could be an issue as we will add patchy fog to the forecast/grids. The clouds will thicken again overnight from the south and west towards sunrise. Lows will be on the mild side with mid 30s to mid 40s. Wed-Wed night....More rain on the way. Deep transport of moisture from the Gulf of Mexico, as low pressure approaches from the Ohio Valley during the morning. Strong/Impressive isentropic lift increases ahead of the cyclone and warm front again. PWATS surge back to 2-3 standard deviations above normal. In the area of upper level diffluence aloft, expect periods of moderate to heavy rain to overspread the region by the afternoon into the evening period, especially along the enhanced FGEN band expected to lift northward across the region. Likely to categorical pops were used again through Wednesday into the early evening hours. An additional two-thirds to around 1.25 inches of rainfall is expected and well coordinated. These rain amounts should help out the drought conditions across the region (see hydro section for additional details). Above normal temps are likely in the mild air mass with mid 40s to mid 50s again...and lows mid and upper 40s south and east of the Capital Region...and mid 30s to lower 40s from Capital District north and west. Triple point per the NCEP model suite and ECMWF is expected to move across the mid-Hudson Valley into northwest CT Wednesday evening. There could be another brief period of thunder potential for the southern portions of the region which we may add in future forecast updates. Precipitation should taper back from southwest to northeast as dry slot advances quickly into the region. Once again, southeast low level jet may enhance wind gusts into the Catskills, Taconics and Berkshires and southern Greens early Wednesday evening. && .LONG TERM /THURSDAY THROUGH MONDAY/... The long term period starts out with a departing surface low off the New England coast. A second low over eastern Canada will be responsible for some wrap around moisture across the northern mountains on Thursday along with some lake enhanced pcpn downwind of Lake Ontario. The remainder of the forecast area should be dry. Highs on Thursday will be in the Upper 30s to lower 50s. Thursday night through Friday night...Another weak clipper system moves across southern Canada bringing more light pcpn to the region with some lake enhanced pcpn continuing downwind of Lake Ontario through Friday. Lows Thursday night are expected to range from the upper 20s to mid 30s with highs on Friday in the mid 30s to upper 40s and lows Friday night in the mid 20s to lower 30s. Saturday through Sunday...A mainly dry forecast is expected as high pressure ridges into the region. There still may be a little lake effect activity into northern Herkimer county but that should be the extent of it. Highs on Saturday and Sunday will be in the upper 20s to mid 40s with lows Saturday night mainly in the 20s. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... VFR conditions with sct high level cirrus clouds expected through the afternoon as high pressure moves eastward across the region. Clouds will thicken overnight and ceilings will gradually lower after midnight. Expect VFR conditions to persist until around 12Z Tomorrow, with light rain beginning between 09Z-12Z. Light to moderate rain during the morning combined with a moist southeast flow off the Atlantic Ocean should allow for MVFR/IFR ceilings and visibilities by late morning. Surface winds will be variable around 5 kt or less through 12Z tomorrow before increasing from the southeast to 5 to 10 kts with gusts to 20kts later in the morning. Outlook... Tuesday Night: Low Operational Impact. Slight Chance of SHRA...FG. Wednesday: High Operational Impact. Likely RA. Wednesday Night: High Operational Impact. Breezy Definite SHRA...RA. Thursday: Slight Chance of SHRA. Thursday Night: No Operational Impact. NO SIG WX. Friday: Low Operational Impact. Slight Chance of SHRA. Friday Night: No Operational Impact. NO SIG WX. Saturday: No Operational Impact. NO SIG WX. && .FIRE WEATHER... Wet conditions will prevail through the middle of the week. && .HYDROLOGY... No widespread hydro problems are expected the next 5-7 days ending Friday. Diurnal snow melt will continue over the higher terrain through the mid week period. A widespread rainfall along with milder temperatures are expected Tuesday into Thursday with a series of disturbances impacting the region. The first round of rainfall with a brief light mix of sleet snow and ice north of the Mohawk Valley and Capital Region occurs Tuesday morning, then all rain by late morning. Rainfall amounts of a third of an inch to three quarters of an inch are expected with up to one inch south of Albany. The second round of rain comes late Wednesday morning into Thursday. Total rainfall may be three quarters of an inch to an inch and a quarter. The runoff from the rainfall combined with some higher elevation snowmelt may cause some elevated flows, but a widespread flood potential is not expected at this time. It has been quite dry in past months but vegetation and trees are not soaking up water this time of year. MMEFS and latest NERFC outlooks suggests no problems at this time but some areas just west of our area are showing the potential to perhaps get solidly into action stage (mainly southern tier of NY). Overall, the rain should help the drought conditions across the ALY HSA. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...BGM NEAR TERM...BGM/11 SHORT TERM...BGM LONG TERM...JPV AVIATION...SND FIRE WEATHER...BGM/Wasula HYDROLOGY...BGM/Wasula
Area Forecast Discussion
National Weather Service Binghamton NY
557 PM EST Mon Nov 28 2016 .SYNOPSIS... A storm system will spread rain showers and mild temperatures into NY and PA late tonight and Tuesday. A second storm system will ride up the east coast on Wednesday, bringing another round of rain. && .NEAR TERM /THROUGH TUESDAY/... 555 PM Update... The timing of rain tonight looks good and so do our minimum temps. The latest RUC has the 850 MB 0C line up across northeast, well removed from our area. Despite some cooling in the mid levels thanks to evaporational cooling, strong warm air advection tonight will be enough to keep the precip all in the liquid form. We only had a few tenths of snow in the far east but that is the only minor change I made, removing it from our forecast. The previous AFD is below. 210 PM update... A large storm system spinning over Minnesota and Wisconsin will pull moisture into NY and PA this evening. The model trend continues to point toward slower solutions, and our current forecast does not bring precipitation into our far western counties until after 2z. The slower solution also means the low stratus won`t reach our FA until late, so minimums will be a tad lower than previously forecast. Temperatures are forecast to rise after 6z. With slightly cooler temperatures entrenched over the east, it is possible the front edge of the precipitation will contain a wet snow-rain mix, especially east of I-81. No more than a tenth of an inch of snow accumulation is anticipated. Precipitation will exit the I-81 corridor during the late-morning or early-afternoon hours. Temperatures will max out in the lower or middle 50s Tuesday. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... Main concerns in the short term remain focused around the potential for fog Tue night and Wed morning...the next batch of rain expected during the day Wednesday...and lingering light rain showers Wed night through the day Thursday. Exiting system to the east will leave in its wake a weak area of high pressure along with a brief period of ridging aloft to help keep conditions relatively dry Tue night and Wed morning. The potential for rain will be low during this time, but the threat for fog will increase under this largely suppressed and nearly saturated air mass. With the recent rain Tuesday over much of the area and waa aloft, conditions will be favorable for patchy fog through early Wednesday. The ridge will be amplifying in response to a deepening trough of low pressure cutting through the Great Lakes. There will also be another robust supply of deep layer moisture advecting nwd along the east coast ahead of this system, which will supply the necessary ingredients for widespread rain, with locally heavy rain possible from the Poconos into the srn Catskills. Large-scale dynamics combined with a relatively strong baroclinic zone along the trailing cold front will provide the lift needed to produce rain across the region. PWATs close to 1 inch in ne PA will increase the potential for around 1-2 inches of rain in this area. Locations further to the west and north will likely see around 0.5 to 1 inch through Wed night. Upper low to the north will remain nearly stationary, or slow moving, from srn Ontario into Quebec on Thursday. This upper level support combined with weak caa in the mid levels, the potential for scattered rain showers will exist through the day. Morning low temperatures Wed will bottom out in the mid 40s. Afternoon highs on Wed will rise comfortably into the mid and upper 50s. Low 40s expected again Wed night, with not much warming during the day Thur...only into the mid and upper 40s. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... The extended period will remain quite active Thur night through the weekend with high pressure over the deep south and a series of upper waves tracking ewd through the Great Lakes into the NE under a cool air mass regime. These waves will interact weakly with Lake Ontario to produce periodic daytime/lower elevation rain showers, and high elevation rain and/or snow showers. The showers will likely become all snow by late Saturday and Sunday as the colder air mass arrives. Lows Thursday night will fall into the lower/mid 30s, and rise into the upper 30s and lower 40s Friday afternoon. A bit colder Friday night into the upper 20s/lower 30s. Temps will remain fairly steady into the weekend with highs in the upper 30s and lows in the upper 20s. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... After a quiet early Monday evening, rain will spread into the terminals late overnight, with MVFR restrictions developing toward morning across much of the region. IFR ceilings are likely to develop at KBGM before sunrise, with the possibility for isolated IFR conditions at KAVP and KITH. OUTLOOK... Tuesday night-Thursday...Restrictions expected from periods of rain. Friday...Restrictions possible in rain/snow showers. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...None. NY...None. && $$ SYNOPSIS...DJP NEAR TERM...DJP/Heden SHORT TERM...BJT LONG TERM...BJT AVIATION...DJP
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
311 PM EST Mon Nov 28 2016 .DISCUSSION... Lead batch of showers with initial moisture surge this morning shriveled up and dissipated, as there was a lot of dry air in the low levels to overcome, as 12z dtx sounding checked in with a 44 C dew pt depression at 850 mb. Plenty of moisture over the Western Ohio Valley however, as ILX sounding indicated a 7 C dew pt at 850 mb. Should be no problem to generate widespread showers this evening/tonight as upper wave/cold pool (-26 C at 500 mb) ejecting out of the southern Plains will slide into Southern Lower Michigan by morning. Excellent dynamics/negatively tilted trough axis, coupled with modest instability (sfc-850 MB going slightly negative) supports isolated mention of thunderstorms, as thunderstorms have also been reported upstream over Illinois, although the steep level lapse rate (8 C/KM) arrive toward 12z, and that is associated with the mid level dry slot, and it is likely precipitation activity will have ended by then. Ridiculously strong low level wind shear, as 0-1 KM bulk shear of 50+ knots lifts through overnight, drawing concern for damaging winds and and even non-zero tornado threat (see 17z HRRR STP fields 3-7 AM), but near surface environment likely too stable to allow this to happen, along with the overall limited cape/instability. Good drying/subsidence to take place tomorrow with PW values slipping back below half an inch, although low level moisture (2-3 kft)/clouds will likely take some time to scour out, which could impact maxes slightly, otherwise 925 mb temps around 10 C (per 12z nam) suggests maxes approaching 60 degrees. Weak wave/850-700 mb Theta-E to lift through Tuesday evening, and mid level lapse rates appear steep enough to possibility generate a few high based showers. Despite the near zero showalter index progged, left mention of thunder out, as soundings still indicated a lot of dry air down low and significant cap. Massive Upper Level Low/Trough centered over Red River Valley will slowly wobble off to the East-Southeast, translating through Great Lakes Region during Wednesday-Thursday Time Frame. Upper level PV train/trough axis over Four Corners region tomorrow, tracking through Ohio Valley on Wednesday, with cyclogensis taking place over Eastern Ohio Valley, into the Eastern Great Lakes by Wednesday Evening. Looks reasonable shot of rain shield clipping southeast Michigan in this time frame, per 12z Euro. The beginning of December will start off with longwave troughing over the region through the end of the week before ridging builds back in. Periods of showers will still be possible as the low pressure system continues to push off towards the New England area. Drier conditions come back for the the majority of the weekend before more unsettled weather moves back in by the end of the weekend. Temperatures will remain consistent through the extended period with highs hovering around 40 degrees and lows around 30 degrees. && .MARINE... Southeast winds will continue to increase into tonight as a warm front approaches from the south. This will lead to a period of gale force winds throughout the Lake Huron basin, as well as the Michigan waters of Lake Erie. Peak gusts during the overnight period will climb to between 40 to 45 knots across northern and central sections of Lake Huron. The long southeast fetch will also support extensive wave growth, with waves potential peaking near 20 feet. Small Craft Advisories will transition to Gale Warnings this evening. Winds and waves are projected to improve Tuesday night into Wednesday as direction shifts to the southwest and milder air and more stable conditions overspread the region. && .HYDROLOGY... Rain will overspread the area late this afternoon and continue into tonight as abundant gulf moisture lifts north into area in advance of approaching warm front. This rain will come to an end early Tuesday morning as the warm front progresses north of the region. Total rainfall amounts of one half to three quarters of an inch are expected across the region during this time frame. While this is an above normal amount of rainfall for this time of year, flooding is not anticipated. && .PREV DISCUSSION... Issued at 1250 PM EST Mon Nov 28 2016 AVIATION... Light rain will already be overspreading area by 18z-19z with rain increasing in coverage/intensity into the 00z-06z time frame before tapering off 06z-09z. Ceilings will lower through MVFR to IFR during peak intensity of event. Visibilities will drop as well and at least sporadically reach IFR this evening. SE flow will persist in advance of warm front into tonight with 50-60 knot southerly low level jet producing LLWS. Surface flow will then veer to SSW with passage of warm front 08z-10z with ceilings gradually lifting thereafter as rain shifts north of the area. For DTW...Ceilings will fall below 5000 feet this afternoon as rain overspreads the terminal with MVFR ceilings to follow by late this afternoon. Still anticipate IFR conditions this evening into the overnight as widespread rain lifts through area north of encroaching warm front. Conditions then improve late tonight into Tuesday with the passage of this front. //DTW Threshold Probabilities... * High for ceilings AOB 5000 feet into Tuesday morning. * Low for thunderstorms affecting terminal this evening (00-06z) && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...Gale Warning from 7 PM this evening to 4 PM EST Tuesday FOR LHZ363- 421-422-441-462. Gale Warning from 7 PM this evening to 10 AM EST Tuesday FOR LHZ361- 362-442-443-463-464. Small Craft Advisory until 7 PM EST this evening FOR LHZ421-441>443. Lake St Clair...Small Craft Advisory from 7 PM this evening to 10 AM EST Tuesday FOR LCZ460. Michigan waters of Lake Erie...Gale Warning from 7 PM this evening to 7 AM EST Tuesday FOR LEZ444. && $$ DISCUSSION...SF/SS MARINE.......DG HYDROLOGY....DG AVIATION.....DG You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Northern Indiana
358 PM EST Mon Nov 28 2016 .SYNOPSIS... Issued at 357 PM EST Mon Nov 28 2016 Widespread rain will persist into the overnight hours. While breezy conditions will prevail tonight, an isolated stronger shower or thunderstorm on the back edge of the area of rain may produce wind gusts to 50 mph. Rainfall amounts of one half to one inch are expected, causing ponding of water as well as minor river rises in some areas. Highs temperatures for the day will occur into this evening as rising temperatures are expected. Steady temperatures overnight will climb further on Tuesday with highs well into the 50s to near 60. More seasonable temperatures will return for the second half of the week. && .SHORT TERM...(This Evening through Tuesday) Issued at 357 PM EST Mon Nov 28 2016 Deep low pressure over SE North Dakota was making its impacts felt as far east as the Great Lakes where surge of anomalously moist air was heading north into the region. Expect widespread rain to take over the forecast area into this evening with average rainfall amounts of 0.75 to nearly 1 inch. While this will cause some local ponding as well as minor river rises, somewhat larger concern looms in the 23Z to 05Z window as dry slot rapidly works northeast into the area. HRRR has been steadfast in developing a narrow line of strong showers/isolated storms on the back edge of the rain. 0-1 km shear values in excess of 50 kts and 0-1 km helicity values in excess of 500 m2/s2 would suggest a non zero risk for isolated tornadoes. However, low level inversion/stability may hold just enough to keep the threat at bay. Strong wind fields aloft may be mixed down to bring several reports of 40 to 50 mph winds with the line. A lot of uncertainty with regards to the evolution and amount of inhibition at the surface warrants adding thunder mention and patching up HWO to reflect brief wind threat. Trends will be monitored into the evening. Otherwise...occluded front will quickly push through and bring any rain to an end by Tuesday morning. Rising temperatures this evening will steady out overnight and then climb further on Tuesday with highs into the middle 50s to around 60, depending on amount of sunshine. && .LONG TERM...(Tuesday Night through Monday) Issued at 357 PM EST Mon Nov 28 2016 Deep upper low will slowly drift east into Wednesday night, forcing a cold front and a series of upper level disturbances through the area. This and bringing an end to the above normal temperatures expected into Wednesday. Not much moisture to work with so precip chances will be limited but still worth a mention. Upper low will center SE of James Bay and continue to send several additional waves through the region into the weekend with difficult to time chances for rain and/or snow. No major systems expected at this point so only slight chc to chc pops warranted, mainly in the north. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon) Issued at 1217 PM EST Mon Nov 28 2016 Secondary surge of moisture to likely bring IFR met conditions especially due to ceilings later this afternoon/evening. Timing of dry slot after daybreak Tuesday to bring return to VFR conditions for much of day/later part of forecast. Mention of low level wind shear as low level jet surges into northeast Indiana after 00 UTC. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...Gale Warning until 4 AM EST Tuesday for LMZ043-046. && $$ SYNOPSIS...Fisher SHORT TERM...Fisher LONG TERM...Fisher AVIATION...Murphy Visit us at www.weather.gov/iwx Follow us on Facebook...Twitter...and YouTube at: www.facebook.com/NWSNorthernIndiana www.twitter.com/nwsiwx www.youtube.com/NWSNorthernIndiana
Area Forecast Discussion
National Weather Service Saint Louis MO
322 PM CST Mon Nov 28 2016 .SHORT TERM... (Through Late Tuesday Afternoon) Issued at 322 PM CST Mon Nov 28 2016 Rainfall over the eastern 1/3 of the CWFA will be ending from west to east this evening as the "cold" front passes and drier air filters into the area. Clouds are likewise clearing from west to east, but are not moving out quite as fast as expected. Latest satellite pics show the clearing line probably getting from central Missouri to the St. Louis Metro area by 03-04Z...and then east to our CWFA border by 07-08Z. The RAP seems to have a decent handle on the clearing...so have used it as the basis for my cloud forecast tonight. South to southwest flow tonight into Tuesday isn`t exactly a cold wind...so only expecting lows in the 40s tonight. Additionally there should be a decent amount of insolation on Tuesday to go along with the southerly flow. MOS looks reasonable with highs well above normal again in the upper 50s to mid 60s. Carney .LONG TERM... (Tuesday Night through Next Monday) Issued at 322 PM CST Mon Nov 28 2016 (Wednesday through Friday) Still expect Wednesday through Saturday to be mainly dry. Both the GFS and ECMWF are in good agreement that the upper low that will be over the Upper Midwest on Wednesday morning will lift northeastward through the Great Lakes and not bring any precipitation to the area. In the meantime, zonal upper flow will setup at least through Friday before the ECWMF and GFS begin showing diverging solutions to the forecast over the weekend. With polar cold front staying well south of the area during the period and 850mb temperature staying around -5C, GEFS mean temps support temperatures staying around normal values. (Saturday through next Monday) There continues to be great uncertainty with the forecast over the weekend into early next week as the the ECMWF and the GFS are showing different solutions. The GFS/GFS ensemble has shown more continuity with bringing a northern stream trough across the area Saturday night and Sunday which would bring some light rain/snow to the area. The ECMWF on the other hand has not shown as much run to run consistency, with it bringing out a larger, colder system over the weekend that would have the potential to produce more snow. Given the consistency of the GFS, will lean more toward it`s solution at this point. Temperatures will continue to be close to normal during the period. Britt && .AVIATION... (For the 18z TAFs through 18z Tuesday Afternoon) Issued at 1145 AM CST Mon Nov 28 2016 A broad area of rain with MVFR and IFR conditions is affecting much of southeast and east central Missouri as well as southwest and south central Illinois. A few showers are also moving over parts of north central and northeast Missouri. The lowest ceilings and visibilities will likely continue to be associated with the main area of rain this afternoon. Should see this rain move slowly east...clearing eastern sections of the area out by KSLO by 00-01Z. Expect the MVFR deck to clear as well from west to east through the afternoon and evening hours. VFR conditions with south-southwest flow will prevail after the low clouds clear out. SPECIFICS FOR KSTL: Area of rain with primarily MVFR ceilings will continue to move over the terminal this afternoon. There will likely be a few breaks in the rain...but just to add a little extra complexity to the forecast there are some IFR ceilings in the vicinity and Lambert reported SCT009 this hour. Am covering the possibility for an IFR ceiling with a TEMPO for now. Latest guidance shows the rain ending at Lambert between 23-01Z this evening. Ceilings will clear from the east by mid evening and VFR flight conditions are expected to prevail thereafter. Carney && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Memphis TN
258 PM CST Mon Nov 28 2016 .DISCUSSION... Currently...A potent shortwave is pushing through the Arklatex. Diffluent flow across the region is helping to create tremendous lift which is resulting in widespread heavy rain. Poor lapse rates and little surface based instability is resulting in little if any thunder for the time being. A 995 mb mesolow has developed just NW of Memphis in the Delta. This feature has created a very strong pressure gradient across the Delta from the low to the south into NW Mississippi. Many places have reported gusts over 50 mph with trees down. This feature is forecast to track east northeast across West Tennessee and continue to enhance surface winds as it does so. Winds will probably will not be quite as strong outside of the flat Delta though. A wind advisory will continue for much of West Tennessee and North Mississippi through 6 pm. Areas to the west of the line of strongest radar echoes....just east of a Dyersburg through Memphis to Tallahatchie county line...have seen winds shift to the west and start to diminish. Will be cancelling the wind advisory for areas west of this line with forecast issuance. Heavy rain could cause some flooding of low lying areas especially with leaves clogging drains. This afternoon into early this evening...As the shortwave continues to approach there could be some intensification of the activity as it move east. The mesolow could also advect some higher dewpoints into North Mississippi. Part of the problem is that the winds in advance of the line are SE and the dewpoints in that source region are not terribly high, maybe upper 50s. As a result confidence in severe weather is decreasing. The enhanced risk has been pulled from the region while a slight risk remains for much of West Tennessee and North Mississippi along and east of the line. If any stronger updrafts can develop and tap the stronger winds aloft then perhaps a few bowing segments are possible...mainly over Northeast Mississippi through about 00z. Otherwise the main story really has been the gradient winds produced by the mesolow. Remainder of tonight...Rain and any thunderstorms will quickly exit this evening early this evening with skies clearing from the west. Temps will cool into the upper 40s and lower 50s. Model soundings are showing a strong inversion developing with a saturated layer near the ground. Winds will drop off quite a bit and skies will clear. This combined with a wet ground may produce patchy fog. Tuesday...The main upper trough remains to the west and the Mid- South will be between systems. Mild southerly flow will result in much above normal temperatures in the lower 70s with a good deal of sunshine. Tuesday night and Wednesday...The next shortwave rotates around the main trough positioned over the central states. This feature will fire up showers and thunderstorms along the old boundary...from todays activity...just southeast of our area. Those showers and thunderstorms will push north into at least part of our area as a surface wave moves along the stalled boundary. Northeast Mississippi stands the best chance of seeing showers and thunderstorms with chances diminishing to the NW. A few storms could be strong across Northeast Mississippi since some instability is depicted across the area though the best chance for severe weather will probably remain SE of our forecast area. After the shortwave kicks east cooler and drier air start to push in from the west. Thursday and Friday...High pressure builds in with seasonably cool weather. Highs in the 50s and lows in the 30s. Saturday through Monday...Looks unsettled during this time frame. The 12z ECMWF moves a significant system into the region this weekend while GFS cut off an upper low over Mexico and then ejects it early next week. Will look for some more consistency in future runs to pinpoint rain chances but for now will go with chance pops through the period. SJM && .AVIATION... 18Z TAFs Primary aviation concern is low level non-convective wind shear and surface wind speeds prior to arrival of TSRA. CKM and UTA reported gusts in excess of 40KT earlier this morning, while post TSRA winds in south central AR were slightly weaker at 30 to 40KT. Regarding timing of TSRA into MEM, HRRR and RAP models have dialed back timing just a bit, around 21Z. Primary change with the 18Z TAFs was to include LIFR cigs and vsby at most terminals for the late overnight. NAM Bufr and RAP soundings both depicted a steep moist inversion developing below FL003 toward 12Z, with moisture-laden southerly winds off the deck lifting over the shallow and cooler near-surface air. The stronger winds aloft should mix down by midmorning, returning VFR. PWB && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...Wind Advisory until 6 PM CST this evening for Alcorn-Benton MS- Calhoun-Chickasaw-Itawamba-Lafayette-Lee MS-Marshall-Monroe- Panola-Pontotoc-Prentiss-Quitman-Tallahatchie-Tate-Tippah- Tishomingo-Union-Yalobusha. TN...Wind Advisory until 6 PM CST this evening for Benton TN-Carroll- Chester-Crockett-Decatur-Fayette-Gibson-Hardeman-Hardin- Haywood-Henderson-Henry-Madison-McNairy-Weakley. && $$
Area Forecast Discussion
National Weather Service Marquette MI
415 PM EST Mon Nov 28 2016 .SHORT TERM...(This evening through Tuesday) Issued at 413 PM EST MON NOV 28 2016 WV imagery and RAP analysis indicated a broad mid/upper level trough over the plains with a low centered over ern North Dakota. At the surface, a 975 mb low was located over se ND with an occluded front looping through ern MN into cntrl IA. The combination of a shortwave trough and strong moisture advection supported a large area of rain over WI that was quickly spreading to the north. Tonight, the area of strong 700-300 mb qvector supporting the upstream pcpn over WI is expected to lift to the nne through Upper Michigan this evening and diminish across the cwa from sw to ne between 06z-12z. So, the area of drizzle will give way to a steadier moderate rain. With pwat values from 0.75-0.90 inch, QPF amounts in the 0.50-1.00 inch will be common, especially over the southeast half. Signficant drying will then move in late over the west and south. Temps will remain well above normal with lows in the low to mid 40s. Tuesday, with the occluded front lifting to the north of the area and qvector div and subsidence taking over, expect mainly dry weather. Some wrap-around pcpn may sneak into the far west from nw WI late. Otherwise, expect breezy southwest winds with temps slowly falling into the upper 30 west. However, some sunshine over the east half will help boost readings into the upper 40s. .LONG TERM...(Tuesday night through Monday) Issued at 343 PM EST MON NOV 28 2016 The low pressure system currently W of the region will weaken and slowly meander across the area through Thu, with a couple other waves possible coming down the back side of the system later in the week. Colder air moves in late this week into Sat as an upper trough moves out of NE Canada and into northern Ontario and Quebec. Early next week is quite uncertain as models show differing solutions with a system moving through the region. Ptype will be driven largely by wet-bulb zero height, meaning more snow during the night and over the higher terrain, and snow chances will increase through the end of the week as the airmass gradually cools. Best QPF through Sat looks to be on Thu when a shortwave moves around the back side of the departing system and the SFC trough swings through. However, mild SFC temps will keep precip mixed or at least limit snowfall amounts with snow melting some as it falls. Still some uncertainty there, but not a big concern at this time. Looking way out there, deterministic models are suggesting a much colder trend beyond 10 days out, which is backed up with the CFS. CFS also builds a large mass of very cold air across AK and the NW Territories toward the end of Dec, which would signal a significant pattern change. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) Issued at 1254 PM EST MON NOV 28 2016 Low level moisture streaming into the region ahead of a deep low pressure and frontal system will maintain the low clouds into early Tuesday. The downslope component with the se to s flow will keep cigs mainly in the MVFR range at IWD and CMX. However, IFR/LIFR cigs are expected at SAW. Light rain moving in again late today and tonight along with fog will drop vsby into the IFR range. Drier air moving into the area behind the occluded front as winds veer sw will bring improving conditions by mid to late Tuesday morning. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 413 PM EST MON NOV 28 2016 Southeast gales in the tight pres gradient ahead of the deep ND low will gradually shift off to the northeast tonight into early Tuesday. The low pressure system will linger over the Upper Midwest Tuesday into Wednesday. However the pressure gradient is not expected to be as tight and should allow winds to diminish below 25kt by Tuesday afternoon. Northerly winds to around 25 knots may develop Thursday as the slow moving low moves to the east of Lake Superior into Quebec. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Warning until 10 AM EST Tuesday for LSZ249>251-266-267. Gale Warning until midnight EST /11 PM CST/ tonight for LSZ240>242-245>248-263-265. Gale Warning until 4 AM EST Tuesday for LSZ243-244-264. Lake Michigan... Gale Warning until 4 AM EST Tuesday for LMZ221-248-250. && $$ SHORT TERM...JLB LONG TERM...Titus AVIATION...JLB MARINE...JLB
Area Forecast Discussion
National Weather Service Springfield MO
312 PM CST Mon Nov 28 2016 .SHORT TERM...(This evening through Tuesday) Issued at 241 PM CST Mon Nov 28 2016 Initial shortwave rotating around the deep upper low over the northern Plains was pushing through the area, with the main precipitation shield now over the eastern Ozarks. Skies were clearing across southeast Kansas and far western Missouri just behind a surface boundary. This clearing will continue to progress eastward through the late afternoon and early evening hours. 17Z RAP model does show some instability over the eastern Ozarks early this evening, so have kept lower end probabilities going. Cannot rule out some small hail with any of the storms that may develop. Otherwise, upper low will continue to meander over the northern Plains through Tuesday pushing a weak frontal boundary through southeast Kansas and the Missouri Ozarks Tuesday afternoon. Front will pass through dry, with just a wind shift to the west southwest. temperatures will again be mild with highs in the upper 50s to lower 60s. .LONG TERM...(Tuesday Night through Monday) Issued at 241 PM CST Mon Nov 28 2016 Surface low over the upper Midwest will gradually shift into the Great Lakes region through Thursday. The latest NAM and GFS show some decent moisture wrapping around the back side of this system and clipping central Missouri Wednesday night. However all precip remains north of our area, so will keep this portion of the forecast dry. Next storm system to impact the CONUS will drop southward from the northwest Pacific into the Desert Southwest by Friday/Saturday. The system will tap into a deep moisture fetch over the eastern Pacific and spread it northeastward into the central US by Saturday night and Sunday. While it looks like the main precipitation type will be rain with this system, temperatures will be close enough to the freezing mark to possibly support rain/snow mix, mainly late Saturday night and early Sunday. Will be following the GFS solution for movement of this system as the ECMWF continues to shift the system too quickly to the east. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) Issued at 1134 AM CST Mon Nov 28 2016 For the KSGF/KJLN/KBBG tafs: Shortwave trough rotating through the region has pushed the rain shield to the east of the TAF sites with a steady progression eastward expected this afternoon. Short term models do generate a little instability this afternoon, but mainly over the eastern Ozarks and cannot rule out a thunderstorm or two. However not expecting any impact at the terminals at this time. Back edge of clouds now near KJLN and will continue to push eastward. Expect improving conditions through the afternoon and into the evening with VFR flight conditions prevailing. Could still see a few hours of MVFR ceilings early this afternoon before drier air works its way in. Southerly winds should also begin to subside bit by mid to late afternoon. Enough mixing tonight is expected to preclude any mention of fog at the terminals. Better chances for some MVFR visibilities will reside over the far eastern Ozarks well east of the TAF sites. Otherwise, VFR conditions expected. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ SHORT TERM...Raberding LONG TERM...Terry AVIATION...Raberding
Area Forecast Discussion
National Weather Service San Diego CA
200 PM PST Mon Nov 28 2016 .SYNOPSIS... An upper level disturbance moving southeastward through the Great Basin this afternoon will bring strong onshore flow with gusty west winds in the mountains and deserts and also bring a chance of showers to San Diego County this afternoon and evening. Gusty northeast winds will follow near the coastal foothills late tonight into Tuesday...weakening Wednesday. It will be warmer Tuesday. A cold low pressure system will develop late in the week over the southwest United States and northwest Mexico with coolest weather around Friday and possible strong gusty northeast winds Friday through Saturday. Some daytime warming will occur over the weekend, but the nights will remain chilly. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Skies were mostly cloudy this afternoon with a mix of low clouds and high clouds. Windy conditions were occurring along east/southeast mountain slopes and some passes. Burns Canyon, a local windy spot, had a gust of 76 MPH around 8 AM, and White Water in San Gorgonio Pass had a gust of 66 MPH around 10 AM. We are currently under a northwest flow pattern with a 150-knot jet over Nevada and 700 MB winds up to about 55 knots over our area. The HRRR and WRF has the areas of strong winds on the east slopes and into the deserts continuing through about 5 PM with fairly rapid weakening after that. The wind advisory looks good for most locations as most gusts will be in the 40s and 50s MPH, but local areas will be in the high wind warning range. The long-wave low pressure trough covers most of the western US with a weak wave moving southeast on the back side over Nevada. There is a chance of showers over San Diego County late this afternoon and this evening due mostly to the over-the-water trajectories and residual moisture. Precip amounts should mostly be under 1/10 inch. We will transition to moderate offshore flow by Tuesday morning with the strongest winds from just below Cajon Pass through west parts of the Inland Empire to the Santa Ana Mountains. There will be a mountain crest stable layer around 750 MB and a 6 MB MSLP gradient from Las Vegas to San Diego. Local gusts could exceed 50 MPH. Weaker winds will occur Wednesday morning. The offshore flow will bring drier air and clear skies, and there will be some warming to almost seasonal norms west of the mountains, with less warming over the mountains/high deserts. In wind sheltered valleys Tuesday/Wednesday night there could be local frost, though MOS guidance shows this should not be widespread. Looking ahead to late week, there is still a strong upper low moving down from the north, and latest model guidance keeps moisture sufficient for precip to our south, so we should stay dry. With the upper low cutting possibly off to our SE, there will likely be tight height gradients aloft and strong MSLP gradients at the surface, though the 00Z and 12Z runs of the ECMWF have had the low weakening and trending towards an open wave versus tighter closed low and also further east than before. Especially if the stronger GFS solution verifies, it could be quite windy over most of the region with the wind direction from the northeast, with strongest winds in the normal wind areas through/below passes/canyons. Humidities will be quite low, but recent rains should reduce the fire weather threat. Temperatures will decrease by Friday, especially over higher terrain, but winds may keep nocturnal temperatures from falling too low in the valleys at least Thu/Fri nights. With an East-Pacific ridge following the upper low over the weekend, daytime temps should be higher, with quite a few 70s at lower elevations, but dry air could bring a chilly night to the valleys Saturday night as the winds decrease. && .AVIATION... 282100Z...Through 29/0900 UTC...clouds becoming BKN-OVC in the 2000- 7000 ft msl layer over and W of the mountains in San Diego county and over the Riverside county mountains, with gradually increasing -SHRA, mountain obscuration of coastal slopes, areas of vis 2-5 sm, and local vis 1 sm due to SHRA. Elsewhere, mainly unrestricted vis expected to continue with SCT-FEW clouds in the 2000-7000 ft msl layer and SCT-BKN clouds AOA 20000 ft msl. 29/0900-1500 UTC...clouds and any remaining -SHRA clearing out quickly, with mostly SKC and unrestricted vis expected for all areas. Through 29/0300 UTC...W winds in the mountains and deserts becoming 20-30 kt with gusts 40-50 kt, resulting in stg-svr uddfs/llws/rotors. 29/0300-1500 UTC...W winds and associated uddfs/llws over and east of mountains weakening, while NE winds increasing to 15-25 kt with gusts 30-35 kt over coastal slopes/foothills and through/below passes/canyons will create mod- stg uddfs/llws over and W or SW of the mountains. && .MARINE... Reports from the San Clemente Basin buoy show that northwesterly winds are currently at 16 kt gusting to 19 kt with 9.5 foot seas. However, hi-res models show wind gusts increasing again in the outer waters this afternoon and evening (up to around 25 kt) as another upper level disturbance moves near the region. Thus, a Small Craft Advisory continues for the outer waters through 10 pm tonight. Winds and seas will diminish late tonight. There is the possibility of strong offshore winds (N to NE) Friday and/or Saturday which could result in hazardous sea conditions. However, confidence is low at the moment. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory until 6 PM PST this evening for Apple and Lucerne Valleys-Coachella Valley-Riverside County Mountains- San Bernardino County Mountains-San Diego County Deserts- San Diego County Mountains-San Gorgonio Pass Near Banning. Wind Advisory from 10 PM this evening to 2 PM PST Tuesday for Orange County Inland Areas-San Bernardino and Riverside County Valleys-The Inland Empire. PZ...Small Craft Advisory until 10 PM PST this evening for Waters from San Mateo point to the Mexican Border Extending 30 to 60 nm out including San Clemente Island. Small Craft Advisory until 4 AM PST early this morning for Coastal Waters from San Mateo Point to the Mexican Border and out to 30 nm. && $$ PUBLIC...Maxwell AVIATION/MARINE...Harrison