Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/09/18

Area Forecast Discussion
National Weather Service Bismarck ND
911 PM CST Thu Nov 8 2018 .UPDATE... Issued at 911 PM CST Thu Nov 8 2018 Snow is beginning to wind down across southwest ND as anticipated. Still have Hettinger at 1 1/2 mile visibility as of 03Z, but have seen improvement at other stations and on webcams. Elsewhere, GOES-East satellite imagery shows bands of lake-effect snow streaming off of Lake Sakakawea, particularly south of Van Hook Arm over northeast Dunn County. This may continue into the overnight as low-level winds remain northerly. Very localized snow accumulations of 1 to 2 inches are not out of the question. Decreased low temperatures by a few degrees from northwest into central ND, as some stations were already approaching forecast lows. However, given scattered clouds moving across the region, expect to see up-and-down temperature trends through the night. UPDATE Issued at 556 PM CST Thu Nov 8 2018 6.95 and 7.34 micron GOES-16 water vapor imagery show a mid-level disturbance moving over southwest ND early this evening. This is reflected well in the RAP 700 mb vorticity and 925 to 850 mb frontogenesis fields. Periods of moderate to heavy snow have been observed across southwest ND late this afternoon, with surface stations and webcams showing visibility below a half mile at times at Dickinson, Belfield, Beach, and Amidon. The 22Z RAP moves the best forcing to the south and east, exiting ND around 03Z. Until then, expect these conditions to continue, gradually migrating southeastward over time. Will have to keep an eye on cloud cover trends through the evening, which may impact low temperatures. Even with scattered clouds, still expecting widespread lows in the single digits above zero with wind chills approaching -15. && .SHORT TERM...(This evening through Friday) Issued at 308 PM CST Thu Nov 8 2018 Its a rather messy precipitation forecast this afternoon and evening with fairly widespread flurries/snow showers within a cold upper trough. Then a short wave trough will move through the upper trough across the southwest later tonight. And mixed in with this, there should be some lake effect snow with Lake Sakakawea temperatures in the 40s and air temperatures in the teens. NAM Model soundings support flurries or light snow showers well into the night, with low level supersaturation and weak vertical motion supporting them. So we were slow to clear the precipitation tonight, carrying flurries/light snow through midnight most areas central and west, and through the night south central. The best chance for accumulating snow will be southwest with the short wave, but this should be an inch or less. Model consensus depicts a 1040 surface high pressure moving into western North Dakota tonight. this should be a very cold night with a few readings below zero west and north. Along with this expect wind chills of 15 below, perhaps a few 20 below zero chills Friday morning. The clouds will clear Friday, but highs will only be in the teens. .LONG TERM...(Friday night through Thursday) Issued at 308 PM CST Thu Nov 8 2018 The main concern for the long term will be some accumulating snow Saturday, and cold temperatures Monday and Tuesday. This will be followed by a gradual warming trend by the end of the week. Model consensus supports one to 2 inches of snow Saturday, with the best chance for 2 inches of snow northwest. At this time, will keep the weather messaging high confidence of minor travel impacts. A second push of cold air will arrive Sunday night through Tuesday. Will see lows in the low single digits above zero both days, with highs Monday in the Teens most areas. This will then be followed by a dry warming trend, but not quite to above normal. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 556 PM CST Thu Nov 8 2018 Expect snow causing LIFR to IFR visibility reductions and MVFR ceilings to continue at KDIK through around 01Z, with conditions improving by 02Z. Otherwise, mainly VFR conditions are expected, though a brief period of MVFR ceilings cannot be ruled out into Friday morning at any TAF site. North to northwest winds around 10-15 kts through the night will become light and southerly Friday morning and afternoon. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Hollan SHORT TERM...WAA LONG TERM...WAA AVIATION...Hollan
Area Forecast Discussion
National Weather Service Des Moines IA
612 PM CST Thu Nov 8 2018 ...Updated Aviation Discussion... .SHORT TERM.../Tonight through Friday/ Issued at 359 PM CST Thu Nov 8 2018 Main concern over the next 24 hours will be snowfall associated with a shortwave trough sweeping across the northern Great Plains and Upper Midwest. Strong PV anomaly will provide widespread ascent across most of the CWA, with the vertical profile becoming more saturated as it digs southward across Iowa before lifting northeast into the upper Great Lakes Region. With northwesterly to northerly low-level flow, a shot of cold air has made it into the area. Model soundings favor temperatures below freezing through much of the profile. With increasing saturation through 20 kft, there should be plenty of ice introduction to keep the precip type all snow this evening and overnight, allowing for healthy dendritic growth. Main challenge regarding snowfall amounts has been QPF, with some spread between model guidance. The higher amounts are favored south of Interstate 80 this evening. One to one and half inches is likely along the Iowa-Missouri border up to around U.S. Highway 34 corridor, while half of an inch to one inch favored for central and northern Iowa. The bulk of these snow showers should move out of the CWA by 9 UTC. Friday afternoon, there are two concerns. The first, will be another surface feature development on the backside of the PV anomaly moving across the area that will likely produce snow showers, especially in western Iowa and possibly southern Iowa. RAP and NAM model soundings indicate lapse rates that would be favorable for snow showers to be more convective in nature. Most likely timing for this short round of snow will be between 12 and 20 UTC. Depending on how quickly this feature moves through, this could drop another half to one inch in western and southern portions of the CWA, though there is a possibility this could be less. The other concern Friday afternoon will be gusty winds, as a strong pressure gradient develops across Iowa as surface high pressure over the Plains slowly shifts eastward into Iowa. These winds could present some visibility issues during times of snowfall, but overall is not anticipated to be a hazardous issue at this time. Following the winds, colder air will begin to settle in. .LONG TERM.../Friday night through Thursday/ Issued at 359 PM CST Thu Nov 8 2018 Key Points: Very cold temperatures expected Saturday, Monday, Tuesday. No high-impact/hazardous precipitation impacts forecast at this time. Gradual warm-up towards the end of next week. This Weekend... Very high confidence in strong CAA behind the tonight/Friday system described above in the short-term AFD. 850mb temps drop from around the -4C to -6C range they were this morning to the -13C to -15C range Friday night. CAA aided by a very fast-moving sfc high that should be near the IA/NE border by 06z Sat... and into south-central Illinois by 18z Sat. As this sfc high pushes east/southeast, a weak wave will push eastward across Minnesota into Sunday, bringing a brief warm-up for Sunday, before cooler temperatures return to Iowa for Monday and Tuesday. Digging into details a little further, Saturday morning`s lows will likely be impacted by cloud cover as it appears high to mid-level clouds will be entering Iowa from west to east from around 06z Sat through Saturday. These clouds can be traced back to the Pacific NW in advance of the aforementioned wave above. So, it will not be a purely radiational cooling night. Regardless, forecast temperatures are within a few degrees of record lows at almost all major climo sites in our area (exception at KMCW). Given the wind chill values slated to be in the single digits, plus the fact this will be the first surge of "very cold" air this season, plus outdoor activities likely Saturday morning, worth heightened messaging for this cold weather. Am watching northern Iowa Saturday afternoon for the slight potential of some light snow/flurries in the northern two or so tiers of counties. In short models are converging on a solution where an upper wave/impulse leading the main "trough" propagates eastward through Minnesota Saturday PM. There is decent 500mb-300mb Q-vector convergence ahead of this impulse, and models show a broad area of 850mb moisture flux convergence plus a band of 850mb theta-e advection that is well phased with this impulse. Looking at KMCW forecast soundings, the snow growth zone looks saturated where the 850-700mb level ascent processes are occurring. Challenge is sfc dwpts in the single digits... so obviously a lot of sub-cloud dry air to contend with. For now, have precip formally out of forecast, but may need to add these flurries in next update. With forecast winds in the 10 to 20 mph range, any uptick in intensity beyond flurries could lead to reduced vsbys and slight travel impacts. Monday and Tuesday... An upper low at the heart of the longwave trough in terms of impacting the Midwest passes on the Canada side of the Great Lakes region Monday through Tuesday. Models in good agreement with keeping associated forcing, moisture, etc. north and east of Iowa. Concurrently, a 1040mb or so sfc high builds off the Rockies and heads towards the Dakotas. This synoptic combination/setup will put Iowa back into strong CAA for Monday and Tuesday. 850mb temps once again drop to the -13C to -17C range by 12z Tue. With slight pressure gradient in advance of sfc high, winds may be in the 10-15mph range Tuesday morning, which would yield wind chill values near to slightly below zero as far south as Highway 30. Wednesday and Beyond... A huge thermal ridge that is forecast to build over the Intermountain West on Monday and Tuesday, is slated to come crashing down over Iowa Wednesday into Thursday. Long-range models show the 850mb temps making it roughly into the +4C to +7C range at 12z Thu... which would obviously be a stark contrast from their 12z Tue values. Per usual a this range out, long range models in some disagreement with handling a few Alberta clipper-type systems that look to stay north and east of Iowa. What is noteworthy, is the northward retreat of the polar jet. Initial impressions are that Iowa could return a prolonged period of at least near-normal temperatures. && .AVIATION.../For the 00Z TAFS through 00Z Friday evening/ Issued at 610 PM CST Thu Nov 8 2018 Light snow continues to spread over central and southern Iowa. Currently, visibility remains VFR but expecting some MVFR and possibly brief IFR visibility restrictions later tonight as the peak of the snow gets going. Confident in the MVFR ceilings through tomorrow morning, once they set in. Added a break in the light snow towards Friday morning before the second round comes in past 12-15z. This should likely have some MVFR visibility with the stronger winds associated with this shortwave. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Krull LONG TERM...Kotenberg AVIATION...Podrazik
Area Forecast Discussion
National Weather Service Grand Rapids MI
825 PM EST Thu Nov 8 2018 LATEST UPDATE... Update .SYNOPSIS... Issued at 249 PM EST Thu Nov 8 2018 A weak area of high pressure will track eastward through Lower Michigan providing the region with dry weather to start the night. A storm system begins to move in from the west later tonight spreading light snow into the area. As this storm system tracks through Friday into Saturday additional snowfall is forecasted at times. The cold weather then persists right through Sunday. && .UPDATE... Issued at 825 PM EST Thu Nov 8 2018 The forecast is largely on track with not much changed in expectations over the next 24-36 hours. No changes to headlines will be introduced for the evening update. However, there are a few things we are monitoring closely: 1). The potential for a north/south oriented band of heavy lake effect snow to come ashore around the noon hour with associated impacts. Should this occur, quite a bit more snow may fall west of US-131 Friday than currently reflected in our forecast before the well-advertised lake- effect snow event begins Friday evening. Note that the latest few runs of the HRRR would be a worst-case scenario with such a band making it through nearly our entire area of responsibility. 2). The potential for areas of blowing snow and significantly reduced visibilities Friday night as the lake-effect snow ramps up and westerly winds gust upwards of 40-45 mph, especially along the lake shore. We will obviously be taking a closer look at the aforementioned concerns for the 3:30 AM forecast package. Updated products will be sent out soon. && .DISCUSSION...(This evening through next Thursday) Issued at 249 PM EST Thu Nov 8 2018 The main challenge in the forecast deals with the potential impacts from the storm system Friday into Saturday. Models are in relative agreement in tracking and deepening a surface low from Central Appalachians northward into Ontario Friday into Saturday. This is an unusual track for the region. This system will provide the region with several opportunities for precipitation, most of which will be snow. Initially with warm and moist air advection arriving later tonight then through the morning commute...some snow is expected. Overall the lift is shown to remain weak, but the moisture is forecasted to be relatively deep, through the DGZ. So it looks like light snow will occur that moves in just before or during the morning commute. With surface temperatures starting the day near or just below freezing, this is expected to support a period of slick conditions for the morning commute, especially on elevated surfaces. If surface temperatures end up a few degrees warmer, not much in the way of impacts would occur. Guidance has lately been showing a stronger band of snow over Lake MI during the morning that moves onshore around noon. It appears that temperatures during the middle part of the day will be above freezing...but any steadier/heavier band of snow could lower values back down to near freezing. We will keep the headlines going. After this band tracks eastward through the region...a lull in the snow may occur mid to late afternoon. The second round of snow develops most likely Friday evening. This is when the shortwave that digs down into the area evolves into a rather deep mid level low. Beneath this feature deep cyclonic flow with temperatures supportive of lake enhancement suggests widespread snow showers some of which could be heavy. Couple that with deeper mixing and stronger wind fields not too far off the ground and you have impacts. We may need to extend the Friday night advisory further inland if these strong winds do draw the snow bands into the central part of Lower MI. Low level ridging moves in Saturday afternoon with an area of high pressure moving up the OH Valley. Thus much less in the way of precipitation will be around. Well below normal temperatures will continue. Snow and rain showers return by Monday as a weak low pressure system moves in from the west. This system then transfers it energy to another low riding northward up the east side of the Appalachians on Tuesday. This system then bombs out on its way to Eastern Quebec. The result of this for our CWA will be for stronger cold air advection to develop that draws down another arctic surge of air. Lake effect snow showers can be expected. With more of a northerly component, highest POPs will be for the lakeshore. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 743 PM EST Thu Nov 8 2018 There is little question a significant winter storm will move through the Great Lakes tonight into Saturday. The first phase will be the warm advection precipitation event. That will be from around 09z to around 18z. For the most part this should be snow but in the I-94 TAF sites it may be mixed with rain when the precipitation is not moderate or greater. Once this moves out there may be a period of drizzle or mixed flurries or drizzle. Finally the cold air comes in by mid afternoon and that will push a band of heavy snow showers on shore. The band will weaken as it moves on shore but MKG and possibly GRR will see 1 to 2 hours of heavy snow as that moves through. Clearly this means IFR conditions across the TAF sites from around 09z on into Saturday. There will be very strong winds Friday evening, gusting over 35 knots so expect considerable blowing snow on landing in GRR or MKG after 03z Saturday. Given this will bring snow into the area expect moderate in cloud icing tonight through Saturday morning. Also expect moderate turbulence above 9000 ft tonight into Friday. && .MARINE... Issued at 249 PM EST Thu Nov 8 2018 With a relatively weak pressure gradient in place through tonight the winds and resulting waves will be limited. As the storm system moves in for Friday into Saturday the winds will increase considerably with gales looking likely to develop Friday night. That combined with strong cold air advection will result in big waves out on Lake MI. The hazardous conditions will likely persist through Saturday. Will need to monitor the potential need for a lakeshore flood headline given the risk for big waves Friday night to Saturday. && .HYDROLOGY... Issued at 942 AM EST Thu Nov 8 2018 River levels are generally above normal for the time of the year with most sites nearing or already past their crests due to recent rainfall. No rivers are expected to rise to flood stage. Lake-effect showers will occur into the weekend with fairly light precipitation amounts. We will see some snow accumulations Friday and Saturday. This should have little impact on area rivers, and temperatures will not yet be cold enough to worry about rivers freezing or ice jam formation. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Winter Weather Advisory from 1 AM Friday to 7 AM EST Saturday for MIZ037-038-043-044-050-056-057-064-065-071>073. Winter Weather Advisory from 1 AM to 7 PM EST Friday for MIZ039- 040-045-046-051-052-058-059-066-067-074. LM...Gale Watch from Friday evening through Saturday morning for LMZ844>849. Small Craft Advisory from 7 AM to 7 PM EST Friday for LMZ844>849. && $$ UPDATE...Borchardt SYNOPSIS...MJS DISCUSSION...MJS AVIATION...WDM HYDROLOGY...63 MARINE...MJS
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
949 PM EST Thu Nov 8 2018 .SYNOPSIS... A cold front will move through the Carolinas tomorrow, with cool and dry Canadian high pressure spreading back over the southeast for the weekend. Expect the coldest night so far on Saturday night. Next week will be chilly and unsettled, with numerous rainy systems moving through. && .NEAR TERM /THROUGH FRIDAY/... As of 945 PM: The latest RAP runs have nicely captured a passing 500 mb vorticity lobe moving northeast across piedmont sections southeast of I-85 this evening. This appears to be associated with the better showers and rainfall rates observed on regional radars. The next in the series of upper waves in the southwesterly flow will likely not arrive until daybreak across the southwest zones. However, coverage should still increase overnight, even if rates diminish a bit, as isentropic lift increases and moisture deepens in the profiles. A cold air damming wedge should get established overnight with the surface high center setting up over eastern PA and precipitation increasing in the nose of the surface ridge across the western Carolinas. Will also likely see some low end gusts as the CAD gets firmly established. Lows will be 5 to 10 degrees above normal. The upstream upper trough axis moves toward the area Friday pushing a cold front into the region. This brings deep moisture and synoptic scale lift into the area. The CAD remains locked in through much of the day, but does begin to erode from the south and west late in the day as the cold front begins scouring the CAD. Surface CAPE should be nil, however muCAPE increases to around 500 J/kg southeast of I- 85 with non-zero amounts elsewhere. Therefore, maintained slight chances of thunder across the far southern CWFA as the front moves in. Also kept the character of precip as showers instead of rain and drizzle as would be expected in a classical CAD. This also means some heavier QPF values, especially across the mountains. However, the flood threat remains low. Did keep highs in a CAD configuration. This means highs 10 to 15 degrees below normal with only a small diurnal curve. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... As of 100 PM EST Thursday: Guidance has dried out considerably Friday night, resulting in what will likely only be light isolated shower activity in the eastern half of the CWA by the time the short term period picks up at 00Z Saturday. The area will dry out through the balance of the evening, with just very light NW flow snow possible in the higher elevations of the NC mountains through Saturday morning behind the passing surface front. Saturday morning will be chilly, with lows ranging from the high 20s in the mountains to the high 30s elsewhere. Saturday will be generally clear as dry surface high pressure slips eastward, though persistent cold air advection through the day will keep max temperatures about 10 degrees below average. Sunday morning will likely be the coldest morning so far this year, with the center of the surface high parked just to our north over the Virginias. Anticipate a widespread freeze across the whole CWA, so freeze products will probably be raised in the next few days. Despite plentiful insolation on Sunday, max temps will be more on par with early January averages than mid-November, close to 15 degrees below climo. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 300 PM EST Thursday: Beginning Sunday night, the medium range forecast period kicks off dry, with overnight low temperatures above normal, as sfc high pressure meanders in place across the Mid- Atlantic and down into the Carolinas through early Monday. As this feature retreats off to the northeast, in true long-term forecasting fashion, the temporal and spatial details of the next approaching system vary. But overall consensus continues, thus have kept with the general trend of increasing chances for precipitation from SW to NE beginning Monday ahead of an approaching cold front, progged to push eastward through the area Tuesday morning, and a trailing deepening upper trough. A plume of moisture is expected to infiltrate into the Carolinas for the early part of the week, bringing the potential for rainfall amounts around 1 to 2 inches, with higher amounts possible over portions of the southern mountains through Tuesday overnight. With temperatures around or just below freezing before to around daybreak on Monday, would entirely not rule out showers mixed with light snow across western NC and areas north of the I-40 corridor, transitioning to all rain as temperatures warm. Overnight Monday into Tuesday, any mix of snow with rain will remain confined to areas along the TN border. Into Tuesday afternoon, periods of overlapping colder air and rainfall may allow for an additional mix of rain with light snow before tapering off behind the cold front. Any light snow accumulation will remain confined to the western NC mountains, but even then, confidence remains low attm given how far out this system is and will continue to monitor as the system nears the area. Behind the front, arctic high pressure will build in, leaving conditions dry with below normal temperatures Wednesday and Thursday, as latest guidance even progs low temperatures Thursday morning below freezing across the entire FA. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... At KCLT and elsewhere: Cold air damming continues to get slowly established across the region, with high pressure setting up to the north, northeast winds increasing, and precipitation coverage becoming more widespread as ceilings lower. Expect a steady transition down through lower VFR ceilings into the MVFR range circa midnight and then on toward IFR by daybreak. The wedge should be locked in through most of Friday as a cold front approaches from the west. Mainly IFR or less cigs will continue with intermittent rain and generally MVFR vsby in fog. Any improvement will only occur late in the period as the front moves through and winds turn NW with fropa. Outlook: Rain and restrictions will come to an end Friday night as a cold front moves east. Dry and generally VFR conditions will continue through the weekend, but yet another storm system will likely bring a round of rain and restrictions early in the work week. Confidence Table... 02-08Z 08-14Z 14-20Z 20-00Z KCLT High 84% High 98% High 89% High 82% KGSP High 97% Low 48% High 88% Low 59% KAVL High 84% Med 60% Med 64% Med 70% KHKY Med 79% Med 75% Med 60% Med 70% KGMU High 97% Low 56% High 88% Med 63% KAND High 93% High 91% High 88% Med 74% The percentage reflects the number of guidance members agreeing with the scheduled TAF issuance flight rule category. Complete hourly experimental aviation forecast consistency tables and ensemble forecasts are available at the following link: && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...Carroll NEAR TERM...HG/RWH SHORT TERM...Carroll LONG TERM...SGL AVIATION...HG/RWH
Area Forecast Discussion
National Weather Service Wilmington NC
910 PM EST Thu Nov 8 2018 .SYNOPSIS... Skies will remain cloudy with occasional light rain and drizzle overnight. Cool high pressure to the north will build south over the Carolinas into Friday. Colder and drier conditions will arrive over the weekend, with frost possible early Sunday. Another pool of chilly air may migrate into the region during the middle of next week. && .NEAR TERM /THROUGH FRIDAY/... As of 915 PM Thursday...Areas of light drizzle falling from widespread low stratus clouds are being supplemented by showers across eastern South Carolina falling from deeper clouds up above the frontal inversion in the southwest flow aloft. Models continue to indicate low potential for measurable rain overnight. For the overnight period forecast PoPs range from 20-30 percent from Bennettsville and Lumberton to Whiteville, up to 40-60 percent across Williamsburg County to Conway and Georgetown. But even here rainfall amounts of only one or two hundredths of an inch are expected. Temperatures at 8 and 9 PM were running a couple degrees higher than most models had indicated. I`ve adjusted hourly readings upward through about 1 AM, but still believe we`ll see lows reach the mid to upper 50s by morning as cooler air entering northeastern North Carolina is pulled southward. The HRRR was the primary model used to tweak PoPs, temperatures, and dewpoints for this evening update. && .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... As of 300 PM Thursday...A light southerly flow will increase slightly as it veers around to the SW to W ahead of a cold front Fri eve. May see some breaks in the clouds along the coast, but inland should see wedge hold on with fairly steep low level inversion maintaining moisture and low clouds below 1500 ft. Overall expect more in the way of stratiform pcp inland up through FROPA which should come around midnight inland and toward daybreak along the coast. Soundings show some elevated instability with pcp water values reaching up near 1.7 inches and dewpoint temps in the mid 60s just ahead of the front Fri eve. Have left out thunderstorms along the coast for now. Any lingering pcp will clear the coast shortly after daybreak with clearing skies behind cold front with plenty of cold and dry air advecting in. Temps will drop behind the front, with overnight lows down below 50 west of I-95 and closer to 55 near the coast. Cold and dry high pressure will build in through Saturday with pcp water values just under an inch along the coast by Sat morning but near a quarter of an inch inland. Expect sunny but chilly weather with gusty northerly winds on Saturday. Temps will not increase much from morning lows in deep CAA with max temps in the mid 50s to around 60 along the coast. Clear skies and very light winds will prevail Sat night with frost or freeze a possibility. Light northerly winds may prevent ideal radiational cooling as the center of the high moves east and should reach the VA/NC border by Sun morning. Soundings do not look like atmosphere will decouple completely, but wind sheltered areas should drop out. The light winds and very dry air mass in place may also prevent frost with temps not quite making it down to dewpoint temps in the mid 20s. Places closer to the coast should see higher NE winds and should help keep temps up a bit more. Overall expect possible frost or freeze in spots with temps near freezing inland and closer to 40 right along the coast. Confidence is not high enough to include any frost in the forecast at this time. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 300 PM Thursday...Flat mid-level flow on Sun will quickly shift surface high from the Mid-Atlantic to the Northeast as weak coastal trough develops. Resulting wedge will keep the region cool Sun and Mon. Pattern aloft starts to become more amplified Mon as shortwave drops south across the central part of the country. Southwest flow aloft slowly spreads Gulf moisture over the southeast, as clouds late Sun and Sun night. Isentropic lift taps into the increasing moisture and precip chances increase Mon with the best chances Mon night and Tue. Disagreement over the handling of the surface wave/low developing along the Gulf Coast front continue between the GFS/ECMWF. Concerning rainfall both solutions are wet with similar timing and amounts. The main difference concerns temperatures. GFS has a coastal low which keeps areas away from the coast below climo early next week while the ECMWF has the low tracking inland, with the entire forecast area rising above climo early next week. Confidence is low so for now will stay with the cooler/inherited solution to avoid jumping back and forth. Strong cold front crosses the area Tue night, bringing about a big airmass change. Strong cold advection on Wed will likely result in morning highs with temps falling during the afternoon. Lingering low- level moisture behind the front keeps low cloud hanging around through Wed and Thu may end up turning cloudy in the afternoon with some heating. Partial thickness suggest highs will struggle to reach mid 50s Wed and 60 on Thu. Lows will be in the mid 30s with potential for upper 20s to lower 30s inland Wed night if winds are light. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... As of 00Z...A cold air damming pattern will persist overnight and begin to relinquish tomorrow afternoon. Except for potential IFR at KCRE/KMYR until 01-02Z, MVFR cigs will be predominate, lowest around 12Z. Best chance of light showers will be through 06Z at the coastal terminals. Northeast winds will persist overnight and become more variable to light south tomorrow afternoon. Extended Outlook...Brief clearing later Friday before another cold front passage late Friday and high pressure will build into Sunday before a coastal trough/cold air damming pattern develops Monday and Tuesday. MVFR/IFR possible Monday into Tuesday. && .MARINE... NEAR TERM /THROUGH FRIDAY/... As of 915 PM Thursday...Small Craft Advisory conditions are close to developing across the outer portions of the Cape Fear coastal waters as winds reach 25 knots in gusts and seas are approaching 6 feet. Models indicate the highest winds should occur now through about 2 AM Friday before diminishing slightly by sunrise Friday. Seas, currently ranging from 4 feet at the nearshore Cape Fear buoys to almost 6 feet out at the Frying Pan Shoals buoy, should build by another 1 or 1.5 feet overnight in response to the steady northeast winds. Winds and seas over the South Carolina coastal waters are inferred to be 5 knots and 1 to 1.5 feet lower than over the North Carolina waters, and an `exercise caution` headline should cover anticipated conditions overnight. The HRRR, GFS and NAM models were blended to create wind speed/direction forecasts for the overnight period. SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... As of 300 PM Thursday...Lighter winds Fri eve with winds coming around to the south and increasing slightly ahead of a cold front. Winds do not look very impressive ahead of the cold front remaining 5 to 10 kts until winds shift to the W-NW after midnight with cooler and drier air making its way over the waters heading toward daybreak Saturday. May see a slight increase in winds and seas at that time, but initially winds will be off shore. High pressure will build down across the waters through Saturday with decent N-NE winds up to 20 kts developing. Expect a well mixed marine layer heading into Sat night as cold air rushes over the relatively warmer waters. Expect seas to rise through Saturday up to 3 to 5 ft with precautionary headlines and then SCA thresholds reached for a brief period overnight Sat into early Sun in stronger NE flow. LONG TERM /SUNDAY THROUGH TUESDAY/... As of 300 PM Thursday...Weak coastal trough develops Sun as high pressure to the north retreats northeast for Mon. Northeast flow around 20 kt at the start of the period weakens late Sun and Sun night as the trough develops. East-southeast flow starts to increase late Mon into Mon night as surface wave moving northeast from the northern Gulf of Mexico develops into weak low pressure. Strong southwest flow develops in the wake of the low Tue as a cold front moves into the region. Seas 3 to 5 ft at the start of the period will drop to 2 to 3 ft later Sun and Sun night. Increasing winds Mon into Tue build seas with 3 to 5 ft likely by the end of Mon and 4 to 7 ft on Tue. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory until noon EST Friday for AMZ250-252. && $$ SYNOPSIS...III NEAR TERM...TRA SHORT TERM...RGZ LONG TERM...III AVIATION...MRR
Area Forecast Discussion
National Weather Service Jacksonville FL
705 PM EST Thu Nov 8 2018 .UPDATE...Have had to update hourly POP/Weather grids over the past few hours for evolution given radar showing large area of showers and a few t-storms over n-ctrl FL with dry conditions further north. As shown by the HRRR, expect current area of showers to gradually diminish over the next few hours, with an isolated shower or two possible further north later Tonight. Latest HRRR and SREF guidance suggests potential for areas of fog and low clouds to develop later Tonight and have maintained this in the forecast. Low temperature forecast supported by latest consensus guidance. && .AVIATION...Areas of MVFR CIGs this evening, with latest guidance suggesting potential for IFR CIGs and areas of fog to develop late Tonight. Latest TAFs reflect this potential. Area of showers around KGNV should diminish next hour or two. && .MARINE...A weak frontal boundary across the area waters will lift north of the waters as a warm front Friday. A cold front will pass through Friday night with high pressure building to the northwest then north over the weekend. A period of exercise caution appears likely offshore with advisory conditions possible during the weekend in the wake of the cold front. Another strong cold front will approach the waters Tuesday with winds veering and increasing to exercise caution and possibly to advisory criteria. Rip Currents: A moderate risk anticipated for the Ne Fl beaches and low risk for the Se Ga beaches for Friday. && .PRELIMINARY POINT TEMPS/POPS... AMG 66 79 53 65 / 30 40 40 0 SSI 68 78 58 67 / 20 30 30 10 JAX 67 83 59 70 / 10 30 20 10 SGJ 68 82 63 72 / 30 30 20 10 GNV 67 84 61 73 / 50 20 10 10 OCF 66 85 63 76 / 30 10 10 10 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$ Wolf/Bricker
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
831 PM CST Thu Nov 8 2018 .UPDATE... Issued at 811 PM CST Thu Nov 8 2018 The forecast looks to be generally on track this evening. Have had many reports of light snow accumulations on elevated surfaces ranging from a dusting to around an inch on the west side of Columbia Missouri. Not much more than a dusting yet on the ground outside of grassy surfaces, and wet roads except for a dusting on the roads reported earlier in Monroe City Missouri. Still think the primary accumulations will be on elevated and grassy surfaces. The 2 inch soil temperature at the NWS office in Weldon Spring was 47 degrees, and at 4 inches it was 48 this evening. Think snowfall rates will have to be truly heavy to overcome that amount of heat in the ground. There could certainly be slick spots on bridges and overpasses, but I don`t think there will be anything widespread until temperatures fall below freezing. RAP is indicating that we are likely seeing the heaviest precipitation now, and that it will last until between 11 PM and 1 AM. Low level warm advection weakens substantially after that, and the low level frontogenesis also weakens/moves southeast away from us. At the very least, the snowfall should rapidly diminish as this occurs as the frontogenesis is what`s likely producing the heavier snow bands that we`re seeing right now. Ending times of precipitation still look good as well, going from southwest to northeast from central and northeast Missouri around 200 AM, and east central Missouri between 400-500 AM and then our south central Illinois counties by around 800 AM. Highest accumulations of 1-2 inches still look good from central into northeast Missouri and west central Illinois, with lesser amounts further to the south and east...again, mainly on elevated and grassy surfaces. Carney && .SHORT TERM... (Through Late Friday Afternoon) Issued at 307 PM CST Thu Nov 8 2018 Focus thru the period will be the two different snow events. The first snow event is falling into place. The upper trof is approaching the region bringing with it a large area of rain and snow. Current observations show that 34 degrees F is the magic temperature at which the rain switches to snow. With wet-bulb temp above the shallow boundary layer well below freezing, see no reason this will change tonight. The uncertainty in the forecast thru tonight will be where and when the temp will cool to 34 degrees due to wet bulb effects. Given the dry air across the area, much of the region north of roughly KVIH to KSTL to K3LF, may not see any rain and precip simply begin as snow. Have increased snow amounts slightly from roughly KCOU to KPPQ as models have come into better agreement with slightly higher QPF amounts. While this results in snowfall amounts of up to 2 inches in this area, the overall impact is still expected to be minimal. This is due to both the timing of the snow as well as the warm ground which should keep the roads generally clear. However, bridges and overpasses may become slick, especially across northern portions of the CWA where temps will be cooler. The precip should be east of the CWA by sunrise on Friday, but have kept some low PoPs in far eastern counties to account for some timing uncertainty. Focus then turns to the second event, occurring on Friday. This event, due to a clipper digging the main trof into the region, is a more classic setup for convective snow showers with deep cyclonic flow and steep low level lapse rates. The main question with this event will be coverage, but also snowfall amounts with the heavy snow bursts. Given these showers are quick hitting and short lived, amounts where these showers hit are expected to be less than an inch. However, snowfall rates will be high within these showers. Also of concern is the anticipated timing of these snow showers. Since more of this is discussed below, will omit it here. As for coverage, models generally agree with the highest coverage being northern and into western portions of the CWA, which will gradually transition to northeastern portions of the CWA...areas along and downshear of the main vort. However, isolated snow showers are possible across much of the area. With high confidence in occurrence, have chosen to use coverage wording over chance. Believe that most of the precip with these showers will be snow given the thermal profile and expected convection. However, some light showers may be rain. Strong and gusty nwly winds and much cooler temps will also accompany this clipper. Tilly .LONG TERM... (Friday Night through Next Thursday) Issued at 307 PM CST Thu Nov 8 2018 Main concern for Friday evening will be during the early evening hours as scattered snow showers and bursts continue across portions of the area. Highest chances of snow showers will start off centered near the St. Louis metro area and shift southeastward through late evening along/ahead of a secondary cold front. These snow showers may be moderate to heavy at times, with low visibilities a concern for the conclusion of the evening rush hour. Breezy northwest winds will only help decrease visibility further. In locations that do see some of these heavier bursts of snow, accumulations up to a half inch are possible. While total accumulations of snow will likely be on the light side, impacts to the evening rush hour in the St. Louis metro area could be high due to the aforementioned low visibilities within the heavier snow showers/bursts. The loss of daytime instability is expected to lead to lessening coverage and intensity of snow showers by mid evening. Very cold arctic air will be the main story for the remainder of Friday night as cloud cover decreases and a strong surface high pressure center heads toward central Missouri. Lows should drop into the mid teens to low twenties across the area, which should be the coldest night so far this young winter season. To put these readings in more perspective, lows Friday night will be about 20-25 below normal and may threaten record lows for the date. Record lows for Saturday 11/10 at KSTL (18F/1973), KCOU (18F/1926), and KUIN (14F/1950) are all within reach, but most likely to be broken at KCOU. Well-below normal temperatures will continue through the weekend along with a period of dry weather. Highs on Saturday will only reach into the 30s across the area, but look for moderating temperatures back into the 40s is likely on Sunday ahead of the next cold front. There is still a fair amount of uncertainty with early next week, but general indications are still for a shortwave trough to eject out of the south-central Plains on Monday. The interaction (or lack thereof) with a northern stream shortwave is one of the main sources of uncertainty. The 12Z deterministic GFS remains the dry holdout Monday/Monday night due to a weaker ejecting shortwave trough out of the south-central Plains and a further south placement of the low-level baroclinic zone. Believe the ECMWF/CMC probably has more of the right idea with a round of light rain/snow mix ending as snow across the southeastern 1/2 of the CWA. In actuality, the possible Monday/Monday night event may turn out to be very similar in many respects to tonight`s forecast, just moved to the southeast about 100 miles. While still about 4 days out, it appears there is the potential for a couple of inches of snow across northwestern portions of the precipitation shield. Main story from Tuesday through the remainder of the forecast will transition back from the potential of wintry precipitation back to very cold air. While probably not record breaking due to some very cold daily records, temperatures 15 to 25 degrees below normal are once again likely during this period. The airmass coming in on Tuesday actually appears to be more impressive than expected early this weekend as evidenced by 850-hPa temperatures which are forecast to drop into the -10 to -15C range. Coldest daytime highs are forecast to be on Tuesday, with readings struggling to even hit the freezing mark. Coldest morning will likely be on Wednesday morning with low temperatures dropping into the teens. The arctic high pressure center is forecast to slide into the Ohio Valley through Wednesday night with strong warm air advection at low levels on its western flank. Moderating temperatures are expected for the middle of next week as high temperatures reach back into the upper 40s to low 50s on Thursday. Gosselin && .AVIATION... (For the 00z TAFs through 00z Friday Evening) Issued at 533 PM CST Thu Nov 8 2018 Light rain and snow is overspreading the forecast area from the west. Expect precipitation to begin in central Missouri within the next hour and into eastern/northeastern Missouri and west central Illinois by 02Z. Temperatures are borderline for snow, but think most of the precip will be snow in central and northeast Missouri as well as west central Illinois. Further south...still think there will be a period of rain-rain/snow mix this evening changing to all snow between 05-07Z. Flight conditions will start out VFR, but should deteriorate to low MVFR/IFR as rain changes to snow. Low MVFR and IFR will continue to prevail after the snow ends early Friday morning, but should be improving during the late morning and early afternoon. Scattered snow showers are expected across the area on Friday afternoon. Any snow shower will be capable of briefly reducing flight conditions to IFR. SPECIFICS FOR KSTL: Still expecting precipitation to start at Lambert between 02-03Z. Temperatures in the area of the terminal are right on the edge between rain/ initially I think there will be a period of rain, then a mix before finally going over to all snow between 05-07Z. Precip should be light, but anytime you have snow in the mix the visibility and ceiling will deteriorate pretty quickly. Think low end MVFR and IFR are likely, especially after the rain changes totally over to snow. IFR ceilings will likely prevail through the early morning hours Friday, increasing to MVFR by 12Z or within an hour or two thereafter. Scattered snow showers are likely to be in the vicinity on Friday afternoon. Any snow shower that hits Lambert will be capable of briefly reducing flight conditions to IFR. Carney && .PRELIMINARY POINT TEMPS/POPS... Saint Louis 32 36 22 36 / 90 50 50 0 Quincy 29 33 17 34 / 100 50 5 0 Columbia 29 35 16 36 / 100 30 20 0 Jefferson City 30 35 16 37 / 100 20 20 0 Salem 34 39 22 36 / 60 20 30 0 Farmington 33 39 20 37 / 60 20 20 0 && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
627 PM EST Thu Nov 8 2018 .SHORT TERM...(This evening through Friday) Issued at 311 PM EST THU NOV 8 2018 ...Areas of heavy snow expected... WV imagery and RAP analysis indicated a broad mid/upper level trough through the central CONUS. A vigorous shortwave trough and 120 knots 250 jet was diving se into eastern Montana. At the surface, a weak ridge sliding through the northern Great Lakes bringing an end to the lingering LES over eastern Lake Superior. 700-300 mb qvector conv ahead of the mid level trough axis supported a developing area of light snow from srn MN into wrn WI. Tonight, expect the area of snow to continue to expand into west and central Upper Michigan as the forcing strengthens ahead of the nrn plains shortwave trough with general accumulations of around an inch. The light wind field with mid level forcing will also favor Meso-low development over central into western Lake Superior. 850 mb temps around -10C will provide enough instability for heavier snowbands that are expected to affect mainly the nrn portion of the Keweenaw Peninsula by late this evening. However, there is still uncertainty with the duration and location of this feature. By late tonight, a mid lake snow band is also expected to move from Lake Michigan into portions of the se cwa, likely in an area from the Garden peninsula to Seul Choix Point. Friday, Although there is uncertainty on how the Lake Superior meso- low will evolve, as the trough axis moves onshore across the west periods of heavy snow and strong winds will develop from closer to KIWD in the moring through the rest of the Lake Superior counties in the west, mainly during the afternoon. The Lake Michigan snowband should still bring moderate to heavier snow to the southeast. There will likely be a lull in the snowfall through much of central Upper Michigan. Friday night, A burst of heavy lake enhanced snow should move into north central Upper Michigan btwn 00z-03z/Sat. However, some models have trended slower with this feature more toward the GEM/ECMWF which have shown a slower progression with the 500 mb low. Since there is higher uncertainty with the timing, an SPS rather than winter headline remains in effect for the north central cwa. However, once the trough moves on shore by late evening or even overnight, a period of heavy lake enhanced snow and strong winds will result in very difficult travel. .LONG TERM...(Friday night through Thursday) Issued at 355 PM EST THU NOV 8 2018 With significant weather in the short term, spent much of the day assisting with efforts related to that. Long term can be summarized by continued cold conditions with occasional chances for snow. Most notable potential impacts are the potential for SE wind lake enhanced snow over the eastern U.P. Sun into Sun night and potential for moderate to heavy NW wind LES Mon night into Tue night. For the Sun-Sun night snow, there is uncertainty with the duration and amount of snow, but does not look too significant at this time. The NW winds LES event is handled well by blended initialization. There is uncertainty with the magnitude and location of the coldest air and enhancing forcing from a shortwave, so can`t get very specific at this time. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 611 PM EST THU NOV 8 2018 Lake effect snow band over the Keweenaw brushing KCMX with IFR vsbys at present will weaken and lift out over Lake Superior this evening as conditions improve to MVFR. A low pressure trough over the lake will begin to move onshore late tonight and Fri lowering conditions back down to IFR and possibly LIFR in moderate to possibly heavy lake enhanced snow at KIWD/KCMX. Expect mainly MVFR conditions until heavier lake enhanced snow band associated with the trough moves onshore Fri night lowering conditions to IFR/LIFR. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 355 PM EST THU NOV 8 2018 As a low slides over western Lake Superior tonight, expect NE winds to increase to 25 kts over portions of the lake late tonight. As the low and associated trough slide drop across Lake Superior and Upper Michigan Fri, expect N gales to 35-40 kts to develop over much of Lake Superior. Gale warnings have been posted. Possible that gales may end up stronger to 40 kts Fri aftn into Fri evening, especially central sections. NNW gales to 35 kts finish up on Sat morning over eastern sections. Winds rest of weekend into early next week should stay 25 kts or less. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Weather Advisory from 5 AM Friday to 3 AM EST Saturday for MIZ007-013-014-085. Winter Storm Warning from 10 PM this evening to 7 AM EST Saturday for MIZ001-003. Winter Storm Warning from 7 AM EST /6 AM CST/ Friday to 7 AM EST /6 AM CST/ Saturday for MIZ002-009. Lake Superior... Gale Warning from 7 PM Friday to 4 AM EST Saturday for LSZ266. Gale Warning from 7 PM Friday to 1 AM EST Saturday for LSZ245>248-265. Gale Warning from 1 PM Friday to 1 AM EST Saturday for LSZ244- 264. Gale Warning from 1 PM EST /noon CST/ to 11 PM EST /10 PM CST/ Friday for LSZ241>243-263. Gale Warning from noon EST /11 AM CST/ to 9 PM EST /8 PM CST/ Friday for LSZ162. Lake Michigan... Gale Watch from late Friday night through Saturday morning for LMZ221-250. && $$ SHORT TERM...JLB LONG TERM...Titus AVIATION...Voss MARINE...Titus
Area Forecast Discussion
National Weather Service Nashville TN
820 PM CST Thu Nov 8 2018 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... As of now, the 88D shows a dearth of activity across Middle Tennessee. An inverted trough is in the process of developing across the mid state, and this will provide the impetus for widespread rain, mainly after 06Z. The HRRR has been consistent in bringing precipitation into the mid state between 06Z and 18Z, so the best POP`s are being held off until the overnight period. Current forecast appears to be on track, so no changes are planned at this time. && .AVIATION... 00Z TAF DISCUSSION. BNA/MQY/CKV/CSV...The evening begins with VFR wx across the mid state. During the next several hours, a surface low will develop along an inverted trough that is currently digging into Middle Tennessee, and widespread rain and MVFR/IFR ceilings will settle in after 06Z. Drier air will move in behind this system from west to east during the day Friday. && .OHX WATCHES/WARNINGS/ADVISORIES... Freeze Warning from 11 PM Friday to 11 AM CST Saturday for Bedford-Cannon-Cheatham-Clay-Coffee-Cumberland-Davidson-De Kalb- Dickson-Fentress-Giles-Grundy-Hickman-Houston-Humphreys-Jackson- Lawrence-Lewis-Macon-Marshall-Maury-Montgomery-Overton-Perry- Pickett-Putnam-Robertson-Rutherford-Smith-Stewart-Sumner- Trousdale-Van Buren-Warren-Wayne-White-Williamson-Wilson. && $$ DISCUSSION......08 AVIATION........08
Area Forecast Discussion
National Weather Service Blacksburg VA
1106 PM EST Thu Nov 8 2018 .SYNOPSIS... A warm front lifts north tonight. A strong cold front will approach from the west Friday, sweeping through the area Friday night. High pressure will settle across the area for the weekend, but wet weather is expected to return by Monday as an area of low pressure moves northeast along the Atlantic coast. && .NEAR TERM /THROUGH FRIDAY/... As of 1100 PM EST Thursday... Rain starting to pick up in coverage across the area, but still more in a scattered nature. Low pressure sits over the middle TN Valley with inverted trough extending northeast into the southern WV mountains, while wedge of high pressure situates itself over the piedmont. The theme overnight will be increased chances of rain, but appears most of it will be on the light side, with steadier to more moderate showers arriving with the front Friday. Otherwise not too many changes to the forecast with cloudy skies and temperatures not falling too much with 40s most places overnight. Previous discussion from early evening... Radar showing higher dbz over southside VA into the NC piedmont but surface obs only showing light rain. This should help moisten the low levels, while at the same time we are seeing the wedge work in from the northeast. Forecast on track for seeing patchy light rain over the area toward late evening with drizzle and fog possible as well. Previous discussion from 4pm... Stream of moisture continues to advect northeastward from the Deep South, this moisture advection occuring atop a residual surface high pressure which is wedging down the Carolinas into the southern Appalachians. Visible satellite reveals this moisture manifesting as a shield of low to mid-level cloud cover which will continue to advance northeastward through the rest of the afternoon. Current radar mosaic shows some intermittent light showers in the western NC mountains but it`s unlikely this is reaching the ground as the air mass below cloud base is still rather dry. Most synoptic scale and higher-resolution convection-allowing guidance generate isentropically driven precip falling into the wedge for tonight but given the dry air in place, it likely will take some time for the column to saturate. Think radar echoes we do see this evening will likely be more virga at least through midnight - in fact the HRRR is dry until early Friday morning. Will therefore show very light rain or drizzle in the forecast, along with areas of mist. Best surge of warm advection occurs after midnight, which should help to produce a steadier light rain. Despite the nocturnal increase in clouds and an 850 mb southerly/southeast jet of 40-45 kts which would normally keep temps from falling much, think temperatures tonight should show some slow diurnal cooling trend given evaporative/wet bulb cooling helping offset the above factors. Shown lows in the 40s areawide for tonight, though upper 40s across the Piedmont and Southside. Also trended QPF down towards a few hundreths to no more than a tenth of an inch, given evaporation effects and expected very light nature to rain intensities, with the best chance of measuring being early Friday morning. Overcast wedge conditions with intervals of mist/fog and light rain should be ongoing early on Friday, which will help keep temperatures from climbing much from overnight lows. We`ll then await the approach and eventual passage of a strong cold front which will herald a change toward a much cooler air mass. Today`s model guidance have slowed the front`s eastward passage some, closer to an 16-00z passage areawide, when compared to earlier model runs. We should start to see a period of steady light to moderate-intensity rain (with Categorical PoPs) between 11-1 pm in southeast WV and into Bland/Tazewell Counties, toward early to mid afternoon across the mountains of NW NC up through the Blue Ridge/NRV and southern Shenandoah, and toward late afternoon in the foothills, Piedmont and Southside. Forecast sounding show a limited amount of instability elevated over the wedge inversion, which may only go to augment rain rates. Have currently downplayed the threat of thunder, but if we can realize the elevated instability, a few rumbles within the line itself not out of the question. Shown total rainfall amounts from a third to half inch generally, but with amounts from two thirds to 0.80" across the northern and western third of the forecast area. Amounts this much are not expected to result in hydrologic issues, but localized ponding or nuisance issues from storm drains clogged from leaves I suppose could be a possibility. Opted for a non- diurnal temperature trend, which will show temperatures rising very little if at all given persistent cloud cover and at least off and on rain for a good part of the day. May see temperatures rise into the 50s across Smyth and Tazewell, but otherwise looking at temperatures in the mid/upper 40s. Forecast confidence is high, though is moderate on rainfall amounts and lower confidence on coverage of thunder, if any, on Friday. && .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... As of 349 PM EST Thursday... A significant shot of cold air lies behind the cold frontal passage late Friday into early Friday night - expected to be the coldest shot of air yet experienced to this point in Fall - and cold advection should begin in earnest areawide into Friday evening. Main potential weather-related impacts of note this period are gusty to potentially strong northwest winds Friday night into Saturday for our Blue Ridge counties, and rain changing to a period of light accumulating wet snows in the higher elevations from western Greenbrier County down into the mountains of northwestern North Carolina Friday night. On the wind threat, most areas in the western CWA should at least see breezy conditions with gusts at times up to 30 mph. However, 850 mb jet maximizes to near 50 kts near the Blue Ridge overnight which should support gusty northwest winds at least through the southern Blue Ridge from Watauga County through Roanoke starting overnight into early Saturday morning. A couple potential hindrances to potential for Wind Advisory level gusts include really high inversion heights (above 4000` in most western locales from the 12z GFS), and the likelihood for post-frontal clouds/precip. Best pressure rises occur more on Saturday with breezy conditions developing into the Piedmont to around 25 mph, even as the low-level jet begins to weaken. It`s still not certain we`ll see Advisory- level wind gusts from this event, but I did bump wind gusts in the southern Blue Ridge to near-Advisory level (around 45 mph). Best cold advection occurs tomorrow night into early Saturday, with 850 mb temperatures by 12z Saturday expected to plunge to values from near 0C in our northern NC Piedmont counties, to -6 to -9C from the Blue Ridge west. Expect a rather quick transition of mountain rain to snow showers before midnight in western Greenbrier County, and then into the overnight across the mountains of northwestern NC. Cold advection is so strong that even areas from the New River Valley and southeastern WV may see their first snowflakes since last winter overnight. Soundings at Elkins and Beckley show some level of shallow instability that could help bump snow accumulations to some extent in western Greenbrier County, but do expect snow ratios to be better than 10:1 (up to 13:1) at these elevations overnight. Overall looking for a few to several flakes from the New River Valley west, with expected accumulations of a dusting to an inch towards Mt Rogers and the mountains of northwestern North Carolina. Up towards western Greenbrier, amounts there of around 1 to as much as 2". In terms of temperatures, looking at lows Friday night into the mid 20s to lower 30s, while highs on Saturday should range from the lower-mid 30s in the higher elevations in western Greenbrier and the mountains of northwestern NC, the upper 30s to near 40 in the New River Valley, and into the 40s across the eastern half of the area. Cold, dry high pressure settles overhead Saturday night leading to overall dry weather. It will be quite cold given near ideal radiational cooling Saturday night. 850 mb temperatures should be sub-zero (-2 to -4C) in most locations with good conditions for early-season snowmaking for the ski areas in northwest NC and the mountains in WV. Should see widespread lows in the mid 20s, with mid to upper teens in the western mountains and the New River Valley. Confidence is high on the cooler weather pattern ahead, but is low to moderate on mountain snow amounts and on peak wind gusts overnight into Saturday morning. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 349 PM EST Thursday... Deep synoptic scale trough will develop over the central United States Sunday and Monday. Spread in solutions between the models gets larger and larger after Monday night. Starting out at the surface with high pressure centered over Virginia Sunday morning. Then southwest flow and warm air advection Sunday, Sunday night and Monday. Cold front will move through Tuesday night and lead in 850MB temperatures in the -6 to -10 range. Air mass moderates Wednesday and Wednesday night. Deep moisture returns to the Mid Atlantic region throughout the day Monday. May take until Tuesday night to clear out the upslope clouds on the western slopes of the central Appalachians. Rest of the area will clear out on Tuesday. High pressure builds in for Thursday. Wednesday and Thursday are much more uncertain. Some suggestion that a coastal low may bring widespread precipitation to the area by Thursday. Confidence is average for all elements until Wednesday, then below average. && .AVIATION /04Z FRIDAY THROUGH TUESDAY/... As of 554 PM EST Thursday... Expect broken to overcast VFR ceilings through this evening, then should see lower cigs as we head into overnight with patchy light rain/drizzle and MVFR fog. Ceilings/visbys should then begin a steady lower to sub-VFR as warm frontal precip overspreads the TAFs atop wedge conditions early Friday morning. Look for areas of 5-6 SM rain with mist/fog through the early to mid-morning Friday hours, with ceilings lowering to a widespread MVFR-IFR range. A strong cold front will likely introduce a period of steady moderate-intensity rain for western terminals by 13-15z, then east by 17-19z, with rain dissipating to light rain or nothing toward the end of the taf period. While surface winds should be variable under 5 kts at most sites (except southeast at Bluefield 6-10 kts) in the pre- frontal air, a strong south- southwest jet of 45-50 kts within the temperature inversion around 4000` could lead to choppy conditions for small aircraft flying in the western slope of the Appalachians. Forecast confidence is high for through the evening, then medium overnight into Friday. Extended Discussion... A Cold front will shift east of the region Friday night. Expect sub-VFR in the mountains with upslope rain/snow showers with improving conditions east. High pressure and mainly VFR conditions return to the region Saturday night into Sunday. Clouds and light precipitation will be on the increase again during the day Monday thanks to a southern stream system approaching the Carolinas. Expect an increase in sub-VFR conditions as the day progresses, especially during the late afternoon, with sub-VFR continuing into Tuesday as the storm system moves overhead. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AL/PM NEAR TERM...AL/WP SHORT TERM...AL LONG TERM...AMS AVIATION...AL/PM/WP
Area Forecast Discussion
National Weather Service San Angelo TX
503 PM CST Thu Nov 8 2018 .AVIATION... /00Z TAFS/ IFR/LIFR ceilings will continue at all sites through the overnight hours. Ceilings will begin to lift into the MVFR category by mid morning Friday, with VFR ceilings returning by mid to late afternoon. Scattered showers along with areas of drizzle will be possible overnight. In addition, patchy fog will be possible, especially at KABI, this evening. North to northeast winds will increase to 8 to 14 knots, with higher gusts, this evening and continue into the morning hours. Winds will decrease to near 10 knots by mid to late afternoon. && .PREV DISCUSSION... /issued 406 PM CST Thu Nov 8 2018/ UPDATE... Issued a Dense Fog Advisory for the Big Country until 9 PM. The current visibilities are 1/4 to 1/2 mile from Abilene to Sweetwater. The latest HRRR Hi Res model has visibilities less than 1/2 of a mile through 6 PM, and will keep an eye on surface observations. 21 PREV DISCUSSION... /issued 254 PM CST Thu Nov 8 2018/ SHORT TERM... (Tonight and Friday) The cloudy skies and patchy mist and drizzle will continue into the evening. A slow moving frontal boundary located across the northwest portions of the area will continue its slow march to the southeast through the evening. We are going to watch our southeastern counties, primarily; Mason, Kimble and San Saba counties for the potential for some convective activity to develop late this evening. Upper air SKEW-T soundings show a pronounced low level inversion across these areas. Just above that inversion, CAPE values are running in the 1000 J/kg range suggesting that elevated convection will be possible as the frontal system moves into the area. The window for thunderstorm development will be a couple of hours at best with the threat of any of the storms becoming severe is very low. There could be isolated cases of a storm or two producing small hail. Behind the front, continued overrunning will over the shallow cold airmass in place will keep skies overcast through the night. Temperatures will drop 5 to 8 degrees from where they are right now. Overnight lows will be in the upper 30s across the Big Country, with 40s across the rest of the region. By tomorrow a tightening pressure gradient will increase the strength of the northeasterly winds. Winds will increase to 15 mph with gusts up to 25 mph possible. Drier air moves into the region and the clouds will finally begin to dissipate and bring an end to any lingering rain showers that may develop during the early morning hours. Skies will begin to clear out by the late morning and perhaps we could see some peaks of sunshine by lunchtime. With the winds still out of the northeast and a cold, dry airmass in place, temperatures will remain cool across the area on Friday. Expect highs only in the upper 40s to low 50s. LONG TERM... (Friday Night through Wednesday) It will be cold again for Friday night but due to some increase in cloud cover, temperatures should remain above freezing across the area. Could see a few readings near 32 degrees towards daybreak over the northern Big Country but most of the area will see lows in the mid and upper 30s. Should see a fair amount of cloud cover on Saturday, which will keep temperatures on the cool side, with highs in the lower 50s. Warmer temperatures are on tap for Sunday ahead of a strong cold front approaching from the north. Skies will be partly cloudy, with light south winds and afternoon highs in the lower and middle 60s. A strong upper level shortwave will move across the Plains Sunday night and Monday, with an associated strong cold front moving south across the area. The front is expected to clear far southern counties by the mid morning hours on Monday, with much colder temperatures following the front. High temperatures in the 40s will occur early on Monday, with temperatures likely falling into the upper 30s across the northern two thirds of the forecast area by afternoon. Blustery north winds will also follow the front on Monday, with wind chill readings possibly in the upper 20s and lower 30s by afternoon. There will also be a chance for some rainfall behind the front as the upper trough moves across West Texas. Latest model guidance indicates that temperatures may be cold enough to support a rain/snow mix across the Big Country on Monday but confidence remains low at this time. The first freeze of the season will likely occur next Monday night, with temperatures falling into the upper 20s and lower 30s. Freezing temperatures are also possible again Tuesday night, with forecast lows in the 30s. && .PRELIMINARY POINT TEMPS/POPS... Abilene 38 52 34 52 / 40 5 0 10 San Angelo 41 53 37 54 / 60 10 10 10 Junction 46 54 40 53 / 70 30 10 10 Brownwood 42 53 36 52 / 60 5 5 10 Sweetwater 37 49 35 52 / 40 5 0 5 Ozona 42 50 40 51 / 50 20 10 10 && .SJT WATCHES/WARNINGS/ADVISORIES... Dense Fog Advisory until 9 PM CST this evening for Callahan- Fisher-Haskell-Jones-Nolan-Shackelford-Taylor-Throckmorton. && $$ Daniels