Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/07/17

Area Forecast Discussion
National Weather Service Caribou ME
909 PM EST Wed Dec 6 2017 .SYNOPSIS... High pressure will build south of the region tonight into Thursday and remain to our south Thursday night into Friday. Low pressure will develop off the East Coast Friday night and track to our east on Saturday. && .NEAR TERM /THROUGH THURSDAY/... 9:09 pm update...Low pressure is seen on satellite pictures pulling just east of James Bay. The 00Z KCAR sounding showed strong southwest flow aloft around a mid to upper level low in Canada. Clouds have been increasing over the past couple of hours across the western Saint John Valley and North Woods, and another patch of clouds more or less just developed in place across the Bangor Region. Other clouds are along the immediate coast. The clouds are having an impact on temperatures, and have caused them to hold steady or rise a couple of degrees where they have either formed or moved into an area. Regional and MRMS radar data and observations indicating snow showers in parts of northern NY (lake effect) and an isolated snow shower or some flurries could move into mainly far western portions of the CWA overnight. Made some tweaks based on the latest conditions, but at this time nothing too significant. Previous discussion... Colder but still above normal for the first week of December. The cold front has pushed its way into the coastal waters w/clouds pulling away w/it. Things are setting up to be much colder tonight than last night w/skies starting out mostly clear. An upper disturbance is forecast to move across the region tonight into early Thursday. This feature was picked up well on the satl wv imagery moving across Ontario. The NAM and RAP pick up this feature well and show increasing clouds overnight especially north and west. 12Z UA showed a 50 kt jet streak residing across Ontario. Then NAM and RAP push this feature across our CWA overnight into early Thursday. The 12z run of the GFS was picking up on this feature as well. The sounding data showed moisture available from 850mbs to about 700mbs. Weak forcing could be enough to set off some flurries or perhaps a snow shower. Interesting enough, the BTV SNSQ parameter showed some potential for activity for northern and western areas. Other parameters such as CAPE and 850-700 mb lapse rates are lacking. Therefore, decided to go w/slight chance(20%) for snow showers across the far western areas by early Thursday morning. Temps will be held up some w/the clouds especially across the north and west where the cloud cover will be most prominent. For Thursday, that trof is shown to move across the CWA w/the potential for some snow showers/flurries again north and west. The downslope component to the winds will aid in keeping skies partly sunny. Winds will pick up later in the morning at speeds of 10 to 15 mph adding a chill to the early December air. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... A large trough of low pressure will be anchored over the northeast Thursday night. We will be in a corridor or dry air that runs between a long band of moisture along a southern branch jet stream to our south and some moisture pooled in the center of the trough to our west. Some of the moisture from the center of the trough may bring a few flurries to the higher elevations to the west later Thursday night or Friday. Low pressure will be forming along the southern branch jet stream to our south Friday night into Saturday as a strong upper level shortwave dives south through the Great Lakes. The wave of low pressure offshore appears very flat with the flow open and positively tilted. Therefore, it will likely slide out to sea well to our east but may brush the eastern Downeast coast with a bit of light snow late Friday night into early Saturday. It is noted that the Canadian model and the ECMWF bring the system close enough for some light to moderate snow over our region. The GFS and its ensembles, however, favor the system sliding away to our east. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... A large, deep cold trough will remain over the northeast through the weekend and into early next week. Some moisture from within the trough may bring some light snow or flurries across the area Saturday night into Sunday and again on Monday. However, currently there are no well organized storms to bring more than some light snow. A more substantial storm is still expected to form off the southeast coast and intensify as it lifts north on Wednesday. Latest GFS guidance is showing the eastern trough to be too large and too far east to allow this system to impact us, possibly taking it well to our east and out to sea during the mid-week period. The ECMWF, however, brings the storm much closer with possibly a significant impact on our region. Will just introduce chances for precipitation this far out. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... NEAR TERM: VFR for this term for all terminals. SHORT TERM: VFR conditions are likely Downeast Thursday night through Friday with some occasional MVFR conditions possible in patchy stratus over the far north. VFR conditions are likely Friday night through Saturday. Coastal areas may briefly drop to MVFR late Friday night through Saturday morning as low pressure slides to our east. MVFR conditions are likely across the north Sunday in low to mid level clouds and flurries with VFR to MVFR conditions Downeast. && .MARINE... NEAR TERM: The wind has diminished on the coastal waters this evening below SCA levels and the seas have subsided to 7 to 8 feet on the coastal waters. The wind will likely pick up again as the colder air spills out over the waters, so at this time will not transition to a small craft advisory for seas only as there likely will be a pick up in the wind later tonight into Thursday. Thursday is tricky as the GFS and NAM both show a 25 kt wind at 925 mbs over the waters w/the passage of the trof. Conditions for a full SCA(Winds/Seas) appears marginal attm. The later crews can assess this further w/the later model guidance. SHORT TERM: A SCA may be needed Thursday night for winds gusting up to 30 kt over the offshore waters. Winds may remain close to SCA Friday into Friday night over the offshore waters. Winds should then be below SCA Saturday into Sunday unless the offshore storm system ends up stronger or closer in to the coast. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory until 4 AM EST Thursday for ANZ050-051. && $$ Near Term...CB/Hewitt Short Term...Bloomer Long Term...Bloomer Aviation...CB/Hewitt/Bloomer Marine...CB/Hewitt/Bloomer
Please see the 00Z aviation forecast discussion below.

AVIATION... Light rain is ongoing across all TAF sites and is expected to continue through the overnight hours into Thursday morning. Models show a little more dry air in place at AUS when compared to SAT, SSF and DRT. For AUS, we will keep -RA in the forecast overnight, along with VFR cigs. Shortly after sunrise Thursday, the rain shield should shift south of the terminal and we will remover the mention of -RA and keep skies VFR. At SAT and SSF, the low-levels will be a little more saturated and will go with MVFR cigs and light rain through mid-morning Thursday. Rain should begin to taper after 16Z and will show conditions improving to VFR. At DRT, we will also keep MVFR cigs and -RA in the forecast overnight. There is a concern that some of the rain could mix with light snow early Thursday morning during the 08Z-12Z time frame. At this time, am not quite confident enough to mention any frozen precipitation in the forecast. In addition, surface temperatures are expected to remain above freezing overnight. PREV DISCUSSION... /ISSUED 341 PM CST Wed Dec 6 2017/ SHORT TERM (Tonight through Thursday Night)... A very complicated short term period in regards to winter weather prospects overnight and through Thursday. The rain shield currently observed across South Central Texas will evolve to include snow mixed in this evening and overnight for locations mainly on the Plateau and Hill Country but could reach as far east as the I-35 corridor. Exhaustive interrogation of forecast soundings have not made things much easier either. While surface temperatures will struggle to fall due to an extensive cloud shield over the region, they will come very close to the freezing threshold across western Val Verde, much of Edwards and Real counties, and into Gillespie and Kerr counties. However, low level temperature profiles have been trending colder lending more credence to the possibility for snow/rain mix, and perhaps even all snow for periods of time after midnight until daybreak for these same areas. Farther to the southeast, reaching the I-35 corridor, rain should be the most dominant precip type, but still cannot rule out some snowflakes mixed in as well. Regardless, with surface temperatures likely to hover at or just above freezing for these areas, and still quite a bit above freezing elsewhere, little to no accumulations are expected. If accumulations do occur, they will likely be dustings at best, likely in far western Val Verde and across our northern CWA border to Gillespie county. Perhaps more of a concern is any standing water due to today`s rainfall activity freezing on bridges and overpasses where temperatures will be the coldest, again in the Hill Country and Plateau areas. Tomorrow morning, some folks may wake to find a few snowflakes still before transitioning back to all rain late in the morning and into the afternoon hours. The rain shield is expected to push slowly southward over the course of the day and likely south of San Antonio shortly after the noontime hour. Have trended PoPs down over the course of the day tomorrow closely following the trends of the TTU- WRF and HREF. Even colder temperatures are expected Thursday night and overnight into Friday morning and if lingering rain activity continues in the southern zones when temperatures begin to fall to near freezing, some wintry mix could be seen in our southwestern zones, but again, no accumulation is expected at this time. LONG TERM (Friday through Wednesday)... As the shortwave responsible for this cold front passes over Friday, it will begin a trend of warming through the weekend, reaching highs in the 60s over the weekend and through the first half of next week. By mid week, a broad and weak low over the Gulf of California is expected to slowly traverse over the US/Mexico border. While a dry forecast is expected through the week during this transition, our next best shot at PoPs could be Friday as this low further weakens into a shortwave as it passes over Texas. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 43 38 51 31 55 / 90 70 30 10 0 Austin Bergstrom Intl Airport 43 36 51 30 56 / 90 80 40 20 0 New Braunfels Muni Airport 43 37 50 32 55 / 90 90 60 20 0 Burnet Muni Airport 41 36 48 27 55 / 90 70 20 10 0 Del Rio Intl Airport 46 37 46 31 55 / 80 90 60 20 0 Georgetown Muni Airport 42 38 50 28 54 / 90 70 20 10 0 Hondo Muni Airport 46 38 49 29 57 / 90 100 80 20 0 San Marcos Muni Airport 43 37 49 31 55 / 90 90 60 20 0 La Grange - Fayette Regional 42 37 49 31 52 / 90 90 60 30 0 San Antonio Intl Airport 44 37 49 34 56 / 90 90 70 20 0 Stinson Muni Airport 45 38 48 34 55 / 90 100 80 30 0 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Mesoscale/Aviation...24 Synoptic/Grids...Treadway Public Service/Data Collection...Williams
Area Forecast Discussion
National Weather Service Jackson MS
933 PM CST Wed Dec 6 2017 ...WINTER WEATHER POTENTIAL THURSDAY INTO FRIDAY... .UPDATE... Updated for evening discussion. && .DISCUSSION... Previous forecast remains on track, with a precipitation shield draped across the southern half of the CWA as moisture aloft interacts with a frontal boundary parked to our south over the north-central Gulf of Mexico. It consists primarily of light rainfall, although some sleet could continue to mix in occasionally throughout the overnight period. No sleet accumulation is expected. Light northwesterly surface flow will continue overnight and low temps will be in the upper 30s for most locations. /TH/ Prior discussion below: Getting some reports of some light sleet in Northeast Louisiana as well as our Southern Mississippi counties. So have included light sleet in the forecast through the night. Latest HRRR model soundings shows some low level wet bulbing in the low level dry layer going on through the night for some patchy sleet to continue. With warm ground temps expecting no impacts on roadways./17/ Prior discussion below: Been getting reports of some patchy light sleet across the southern counties late this afternoon due to wet bulbing. So have included it in the grids through this evening until midnight. Expect no impacts on road conditions./17/ Prior discussion below: Through the day Thursday: Expect cold and generally cloudy conditions to continue across the region through tomorrow afternoon with light precipitation intermittently spreading east/northeast-ward across mainly the southern half of zones. All this is occurring as the big surface frontal boundary that came through our region yesterday remains stalled in the northern Gulf of Mexico and moisture aloft overruns the sloped frontal surface in advance of another upper wave digging into the backside of the big trough overhead. Some sleet has been observed this morning in central zones where the sub-cloud layer was dry enough to create ice pellets through a wet- bulbing process a few thousand feet above the ground. No impacts were seen as surface temperatures were at least several degrees above freezing. The same process could occur, primarily on the northern edge of the precipitation shield, tonight into tomorrow, with the potential for impacts through this time remaining very low because temperatures will be above freezing. At this time we will keep mention of anything of this sort (at least through tomorrow afternoon) out of the official forecast because rain will be predominate and any sleet non-impactful. Of course the forecast could be modified if sleet becomes prevalent at times. Once again tomorrow the presence of thicker clouds and continuing light precipitation will keep the chilliest high temperatures oriented in southern zones (contrary to what is usually the case). /BB/ Thursday night through next week: Thursday night into Friday will be the most impactful part of the long term forecast as well as the most challenging part. The lingering axis of stratiform rain over the southeast parts of our CWA will continue to slowly push out of the area, but not until much colder air advects into the area overnight Thursday and early Friday morning. Temps will fall into the upper 20s in the north and near to slightly above freezing in the south. Beginning after midnight Friday morning, a slow transition from rain to snow is likely in areas south of the Natchez Trace Parkway. The question continues to be how much dry air will filter in on the backside of the precip axis and at what rate will the precip fall. This precip rate could be a factor of how much snow accumulates, how much rain is able to transition to snow, or even more importantly how cold the temperature even falls. The science behind rain to snow transition and latent heat release is very intricate and holds the way for a lot different possibilities. Overall, the Euro and Canadian models still show more precip and precip farther north with this system. For this forecast, we went with a blend of the Euro and the main guidance. Confidence continues to increase in snow chances. Flurries in the metro area cannot be ruled out now. Any snow is not expected to impact roadways at this point and is only expected to accumulate on grassy areas or rooftops. As the temperature rises Friday morning after sunrise, there will be another transition back to all rainfall with the rain finally pushing out of the area in the afternoon. The trough axis will cross the CWA Friday night and bring the coldest temps of the season so far. A hard freeze is certainly expected Saturday morning. One thing to watch for that morning will be black ice. If any roads have not dried by then, then black ice will certainly be a threat. Once on the back side of the trough though and with rising heights, temps will warm into the 50s for the rest of the weekend. Skies will clear with subsident air around a surface high pressure over the northern Gulf Coast. Temps will continue warming on Monday to about normal for this time of year. Going into early Tuesday next week, another upper trough will swing through the eastern U.S. and slide an associated dry cold front into the CWA and once again cool temps off just a bit. /10/ && .AVIATION... 00Z TAF discussion: Expecting mainly VFR conditions through the next 24 hours although there will be plenty of clouds around and a fair amount of light rain spreading across along and south of the I-20 corridor through this time. A few sleet pellets mixing in with the rain at times cannot be ruled out over this period but surface temperatures where this is occurring will be above freezing and no impact is expected, at least through tomorrow afternoon. Ceilings will be lowest intermittently through this time at MEI/HBG, although even here they will almost entirely be above 3 kft. Winds will be light from the north/northeast through 24 hours. /17/BB/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 39 50 31 43 / 28 24 21 20 Meridian 38 47 32 42 / 33 47 34 38 Vicksburg 38 49 31 44 / 22 16 17 13 Hattiesburg 39 45 34 41 / 79 86 61 66 Natchez 38 48 31 43 / 53 43 27 23 Greenville 37 48 29 42 / 5 2 3 3 Greenwood 36 49 28 43 / 7 5 4 4 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
949 PM EST Wed Dec 6 2017 .SYNOPSIS... A cold front will be stalled offshore through the end of the week with areas of low pressure developing along it. An arctic air mass will move in over the weekend behind a stronger cold front. Another arctic cold front will move through by mid week next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... As of 940 PM Wednesday...Bands of light rain continues to move northeast across the region through the overnight hours. Latest HRRR shows continuing light rain with light QPF overnight before thinning out inland late tonight. Will continue with near 100 percent PoPs overnight as most areas will at least receive measurable rain. No other big changes to the forcast as lows should be in the upper 30s to lower 40s in most locations with mid 40s along the Outer Banks. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... As 3 PM Wed...A break in the widespread rain occurs on Thursday as weak ridging briefly builds in from the north. Have just chc pops northern half while likely pops reside across the southern half, with best chances of rain along the Crystal Coast. Otherwise, cloudy and chilly conditions will be the rule. Highs expected to reach the upper 40s. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... As of 330 AM Wednesday...Models continue to indicate cold and wet period through Friday night, followed by Arctic air mass spreading in over weekend. Some model differences persist on timing of precip ending Saturday, otherwise in good agreement most of period. Main adjustments with this issuance were to have likely to categorical POPs across most of area through Friday night, and did add mention of possible mix with light snow over western-most sections late Friday night and Sat morning. Thursday Night through Friday night...Models remain in good agreement of wet pattern this period as slow moving upper trough from eastern Canada to SW U.S. will tap atmospheric river from Pacific Ocean for favorable overrunning precip development with frontal boundary stalled offshore. This will result in periods of light to occasionally moderate rain through Friday night with storm total rainfall of 1 to 3 inches, heaviest along and east of Hwy 17. Have adjusted POPs accordingly with main threat of moderate rain mentioned Thu night and Friday as main trough axis begins to approach from west, resulting in stronger low pressure wave development south and east of area along stalled boundary. Main core of colder air mass will remain west and north of area until late Friday night into Saturday. Still looks mainly likely cold air moving in as moisture exits but enough support to mention rain possibly mixed with some light snow over west/northwest portions of Duplin-Martin counties late Friday night into Saturday morning. No accumulation expected due to relatively warm ground temps. Temps mainly between 35-45 degrees most of period except some highs near 50 along coast. Saturday...Model timing differences continue with GFS faster on upper trough while ECMWF slower and lingering precip through the day. Used model blend with chance POPs lingering over eastern sections during the day, then tapering off by evening. Highs from lower 40s inland to near 50 coast. Saturday night through Monday...Arctic air mass will spread over area producing temps 10-15 degrees below normal. Lows mainly mid 20s to mid 30s and a few degrees colder Sun night with possibly frost or light freeze for Outer Banks where growing season has not ended. Highs Sunday mainly in 40s, moderating to around 50 Monday. Monday night and Tuesday...Approach of next upper trough will lead to moderating air mass Monday night and low chance POP for showers on Tuesday. 00Z ECMWF is faster with this trough and is indicating potential for light mixed or frozen precip, while GFS slower and warmer. Given uncertainty for day 7, will keep precip as just rain showers at this time. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... Short Term /Through 00Z Friday/... As of 630 PM Wednesday...MVFR conditions currently observed at KEWN, KPGV and KOAJ. With precipitation remaining light, think this will continue for a few hours before becoming VFR as rain area starts to diminish later tonight. A break in the rain expected on Thursday , especially for KISO and KPGV where some drier air works in from the north. Winds will be light northerly through the period. Long Term /Thursday Night through Sunday/... As of 400 AM Tuesday...Sub-VFR conditions likely with widespread overrunning precip Thu night through Friday night. Conditions improving to VFR for weekend with drier and colder air mass building in. && .MARINE... Short Term /Through Tonight/... As of 950 PM Wednesday...Based on current observations showing generally 10-15 knot winds and 3-5 foot seas, have allowed the SCA for the waters north of Oregon Inlet to expire. Will continue the SCA into noon Thursday from Oregon Inlet south to Ocracoke where winds are more gusty with seas hovering around 6 feet. Expect northerly winds of 10-20 knots overnight and Thursday. Seas should subside in all areas by midday Thursday. Long Term /Thursday night through Sunday/... As of 400 AM Wednesday...Elevated seas will linger into Thu morning. Persistent gradient between high pressure to west and low pressure development along stalled front offshore will keep NW-N winds 10-15 KT through Thu night. Models have trended stronger with winds Friday and Friday night with stronger low development and adjusted forecast to indicate period of 15-25 KT winds mainly outer waters. Winds will become NW and diminish to 10-15 KT Saturday, then increase to 20-25 KT Sat night and Sunday as Arctic air mass moves in. Seas will subside to 3-5 ft Thu night, then some 6 foot heights expected outer waters Friday into Saturday and 5-7 ft there Sat night into Sunday. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...None. MARINE...Small Craft Advisory until noon EST Thursday for AMZ152-154. && $$ SYNOPSIS...TL NEAR TERM...CTC SHORT TERM...TL LONG TERM...JBM AVIATION...CTC/TL MARINE...CTC/TL
Area Forecast Discussion
National Weather Service Blacksburg VA
943 PM EST Wed Dec 6 2017 .SYNOPSIS... A cold front will stall off the coast tonight. Colder and drier weather continues into Thursday. Friday, low pressure will shift along the front bringing some snow the piedmont/foothills. This system pulls east by Saturday morning. && .NEAR TERM /THROUGH THURSDAY/... As of 930 PM EST Wednesday... The late evening update will continue to reflect little change in the overall forecast. Have made some minor adjustments to the exiting scattered sprinkles across the the far southeastern sections of the region as that activity continues to edge eastward. Sky cover has remained on the cloud side across the entire area. A decrease in coverage across the northwestern sections looks more probable later tonight. Temperatures are within a couple of degrees of the forecast values, so not notable adjustments there. As of 610 PM EST Wednesday... The forecast update for early this evening will reflect little change from the afternoon issuance. However, one adjustment will be the inclusion of some patchy sprinkles across parts of Southside Virginia and neighboring sections of north central North Carolina. Radar returns are indicating dBZ values in the 20s to lower 30s values over parts of this area. Given cloud heights are still around 10,000 ft AGL, suspect that at best some sprinkles are reaching the ground in a few spots. Currently, there is an enhanced band of these 20-30s dBZs along a line from near Reidsville, NC to Danville, VA to Phenix, VA. Have also adjusted hourly temperature, dew point, wind, gusts, and sky cover to better reflect the latest observations and expected trends through the late evening hours. As of 145 PM EST Wednesday... Upper flow remains southwest this evening with jet induced cirrus/cirrostratus overhead, so sky cover will stay mainly cloudy this evening. Stronger shortwave dives into the Lower Great Lakes late tonight with several embedded vorts ahead of it moving across the southern Appalachians into Virginia. 8h flow will be northwest with models favoring some upslope lower clouds overnight in the west but precip threat will be very low with deeper moisture along baroclinic zone along the coast. Some low/mid level cloudiness early on this evening in southside VA and may see a sprinkle. Lows tonight will be actually closer to normal, with mid to upper 20s in the mountains, to lower to mid 30s east. Thursday, more of the same with mid/high clouds keeping the area cloudier, with main moisture axis of precip well to our southeast, as main shortwave shifts toward the eastern Ohio Valley to mid Mississippi Valley. Highs should range from the mid 30s higher ridges, with upper 30s to around 40 rest of the mountains/west of Blue Ridge, with mid to upper 40s east. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... As of 300 PM EST Wednesday... The region will remain in the RR quad of energetic upper jet with broad synoptic ascent through Friday night, while waves of low pressure ripple along a baroclinic zone along the coast. As the baroclinic zone buckles a bit, additional forcing associated with deformation on the northwest side of a wave will push precipitation into the piedmont Friday/Friday night. As the precipitation nudges into the region Friday, precipitation type will favor all snow up to the Blue Ridge where QPF will be lightest and result in just some flurries. In the piedmont where a bit more QPF is expected it is looking like a mix of rain/snow and with the ground still warm any accumulations will be limited to a slushy coating. Latest model runs are trending the back edge of the precipitation a bit further to the northwest. If this continues QPF may increase with a corresponding change to any snow accumulations, so this will be watched closely. Any lingering precipitation will be pulling off to the east late Friday night/Saturday morning. After a brief lull Saturday afternoon, a vigorous short wave will drive a low through the Great Lakes and into New England with a trailing cold front moving through the Appalachians. This will bring a good chance of upslope snow showers to locations west of the Blue Ridge Saturday night/early Sunday morning, along with very blustery winds ushering another shot of cold air. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 300 PM EST Wednesday... CONUS remains locked in an amplified pattern featuring a western ridge and an eastern trof, keeping the Appalachians and central mid Atlantic region in temperatures well below normal through the middle of next week. Short wave energy moving through the upper trof will fuel blustery northwest winds as they drive periodic reinforcing surges of cold air into the region. There will also be a chance for upslope snow showers west of the Blue Ridge mainly through the first part of next week, possibly mixed with rain. There are also hints of some synoptic forcing developing along a baroclinic zone just off to our southeast which may brush close enough to bring some rain and/or snow showers to Southside and portions of the piedmont Tuesday, though the bulk of precipitation will remain closer to the coast. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... As of 605 PM EST Wednesday... VFR conditions are expected during the extent of the TAF forecast period concluding at 00Z Friday/7PM Thursday. Winds will generally be light and variable or light from the west overnight. During the course of the daylight hours Thursday, most areas will see a slightly stronger west or southwest wind. Extended Discussion... Should see continued VFR Thursday night into early Friday with light north to northwest winds, as a disturbance rides along a frontal zone well south of our region. The front to our southeast will have a low pressure wave along it while the upstream trough digs a little. Could see some snow and sub-VFR cigs/vsbys toward DAN/LYH in the Friday afternoon through Saturday time frame. An arctic cold front this weekend, could also bring snow showers to the mountains with potential sub- VFR ceilings and intervals of sub- VFR vsby mainly at BLF/LWB, with post- frontal strong northwest winds Saturday night into early Sunday. VFR conditions then return Sunday evening. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AL/WP NEAR TERM...DS/WP SHORT TERM...MBS LONG TERM...MBS AVIATION...AL/DS/WP
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Thursday) Issued at 231 PM CST Wed Dec 6 2017 An elongated region of H925-H850 Fg forcing was wrapping southward along the upstream flank of an H500 trough axis early this afternoon. Light to moderate snow has been reported across central Nebraska and western Iowa with this forcing band with visibilities of a mile or less in a few locations. CAA behind this line coupled with large T/Td spreads and wet bulb temps near freezing has allowed SN to be reported despite surface temps near 40 degrees. The HRRR has done a decent job depicting this region of forcing and continues to weaken it through the afternoon. RAP/NAM model along with the 12Z TOP RAOB depict a wedge of dry air over SE Nebraska and NE Kansas under the precip generating layer with surface Td depressions of 10 to 15 C. Thus, leveraged a compromise in the precip forecast for the rest of the afternoon, trending upwards in coverage and intensity in the far northern counties while at the same time decaying the band rapidly from 22 to 01Z. Likewise increased cloud cover through the evening hours for the passage of the band--which clears out quickly before 06Z. Surface ridging builds for the day on Thursday with and -12 C H850 thermal trough overhead and keeping surface temps around the freezing mark. .LONG TERM...(Thursday night through Wednesday) Issued at 231 PM CST Wed Dec 6 2017 The extended pattern will be characterized by continued NW flow due to a strong synoptic block anchored over the west coast. Multiple weak perturbations will drop southward during this time, but with minimal forcing and moisture to realize, the sensible weather effects will be minimal. A downslope airmass will translate southeastward into the region starting on Friday, with increasing H850 temps through the weekend. By late Sunday, H850 temps will be above +10 C with corresponding surface temps in the upper 50s to near 60. A second push of cold air will arrive for early next week and drop temps back to near average. The next decent chance of precip may not be until next Monday has the H500 wave/vort max drops through, along with some very low chances of flurries/sprinkles attendant to synoptic jet dynamics on Friday and Tuesday. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 514 PM CST Wed Dec 6 2017 VFR conditions are expected throughout the period. There is a slight chance for some flurries at sites for the next couple hours, but with such scattered coverage of precipitation have left this mention out of the TAF. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Skow LONG TERM...Skow AVIATION...Heller