Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/29/17

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
856 PM CST Thu Dec 28 2017 .UPDATE... Regional aircraft soundings, in addition to the 00z KFWD RAOB, indicate that the remnant frontal inversion (left over from Tuesday`s cold front) has resaturated. This has resulted in gradually lowering cloud heights across the region this evening, with the lowest cloud cover along and west of the I-35 corridor where the deepest moisture resides. The combination of cloud ceilings of less than one thousand feet, fairly deep saturated depths of 3-4 kft, negligible dewpoint depressions, and just a hint of upglide all spell a potential for drizzle and fog here. Indeed, we`ve seen surface observations indicating the development of mist and some drizzle over the last hour slowly expanding eastward to Bowie, Bridgeport, and Mineral Wells. Latest runs of the RAP suggest that isentropic ascent along the 280 K theta surface will only increase as the night wears on, which means we`ll probably be able to squeeze moisture out of the low cloud deck. Given all of this, I`ve gone ahead and added in a mention of drizzle and fog initially west of US-281 this evening, expanding to near and just west of the I-35/35W corridor towards Friday morning. While surface temperatures this hour are running in the mid and upper 30s, I`m not expecting temperatures to fall all that much more overnight given such an expansive low cloud deck and weak warm advection. Thus, the official forecast will keep most of the area above 32F tonight, but we`ll need to keep an eye on the far north and western areas like Bowie, Gainesville, Graham, and parts of Eastland County where temperatures may flirt with the freezing mark. Given the marginal temperatures, elected to forgo any mention of freezing drizzle at this time, but we`ll closely monitor trends this evening and overnight. Otherwise, bumped sky cover up through much of the day on Friday. There are signs that we should get a decent push of drier air as some stronger westerlies arrive just off the deck, so we may yet get to see the sun by late tomorrow afternoon. Updated products have been transmitted. Carlaw && .AVIATION... /Issued 559 PM CST Thu Dec 28 2017/ /00Z TAFs/ The Seattle-like weather featuring a seemingly unending stretch of low cloud cover will continue tonight and through much of the day on Friday. Moisture remains stubbornly wedged between an old frontal inversion, with a base around 2 kft AGL, and a larger subsidence inversion at around 850 mb (around 6 kft AGL). Our presently-ascending 00z balloon corroborates recent ACARS soundings which show this roughly four thousand foot layer is completely saturated, indicating that earlier hopes of some clearing appear quite unlikely. A combination of very modest isentropic upglide and nocturnal cooling will ensure that CIGs continue to gradually build downwards tonight. As a result, I have favored the more pessimistic guidance and show low-MVFR CIGs developing around 03z this evening across the western Metroplex sites, and a few hours later to the east. Similar trends are anticipated at the Waco TAF site as well. Winds during the overnight period will be light at speeds under 6 knots and eventually become easterly. Short-term guidance indicates that very modest ascent may materialize after midnight within the saturated lower-levels as a large mass of warm advection passes by to our north. Since cloud depths will be near 4 kft and bases just 1-2 kft AGL, I can`t discount some drizzle if this lift does in fact materialize, with the most likely time frame around 10-16z. Given the widespread cloud cover, temperatures will not move a lot tonight, but may briefly approach freezing across the outlying Metroplex sites (AFW, FTW, GKY) towards daybreak on Friday. It looks like we`ll finally get an injection of drier air on strengthening westerlies late Friday afternoon and VFR conditions are expected to return. This may be short-lived, however, as re- saturation occurs Friday night and MVFR/IFR CIGs return once again. Carlaw && .SHORT TERM... /Issued 416 PM CST Thu Dec 28 2017/ /Tonight through Friday Night/ The sharp subsidence inversion aloft has acted as a lid, keeping enough moisture trapped to prevent much dissipation in the clouds throughout the day today. This will be the case through the night as well, with an improvement expected to begin Friday morning. Given the slow thinning of cloud cover expected to happen overnight, and light winds, temperatures will remain in the low to mid 30s. Additional west to east clearing is expected during the day on Friday, with clouds sticking around in the northeast. High temperatures on Friday will be dependent on how much, and how far east, clouds manage to clear out. The more hours of sunshine a location gets, the higher the temperatures will be. In the west, temperatures will reach the mid 50s, while low to mid 40s are expected in the northeast. Winds are expected to veer to the south through the day, but not much warm air advection will be associated with the southerly winds. A weak surface low will start to develop in the Texas panhandle overnight on Friday, allowing for a surge of moisture to stream across the the area. Dew point temperatures will climb from the low 30s to mid 40s across Central Texas through the night. With weak isentropic ascent, and a saturated lower atmosphere, patchy drizzle will be possible after midnight and across southern portions of North Texas south of I-20. Temperatures Friday night into Saturday morning will be in the mid 30s across the Red River and mid 40s across Central Texas. Hernandez && .LONG TERM... /Issued 416 PM CST Thu Dec 28 2017/ /Saturday through Thursday/ Our well-advertised arctic outbreak is still on schedule to envelop North and Central Texas beginning Saturday afternoon, and culminating with likely some of the coldest air of the winter by New Years Day and Tuesday. The latest guidance is in decent agreement in bringing the leading edge of the cold air southward through the forecast area during the daytime hours Saturday. One challenging aspect will be the presence of a subtle wave on the front, which the GFS and NAM track southeastward toward Palestine/College Station by late afternoon Saturday. Depending on how this low plays out, we could see a bit more baroclinicity along the front, which in addition to enhancing the temperature contrast across North Texas, may affect the cloud and precipitation forecast for Saturday. Not a lot of confidence on Saturday`s forecast, but suffice to say there`ll be a significant contrast in temperatures by mid afternoon from, say, Gainesville to Killeen and Palestine. For now, have kept small pops across eastern North Texas for the potential of intermittent light rain showers. Things get a bit more straightforward, temperature-wise from Saturday night onward. The freezing line by 12z Sunday may extend from near Comanche to DFW to Sulphur Springs, and driving southward. Cold air advection will start increasing Sunday as north winds pick up. Temperatures along and north of I-20 will have a hard time rebounding at all from their Sunday morning readings. Farther south, some areas will be able to reach the 40s prior to midday, before the colder air starts to invade. By New Year`s morning, low temperatures will have dropped well into the teens across virtually all but the southernmost counties of the forecast area. A rebound into the lower 30s will occur across the south, but from I-20 northward, readings will remain entrenched in the mid to upper 20s, despite the presence of low- angle winter sunshine. The other big challenge remains the precipitation forecast. To cut to the chase, held onto chance pops for generally the eastern half of the area Saturday night, trending southward during the day Sunday. Small pops were maintained elsewhere. Large-scale lift associated with cyclonic vorticity advection or warm advection is not pronounced whatsoever. However, there is a modest amount of isentropic upglide being depicted by the models across North and Central Texas Saturday night/early Sunday morning, well behind the cold front. This lift may be sufficient to induce some widely scattered LIGHT rain, or more likely, some occasional drizzle across much of the area. There simply isn`t enough deep moisture to suggest any significant amounts...BUT...where the liquid precipitation coincides with temperatures below 32 degrees - we could see some light icing, particularly on elevated road surfaces. We may also see a few snow flurries across the northern counties on Sunday, but again, with moisture in limited supply, don`t expect any accumulations from this precipitation type. The main time period to be concerned about any slick spots would be across far North Texas early Sunday morning, especially between I-20 and the Red River, shifting into central Texas by early New Year`s Eve. The models are in good agreement about drying the airmass from north to south during the day Sunday, likely bringing an end to any precipitation in a similar fashion. For Tuesday onward - didn`t make any major changes to the previous forecast. It will remain cold through the period, yet dry. Bradshaw && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 36 49 39 48 32 / 5 5 5 10 30 Waco 37 50 40 56 35 / 5 5 10 10 30 Paris 29 43 33 41 29 / 0 5 10 20 30 Denton 33 47 35 45 29 / 5 5 5 10 20 McKinney 32 46 36 45 31 / 0 5 5 20 30 Dallas 35 48 40 48 33 / 5 5 5 20 30 Terrell 34 47 38 48 32 / 0 5 5 20 30 Corsicana 36 48 41 52 36 / 0 5 10 20 30 Temple 38 51 42 61 39 / 5 5 10 10 20 Mineral Wells 34 51 35 48 28 / 5 5 5 10 20 && .FWD WATCHES/WARNINGS/ADVISORIES... None. && $$ 90/58
Area Forecast Discussion
National Weather Service Hastings NE
559 PM CST Thu Dec 28 2017 .SHORT TERM...(This evening through Friday) Issued at 258 PM CST Thu Dec 28 2017 This afternoon, high temperatures have climbed into the 20s for most of the area under mostly clear skies. Cloud cover will increase tonight thanks to an approaching upper level jet and low- level moisture transport. That should keep temperatures from falling much lower than the upper single digits. Models have remained consistent that whatever snowfall occurs in association with the jet streak tonight will stay just northeast of the forecast area. That said, it will be close, so I`ve included flurries for the far northern fringes of the area. Also of concern tonight is low stratus and fog. Southerly flow ahead of a surface trough will will advect in some low-level moisture, but it is questionable whether fog will actually develop. The RAP and HRRR visibility forecasts certainly hint at the development of fog, and their soundings look favorable as well. That said, several inches of snow on the ground and lows around 10 degrees aren`t a "classic" setup for fog by any means. Part of the reason that the HRRR and RAP are so aggressive is likely because they are melting off too much snow cover. For now, I`ve kept fog out of the grids, but upcoming shifts will monitor this closely. Either way, I do expect that skies will be mostly cloudy through the day on Thursday, aside from maybe northern Kansas. As a result, highs may reach the low 30s in northern Kansas, while central Nebraska stays stuck in the teens to mid 20s. .LONG TERM...(Friday night through Thursday) Issued at 258 PM CST Thu Dec 28 2017 The main story for the extended forecast continues to be the extremely cold temperatures over the weekend. Overall, model agreement has improved on the magnitude of the cold air. Northerly surface flow Friday night will make for lows between -5 and 5 degrees, but the noticeable cold will arrive on Saturday, when high temperatures will remain in the single digits and overnight lows will drop into the -5 to -15 range. The GFS continues to back off on the snow potential on Saturday and Saturday night, and the Euro has remained consistent that most of the snow will stay across the NE/SD border. Nevertheless, we still have light snow accumulations possible north of I-80, and given the strength of the cold air advection, I wouldn`t be surprised to see flurries across the entirety of the forecast area. New Year`s Eve will be the coldest day. Daytime Highs will be -5 to 5 degrees and overnight lows are expected to dip into the -10 to -20 range. The latest GFS and Euro actually take the center of the 1050mb surface high just east of the forecast area, which would be slightly less favorable for extreme cold. Nevertheless, wind chills will be dangerously cold...even as light as the winds are. A slow warming trend is expected into the early part of next week, and the threat for additional snow continues to look quite low. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday) Issued at 545 PM CST Thu Dec 28 2017 Ceilings will lower to MVFR on Friday as another upper system moves through, although best lift will be northeast, so any snow should remain northeast. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ SHORT TERM...Mangels LONG TERM...Mangels AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Grand Rapids MI
909 PM EST Thu Dec 28 2017 LATEST UPDATE... Update .SYNOPSIS... Issued at 324 PM EST Thu Dec 28 2017 Several waves of low pressure will move across the Great Lakes over the next few days generating more lake effect snow showers and reinforcing the cold air already in place. Several inches of snowfall are expected along the lake shore north of Muskegon tonight and again Friday night and Saturday. && .UPDATE... Issued at 910 PM EST Thu Dec 28 2017 The primary snow band has for the most part been off shore until very recently. As a strong upper shortwave currently over central Wisconsin, will move across Lower Michigan during the early morning hours of Friday. The latest runs of the HRRR, HRRRX, RAP and NAM show strong lift and wind convergence in the 950 to 850 layer as this system moves onshore. The lake snow band has become much better organized within the past hour or so. If fact LDM is now reporting steady heavy snow with winds gusting to 30 mph. It seems to me the warning counties will see two to three hours of 1 to 2 inch per hour snowfall rates as this band moves onshore. So it makes sense to continue the headlines as is. Once the upper jet moves through around sunrise, inversion height crash to 5000 ft, so snow shower activity will diminish but not end. There may be a brief break between the lake enhanced snow showers from the current system and the snow showers from the next system that moves in by sunset Friday. && .SHORT TERM...(This evening through Saturday night) Issued at 324 PM EST Thu Dec 28 2017 Forecast concerns deal with ongoing headlines winter weather through the period. We`ve been watching a strong meso vort generated band of lake effect snow moving NNE up the lake. It`s now beginning to make landfall north of Muskegon. Widespread 30+ DBz echos are in this band and will no doubt result in 1-2 inch per hour snowfall along US-31 from Muskegon to Ludington this afternoon and evening. For that reason, we`ve kept the headlines in place. Bufkit thermal/omega profiles reveal 30-40 microbars/sec of upward motion around 00z tonight in the warning area. It`s expected that locations near the shore will see 6 to 9 inches of snow from this. Additionally, a short wave moving across Wisconsin as noted on current water vapor imagery will provide light synoptic and lake enhanced snowfall across the cwa this evening. We`ll probably see a lull in the snow Friday before the next short wave arrives Friday night. H8 temps fall from -18c to -24c over the lake and the resulting upward motion form the short wave will enhance the lake effect and another few inches of snow is possible Friday night and Saturday and new headlines may be needed. .LONG TERM...(Sunday through Thursday) Issued at 324 PM EST Thu Dec 28 2017 The main theme in the long term period of Sunday through next Thursday is continued cold weather. A surge of Arctic air moves in Monday into Tuesday with 850MB temps colder than -20C moving through the Great Lakes region. A brief period of slightly "warmer" air moves through on Tuesday when 850MB temps rise to around -10C. This is short lived however as near -20C air moves back in for Wednesday and Thursday. Temperatures will remain well below normal in the teens for highs most likely with lows in the single digits above and below zero. As for snow potential, we maintain a northwest flow aloft, so lake effect snow will continue. High pressure will be the dominant surface feature throughout the long term so not expecting significant accumulations. Light lake effect snow will be fairly persistent towards the lakeshore. The one synoptic snow event looks to be late Tuesday night into Wednesday as a cold front sags south through the Great Lakes. Bottom line...winter will remain in full swing through the long term with cold air and persistent light lake effect snows. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 652 PM EST Thu Dec 28 2017 This is not an easy forecast tonight as there is a rather intense snow band just off shore of MKG and the question is does it come inland and impact MKG or does it mostly stay just off shore this evening and when it finally does come on shore it will have weakened considerably (around 06z)? I went with the later version of this. Elsewhere and otherwise, we have a weak upper air system passing over the southern 1/3 of Lower Michigan this evening and that system is east of the area by 09z. That is when the system snow should end. However we do have westerly winds with air cold enough and moist enough for lake effect snow showers. So, I timed the system snow through the I-94 TAF sites this evening and brought the lake enhanced snow showers in by morning. For the most part the snow showers during the daylight hours of Friday will be very light. Another system comes in Friday evening bringing IFR CIGS/VSBY by 21z or so. && .MARINE... Issued at 324 PM EST Thu Dec 28 2017 No changes to the current marine headlines. South winds ahead of the next short wave will boost winds above 20 knots tonight and wave will build to 3 to 6 feet. && .HYDROLOGY... Issued at 1029 AM EST Thu Dec 28 2017 Rivers are ice covered and fluctuations in river levels are being reported. A river advisory continues at Smyrna on the Flat River, where an ice jam is thought to have formed downriver of the site. No flooding is expected. Temperatures will remain below 20 degrees for at least the next week, so little change should occur in the short term. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Winter Weather Advisory until noon EST Friday for MIZ038-044-056. Winter Storm Warning until noon EST Friday for MIZ037-043-050. LM...Small Craft Advisory until 7 AM EST Saturday for LMZ844>849. && $$ UPDATE...WDM SYNOPSIS...04 SHORT TERM...04 LONG TERM...Duke AVIATION...WDM HYDROLOGY...63 MARINE...04
Area Forecast Discussion
National Weather Service Northern Indiana
801 PM EST Thu Dec 28 2017 .SYNOPSIS... Issued at 757 PM EST Thu Dec 28 2017 Light snow will persist early tonight and create slick spots on roadways. Light snow accumulations of an inch or less are expected with the greater accumulations closer to an inch across far northern Indiana, far northwest Ohio, and southern Lower Michigan. Localized greater accumulations are also possible through Saturday morning closer to Lake Michigan across southwest Lower Michigan where some lake effect snow showers are expected. The next system will bring additional snow accumulations of 1 to 3 inches to the area late Friday afternoon through Friday evening, with locally higher amounts once again associated with lake effect snow showers. Arctic air will be reinforced behind the Friday night system, with bitterly cold conditions this weekend into the early next week. Lake effect snow showers will be likely through much of the weekend into early next week. && .UPDATE... Issued at 756 PM EST Thu Dec 28 2017 Update to greatly increase pop for measurable per observations/latest HRRR signals. Quick exit after midnight, save for lingering lake effect/enhancement. Increase in qpf countered by lowered slr per small/fine flake size/needles with deep layer of supersaturation above shallow/3kft dgz...leaning to wetter observed slr. Cold surface/road temps to lend lessened effectiveness of winter road treatments. && .SHORT TERM...(This Evening through Friday) Issued at 340 PM EST Thu Dec 28 2017 Light snow overspreading much of the forecast area this evening, and another round of accumulating snow for later Friday afternoon/evening will continue to be the primary forecast challenges for the short term. A weak warm advection pattern continues across the area this afternoon with gradually moistening low levels. Earlier 12Z RAOB data from KILX depicted a fairly dry low level layer around 5k feet, and much of initial lift ahead of the stronger forcing for this evening has been spent on moistening these low levels. Should see uptick in isentropic forcing and upper level forcing in the 23Z-03Z timeframe as eastward progression of fairly strong upstream vort max across northern Iowa allows zone of stronger isentropic lift to overspread the southern Great Lakes. The duration of deeper moisture profiles appears to be fairly limited to a 4 to 6 hour window this evening, and still expecting most of the light snow accumulation in the 23Z-05Z timeframe. The exception to this would be across southwest Lower Michigan where westerly flow behind this system should add some lake effect snow accumulation to Berrien/Cass counties. Still expecting snow accumulations to be an inch or less for most locations with the exception of lake effect areas where storm total amounts in the 1 to 3, localized 4 inch category appear more likely. Will hold off on winter weather advisory headlines at this time, and indicate potential impacts in SPS late this afternoon. Synoptic snows will diminish late evening/overnight with attention then turning to next highly sheared fast moving short wave working across the Pacific Northwest this afternoon. This wave will have fairly strong low/mid level downstream baroclinicity to work with, and models continue to depict weak to moderate axis of low-mid level fgen forcing affecting approximately southern two thirds of the forecast area late Friday afternoon into Friday evening. One difference with this system in comparison to the one this evening, is that more favorable moisture profiles should be in closer proximity to the area. Substantial low/mid level portion of profiles will be in DGZ with favorable overlay with strongest forcing. Inspection of mid level instability profiles does suggest fairly stable conditions in mid levels however, which could hinder higher end amounts. A swath of 1 to 3 inch snowfall appears likely from northwest to southeast across especially southwest half of the area late Friday afternoon into Friday evening before strongest forcing quickly translates eastward. Another arctic intrusion behind this system should keep lake effect snow showers going across southwest Lower Michigan into Saturday morning, and winter weather advisory headlines may be needed for these areas that experience the combo synoptic/lake effect portions of this system late Friday afternoon into Saturday morning. In terms of temperatures, WAA this afternoon/evening and abundant cloud cover will allow for significant moderation in temps compared to previous few nights, with highs again by Friday afternoon back into the mid-upper teens. && .LONG TERM...(Friday Night through Thursday) Issued at 340 PM EST Thu Dec 28 2017 Lake effect snow showers should be ongoing early Saturday, with veering winds resulting in increasing lake effect snow chances across favored areas in far northern Indiana. Forecast soundings do depict rising inversion heights to around 5000 feet Saturday morning, although deeper mid level saturation should be lost by mid morning. As mentioned in short term discussion, may eventually need a winter weather advisory to cover this Friday evening- Saturday period for ongoing lake effect snow showers. Temperatures not likely to have any recovery on Saturday due to arctic intrusion with temps steady in upper single digits to the lower teens. Lake effect potential will need to be watched closely by Saturday night through the early parts of next week with favorable north- northwest trajectories becoming established, and lake-700 mb delta T`s approaching 30 degrees. Lake aggregate troughing should sharpen again by Saturday night, and guidances does indicate better potential of deeper mid level saturation developing again by later Saturday night/early Sunday as upper vort lobe across western Great Lakes drops southward. Still not a good deal of confidence in the specifics regarding timing/instability magnitudes/wind fields as this setup could favor mesolow generation over the open waters that will have a large impact on placement/duration/intensity of lake effect bands. While guidance has been consistent in general idea of mesolow formation over open waters working southward down Lake Michigan, specifics still difficult to resolve at this forecast distance. Potential does exist for some significant lake effect snow Saturday night-Monday given magnitude of air mass overspreading area and potential of favorable trajectories. Outside of lake effect snow potential, bitterly cold wind chills will be in store late weekend/early next week. Wind chill advisories will likely be needed for at least portions of this multi-day period. Minor moderation appears possibly by middle of next week, but synoptic setup will be prone to additional arctic intrusions toward end of this forecast valid period. && .AVIATION...(For the 00Z TAFS through 00Z Friday Evening) Issued at 636 PM EST Thu Dec 28 2017 Warm, moist advection has allowed for snow during the overnight hours tonight as a low pressure system passes by to the north. This will bring snow to the region along with MVFR CIGs and IFR VISBY especially with the smaller flakes and the low DGZ. Attention then turns to another system that comes in later tomorrow. There is a possibility that conditions stay MVFR most of the day at SBN with some lake effect clouds forming, but FWA may have a period around midday where flight conditions increase back up to VFR, as dry air works its way in. As we get into the later afternoon, conditions are expected to decrease back into MVFR as the next wave provides more snow. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...Small Craft Advisory from 1 AM Friday to 7 AM EST Saturday for LMZ043-046. && $$ UPDATE...Murphy SYNOPSIS...Murphy SHORT TERM...Marsili LONG TERM...Marsili AVIATION...Roller Visit us at Follow us on Facebook...Twitter...and YouTube at:
Area Forecast Discussion
National Weather Service Lake Charles LA
945 PM CST Thu Dec 28 2017 .DISCUSSION... Main changes to the grids/zones this evening was to nudge up temps a degree or two as increasing cloud cover/nerly winds should limit further cooling a little...this leads to readings just below freezing as opposed to the upper 20s for the far nern zones tonight. Elsewhere regional 88Ds show a few light returns along the upper TX coast sw of Houston...last few HRRR runs have been picking up on the possibility of very light showers/drizzle moving newd into the forecast area later tonight, but confidence is lacking at this time to insert such wording into the grids/zones right now as most of this activity should remain over the coastal waters. Update out shortly. 25 && .PREV DISCUSSION... /issued 554 PM CST Thu Dec 28 2017/ DISCUSSION... 00Z TAFS AVIATION... Overcast skies tonight will remain generally MVFR with skies gradually clearing by mid to late morning Friday. Mid to high clouds are once again expected to build into the region Friday night into Saturday. High pressure centered over central Arkansas will keep winds generally light out of the northeast tonight gradually shifting out of the east Friday afternoon. Jones PREV DISCUSSION... /issued 345 PM CST Thu Dec 28 2017/ .Bitter Cold on the Way... DISCUSSION...A long wave trough remains over most of the lower 48 today with a Canadian air mass coating most areas east of the Rockies. The surface ridge is centered over the Great Lakes and stretches to the gulf coast. Friday and Saturday the ridge currently centered over the Great Lakes will slip into the Atlantic which will produce a brief warm up locally as the flow becomes east to southeast. Moisture will increase with the southeast flow by Saturday returning drizzle and showers. Also during this time another ridge will drop out of Canada and southeast across the plains. The strong cold front will arrive early during New Year`s Eve with cooling ongoing through the day. Enough lift will linger behind the front to keep light rain or drizzle lingering through New Year`s Eve through early New Year`s Day, however while temps are falling below freezing conditions will be drying. There may be a very small window across the lakes and CenLA for ZR or IP, however this will be very short lived. The bigger threat will be the cold that will linger through the week. The coldest stretch of weather this area has seen in a few years will occur next week as teens and 20s will be common each morning. Wind chills of the single digits to the 20s will also occur. A couple of reinforcing fronts will also pass through the area with one likely Tue and one Wed/Thu. Operational models have trended drier with the short wave and front Monday Night/Tuesday, however there may by a slim window for some precip to work into Acadiana. MARINE...High pressure will move across the region through Saturday keeping a moderate east to southeast flow in place, however a very strong front will move through during New Year`s Eve. Strong offshore wins and low water conditions can be expected early next week. && .PRELIMINARY POINT TEMPS/POPS... AEX 30 49 38 52 / 0 10 10 30 LCH 36 52 44 59 / 0 10 20 30 LFT 36 52 43 56 / 0 10 10 30 BPT 38 53 45 61 / 10 10 20 30 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...None. && $$ PUBLIC...04
Area Forecast Discussion
National Weather Service Lubbock TX
1003 PM CST Thu Dec 28 2017 .UPDATE... The fog that has rolled into Lubbock and Plainview has been dense at times. Given this we have decided to hoist a freezing fog advisory for much of the Caprock through the rest of the night. The low clouds and freezing fog will continue to advance westward over much of the remainder of the South Plains before winds begin to veer to the south and southwest around and after 08Z. Our far northwestern zones around Friona may avoid the fog as winds veer there before the higher moisture levels can arrive. Otherwise, much of the remainder of the locations on the Caprock will should see the fog. There could also be some fog/freezing fog in the Rolling Plains, though with low clouds already in place and minimal moisture advection, widespread dense fog is less certain there. Any fog should quickly diminish by mid to late Friday morning as drier downslope winds spread out of New Mexico. Until then, the freezing fog advisory is in effect for all of our counties on the Caprock, aside from Parmer County, through 10 am Friday. && .PREV DISCUSSION... /issued 757 PM CST Thu Dec 28 2017/ UPDATE... Minor adjustments were made to the temperature and dewpoint grids through the remainder of the night, primarily to account for current observations and trends. Where skies are clear temperatures are rapidly falling and we would not be surprised to see a few teens across the northwestern zones later tonight. Further east, the low clouds that persisted over the eastern Rolling Plains during the day were now advancing westward. As this cool and moist airmass spreads back up onto the Caprock widespread low clouds and freezing fog will quickly follow. This was well captured by the ongoing forecast though we did add a patchy freezing fog mention over the lower elevations too where slight cooling and weak moisture advection may eek out some fog development too. Given that fog density is often quite fickle, we are holding off on any headlines at this time, though if the HRRR, RAP and NAM are correct a freezing fog advisory may be needed for much of the CWA. We will watch trends closely and hoist a freezing fog advisory if it becomes warranted. PREV DISCUSSION... /issued 532 PM CST Thu Dec 28 2017/ AVIATION... VFR conditions at KLBB and KPVW with MVFR at KCDS at the start of this TAF cycle. Low clouds will redevelop and push west over the KPVW and KLBB terminals after sunset tonight and will rapidly drop back into LIFR range with VLIFR possible in the early morning hours. Confidence is high on this occurrence with a bit lower confidence on when the transition will actually take place. Temperatures will fall below freezing around midnight local time so periods of freezing fog/drizzle will be possible through Friday morning. Similar to today, low clouds will remain in place through late morning with gradual improvement to VFR conditions before mid-day Friday. West wind will increase through the day as well at KLBB and KPVW helping to clear out skies fairly fast. Jordan PREV DISCUSSION... /issued 345 PM CST Thu Dec 28 2017/ DISCUSSION... 3 pm temperatures ranged from near 70 in the southwest South Plains to only in the 30s out in the Low Rolling Plains. The low stratus bank has retreated off the Caprock, but the latest satellite imagery suggests that it`s eastward progress is slowing and we expect it to soon stall, then begin to move back west this evening. Forecast soundings suggest the threat of freezing fog developing overnight across much of the Caprock, and perhaps some light freezing drizzle across the far Southern Texas Panhandle into the northern Rolling Plains. Friday, the shallow moisture should be scoured even more readily than today as deep-layer westerly flow increases in conjunction with a passing shortwave. Very warm temperatures should spread farther east, although there is still a bit of uncertainty just how warm the lowest elevations will get, with the deeper inversion to overcome. For now we are looking at highs mainly in the 60s on the Caprock and 50s off. The warm and dry conditions will bring an elevated fire danger to the western South Plains and far southwest Texas Panhandle. Meanwhile, a series of shortwaves rotating through broad cyclonic flow over eastern CA and north-central US will unleash Arctic air currently residing in northern portions of the Canadian provinces. The leading edge of the cold air is still on track to move into our area Saturday. With the really frigid air lagging behind to the north, there is some question regarding temperatures Saturday, as the shallow cold air could tend to erode across the higher terrain out west. And we could see some light freezing drizzle Saturday off the Caprock, but with meager amounts of moisture in this airmass any precip will be very light. The really cold air will come in Sunday. With just some weak shortwave energy passing aloft, this combination could gin up some light wintry precip., again mainly off the Caprock, but at this time the precip. does not appear to be significant (aside from perhaps creating some icy roadways). The main story may be the period of bitterly cold temperatures starting Sunday. Highs Sunday and Monday should mainly in the 20s, with lows Monday night and Tuesday night primarily in the single digits to low teens. And we would be surprised to see some near zero temps Monday night across our northwest counties. Wind chill values New Years Eve could be below zero and possibly even below -5 degrees in the north. Wind Chill highlights are certainly a possibility during this period. Moderation in temperatures will be a slow slog through midweek as continued north-northwest flow across the nation`s midsection keeps supplying cold air, but our temps should gradually recover as the cold airmass modifies/retreats northeast. && .LUB WATCHES/WARNINGS/ADVISORIES... Freezing Fog Advisory until 10 AM CST Friday for TXZ022>024- 027>030-033>036-039>042. && $$ 23/14
Area Forecast Discussion
National Weather Service Miami FL
811 PM EST Thu Dec 28 2017 .UPDATE... Satellite imagery suggests that a surface low has formed about 70 miles east of Cocoa Beach. This is the same surface low that the models show developing early Friday and then moving ENE out to sea in the Atlantic. However, the HRRR indicates that the surface low will move slowly SSE through 06Z before slowing down. After 12Z, it should begin moving out to sea. A broken line of showers extends as a tail from the low southwestward to the coast of Palm Beach County. Showers also extend to southern Collier and Mainland Monroe. This shower activity should migrate southward over the next few hours. A few showers may linger around South Florida until a few hours after midnight. Patchy dense fog is likely across portions of Glades, Hendry, Collier, Palm Beach and inland Broward Counties between 09Z-14Z. Elsewhere, the frontal boundary over Central Florida will slither slowly southward during the next day or so, perhaps spreading some cloud cover, but not rainfall, over the northernmost portions of South Florida later on Friday. Once the weak front passes, winds will become more northerly, allowing slightly cooler air to filter into South Florida. && .PREV DISCUSSION... /issued 642 PM EST Thu Dec 28 2017/ AVIATION... The winds will be light and variable tonight over all of the taf sites. There could be some showers around the KPBI taf site through 02Z before going dry. Therefore, KPBI will have VCSH until 02Z, then dry conditions after 02Z tonight With VFR conditions. Rest of the taf sites will remain dry tonight along with VFR conditions. AVIATION...54/BNB PREV DISCUSSION... /issued 436 PM EST Thu Dec 28 2017/ DISCUSSION... Tonight-Sunday: A lingering frontal trough over central and northern Florida along with high pressure over the eastern U.S. will keep NE winds and some moisture over South Florida through tonight. Isolated showers will continue to be possible, especially over the eastern half of South Florida, through this evening. On Friday, a surface low strengthens east of northern Florida and moves out to sea in the Atlantic. As the low leaves, a surface ridge over the northern Gulf of Mexico noses its way into Florida beginning Friday. The surface ridge will continue to have enough influence on our weather, that it should keep South Florida dry through the weekend. Since we will be on the east side of that surface ridge, winds will be more northerly Friday through Sunday, which will filter in slightly cooler air. Expect temperatures Friday night through Sunday morning to be a few degrees cooler than they have been during the last few days. Sunday Night-Thursday: An unsettled weather pattern is forecast to arrive in South Florida for the beginning of the New Year. Rain chances start to increase Monday as a cold front heads toward South Florida. The front should arrive in South Florida late on Monday. The front moves through rather slowly, and moisture lingers into Tuesday. To complicate matters, the GFS and ECMWF now want to form a surface low along that same front over the southeast Gulf of Mexico, which then moves near or over South Florida mid-week. As a result, it could potentially be quite rainy here through midweek. It is not looking quite as cold on Tuesday into early Wednesday now, as what the models were showing the past 2 days. However, after the low and rain finally get out of here, models are beginning to hint at a large surge of arctic air, that has at least some potential to make it down into Florida for late next week. The models have been so inconsistent lately on anything beyond 5 days. Our temperature forecast at day 7 is a blend between the models and climatology. MARINE... Moderate NE winds will shift to N and then increase to 15-20 kts on Friday for the Atlantic waters. These winds, combined with a NNE swell of 3 to 4 feet with create hazardous seas for small craft. Thus, a small craft advisory is in effect from 5AM Friday to 7AM Saturday for the Atlantic waters. Seas of 6 to 8 feet are expected Friday and Friday night. Seas will diminish on Saturday. For the Gulf waters, waves will remain 1 to 2 feet through Sunday night, with seas building late on New Year`s Day. BEACH FORECAST... The rip current risk will increase along the Atlantic beaches Friday night into Saturday despite northerly winds, as large NNE swells affect the coast. AVIATION... Few showers possible this afternoon east coast but probabilities dont warrant mention in terminals. CIG restrictions have finally lifted at KAPF, but expect MVFR/IFR CIGs to reappear later tonight through Friday morning. Elsewhere, VFR conditions prevail. NE wind 10 knots today, then calm tonight, then N around 10 KT on Friday. && .PRELIMINARY POINT TEMPS/POPS... West Palm Beach 64 78 63 78 / 20 0 10 10 Fort Lauderdale 66 79 63 78 / 30 0 10 10 Miami 67 81 64 79 / 20 0 0 0 Naples 64 77 59 77 / 0 0 0 0 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...None. AM...Small Craft Advisory from 5 AM Friday to 7 AM EST Saturday for AMZ650-651-670-671. GM...None. && UPDATE...98/ABH DISCUSSION...98/ABH MARINE...98/ABH AVIATION...54/BNB BEACH FORECAST...98/ABH
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
924 PM EST Thu Dec 28 2017 .SYNOPSIS... Arctic high pressure will continue to extend into our region through tonight. Low pressure is forecast to develop well south of the area late tonight and Friday and move northeast of the region over the weekend as very cold air spreads across the area in its wake. Another low pressure system will lift northeast offshore of the coast early next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... As of 925 PM Thursday...Temperatures continue to fall as Arctic high builds east toward the Carolinas. Have once again lowered temperatures a degree or two based on current readings. Expect upper teens inland to low/mid 20s coast, with upper 20s Outer Banks. Based on the 00Z MHX sounding, the low-levels remain very dry, and despite some support for very light precipitation from some of the high-resolution models such as the HRRR and 3 KM NAM, feel that it will be difficult to overcome the dry sub- cloud layer and will keep the overnight and early morning period dry. Expect winds to gradually subside after midnight as axis of surface high pressure builds east of the central and eastern Carolinas. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... As of 330 PM Thurs... The Arctic high pressure will remain in place, but weaken due to an airmass modification and a low pressure system to the south of the area. This will lead for low level thicknesses to increase and causing temperatures to recover back into the low/mid 40s. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... As of 230 am Thu...Deep cyclonic flow expected to dominate during period with southern stream moisture suppressed to south, and reinforcing shots of cold air for Sat-Sun and again Mon- Tue. Precip chances through the extended a bit problematic. 00Z GFS is dry through the entire period. The 00Z ECMWF brushes south coast and OBX with light snow late Sunday night through midday Monday with a surface low passing by to the south. National guidance is higher with slight chance PoPs northwest and chance along the south coast and southern OBX. Due to uncertainty, for now will take a middle course and lean toward the ECMWF solution. Large differences Wed with the ECMWF passing a strong low just off the coast while the GFS has a weaker low far to the southeast. With such large differences that far out in time, will not include PoPs at this point. Lows mainly 25-35 for Friday night, lower/mid 20s Sat night, then colder with upper teens inland to 25-30 coast rest of period. Highs in mid/upper 40s for Saturday and then mainly in 30s rest of period, with guidance generally indicating temps barely above freezing for inland sections Sun-Tue. Slightly warmer Wed, with mid 30s west to lower/mid 40s south coast and Outer Banks. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Short Term /through 00Z Saturday/... As of 645 PM Thursday...VFR conditions expected to prevail through the next 24 hours with mostly mid/high level cloudiness anticipated. Gusty N/NE winds should subside after midnight as axis of high pressure ridge build east over the central and eastern Carolinas. Long Term /Fri through Mon/... As of 230 am Thu...VFR/dry through the period. Surface winds NW 5 knots Fri, W 5 knots Sat, N 10 knots Sun and N 10-15 kt Mon. && .MARINE... Short Term /Through Tonight/... As of 925 PM Thursday...Winds have subsided over the Sounds and southern waters, with northerly winds at 15-20 knots. Gusts to around 25 knots and 6-foot seas continue over the waters north of Ocracoke and have extended the SCA there until 09Z Friday morning. As the axis of Arctic high pressure builds east and settles over the central and eastern Carolinas overnight, the winds and seas should subside toward morning. Seas will subside 3 to 5 ft by daybreak. Friday...N winds 10-15 knots in the morning, becoming NW 10-20 knots in the afternoon as low pressure sys deepens and causes the gradient to tighten. Seas will remain mostly 3-4 ft. Long Term /Fri through Mon/... As of 230 am Thu...Winds mostly north to northwest through the period. Wind speeds generally 15 knots or less for Friday into Saturday, then reinforcing shot of arctic air likely to produce another period of 15-25 knot winds Saturday night into Monday. Wave guidance indicating seas mainly 2-4 feet Friday into Saturday. Increasing winds will then build heights to 4-8 feet Sat night into Monday north of Ocracoke, with 3-5 feet south. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...None. MARINE...Small Craft Advisory until 5 AM EST Friday for AMZ150-152-154. && $$ SYNOPSIS...RF/BM NEAR TERM...CTC SHORT TERM...BM LONG TERM...HSA AVIATION...RF/CTC/BM MARINE...CTC/BM
Area Forecast Discussion
National Weather Service Melbourne FL
806 PM EST Thu Dec 28 2017 .DISCUSSION... Current-Overnight...A weak quasi-stationary frontal boundary remains entrenched from near Melbourne west-southwest to south of Tampa this evening. A weak, developing surface low well off of the Cape along with fairly strong high pressure along the eastern seaboard will provide enough influence to push the aforementioned surface trough southward to near the Treasure Coast/Lake Okeechobee region by around daybreak Fri morning. On the backside of the front thick low stratus clouds with 500- 1000ft ceilings. The main forecast concerns overnight revolve around how far south these low clouds will venture, as well as any patchy, locally dense fog potential that may exist, especially south of Orlando. The local HRRR and LAMP guidance continue to focus from near central Osceola/central Brevard southward for the edge of some potentially thicker fog extending through the remainder of our coverage warning area; Okeechobee/Martin counties. Will update the zones forecast for addition of patchy fog from Osceola-south Brevard southward overnight into early Fri morning. Otherwise, MAV MOS guidance continues way too high on precipitation potential. Will hold onto an isolated sprinkle or light shower along the east coast until 06Z/1AM, though this continues to be very generous on the part of the forecaster. The abundance of low clouds, especially northward, will keep most areas in the M-U50s overnight, except some L60s possible along the immediate east coast from south Brevard thru Martin County. Wind component will remain from out of the NNW-NNE with speeds 5-10 mph. && .AVIATION...Low CIGs 500-1000 ft from near KMLB northward this evening. Expect this IFR group to prevail thru the night and early Fri morning. This area may make it further south to across the Treasure Coast overnight as a weak frontal boundary sags slowly southward. Recent local short-term model guidance suggests some visibility concerns as well southward from KISM-KMCO-KTIX late in the night. Expect CIGs/VSBYs to improve from mid-morning on, though IFR-MVFR CIGs may prove a nuisance at some sites into the afternoon. && .MARINE...Overnight-Fri...Poor to hazardous boating conditions increasing (from north to south) across the local coastal waters this evening and overnight, and through the day on Fri. Some higher northerly winds will overspread the area on Fri, though seas begin to build out ahead of this new wind surge tonight, due to an increasing swell. The stronger winds will initially be delayed due to a weak low pressure system well off of the Cape, that will keep the local pressure gradient disturbed. ISOLD-SCT light shower activity will be possible over the area, especially the Gulf Stream. Seas are forecast to build (by daybreak) up to 9 ft, well offshore, north of the Cape, and generally 5-7 ft most everywhere else. Small craft advisories begin at 00Z/7PM for the offshore waters (Flagler Beach-Jupiter Inlet), as well as for the near shore Volusia coastal waters. By 09Z/4AM, the SCA gets expanded areawide and remaining thru the day on Fri. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...Small Craft Advisory from 7 PM this evening to 10 PM EST Friday for Flagler Beach to Volusia-Brevard County Line 0-20 nm. Small Craft Advisory from 7 PM this evening to 5 AM EST Saturday for Flagler Beach to Volusia-Brevard County Line 20-60 nm- Sebastian Inlet to Jupiter Inlet 20-60 nm-Volusia-Brevard County Line to Sebastian Inlet 20-60 nm. Small Craft Advisory from 4 AM to 10 PM EST Friday for Sebastian Inlet to Jupiter Inlet 0-20 nm-Volusia-Brevard County Line to Sebastian Inlet 0-20 nm. && $$ Sedlock/Volkmer
Area Forecast Discussion
National Weather Service Omaha/Valley NE
603 PM CST Thu Dec 28 2017 .SHORT TERM...(Tonight through Monday) Issued at 316 PM CST Thu Dec 28 2017 Colder temperatures this weekend is the main weather story, however we will see a couple chances for light snow over the next couple of days as well. Upper level flow pattern will remain wholly unchanged for the central part of the country through Sunday, as jet stream rounds the top of broad high pressure in the eastern Pacific then dives southeast into a broad trough covering the east half of the CONUS. Models show two distinct shortwaves riding through the flow from southern British Columbia into the Plains, one later tonight into Friday, and the second affecting our area Saturday into Saturday night. Each will bring a chance for light snow and a reinforcement of colder air in their wake. Temperatures warmed up nicely this afternoon with most spots seeing highs in the 20s. Could see some 20s again Friday in our south, but cool east to northeast winds and cloud cover associated with shortwave will keep a lid on highs for the most part. Then with cooler air to follow, Friday night lows should again drop below zero most of eastern Nebraska and western Iowa, especially in the north where a new layer of snow is possible. Some mid and high level cloud cover could keep lows a bit warmer, but airmass is cooling and a north wind will provide cold advection. Not looking for much of a warmup on Saturday with thickening cloud cover and continued oozing of arctic air south. Then more reinforcing cold advection follows second shortwave for Saturday night through Sunday night when 1054mb arctic high pressure begins to settle into the Mid Missouri River Valley region. Haven`t seen high pressure of that magnitude in a while. So even with some sunshine Sunday, can`t see highs eclipsing zero. GFS indicates center of high pressure will be over Omaha at 12Z Monday. And given airmass combined with snowcover and decreasing winds, strong radiational cooling regime will likely allow lows to drop to colder than 20 below for much of our CWA. Wind chills are also a concern for the weekend. Even a light breeze with expected temperatures will likely mean sub-30-below wind chills for part of the day Sunday and for sure Sunday night into Monday morning. We will likely see wind chill advisories needed perhaps on Saturday, then advisories and warnings for the Sunday and Monday timeframe. As far as potential precipitation, the first shortwave of consequence was noted on water vapor imagery and RAP analysis moving onto the southern coast of British Columbia at early afternoon. Strong 150kt upper level jet will usher it into the central and northern Plains later tonight and Friday. Initial band of associated forcing will arrive this evening when light snow could develop over northeast Nebraska. Then a more pronounced area of lift moves through South Dakota into northern Iowa overnight and Friday morning. Model QPF and pressure deficit forecasts suggest main band of snow will fall to the north and northeast of our CWA, with southern edge of measurable snow likely north of an Albion to Omaha and Red Oak line. Precipitation should be moving into central Iowa by Friday afternoon. Then another strong upper level jet segment is advertised by GFS knifing through North Dakota into Minnesota Friday night. No major affect here but right entrance region of that jet could spark some light snow in our northern counties once again. Then second shortwave will begin to affect our area by Saturday afternoon, and again accompanied by strong upper jet streak. This shortwave looks to take a little more southerly track across eastern Nebraska and western Iowa, and subsequent forcing fields suggest more widespread but still light snow of an inch or two. Associated precipitation should be moving east by Sunday morning, with the much colder air to follow. .LONG TERM...(Monday night through Thursday) Issued at 316 PM CST Thu Dec 28 2017 Still not much change in sight as far as temperatures are concerned for next week. Overall pattern does shift after Saturday shortwave passes by, going from northwest flow in the Plains to northerly. This does not bode well for warming in much of the central CONUS. Another cold night is expected Monday night with double-digit negative lows are forecast. Then airmass does show some sign of moderation as GFS 850 temps warm from the minus 20-25C range into the minus teens. However this will only translate to highs in the teens on average Tuesday through Thursday. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 517 PM CST Thu Dec 28 2017 Radar mosaic was showing an area of -SN, associated with an upper level disturbance, expanding SEWD out of WRN SD. Current trends suggest the -SN will skirt very close just to the NE of KOFK and KOMA beginning shortly after midnight into Friday morning. Thus have included PROB30 groups to reflect this. Otherwise, MVFR cigs will likely prevail through Friday afternoon at all terminals. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Dergan LONG TERM...Dergan AVIATION...DEE
Area Forecast Discussion
National Weather Service Paducah KY
527 PM CST Thu Dec 28 2017 .UPDATE... Issued at 238 PM CST Thu Dec 28 2017 We have adjusted sky grids for now through late evening. The RAP model 900-850mb layer RH and wind trajectory suggest the clouds will continue to drift east. How much they hold together on the east edge is somewhat up in the air. But the RAP is fairly aggressive with the eastward push. Currently the line runs from KFWC to KMWA to KPOF. && .SHORT TERM...(Tonight through Saturday night) Issued at 110 PM CST Thu Dec 28 2017 Dry weather in the short term. NW flow aloft will continue. At the surface, high pressure will weaken and move east. This will allow winds to veer around toward southerly into Friday ahead of an approaching front that will bring a reinforcing shot of cold air Friday night into the weekend. Ahead of the front on Friday, most areas will climb above freezing by afternoon. The front is forecast to move through during the late day hours. In the wake of the front, colder air returns for Saturday, with highs in the lower 20s I-64 to around 30 west KY, parts of SEMO. Just some clouds from time to time. .LONG TERM...(Sunday through Thursday) Issued at 110 PM CST Thu Dec 28 2017 The main concern remains the cold. The broad deep mid level trof pattern along and east of the Rockies will persist. New Year`s Eve and New Year`s day will be bitterly cold as the 1045+ high settles south through Monday night. New finalized forecast grids show we will have wind chills colder than -10F New Year`s Eve night into New Year`s Day morning. We trended slightly colder with temps overall, given a strong deviation from the norm is usually not handled well by MOS. Having said that, the raw model output is likely too cold given no snow cover. No end to the cold in sight. Just a slight rise in temps mid week, followed by another cold outbreak late next week. The one light snow chance we have to monitor, appears to be sometime from midday Wednesday to midnight Wednesday night. A signal is more persistent across the Evansville Tri State area for light snow chances. Have not included in the forecast yet. But something to watch. && .AVIATION... Issued at 527 PM CST Thu Dec 28 2017 Expansive stratus deck moving eastward across the WFO PAH TAF sites at this time. Utilized the RAP guidance to provide an estimate of the duration of these clouds across the area. After 08z-11z, return ceilings to VFR conditions for the rest of the forecast period. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ AVIATION...Smith
Area Forecast Discussion
National Weather Service Topeka KS
505 PM CST Thu Dec 28 2017 ...AVIATION UPDATE... .SHORT TERM...(This evening through Friday) Issued at 240 PM CST Thu Dec 28 2017 Clouds have been a little slow clearing the area today with some dissipation seen across central Kansas early this afternoon. This clearing will continue through the afternoon with a brief period of mostly clear skies forecast before clouds move back into the area later tonight. Observations indicate a weak surface front located near the Kansas/Nebraska boarder which will move through the area late afternoon and act to shift winds from the north for the overnight hours. Light northerly winds along with low temperatures in the teens tonight will bring wind chills into the single digits by Friday morning. On Friday, a trough located in the northern Great Lakes region will act to push a cold front through the area Friday night. Ahead of this feature, expect one more day of temperatures in the 30s, although there may be a bit more wind in east central Kansas during the afternoon making wind chills a bit colder in the afternoon. Isentropic upglide will aid in more cloud development by tomorrow morning and clouds are expected to stick around through the period. The front begins to make its way through northeastern Kansas by late afternoon which will act to drop temperatures significantly behind this feature. .LONG TERM...(Friday night through Thursday) Issued at 240 PM CST Thu Dec 28 2017 Overall the main feature of this extended period will be the severely cold temperatures this weekend and through Tuesday morning. A cold front makes its way through the area Friday night with noticeably colder temperatures behind it, with lows Saturday morning reaching (once again) the single digits. Not much of a warm up Saturday as skies stay mainly mostly cloudy with maybe only a warm up of 3 or 4 degrees across the area. Persistent cold air advection will bring low temperatures Sunday morning to a chilling -6 to +1 degrees. Northerly winds will bring the wind chills this morning from -12 to -20. Unfortunately, temperatures only continue to fall from here with New Year`s Eve highs in the single digits. The coldest temperatures of the period are expected to occur early Monday morning with temperatures in the negatives up to -15 near the KS/NE boarder. Dangerously cold wind chills will be seen on this morning ranging from -20 in east central Kansas to -30 in northern Kansas. On New Year`s Day, highs will be very similar to the previous day in the single digits. By Monday evening, a 1050mb high pressure moves overhead or just east of the area keeping cold temperatures in place for that night. Tuesday morning, lows will be in the negatives ranging from -1 to -7 across the area with more wind chills down to - 20 degrees in northern Kansas. With this passing high pressure, winds finally shift from the south aiding with a slight warm up into the 20s which looks to last through the end of the period. There are some very small chances for light snow Tuesday, although the Canadian looks to be the only model picking up on this chance so confidence is not high right now. && .AVIATION...(For the 00Z TAFS through 00Z Saturday) Issued at 505 PM CST Thu Dec 28 2017 VFR conditions should prevail for the evening and much of the overnight hours. However think MVFR CIGS will move back in after 12Z as models increase low level winds from the south southwest. These winds should advect the low clouds over west TX and southwest OK back into the area as the RAP and NAM suggest. Once these clouds move in, it may be difficult to scatter them out with forecast soundings maintaining a steep low level inversion through the afternoon. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Heller LONG TERM...Heller AVIATION...Wolters
Area Forecast Discussion
National Weather Service Tulsa OK
912 PM CST Thu Dec 28 2017 .DISCUSSION... The cloud edge across northeast Oklahoma eroded south a bit in the past couple of hours. That process should continue a couple of more hours, putting the edge of the clouds in the I-44 corridor. After about 1am the clouds should expand back north. Additionally, holes should open up in northwest Arkansas and far southeast Oklahoma. All of this of course will cause local ups and downs in the temps overnight. On the average the low temperature forecast looks on track. Radar and mPing show light precip developed this evening in north Texas from a moist layer between 850mb and 925mb. This precip seems loosely tied to weak isentropic upglide on the 280 K surface. Winds at 925mb are expected to become southeasterly overnight which should keep this precip pattern away from our southeast Oklahoma Counties. So we are not adding any precip at this time for tonight, but we will need to watch how the precip evolves. && .PREV DISCUSSION... /Issued 611 PM CST Thu Dec 28 2017/ AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG. Animated satellite imagery indicates widespread low clouds across ern OK and wrn AR. Areas where clouds eroded this afternoon are already slowly filling back in. As is usually the case with shallow moist layers trapped beneath temperature inversions in the winter, anticipating behavior of stratus layer will continue to be challenging. For now, we have trended 00z TAFs toward HRRR and NAM models, which indicate higher chances of maintaining low VFR ceilings. Ceilings may be a little more prevalent Friday, and may begin to lower into MVFR category. Strong cold front passage expected just beyond the end of this forecast period. PREV DISCUSSION... /Issued 310 PM CST Thu Dec 28 2017/ DISCUSSION... Main forecast concern continues to be winter weather potential Saturday through Sunday in conjunction with very cold temperatures associated with the approaching Arctic airmass. Cloud deck currently atop eastern Oklahoma and western Arkansas has slowly been eroding this afternoon in most areas except far southeast Oklahoma. Some cloudiness may linger through the night across the region, but coverage should eventually be more partly cloudy than at present. As a result, temperatures may be closer to the cooler side of guidance. With continued southerly winds and less cloud cover, temperatures tomorrow will be much warmer than the last few days, with highs closer to normal. The initial cold front will move through the area Friday night and into early Saturday, with the stronger push of cold and very dry air slated for Saturday night and into Sunday. Available low level moisture should be enough during the day Saturday to lead to some drizzle or freezing drizzle, although some erosion of the low level moisture from north to south should occur during the afternoon. Any measurable precipitation with this system would accompany the arrival of the stronger cold air push. Temperature profiles support a transition from freezing drizzle to sleet and snow once moisture in the dendritic growth zone increases. Any amounts still appear to be a half inch or less at this point, but the very cold temperatures could exacerbate the overall travel impacts despite the light amounts. Winds will stay up through Sunday night and into Monday, leading to very cold wind chills to close out 2017 and open 2018. Wind chills will be cold again Monday night/Tuesday morning, but lower wind speeds will lead to higher values than the previous morning. Another fast moving upper level wave will move through far northeast Oklahoma and northwest Arkansas, with a quick burst of snow possible Tuesday morning. Temperatures will be cold enough that snow ratios should be higher than what we typically see here. Right now, it looks like another half inch or so will be possible with this system. The well below normal temperatures will continue through the remainder of the next work week. && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...08