Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/24/20

See below for an aviation forecast discussion for the 00Z TAFs.

&& .SHORT TERM...(This Evening through Monday Night) Issued at 315 PM CST Sun Feb 23 2020 A storm system tracking southeast across the region Monday through Tuesday will be the main forecast challenge in the short term. A dry high pressure over the region this afternoon is producing breezy northwesterly winds, mainly across the James River valley and points east. The winds will diminish through this evening. Even with increasing clouds later tonight, low temperatures should drop into the teens and low 20s. Patchy to areas of fog will be possible tonight, mainly in the James River valley. An area of low pressure and upper level trough will move into the western Dakotas on Monday with light pcpn possible in the northwest portion of the CWA. Am concerned with the dry easterly flow keeping a good portion of the CWA dry until Monday afternoon. NAM/GFS buffer soundings for the Aberdeen area suggests dry conditions until 3Z Tuesday. Accumulating snow in the Mobridge area could be delayed until early afternoon if dry layer between 850-700 mb in the NAM is correct. Saturation looks best after 0Z Tuesday, mainly west of the James River Valley. Snowfall amounts of one to three inches appears likely, especially along the Missouri River where isolated 4 inch amounts could be possible. With the accumulating snowfall occurring Monday night into Tuesday, will hold off on issuing a winter weather advisory. Half km winds of 25 to 35 knot late Monday night into Tuesday morning could cause patchy to areas of blowing and drifting snow. Of note, the 18Z is slowing down the progression of the storm, with snow moving into north central SD during the mid to late afternoon hours on Monday. A narrow band of snow does appear possible with this system. The latest models suggest the band will set-up in ND, and perhaps as far south as northeast SD. Higher snowfall amounts will be possible with this band. .LONG TERM...(Tuesday through Sunday) Issued at 315 PM CST Sun Feb 23 2020 Surface high pressure will settle in over the area Tuesday night, and looks to be the dominant feature through Friday night. This will keep somewhat cooler air over the region Wednesday and Thursday, with high temperatures in the teens and 20s. As the high then exits to the east, will see WAA develop as the region becomes situated between the high and a low pressure trough to the west. High temperatures will range from the upper teens east to the mid 30s west on Friday, then will be in the 30s and 40s Saturday and Sunday. Overnight lows will generally be in the single digits and teens through much of the period, with the exception of Saturday night when temperatures will only fall into the lower to mid 20s. Cannot rule out a few periods of light precipitation during the period, but there is no model agreement on location or timing and any impacts would be minimal, therefore will keep conditions dry for now. && .AVIATION...(For the 00Z TAFS through 00Z Monday Evening) Issued at 547 PM CST Sun Feb 23 2020 Looks as though prevailing VFR conditions are going to erode into some MVFR/IFR conditions within the next 12 to 24 hours. Prior to the onset of the next low pressure system on Monday, there could be some sub-VFR fog/visbies developing later this evening in the James River valley toward 06Z at KABR; between 06Z and 15Z in the James River valley and up on the Prairie Coteau at KABR and KATY. When the low pressure system works through the region Monday and Monday night, expect widespread coverage of lower (MVFR/IFR) cigs and reduced (MVFR/IFR) visbies in snow across central South Dakota (KPIR/KMBG), with intermittent sub-VFR cigs at KABR/KATY. Precipitation may also extend east as far as the KABR/KATY terminals during this next precipitation event, but probably not until some point beyond the current 24 hour TAF valid period. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Dorn SHORT TERM...SD LONG TERM...Parkin AVIATION...Dorn
Area Forecast Discussion
National Weather Service Dodge City KS
504 PM CST Sun Feb 23 2020 ...Updated Aviation Discussion... .SHORT TERM...(This evening through Monday) Issued at 220 PM CST Sun Feb 23 2020 A significant precipitation event is still on track to affect much of southwest, central, and south central Kansas this evening into the overnight hours. Latest satellite imagery showed cumulus expanding in coverage across northeastern New Mexico into adjacent Texas Panhandle as the mid level cold pool aloft was moving slowly east. Temperatures warmed into the upper 60s to around 70 degrees across portions of the eastern Panhandles with 60 degree isotherm as far north as Dodge City at 19Z. The HRRR and RAP did a very good job with the 2-meter temperature forecast, whereas the NAM12 performed quite poorly in this department. The cold outlier NAM12 solution is just not trusted with this storm system, and this goes for tonight as well, and as such the snow amounts have been lowered tonight. Total precipitation, however, still looks very good with an axis of 1.5" plus from Dodge City east into central/south central Kansas. As far as the severe weather risk goes, since it is warmer like the HRRR and RAP, more instability was developing into far southwest kansas. As the cold pool aloft continues to approach southwest Kansas by early this evening, low level convergence will also continue to increase, which will help dewpoints continue to increase to the 48-50F range as far north as Seward and Meade County. This is the portion of our forecast area we are most concerned with for any severe weather. Given the time of year and development of SBCAPE up to 600 to 800 J/kg, the only real severe weather risk would be large hail up to the size of about a quarter or so. There will be enough low level shear to support low level mesocyclogenesis, perhaps supporting a weak, brief tornado, which is something that will have to be watched along the Oklahoma border. Once the convective portion of the event winds down later this evening, the comma-head structure of the storm will take shape overnight as the precipitation becomes more stratiform in nature. It still appears this deformation zone will be focused along the Arkansas River valley in the 06-12Z time frame overnight/early Monday morning. .LONG TERM...(Monday night through Sunday) Issued at 220 PM CST Sun Feb 23 2020 The next upstream system will bring strong northwest winds and another round of (light) precipitation Monday Night and again on Tuesday. This system now appears to be digging south a little bit farther west across Kansas, and as such we will maintain some 20-30 POPs through Tuesday. The first of the two light rounds Monday Night will start off as a cold rain but then change to a wet snow some time around midnight Monday Night. 850mb cold advection ramps up late Tuesday into Tuesday Night as the next lobe of upper level energy swings south into Kansas. The mid levels will be very cold late Tuesday into Tuesday Night, so any little bit of moisture will likely result in some light snow late Tuesday/Tuesday Evening. Another (much weaker) northwest flow wave will reinforce the longwave trough pattern late Thursday-Thursday Night, which will really do nothing more than delay any substantial warm up that we otherwise would be seeing as overall heights increase out west across the Great Basin region. By Friday and especially the upcoming weekend, we will see temperatures warming back into the 50s and eventually 60s for daytime highs. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 437 PM CST Sun Feb 23 2020 Mainly VFR conditions for all TAF sites except for MVFR visibility for HYS due to light rain falling on station as depicted on radar. Expect showers and isolated thunderstorms to push into far southern Kansas out of the Oklahoma panhandle giving way to SHRA and VCTS first at LBL then DDC and GCK by 01Z with ongoing rain for HYS not expecting thunderstorms to push that far north due to the colder air sinking in from northwest and north central Kansas. This will turn to a wintery mix for all locations by 05-11Z with MVFR ceilings expected as low stratus pushes across along the frontal boundary turning winds out of the northwest gusting up to 25-30kts. Improving skies after 12Z as stratus burns off with daytime heating before gusty winds push in after 20-21Z for GCK and HYS before increasing for DDC and LBL after the end of the period due to being along the backside of the low pressure system making its way out of the CWA to the east and southeast. && .PRELIMINARY POINT TEMPS/POPS... DDC 33 52 28 38 / 100 40 30 10 GCK 30 50 25 37 / 100 10 20 10 EHA 30 54 26 38 / 80 10 20 10 LBL 31 53 26 40 / 90 10 30 10 HYS 33 53 29 37 / 80 30 30 40 P28 40 56 33 45 / 100 70 30 10 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Umscheid LONG TERM...Umscheid AVIATION...Lowe
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
938 PM CST Sun Feb 23 2020 .UPDATE... Evening AMDAR Aircraft soundings out of SAT and AUS continue to show a stout capping inversion around 800mb. This cap is the likely reason that the evening high resolution model suite from SPC and multiple runs of the HRRR have backed way off on precipitation along the front late tonight and into tomorrow morning. Forecast soundings do show that cap eroding gradually later tonight so have only pulled back PoPs by 10 to 20 percent across parts of South Central Texas. In addition, with the cap in place the likelihood of a thunderstorm being produced continues to decrease, but can`t completely rule out an isolated rumble of thunder, especially across areas east of I-35. For the most part the forecast is on track though with the front arriving overnight and most of the precipitation clearing the area by sunrise. Skies will clear tomorrow with a northwest wind behind the Pacific front, but temperatures won`t turn cooler until the next front arrives Tuesday. && .PREV DISCUSSION... /ISSUED 534 PM CST Sun Feb 23 2020/ AVIATION... VFR conditions have broken out across all of South Central Texas this afternoon. While DRT will be VFR through the period with the Pacific front arriving by 06z, the I-35 terminals will see deteriorating ceilings through the evening. The front is currently along a KPEQ (Pecos) to KLBB (Lubbock) to KAMA (Amarillo) line and should be to the I-35 corridor by 15z Monday morning. Ahead of the front MVFR cigs will begin around 04z with IFR and possibly a few pockets of LIFR between 08z and 12z. Light right is already showing up on area radars across the Hill Country with showers expected overnight along the I-35 corridor as the front approaches. An isolated thunderstorm is possible, especially around AUS, but should the capping inversion hold the majority of the precipitation should be rain showers so have taken out the mention of thunder from the AUS TAF for now due to the low confidence forecast. Winds along the I-35 corridor will go from south easterly this evening to west and northwest by 14z Monday morning. PREV DISCUSSION... /ISSUED 228 PM CST Sun Feb 23 2020/ SHORT TERM (Tonight through Monday Night)... Aircraft soundings this afternoon from AUS and SAT indicate a strong capping inversion around 850mb. Abundant stratocu is ongoing beneath the cap, with the exception of the southwest CWA. The cap will be key to convective chances later tonight ahead of a Pacific cold front. While the core of the main forcing aloft will pass north of the region, the tail end of the forcing will assist with weakening of the cap just ahead of the cold front across portions of the Hill Country and I-35 corridor. 12Z GFS as well as latest runs of the HRRR and NMM WRF soundings indicate a complete erosion of the cap between 9PM and 3AM, allowing deeper convection to develop along and ahead of the front across portions of the Hill Country and I-35 corridor, north of San Antonio. 12Z 3KM NAM, ARW WRF, and Texas Tech WRF soundings do weaken the cap during the same time, but not as fast, leading to mainly weak showers ahead of the front. The majority of SREF members are indicating precip ahead of the front, along and north of U.S. 90, so we have raised PoPs slightly for showers in this forecast package. However, due to the uncertainty with the cap and deeper convection being able to be realized we will keep thunder chances at 20%. Drier northwest flow and clearing skies will develop behind the cold front Monday morning. The Pacific nature of the front and downsloping flow will actually allow for warmer afternoon high temperatures tomorrow compared to today. Many areas will reach the mid 70s to near 80. Closer to the Rio Grande, elevated fire weather conditions are forecast where low RH values in the teens combined with occasional wind gusts near 20mph occur. Clear and cool conditions are forecast Monday night. LONG TERM (Tuesday through Sunday)... An upper level low will move across the Central Plains Tuesday and send a cold front through South Central Texas. Winds will become northerly bringing cooler, drier air. Cold advection will continue through Wednesday when the pressure gradient will intensify and winds will be breezy. High temperatures Wednesday will be mostly in the 50s. Thursday morning low temperatures will drop below freezing everywhere except the Rio Grande Plains and the Winter Garden region. Lows in the Hill Country and Edwards Plateau will be in the middle 20s. The dry air and breezy winds will make for elevated to near critical fire weather conditions Wednesday afternoon. Surface high pressure will meander around the eastern half of Texas during the second half of the week with no dominant flow regime. This will mean dry weather and gradual warming through the end of the week. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 59 74 47 65 38 / 40 10 0 0 0 Austin Bergstrom Intl Airport 58 75 41 67 38 / 50 10 0 0 - New Braunfels Muni Airport 58 76 45 69 38 / 50 10 0 0 - Burnet Muni Airport 53 71 42 62 34 / 30 0 0 0 0 Del Rio Intl Airport 54 79 46 71 39 / 10 0 0 0 0 Georgetown Muni Airport 57 73 41 63 36 / 40 - 0 0 - Hondo Muni Airport 56 78 43 72 38 / 30 0 0 0 0 San Marcos Muni Airport 59 75 43 68 38 / 50 10 0 0 - La Grange - Fayette Regional 61 75 47 69 40 / 60 30 0 0 - San Antonio Intl Airport 59 77 46 69 40 / 40 10 0 0 - Stinson Muni Airport 60 78 47 72 41 / 40 10 0 0 - && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term/Aviation...Treadway Long-Term...Hampshire
Area Forecast Discussion
National Weather Service Grand Forks ND
948 PM CST Sun Feb 23 2020 .UPDATE... Issued at 944 PM CST Sun Feb 23 2020 Mainly clear over the area at 03z. West winds are diminishing as expected. Did change pops in our far west and southwest after coord with BIS as 00z NAM and latest short term models still indicate a farther south/west band of snow Monday. The narrow zone of frontogenetical forcing that forms Monday and gives the risk of a higher snowfall band now looks safely south/west of the fcst area more so between BIS/JMS. Thus lowered pops further in DVL basin and kept highest pops more so BIS/JMS. Main challenge will be to see if idea of low clouds and fog development in NW/WC MN occurs starting 05z/06z. It would be radiational as skies mainly clear and winds light. Confidence in development and expanse of this overnight into Mon AM over MN fcst area is quite low. UPDATE Issued at 652 PM CST Sun Feb 23 2020 Biggest chance was done to add fog to areas east of the Red River. Strong signal in short range ensembles that fog will form 04-05z time period over WC MN and spread north. Winds will go near calm this evening, so radiational fog situation seems plausible. But still some doubts as had west wind all day, but trends on ensembles and aviation HRRR hard to ignore. Also some chat with ABR and looking at latest RUC/HRRR and 18Z GFS would indicate a less chance for snow into our SW fcst area. RUC still has that narrow band of a bit heavier snow (1-2 inches) extending southeast but that area has been shifting south and it now Valley City to maybe Lisbon. Indications are strong that Fargo, Wahpeton, Devils Lake north and east will be dry. && .SHORT TERM...(This evening through Monday night) Issued at 331 PM CST Sun Feb 23 2020 Quiet weather this evening with decreasing winds and mostly clear skies. Mild temps once again this afternoon despite the weak cold front passage, helped by lots of sunshine. Expect cooler lows if we remain clear, with surface high migrating over our CWA and light/variable winds. We may see some single digits at colder spots, but event that would be near seasonal normals. Main focus will be on the closed trough expected to migrate from Montana across western ND and eventually into South Dakota. Main mid/upper low track is still west of our CWA limiting larger scale synoptic forcing/moisture advection. Considering this, consensus most likely amounts will be less than 1" through Monday evening. At the same time there is still a signal for a mesoscale band associated with brief deformation east of the 700MB low center, and positive frontogentic forcing within axis of WAA nosing into the southern Devils Lake Basin and southeast ND. Soundings tend to show a persistent dry layer that may need to be overcome/saturated and there isn`t any instability of note. HREF and NBM both show a low probability signal though for 4" amounts (generally 20% or less) where this band may form and track in our western CWA maybe as far east as the souther Red River Valley, and most deterministic models are trying to resolve it (but varying in location). Due to the brief nature of this deformation/frontogensis, and lack of instability it may be more likely to achieve rates of 0.25-0.5" per hour at most (matching HREF mean). Still, with morning rush and at least "potential" for 2" or greater over a narrow/localized area we decided to introduce mention to HWO and graphics for minor travel impacts. Luckily winds are not going to be too strong and will be slower to increase (later Monday night). Any blowing/drifting snow impacts Monday night/early Tuesday morning will likely depend on what movable/blowable snow is in place, and right now peak gusts will generally be in the 25-35 mph range (likely not high enough to break up existing snow pack). .LONG TERM...(Tuesday through Sunday) Issued at 331 PM CST Sun Feb 23 2020 Little impactful weather is expected in the long term period as northwest flow aloft shunts moisture away from the region. Closer to seasonable temperatures are expected through the work week before another warming trend ensues late in the period. As an upper low moves out of the central Mississippi Valley into the Great Lakes region, northwest flow aloft will dominate through the work week before riding aloft develops out of the west. This will prevent return flow of any appreciable moisture return from the GoM. Within this flow, there is expected to be one of more passing quick shortwaves. These clippers may acquire moisture from the Pacific source and produce a chance for light snow, although spread in ensemble and lack of appreciable forcing signal negates its inclusion into the forecast. Thus the forecast reflects mostly dry conditions Tuesday through Sunday. With northwest flow aloft and troughing to the east, temperatures are expected to become more seasonable with highs generally in the teens above zero and lows in the single digits below zero. Later in the period towards the weekend, ridging aloft develops increasing the chance for another warming trend with highs near or above freezing. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 602 PM CST Sun Feb 23 2020 Model blends all indicate the potential for low clouds and fog to form just east of the Red River in the 06z-14z period. Winds will go calm this evening allowing for radiational fog formation and then low clouds. Models are bullish on this and in good agreement but west flow at the sfc this aftn not advecting low level moist air in, so should be radiational fog driven. With that, high variability location to location with impacts for MN TAF sites. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...Riddle SHORT TERM...DJR LONG TERM...CJ AVIATION...Riddle
National Weather Service Hastings NE
515 PM CST Sun Feb 23 2020 ...AVIATION UPDATE... .SHORT TERM...(This evening through Monday) Issued at 257 PM CST Sun Feb 23 2020 Closed low over the four corners region this morning continues to track east and will be the impetus of some potential precipitation for our north central Kansas counties tonight. Latest runs of the NAM/HRRR indicate that the surface low is still on track to travel east near the Kansas/Oklahoma border, and probably siding on the Oklahoma side as the NAM has been trending slower and farther south with this track and the HRRR and RAP have consistently placed the surface low on the Oklahoma side and slower to arrive still than the NAM. This all points to less precipitation expected for our north central KS counties, as has been clearly the trend over the past couple of days, and I concur with this direction from the previous forecast. Precipitation amounts continue to look like, and perhaps could start as early as late this afternoon into the evening. The Nebraska side of our CWA still looks pretty much bone dry tonight as has been the trend over the past few model runs. Although latest runs of the HRRR and RAP indicate that precipitation will likely be all rain tonight, I do think that dynamic cooling could very well end our precip with a little bit of slushy wet snow toward the end of precipitation, especially along the west/northwest fringe of the precipitation shield. Almost as soon as this system exits, we have yet another chance of some precipitation coming primarily in the Monday night through Tuesday frame as another wave dives in from the northwest. .LONG TERM...(Monday night through Sunday) Issued at 257 PM CST Sun Feb 23 2020 A period of snow showers is expected, primarily for Monday night into Tuesday evening as a quick-moving wave comes through from the northwest. Overall, qpf/snowfall is backed off in model world and WPC has trended less with snow amounts a bit. Generally one to two inches is possible in the northeast half of the CWA, with highest amounts generally northeast. By Wednesday, we will be within predominantly northwest flow between the mean trough axis over the Ohio and Tennessee Valleys and the broad ridge over the western United States. Going with a blend of GFS/ECMWF ensemble blend in the long term. There still appears to be some agreement between the GFS and ECMWF that a weak perturbation will swing through Thursday night into Friday. It appears that there will be at least some shot at some sprinkles/flurries in this time frame, but models are also in agreement that any precipitation would be rather light. Still looks like a moderating scenario heading toward the weekend as the ridge is encouraged to translate east by an eastern Pacific trough and the exit of the eastern CONUS trough. However, tends in both the ECMWF and GFS ensembles indicate a slower dislodging of colder air through Friday. Still looks like a relatively mild weekend for this time of year, and there is consensus in ensembles that the weekend will be dry. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday) Issued at 509 PM CST Sun Feb 23 2020 An area of low pressure moving over OK will keep mid and high level clouds over the area. Winds will gradually shift from NE to W as the low moves east into AR. VFR expected through the period. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...Heinlein LONG TERM...Heinlein AVIATION...Beda
Area Forecast Discussion
National Weather Service North Platte NE
612 PM CST Sun Feb 23 2020 .SHORT TERM...(This evening through Monday night) Issued at 259 PM CST Sun Feb 23 2020 Concerns in the near-term revolve around the potential for rain/snow and snow chances Monday into Tuesday with the next disturbance moving into the area. The period begins with relatively zonal flow aloft as a compact h5 cut-off trough currently ejecting onto the Southern Plains moves into southeast Colorado and parts of southwest Kansas into the OK/TX Panhandles. This feature has been well advertised for a few days now with concerns that the area could see impacts from its northern fringes of precipitation. Light echos have been prevalent on radar much of the daytime as modest fgen is thrown north from the main trough. This fgen has generally weakened as it lifts now, however, has managed to produce a few pockets of perhaps sprinkles across southwest Nebraska. Inherited forecast contained "Slight Chance" and "Chance" PoPs across these areas but these were removed owing to the abundance of dry air in the lowest 2 km. Both the RAP and HRRR were quick to pick up on this and thus supported the decision to remove and replace with just a mention of sprinkles. Dew point depressions of nearly 40 degrees Fahrenheit and cloud bases of 9k feet AGL or greater back up this thought. Expect these light echoes and possible sprinkles to linger for areas along and south of Interstate 80 through the evening before moving off the south and east, following the stronger mid-level fgen bands. Weak surface high pressure will approach from the north late tonight with a strengthening low pressure further south towards the KS/OK border. Lows tonight will fall into the 20s to near 30 in proximity to the Pine Ridge. Attention quickly turns to the quick approaching shortwave trough moving out of the Pacific Northwest and onto the Central Plains during the day on Monday. Biggest forecast-to-forecast change has been to slow the arrival of precipitation to the area as strongest height falls and vorticity advection look to occur post-sunrise on Monday. Lee-cyclogenesis will begin across western South Dakota during the morning hours, leading to increasing southerly flow across much of western Nebraska. As this low develops and treks east along Interstate 90, an attendant surface cold front will sweep through the region from west to east. It`s this feature and associated lift coincident with it that`ll lead to increasing PoPs through the morning hours into the afternoon. These PoPs will be greatest for areas north of Interstate 80 through Monday evening. Daytime highs will climb into the upper 30s to 40s, with thoughts that any precipitation should be rain or a rain/wet snow mix. Dry air at the surface will also need to be overcome as this system isn`t bringing much moisture with it and residual dry air from Sunday will remain in place. General thoughts are little to no QPF is expected during the day on Monday. Winds behind this frontal boundary will increase out of the west with gusts as high as 35 mph for portions of the eastern Panhandle and 30 mph or less for further east. Elevated winds will continue into Tuesday as h85 flow remains elevated with 30 to 40 knots of flow through the event. The approaching trough will begin cutting off immediately upstream and with this occurring will slow its progression Monday evening into Tuesday, becoming centered over western Nebraska by early Tuesday morning. Strong isentropic ascent, particularly on the 290-295K surfaces, along with peaking differential vorticity advection will lead to increasing precipitation towards sunrise on Tuesday. By this time, temperatures will be well cold enough to support all snow across the region as h85 temperatures approach -8 degrees C and h7 temperatures approaching -20. The main h5 cutoff will have shifted south and east of the area by late morning Tuesday, with subsidence behind the departing wave and downglide across the lowest isentropic surfaces. This should bring a quick end to precipitation through the afternoon and into the evening. Current thinking is the heaviest precipitation will be confined to areas north of Highway 2 with generally 1-3" of snowfall expected and localized amounts closer to 4" possible. Did discuss potential for Winter Weather Advisory with neighbors considering expected snow totals and strong winds, but opted to defer to later forecasts for now given lingering uncertainties with where heaviest snowfall occurs. Tuesday will be well below-normal for temperatures with highs in the 20s and 30s and lows in the single digits to teens. Combined with strong winds, feels-like temperatures will remain in the single digits to teens all day making it feel very raw for late February. .LONG TERM...(Tuesday through Sunday) Issued at 259 PM CST Sun Feb 23 2020 Beginning 12z Wednesday. The extended period begins with highly amplified northwesterly flow as the area is caught between the departing trough and developing ridge along the west coast. Both the ECMWF and GFS advertise a weak clipper-like system moving through the area sometime in the Thursday/Friday timeframe. Both model outputs are similar in thinking with respect to this potential disturbance, although they differ on timing by 6 to 12 hours. Because of this, opted to leave the forecast as is which has a small coverage area of "Slight Chance" PoPs across north central Nebraska Thursday. That appears to be the only blemish on an otherwise dry forecast as the aforementioned ridging pushes eastward onto the Plains by the weekend. This will allow temperatures to climb Wednesday through Friday from the 20s/30s to 30s/40s. Then, as the main ridging arrives overhead by Saturday, temperatures will jump back into the 40s/50s with potential for some 60s on Sunday and dry conditions. For the start of next week, another stout trough will move onshore and approach the region in the Monday/Tuesday time frame. Some uncertainty remains with where the greatest impacts will be seen from this system as the GFS and ECMWF have vastly different evolutions. Either way, be mindful of potentially active weather for next week. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 608 PM CST Sun Feb 23 2020 VFR conditions will rule through noontime Monday. Mid and high clouds will prevail with light winds. A cold front will move into the area Monday afternoon with winds shifting to the northwest with gusts up to 25 kt. In addition some scattered light rain or snow will be possible. An area of MVFR ceilings will accompany the front across northern portions of Nebraska including the KVTN terminal. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Jurgensen LONG TERM...Jurgensen AVIATION...Taylor
Area Forecast Discussion
National Weather Service Marquette MI
742 PM EST Sun Feb 23 2020 .SHORT TERM...(This evening through Monday) Issued at 340 PM EST SUN FEB 23 2020 Water vapor imagery and RAP analysis show a rather vigorous shortwave moving across Lake Superior. Despite its strength, sunny skies have prevailed across the fcst area today after some thin stratus quickly exited/dissipated this morning. Under the sunny skies, it`s been another warm Feb aftn across the fcst area. Similar to yesterday, temps have again pushed above 50F at some locations across the w half of Upper MI. SSW wind off Lake MI is again keeping the e cooler. Cold front associated with the shortwave is currently moving across central Upper MI. Postfrontal winds are fairly strong/gusty as expected. Winds across western Upper MI are gusting above 30mph at many locations with winds across the Keweenaw higher. KCMX has had peak gusts btwn 44 and 51mph over the last couple of hrs. Cold front will clear the fcst area over the next several hrs. With incoming pres rises around 2mb/3hr, modest CAA and waning solar heating, winds will remain fairly strong/gusty over the w. Gustiness will spread eastward with fropa, though cooler conditions over the e as well as the start of boundary layer cooling with setting sun will keep winds quite a bit lower than over the w. Over the Keweenaw, expect gusts to around 45mph over the next few hrs as lingering daytime heating and caa support deeper mixing to winds of 40-45kt. Upstream, a narrow band of low clouds is streaking se into northern MN. With the setting sun and diminished mixing, will probably see these low clouds expand some as they push into the fcst area this evening. With 850mb temps only falling to -5 to -8C across Lake Superior, lake effect pcpn will not be a concern tonight. Min temps will be in the 20s. High pres ridge will build into the area from the nw on Mon, resulting in nw winds veering northerly during the aftn. Fcst soundings, particularly the NAM, indicate quite a bit of low-level moisture and thus more clouds Mon. Other than the band of low clouds dropping se thru northern MN, have to go quite far to the nw to get into more expansive cloud cover. Low-level flow should advect this moisture toward the area, but low-level flow will also become more anticyclonic on Mon. In the end, painted a partly to mostly cloudy sky across the area. High temps will fall back closer to normal, but still above normal for late Feb, ranging from the lower 30s near Lake Superior to about 40F far s central. .LONG TERM...(Monday night through Sunday) Issued at 338 PM EST SUN FEB 23 2020 As the area begins to feel the influence of the developing low pressure system in the Mississippi Valley, winds will veer to NE Monday night. under 850 mb temps of about -7 C at 06z Tuesday, dropping to about -9 C by 12z, the upslope component of this wind along with lake moisture from the still mostly ice-free Lake Superior could end up generating some freezing drizzle over the higher terrain of the NE wind lake-effect belts. NAM and GFS soundings show saturation that is somewhat marginal for precip - only about 2500 to 3000 ft - but that`s ended up being enough several times before recently. With very dry air just above about 3 kft (or just about -8 C) this precip would almost certainly be FZDZ to start, transitioning to a mix of snow showers and FZDZ during the day Tuesday as temps aloft cool and deeper moisture slowly creeps northward. Actual accumulations of snow or ice look minimal, but given that the roads are mostly clear now from a couple days of melting, and in some spots have had the salt washed clean by meltwater, there could end up being slick spots on the roads for the Tuesday morning commute. So this will need to be watched closely. After that attention turns to what still looks like a significant storm system developing over the Central Plains. Models continue to struggle somewhat with the exact timing and locating of the phase between a northern stream short wave diving southeastward through the Plains and a vort max on the southern stream ejecting out of the SW U.S. Contrary to yesterday, the trend in the models today has been back east somewhat and thus towards less synoptic/system snow for the U.P. This includes the GFS and the GEFS, which yesterday were more amplified outliers. Rather than windshield-wiping any more on POPs, mostly kept the chance to low-end likely POPs generated by the NBM for now in case there end up being another shift back west. Regardless of how much "system" snow the area ends up seeing, prospects for a long duration of moderate to perhaps heavy lake- effect snow are increasing for Wednesday night through Thursday night. The GFS and EC are in good agreement that as another short wave merges into the upper level low late Wednesday, an inverted upper level trough develops to the west over Lake Superior which allows moisture to remain deep as strong CAA occurs. The combination of 850 mb temps in the -17 to -20 C range and saturation to, at a minimum, 700 mb, should support plenty of LES for the N to NW wind snow belts, especially on Thursday. Therefore, have increased POPs to likely or higher in those areas at that time. Still too early to talk about potential accumulations though, except to say that while several inches looks possible, this will probably be a long duration of on-and-off snow showers, and a fluffier snow more typical of lake- effect, both points which should reduce the overall impact. That system finally moves out somewhere around Friday. With high pressure expected to build in behind it, next weekend right now looks dry save for any lingering lake-effect snow showers over the eastern U.P. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 738 PM EST SUN FEB 23 2020 Colder air moving in this evening in the wake of a frontal passage will continue to result in gusty winds this evening with gusts to 25 kt at KIWD and to 30 for a few hrs at KCMX. Post frontal MVFR cigs should also develop at KCMX/KIWD this evening and perhaps at KSAW though downsloping may prevent a bkn or ovc cig from developing. Winds will diminish during the night. As winds become more n-ne Mon afternoon expect MVFR cigs to develop at KSAW as well. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 340 PM EST SUN FEB 23 2020 Cold front is currently extending s across central Lake Superior. Expect gales of 35-40kt to continue following the front as it exits the lake over the next several hrs. Winds will then diminish to blo gale force from w to e during the night tonight. Winds will diminish further to blo 20kt on Mon. As low pres slowly lifts across the Ohio Valley, Great Lakes and into Quebec Tue thru Thu, n to ne winds will increase to at least 20-30kt. In fact, over central and eastern Lake Superior, it is looking a little more likely that gales to 35-40kt will occur late Wed night thru early Fri. Winds will then gradually diminish from w to e during the day Fri. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Warning until 5 AM EST Monday for LSZ251-267. Gale Warning until 4 AM EST Monday for LSZ243>250-264>266. Gale Warning until midnight EST /11 PM CST/ tonight for LSZ240>242-263. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...RJC AVIATION...Voss MARINE...Rolfson
Area Forecast Discussion
National Weather Service Nashville TN
759 PM CST Sun Feb 23 2020 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... Radar continues to show light echoes mainly south and west of Nashville. Dew points continue to rise and the atmosphere has undergone considerable moisture advection during the last 12 hours, but the layer below ~800 mb is largely dry and ceilings remain VFR. The HRRR shows only light precipitation until closer to 12Z. Hourly grids are holding up well thus far, so no forecast changes are planned this evening. Will update the public forecast shortly for wording only. && .AVIATION... 00Z TAF DISCUSSION. Light returns are showing up across the area on radar at this time. Low levels are still dry so only a few light showers have reached the ground at BNA and MQY. It will still take a few more hours to moisten the low levels enough for cigs to fall below VFR. Eventually cigs will drop to MVFR/IFR and possibly LIFR at CSV. The probability of showers is high enough to mention through the end of the taf cycle. There could even be a stray storm late Monday afternoon at CKV but probability is not high enough to include VCTS. Winds will be southerly through the taf forecast and become gusty by Monday midday. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......08 AVIATION........Reagan
National Weather Service Charleston WV
932 PM EST Sun Feb 23 2020 .SYNOPSIS... High pressure exits tonight. Warm front lift north Monday. Surface low pressure and associated cold front pass Wednesday. && .NEAR TERM /UNTIL 9 AM MONDAY MORNING/... As of 930 PM Sunday... Adjusted minimum temperatures down at some of the higher elevations based on guidance. Also adjusted dewpoint temperatures for the next several hours to better represent the current conditions. Sky cover was increased for parts of the area for the next few hours to be more representative of current satellite. As of 143 PM Sunday... Surface high pressure exits east tonight as a surface low pressure located over western KY approaches from the west. Models differ on the onset of QPF with the associated warm front. The NAM model is the slower of synoptic models bringing the onset of rain across the WV and KY border by 12Z Monday. Preferred the high resolution RAP model which is even slower and weaker onset of precipitation. Coded chance PoPs with by 12Z and likely PoPs spreading from south to north by 18Z Monday. However, periods of rainfall will continue into Tuesday afternoon. Expecting close to 0.50 inches of rain accumulations across the extreme southern portions of the area, and around 0.25 inches elsewhere. Flash flood guidance range from 1.5 to over 2 inches across the southern coalfields, so flooding problems are not anticipated. After sunset, temperatures will drop into the mid to upper 30s across the lowlands, ranging into the upper 20s higher elevations. It could be not as cold if cloudiness persist tonight, but skies are expected to clear later this evening. There could be a brief period of mixed precipitation along the mountains early Monday morning if pcpn reaches the cold spots by this time, but chances are very low. && .SHORT TERM /9 AM MONDAY MORNING THROUGH WEDNESDAY NIGHT/... As of 147 PM Sunday... Short term period starts out with light rain across the CWA, with an upper shortwave and surface low across the midwest. Temps Monday night should remain rather steady, owing to a southerly flow across the area. Much of Tuesday will dry out across the area as the surface low lifts north. However, a stronger upper trough/closed low will develop across the central U.S., and eventually trek northeast into the Great lakes region by Wednesday, sweeping a cold front across the area. Much colder temperatures, and gusty winds will occur during this period, and will see a change over to snow area wide by Wednesday night, with light accumulations possible mainly across the higher terrain. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 148 PM Sunday... Gusty winds and much colder conditions can be expected to start the long term period, along with overall drier weather taking hold as low continues to move off to the northeast. Another disturbance is possible over the weekend, bringing a reinforcing shot of cold air, and light precipitation. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... As of 625 PM Sunday... Sites will continue to see VFR conditions for the beginning of the period. Ceilings will begin to lower as the next system moves in from the southwest. MVFR conditions in ceilings should occur at the sites in the morning on Monday, starting from the southwest and lowering toward the northwest over the day on Monday. Some sites will see rain during this TAF period, particularly CRW, HTS, and BKW. Visibilities may begin to slightly lower as this rain moves in. Winds will mostly be light and variable throughout the period. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z TUESDAY... FORECAST CONFIDENCE: High. ALTERNATE SCENARIOS: Timing of MVFR conditions could vary. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE MON UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 00Z TUESDAY... IFR possible in rain Monday night through early Tuesday, and then Wednesday and Thursday in rain and snow. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...ARJ/SL NEAR TERM...ARJ/CG SHORT TERM...SL LONG TERM...SL AVIATION...CG