Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/12/20

Area Forecast Discussion
National Weather Service La Crosse WI
1020 PM CDT Wed Mar 11 2020 .SHORT TERM...(This evening through Thursday) Issued at 204 PM CDT Wed Mar 11 2020 At 2 PM, the low clouds are starting to break in northeast Iowa and southeast Minnesota. This will partial clearing will gradually move east this afternoon. High temperatures will be mainly in the 40s. From late tonight into Thursday, a shortwave trough will move southeast through the region. Several bands of showers will develop across the region. With the RAP building CAPES up to 400 J/kg across northeast Iowa, and southwest and central Wisconsin on Thursday afternoon, added a small chance of thunderstorms to the forecast. There is 35 to 45 knots of 0-3 km shear. This is likely too much shear considering the amount of CAPE across the area, so not anticipating any severe weather. Rainfall amounts will be up to a third of an inch. .LONG TERM...(Thursday night through Wednesday) Issued at 204 PM CDT Wed Mar 11 2020 Upper level trough pushes east over northeastern United States/southern Canada Thursday night. Northwest flow aloft will advect a cooler airmass into the forecast area Thursday night into Friday. Highs will mainly be in the 30s to middle 40s. Next concern is the possibility of light rain or snow across the far southern forecast area the deterministic 11.12z models suggest a shortwave tracking into the Central Plains States. The better vertical motion/forcing and saturation will be south of the forecast area. With the weak lift over the far southern forecast area...cannot rule out the possibility of light rain/snow across the far southern forecast area. Otherwise...Surface ridge will remain in control for much of the forecast area Friday night into Saturday. Main forecast concerns Saturday night into Wednesday are precipitation chances through the period. The 11.12z GFS/ECMWF/GEM continue to be in good agreement in developing southwesterly flow aloft. Pieces of energy embedded in the southwesterly flow aloft will track into the Upper Great Lakes Region through the period and provide on and off chances of precipitation across the forecast area. Confidence remains low on timing of each impulse moving into the Upper Midwest and Great Lakes Region. Precipitation looks to be mainly rain for much of the area...however at night when boundary layer cools to near freezing precipitation could change to all snow or snow mix in with the rain. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1020 PM CDT Wed Mar 11 2020 Cigs: low clouds will be on the return Thu morning, looking more after 12z now, as yet another shortwave trough bears down on the region, coupled with an increase in low level saturation. IFR/MVFR currently expected which will likely linger through the day Thu. Expecting improvement Thu night as the shortwave exits east. WX/vsby: associated sfc front with the upper level feature will help spark an area of showers along and ahead of it for Thu morning - with latest meso models trending toward bringing it in a bit earlier than previous runs - roughly 09-11z. A few hours of -shra before exiting east with the front. However, cyclonic flow a loft, coupled with increasing low level lapse rates, could spark a few showers post the front. Winds: southerly through the night, swinging to the northwest for Thu afternoon with the passage of a cold front. Winds will also be on the increase - around 20 kts sustained with gusts in excess 30 kts at times. Meanwhile, LLWS a concern by 12z Thu as low level winds ramp up ahead of the the trough/front combo. Expect 45-50kts by 2 kft from SSW for a few hours Thu morning as a result. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Boyne LONG TERM...DTJ AVIATION...Rieck
Area Forecast Discussion
National Weather Service Duluth MN
652 PM CDT Wed Mar 11 2020 .SHORT TERM...(This evening through Thursday night) Issued at 349 PM CDT Wed Mar 11 2020 Currently southerly surface winds are pushing WAA across the Northland. The warm air overriding the cooler air in place has created isentropic lift over northern MN with snowfall being reported near the International Border. Radar is also picking up elevated snow showers over northeast MN but currently the dry low levels are evaporating the snowflakes before they reach the ground. As we continue into the evening hours the column of air becomes more saturated towards the surface and will result in snow at the surface. Southerly flow off of Lake Superior will trigger some orographic lift enhancement over Cook County leading to possibly an inch of snowfall. The warm front driving this event will propagate to the northeast in the overnight hours and take with it the precipitation. Light southerly winds will provide the needed mixing with the saturated surface to generate patchy fog early tomorrow morning across the Northland. A newly formed low over the Central Plains with strong mid level support begins to swing through the Northland tomorrow bringing precipitation across the region. North central MN will begin the day off with snowfall with east central MN and northwest WI experiencing rain due to their warmer temperatures. As the day progresses the system slowly moves northeast and snowfall in north central MN will transition to rainfall with warming daytime temperatures. Thursday evening rainfall will begin to diminish for northwest WI and east central MN. Winds will flip to out of the northwest and a secondary cold push plunges down out of Canada on the backside of the exiting low. Wrap around moisture and this cold push of air could induce light snow flurries for northern MN. .LONG TERM...(Friday through Wednesday) Issued at 349 PM CDT Wed Mar 11 2020 A break in robust precipitation is expected for Friday through much of Sunday, with the next chances of widespread precipitation, mainly in the form of snow, for Sunday night through Monday. Slightly colder temperatures are expected Friday and Saturday, but will warm back up for Sunday through Wednesday. Friday will be mostly dry, with the exception for perhaps some light snow flurries across the north, thanks to persistent northwesterly, cyclonic flow, and cold air advection, across the region. This should occur in the wake of a large upper-level trough that will continue to move eastward across eastern Ontario and into western Quebec Canada. NAM and GFS model soundings at INL both indicate some marginal saturation within the dendritic growth zone, so have introduced a chance of flurries for Friday. Otherwise, expect mostly cloudy skies in the morning, with some peeks of sunshine in the afternoon. Highs on Friday will remain in the 20s to lower 30s. Colder air remains in place for Saturday, but dry conditions are expected, thanks to high pressure nosing into the region from the Canadian Prairies, along with large-scale subsidence. Highs will remain in the 20s to lower 30s, under partly sunny skies. The next widespread chances of precipitation, mostly in the form of snow, will move into the Northland Sunday night as a mid-level shortwave rides over the upper-level ridge, along with an attendant surface low. Ahead of the surface low will be enhanced low-level frontogenetic forcing and convergence to support these increasing chances of precipitation. Uncertainty remains on the extent and amount of the precipitation, with the GFS farther south compared to the ECMWF, and the GEM model doesn`t have as much QPF. This has resulted in significantly different snowfall amounts over the region, so confidence is rather low for this event at this time. Gradually, this precipitation should shift eastward as a surface cold front passes through Monday. Eventually, drier conditions should return on Tuesday, with yet another chance for precipitation on Wednesday. Some rain may mix in at times with the snow, particularly during the daylight hours and over northwest Wisconsin Monday. Highs Sunday through Wednesday will generally be in the 30s to lower 40s, with perhaps some colder readings on Tuesday. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 652 PM CDT Wed Mar 11 2020 An area of warm air advection and a weak shortwave were producing light snow over portions of the Arrowhead this evening. This is expected to decrease then another shortwave and area of low pressure will move into the region overnight into Thursday. These features will spread light snow, light rain, and possibly some freezing drizzle into the region later tonight into Thursday. We do expect ceilings to lower tonight but there remains some uncertainty how quickly MVFR then IFR ceilings will develop. We followed the RAP for the next couple hours then trended to blended guidance which lowers ceilings quickly overnight to IFR. MVFR ceilings were occurring at KFOZ and KY49 and it`s expected they will increase in coverage and lower. Some fog will also be possible with several of the models indicating that. We lowered the visibility for most TAFs and we may not be low enough as there are indications of them dropping to around a half mile. The fog will lift through the day Thursday as winds become west/northwest and increase on the back side of the area of low pressure. The precipitation will also decrease from west to east with some flurries likely continuing in spots as cold air moves in. && .PRELIMINARY POINT TEMPS/POPS... DLH 31 39 18 28 / 40 60 10 10 INL 27 37 10 22 / 20 30 30 10 BRD 31 38 17 28 / 50 60 10 0 HYR 35 44 21 33 / 50 80 20 10 ASX 33 44 23 33 / 40 80 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...None. && $$ SHORT TERM...BJH/Britt LONG TERM...JTS AVIATION...Melde
Area Forecast Discussion
National Weather Service Quad Cities IA IL
822 PM CDT Wed Mar 11 2020 ...HYDROLOGY UPDATE... .SYNOPSIS... Issued at 258 PM CDT Wed Mar 11 2020 Extensive low clouds have persisted longer across the CWA today, resulting in lower high temperatures. These clouds were trapped underneath a strong inversion around 900mb, as shown on 12z DVN sounding. 18z LAPS MSL pressure analysis shows weak surface low over southern WI, with light west winds over the forecast area. Temperatures at 2 pm, were in the middle to upper 40s and dewpoints were in the upper 30s and low 40s. Latest WV imagery shows a wave over Montana, which will bring our next chance of precipitation to the area Thursday. && .SHORT TERM...(This Evening through Thursday) ISSUED AT 258 PM CDT Wed Mar 11 2020 Forecast concerns in the short term are cloud trends, temperatures, and precipitation timing Thursday. Tonight...low clouds will continue to dissipate from west to east this evening. Back edge of clouds will be near the MS RVR by 5pm. Winds will switch out of the south and despite the mostly clear skies for at least a portion of the evening, will help keep temperatures up overnight with readings only dropping into the low 40s. area of low pressure will track east across southern Minnesota and western Wisconsin during the morning, dragging a cold front through Iowa. An increase in clouds and southerly winds are expected ahead of the front, allowing temperatures to rise into the upper 50s and lower 60s. Latest CAMS and hi-res models show precipitation over northern Iowa in the morning, tracking east into the region after 15z Thursday. Best lift is forecast just to the north of CWA, whereas best moisture along the front appears will be over northern MO and southern IA. In any case, expect to see light rain track over the CWA late morning through early afternoon with amounts generally less than a tenth of an inch. Added slight chance of thunder to the forecast, as there will be some CAPE and latest RAP 700-500mb theta-e lapse rates go negative ahead of the front. Once the precipitation exits, breezy northwest winds and clearing skies will be found behind the cold front. .LONG TERM...(Thursday Night through Wednesday) ISSUED AT 258 PM CDT Wed Mar 11 2020 Key Messages: 1) Quiet conditions expected through daytime Friday 2) Precipitation expected Friday night through Saturday; potential for accumulating snow. 3) Brief break in precipitation Sunday before periodic chances return early and in the middle of next week. Discussion... Thursday Night and Friday... Precipitation associated with the passing cold front will move out of the mid-Mississippi River Valley Thursday night, giving way to clearing skies Friday under northwest winds. Despite 850 mb temps falling to around -5 to -10 C, we will still be near normal for temperatures with deep mixing expected. Afternoon highs will range from the mid 40s north of Highway 30, to near 50 south of Highway 34, which is near normal for mid-March. Friday Night through Saturday Night... Next chance for precipitation arrives Friday night and Saturday with the approach of a 500 mb shortwave ejecting out of the eastern Rockies. Low-level WAA will overspread the mid-Mississippi River Valley leading to widespread precipitation from the Ozarks to southern Iowa and central Illinois. Across our area, forecast soundings are indicative that our precipitation will fall mainly as snow as northerly flow advects plenty of cold air in aloft. Analysis of lift in a fairly saturated dendritic growth zone also suggests accumulating snow is possible. Amounts are still questionable as guidance has not settled on the track of favored lift. The good news is that dprog/dts continue to trend potential heavier snow amounts further into Missouri/central Illinois, with lesser amounts in our CWA. There will likely be a sharp cutoff to the north of the snow accumulation thanks to the northerly flow and dry air. Sunday... A nice end to the weekend is expected with surface high pressure briefly building over the area. Temperatures will fair near to below normal. Monday on... Closed 500 mb low stalled across the western CONUS will be our primary weather concern heading into next week. Guidance shows mainly a zonal flow across the area with periodic shortwaves ejecting out of the closed low towards the Midwest, which signals high confidence of active weather remaining in place. The first of these shortwaves will arrive Monday night and Tuesday, bringing chances of rain. The next shortwave will follow for Wednesday and Thursday, but guidance remains in disagreement on the timing and placement of heaviest precipitation. Temperatures will average near to just above normal. && .AVIATION...(For the 00Z TAFS through 00Z Thursday Evening) ISSUED AT 624 PM CDT Wed Mar 11 2020 The MVFR stratus deck will move out of the terminals early this evening, giving way to mostly clear skies and light winds. This may lead to fog later tonight, which for now is limited to MVFR visibilities. Forecast confidence on the fog potential is below average. A cold front will move through the area Thursday afternoon, likely accompanied by at least scattered showers and a few thunderstorms. The potential for thunderstorms is too low to include in the forecasts at this time. Ahead of the front, low clouds are expected to redevelop with MVFR ceilings in the morning, persisting at least until the front moves through in the afternoon. && .HYDROLOGY... Issued at 821 PM CDT Wed Mar 11 2020 Area rivers continue to rise in response to the spring snowmelt and last weekend`s rainfall. The response has been lower than previously forecast, especially on the Rock River. The latest forecast for Joslin has the river cresting below flood stage Friday night and the flood warning that was in effect has been cancelled. Elsewhere, many tributary rivers are expected to crest near or just above action stage later this week into early next week. There is the potential for more rain or snow this weekend into next week. Those with interests along area rivers should monitor later forecasts. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...Gross SHORT TERM...Gross LONG TERM...Speck AVIATION...Sheets HYDROLOGY...Sheets
National Weather Service Sioux Falls SD
1059 PM CDT Wed Mar 11 2020 .SHORT TERM...(This Evening through Thursday) Issued at 307 PM CDT Wed Mar 11 2020 Temperatures making a quick run into the 50s and even 60s in portions of the area this afternoon, now that stratus and fog have diminished. A breezy southerly wind is expected to persist into the evening hours, preventing and quick drop in temperatures. Tonight-Thursday: Elongated upper trough begins to swing through the area later tonight. Surface low pressure will drift across northern Nebraska after midnight, keeping surface winds breezy, and perhaps inducing a few stronger gusts over NW Iowa after midnight. Feel the stratus/fog redevelopment chances remain lower than last night due to the more mixy wind conditions. Colder air will begin rushing down the backside of the surface low after 3am, with some high resolution models suggesting quick gusts up to 30-40 knots in areas of the Missouri River valley. Have blended in HRRR gusts to account for these frontal winds. Precipitation associated with this wave is again anticipated to be minor, tied to mid-lvl frontogenesis well behind the surface boundary. Will include a low PoP as this corridor of moisture moves through during the morning and mid- morning hours of Thursday. Soundings show increased wind gust potential through the day on Thursday, with potential for 35+ knot winds at times during the afternoon and into early evening. Have bumped up winds throughout the area. These enhanced winds will lead to very high fire danger risks along the Missouri River Valley counties through the day. Increasing cold air advection will limit the upward climb in high temperatures, but we`ll struggle to climb towards the middle 40s. The other thing to watch for would be the potential for convective showers to develop Thursday afternoon given steep mixing rates and shallow moisture at or around 800 mb. Will not include PoPs at this time, but they may need to be added. .LONG TERM...(Thursday Night through Wednesday) Issued at 307 PM CDT Wed Mar 11 2020 Friday: High pressure moves through on Friday, leaving dry conditions and lower cloud cover in the region. Temperatures will struggle to reach normal values mid-March, but winds will be fairly light. Friday Night-Saturday: Shortwave energy is still expected to move out of the Central Rockies late Friday night, inducing a brisk easterly wind by Saturday morning. Further west, an elongated area of warm advection underneath a broad left exit region of an 300 mb jet, will lead to widespread precipitation stretching from the western Dakotas through Missouri. This precipitation area will struggle to reach northeast due to increasing northeasterly fetch of dry air in the lowest levels, however anticipating areas of accumulating snow along and southwest of the James River Valley into Saturday morning. Current indications point to 2-5 inches of snow, with the greatest amounts near the Missouri River and into Nebraska. The positive news though is that temperatures will attempt to rebound into the middle and upper 30s, which should promote quick melting. Sunday: Mid-lvl heights rise on Sunday, which should lead to quiet weather. We`ll likely see temperatures rise just a degree or two above normal during the afternoon hours. Monday-Wednesday: Medium range models are converging on a solution that brings a northern stream trough through the area early next week. There are some differences in the intensity and moisture with this wave, but it could bring additional light rain/snow to the area within the Monday night and Tuesday timeframe. No strong deviation in temperatures from normal are anticipated early next week. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1052 PM CDT Wed Mar 11 2020 With a low level jet of 50 to 60 kts overnight, low level wind shear is expected from 06Z-12Z at KSUX. As the front goes through winds aloft will decrease some and winds at the surface will increase. Otherwise, with the frontal passage, winds will switch to northwest. Obs in southeast MT show that winds briefly gusted over 30 kts just behind the front before decreasing to 20 to 25 kts. So have 1-2 hours of higher gusts with the frontal passage, followed by a brief decrease and then winds increasing again as higher winds mix down in the afternoon. Winds are expected to rapidly decrease after sunset. Otherwise, models show some light showers along and behind the front. All soundings are dry below 4000 ft so expecting at best a few sprinkles and did not include in TAFs. Earlier models had shown the potential for instability showers and the potential for MVFR ceilings with cumulus development in the afternoon but now even the RAP and HRRR show more drying at the surface so expect VFR ceilings through the period. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM...Dux LONG TERM...Dux AVIATION...Schumacher
Area Forecast Discussion
National Weather Service Marquette MI
802 PM EDT Wed Mar 11 2020 .SHORT TERM...(This evening through Thursday) Issued at 425 PM EDT WED MAR 11 2020 WV imagery and RAP analysis indicated a zonal pattern across the northern CONUS with a vigorous shortwave trough from southern Alberta into northern Montana. Weak shrtwv ridging along with sfc high pressure has brought sunshine to northwest Upper Michigan while increasing moisture in the developing southerly low level flow has pushed clouds into the southeast. WAA and isentropic ascent ahead of the a sfc trough into the Dakotas was bringing increasing mid and high clouds into Upper Michigan. Tonight, expect a leading area of stronger WAA and 285k-290k isentropic lift to brush Lake Superior as it moves mainly into northern Ontario. There may also be some light pcpn into Upper Michigan, but with the stronger forcing to the north and a strong 900-700 mb dry layer, any amounts will be light. With temps remaining near or just above freezing, expect mainly rain with the potential for some patchy snow where evaporative cooling is strong enough. Thursday, as the shortwave approaches with moderate to strong 700- 300 qvector conv rain will spread across Upper Michigan. Models were in reasonable agreement with QPF into the 0.25-0.50 inch range, highest over the east. The rain may mix with wet snow over the west late as colder air moves in behind the cold front. However, with the stronger forcing and moisture inflow already shifting to the east, minimal/no accumulations are expected. .LONG TERM...(Thursday night through Wednesday) Issued at 412 PM EDT WED MAR 11 2020 Most of the focus in the long-term period will be on the system Thursday night with precip continuing Thursday evening and then gusty winds Friday. Models are in fairly good agreement that a surface low of about 995-998 mb will be centered more or less over Lake Superior at 00z Friday and will be deepening quickly. The cold front band of precip will mostly be exiting the area to the east by this point although moderate rain will continue through about midnight over the eastern U.P. For the central and west, there`s a question of how much (if any) snow falls behind the front. The NAM is an outlier in showing a couple inches of snow post-front so have disregarded it for this forecast. However will note that given the orientation of the upper-level jet such that the left exit region straddles the front or perhaps falls behind it, and the NAM (naturally) indicating secondary fgen in the cold front, a surprise anafront snowfall isn`t completely impossible. Again, for now the forecast is for just light slushy accums post-front, but this period will bear watching. Although some light upslope, lake-enhanced snow or freezing drizzle could linger over the west through Thursday night, the main story after that point will be the increasing winds. Models are fairly tightly clustered around a 986-989 mb low NE of the lake by 12z Friday with strong CAA of -10 to -15 C per 12 hr and 3 hr pressure rises of 3-4 mb. With 40-50 kt winds aloft and mixing to at least 3 kft on land (deeper over the water, of course) gusts 30-40+ mph continue to look likely area-wide Friday morning through afternoon. Would not be at all surprised to see some 50 mph gusts over the Keweenaw during this time period as well. As the low pulls away to the northeast Friday night, the gradient subsides and so do the winds. Some light lake-effect snow is possible in the west wind snow belts on Friday once 850 mb temps drop to around -14 C but models mix out the low levels quickly so went pretty bearish on POPs and QPF resulting in just a few tenths of an inch of additional snow accumulation during the day Friday. After that the long-term turns quiet. High pressure builds in for the weekend so dry conditions are expected both days. A weak trough around Monday night or Tuesday should provide the next chance for light rain or snow showers. After that it`s another strong high with subsequent dry weather for the middle of next week. Looking out even further than that, the pattern starts to look more favorable by the end of the week for a system to track from the Gulf to the Upper Great Lakes. Today`s 12z GFS, EC, and CMC all have it and all produce either snow or a wintry mix for the area. Given that this is about 8 days out, expect a lot to change, but nonetheless a reminder that winter in the U.P. isn`t over yet. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 749 PM EDT WED MAR 11 2020 VFR cigs will likely continue tonight for IWD and CMX before conditions lower to IFR late Thu morning/afternoon with the onset of rain and fog. VFR conditions at KSAW this evening will lower to IFR cigs and vsbys as an upslope southerly flow from Lake Michigan allows stratus/fog to form. IFR/LIFR conditions will continue on Thu as rain moves in. Some LLWS will also be possible this evening into the early overnight at KIWD and KCMX and at KSAW on Thu as a low-level wind max moves across the area. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 425 PM EDT WED MAR 11 2020 As a developing low pressure system drops south through Manitoba tonight, the gradient increases and winds will increase from the S, with gusts in the mid to upper 20 knots range. As this low pressure system passes to the north Thursday night into Friday, it begins to deepen as colder air brings increasing instability across the lake. As a strong high pressure system builds across the Canadian Prairies behind this exiting low, the pressure gradient rapidly tightens and winds increase from the NW, with some gusts to storm force. The Gale Watch will continue with the potential for an upgrade to a Storm Warning, mainly across the eastern half of Lake Superior. As that high pressure moves east on Saturday morning, the pressure gradient will relax and winds look to remain relatively light below 25 knots through the rest of the forecast period. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Watch from late Thursday night through late Friday night for LSZ249>251-266-267. Gale Watch from late Thursday night through Friday evening for LSZ162-240>242-263. Gale Watch from late Thursday night through late Friday night for LSZ243>248-264-265. Lake Michigan... Gale Watch from Friday morning through Friday evening for LMZ221- 248-250. && $$ SHORT TERM...JLB LONG TERM...RJC AVIATION...Voss MARINE...JLB
Area Forecast Discussion
National Weather Service Nashville TN
924 PM CDT Wed Mar 11 2020 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... Showers have moved off the Plateau this evening, and only a few echoes are showing up in the southwest. CAMs develop some additional showers in the southwest and spread northward slowly overnight. Instability stays south near the AL border, so a few rumbles of thunder will be possible in the south overnight. Looking at tomorrow, so far 00Z runs and latest CAMs have not changed too much from the previous forecast. Still looks like the possibility of some isolated to scattered convection in the afternoon as instability will be on the increase with diurnal help and strong southwest winds bringing in 60 degree dewpoints to the area. Threat with the first round in the afternoon will be some gusty winds and even some hail thanks to decent mid level lapse rates and some drier air aloft. Shear is high enough that an isolated tornado is not out of the question in the afternoon. Right around 00Z, however, most models begin to ramp up the LLJ as the upper trough will be just off to the northwest. LLJ speeds of 50 to even 60 knots will be possible, which ramps up the 0-1km shear to around 30-40 knots and 0-3 SRH to around 500 m2/s2. This window of higher shear appears to be short lived in the early to late evening as the upper trough moves eastward pretty quickly, and the cold front moves closer to the mid state. It will all depend on the storm mode in the late afternoon and evening timeframe, but damaging winds, hail, and even a few tornadoes are not out of the question. CAMs suggest that scattered to widespread thunderstorms will be over KY late in the afternoon, possibly developing into a MCS, with some additional scattered convection diving southeastward into the mid state ahead of the cold front around 00Z. So it appears right now that the late afternoon through late evening timeframe will be the best chance at severe thunderstorms, again with the potential for damaging winds, hail, and even a few tornadoes. Instability and shear fall off quickly after midnight, so it looks like the severe threat will dissipate overnight into Friday morning. This can still change, however, so please stay tuned to the latest forecast updates. In addition to staying on top of the latest forecast updates tonight and tomorrow, and following with messaging from many outlets over the past week, please have multiple ways to get important warning information. NOAA Weather radios are best, but another option is needed, such as WEA alerts from smartphones, and should be enabled. Please take the time to be prepared just in case severe weather develops tomorrow afternoon and evening over our area, as well as the future. && .AVIATION... 00Z TAF DISCUSSION. BNA/MQY/CKV/CSV...Mid-level ceilings cover Middle Tennessee as we head into the evening. A batch of showers affecting the Cumberland Plateau will leave the area shortly, leaving us with VFR wx for the next a few hours. A warm front will move northward overnight, bringing MVFR clouds (and possibly IFR) and a few stray showers. The HRRR doesn`t show enough overnight activity to warrant mention in the TAF`s. In fact, we`ll keep the precipitation out of the TAF`s until tomorrow afternoon when convection is expected to develop ahead of an approaching cold front. At this time, am sticking PROB30 groups at the end of the TAF period to cover the potential for thunderstorms as things heat up toward the expected evening fropa. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......Barnwell AVIATION........08
Area Forecast Discussion
National Weather Service Pueblo CO
337 PM MDT Wed Mar 11 2020 .SHORT TERM...(This evening through Thursday) Issued at 302 PM MDT Wed Mar 11 2020 A weak disturbance will be moving across CO tonight, which will bring snow showers to the Continental Divide and to portions of the eastern mtns. The higher elevations along the Continental Divide will likely see a few inches of snow accumulation overnight. Some windy conditions are expected over the high elevations, and some of the lower east slopes of the eastern mtns. Across the lower elevations, breezy westerly winds overnight will help keep temps mild. The upper disturbance exits the area late tonight, with precip over the higher elevations expected to decrease. Thursday, the weather across the area is mainly expected to be dry, although there may be some light showers in the central mtns. A front over northeast CO on Thu, is forecast to move into the southeast plains at some point, but at this time it`s hard to say exactly when that will occur. The NAM starts backing the front into the far southeast plains and northern El Paso County by about 21Z but it then shows little progress westward thru 00Z. The HRRR backs the front steadily westward from the late morning hours, through the afternoon. The GFS is somewhere in between the NAM and HRRR. The timing of the front will make a difference in high temps for the day, so some areas of the plains, mainly the far eastern areas and over El Paso County, could end up see cooler temps than what is currently forecast, if the front come through sooner. Right now, the forecast high is a blend of the NBM, NAM, GFS and ECMWF. .LONG TERM...(Thursday night through Wednesday) Issued at 302 PM MDT Wed Mar 11 2020 Messy forecast Thursday night and Friday as swrn U.S. upper low weakens as it lifts newrd across Colorado. At the surface, shallow cold air mass will be in place over the plains Thursday night, while strengthening sly flow and mid level warm advection develops above the cold pool after 06z as upper low approaches. Expect some light drizzle to break out toward 12z Fri as lift increases, with some freezing drizzle possible along the I-25 corridor where surface temps drop slightly below freezing. Not expecting a great deal of ice accumulation, but elevated/exposed surfaces could become icy, especially near the Palmer Divide, where temps are slightly colder. Precip begins in earnest area-wide Fri morning, with heavy wet snow over the mountains, especially across the San Juans where orographics look most favorable. Remaining mountains will see a burst of heavy snow from mid morning to late afternoon as best lift comes across, and may need some advisories over the Sangres at some point, though precip does shut down fairly quickly in the afternoon, For most valleys, the I-25 corridor and the eastern plains, mix of rain/snow expected through the day, with any freezing precip coming to an end early Fri morning as mid levels cool and saturate. Could see a slushy few inches in El Paso County by Fri evening, and a couple inches most interior valleys, with only minor accums elsewhere. Travel impacts away from the mountains and Palmer Divide may be fairly limited given expected max temps above freezing at many locations. System moves away Fri night with precip ending, though snow showers may linger over the higher terrain into Sat as weak energy ejects from next wrn trough. Upper ridge should bring mild conditions to the area Sun/Mon, before shallow cold air mass drops through the plains Tue/Wed, with perhaps some light upslope precip along and east of the mountains. Cut-off low still lurks west of the area through the end of the week, keeping at least a threat of snow over the mountains as active pattern continues. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 302 PM MDT Wed Mar 11 2020 VFR conditions are expected at KCOS and KPUB tonight and Thursday, with breezy westerly winds expected tonight and into Thursday morning. VFR conditions are expected at KALS into the late night hours, but there will be the potential for some low clouds for a couple or a few hours early Thu morning. Breezy southwest winds will decrease this evening with light westerly winds tonight and into Thu, and then becoming northwest tomorrow afternoon up to around 12 kts. && .PUB WATCHES/WARNINGS/ADVISORIES... Winter Storm Watch from Friday morning through late Friday night for COZ068. && $$ SHORT TERM...28 LONG TERM...PETERSEN AVIATION...28