Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/14/21

Area Forecast Discussion
National Weather Service La Crosse WI
914 PM CST Wed Jan 13 2021 .UPDATE... Issued at 914 PM CST Wed Jan 13 2021 Based on the HRRR and RAP, adjusted the the onset time of the precipitation tonight and Thursday morning. This resulted in some adjustments in the start time of the winter weather headlines for the area. In addition, with the ensembles trending a bit lower with the probabilities of 6 inches or more of snow and trends in the HRRR and RAP transitioned the Winter Storm Watch to a Winter Weather Advisory. Snow totals from Thursday into Friday night continue to look like 2 to 4 inches south of Interstate 90 and 4 to 7 inches north of Interstate 90. The highest snow total still look to be in southeast Minnesota where the deformation band will likely persist the longest. Some blowing and drifting snow may occur on Friday and Friday night in southeast Minnesota and northeast Iowa. Confidence is still on the lower side with the exact details of this storm system, including snowfall amounts. As such, please keep up to date with the latest forecast information. && .SHORT TERM...(This evening through Thursday) Issued at 245 PM CST Wed Jan 13 2021 GOES satellite imagery showing quite a bit of mid and high clouds over the area early this afternoon associated with a passing mid- level shortwave trough. Otherwise, very mild for mid-January with temperature readings at 2 pm well into the 30s and even a few lower 40s. Some clearing expected behind the mid-level wave later this afternoon/by sunset but then all eyes on incoming winter storms that is currently positioned over southern Manitoba. This low pressure system and cold front will push precipitation into areas west of the Mississippi River during the pre-dawn hours and east of the river mainly after sunrise. Will likely be a wintry mix of sleet/rain/freezing rain and snow before transitioning to mainly snow later in the morning with column cooling as a closed mid- level low causes rapid surface cyclogenesis and deepening surface low over western WI. Could see 1 to locally 3 inches of snowfall through the day across portions of southeast MN into north-central WI with lesser amounts southeast. .LONG TERM...(Thursday night through Wednesday) Issued at 245 PM CST Wed Jan 13 2021 Behind the front, expect a cutoff low to stack somewhere over the region, though confidence remains on the lower side regarding exact location/track. This will impact if any/how much dry air moves into the forecast area, in turn impacting final snowfall amounts. Overall, there is better agreement with the 13.12Z suite of deterministic guidance, generally suggesting the surface low moves directly over the forecast area and then east-southeastward into northern Illinois or far southeast Wisconsin. This would bring dry air mainly into southern/eastern portions of the forecast area, though enough still looks to get far enough north to lead to a lull in snowfall Thursday night into early Friday morning. Consensus shows the main deformation band then picks up again from roughly south-central/southeast Minnesota into north- central Wisconsin owing to a strengthening cold conveyor belt (NAEFS showing better agreement and a more negative U wind anomaly). However, frontogenesis still doesn`t appear to be particularly strong or organized in much of the guidance, which will likely keep snowfall rates down, generally below 1" per hour. Still, model soundings do show a deepening dendritic growth zone through Friday morning, so would expect some higher snow-liquid ratios. Finally, a tightening pressure gradient west of the low will lead to strengthening northwesterly winds, though the strongest winds aloft look to remain west of the forecast area at this time. Still, could be enough for at least some blowing and drifting snow in the open/unsheltered areas. That all said, ensemble guidance still shows some significant spread despite being less than 24 hours from precipitation onset. For example, while GEFS members show some decent clustering of about 3.5 to 8" of snow for KRST, several members do show higher amounts, again owing to differences in low placement/track and likely strength of forcing. In addition, some members keep the heaviest snow band almost completely west of the forecast area while others are nearly completely east, though both such solutions appear to be quite the outliers at this time. Given the remaining uncertainty, sticking with a consensus approach, which would place the heaviest snow from south-central/southeast Minnesota into north-central Wisconsin, which is where a Winter Storm Watch has been issued. While we may not reach true Winter Storm Warning criteria (6" in 12 hrs or 8" in 24 hrs) given the long duration, we get fairly close in some spots, and guidance does suggest the possibility for some heavier snow, especially if we end up with some slightly stronger frontogenesis that interacts with the deepening dendritic growth zone on Friday. In these areas, currently looking at totals in the 6 to perhaps 9 inch range. Farther southeast, going with a long duration Winter Weather Advisory, though there will likely be a period Thursday night into early Friday morning where snow becomes very light or perhaps even stops completely. Snow totals would be more in the 2 to 4 inch range. So in summary, the entire area should see "plowable" snow that lasts for quite a while (Thursday through Friday night) with perhaps a brief lull Thursday night into early Friday morning. Highest amounts look to be from south- central/southeast Minnesota into north-central Wisconsin. The system will exit to the east by early Saturday morning, but another shortwave trough looks to slide through Saturday night into Sunday, bringing some more light snow to the area. Additional shortwave energy may slide through early next week and bring even more light snow, though lots of spread in timing and location. Otherwise, temperatures will be cool, but closer to normal for this time of year, with highs in the 20s and lows in the single digits and teens through early next week. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 518 PM CST Wed Jan 13 2021 Not too many changes from the 13.18z TAFS. The only significant change was to delay the onset of the precipitation by a couple of hours. This was due to a slower trend in the latest HRRR and RAP models. The precipitation will likely move into KRST around 14.11z and KLSE around 14.14z. Snow totals for both TAF sites looks to be still in the 1 to 2 inch range for Thursday. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Winter Weather Advisory from 6 AM Thursday to midnight CST Friday night for WIZ032>034-041-042-053>055-061. Winter Weather Advisory from 9 AM Thursday to midnight CST Friday night for WIZ017-029-043-044. MN...Winter Weather Advisory from 6 AM Thursday to midnight CST Friday night for MNZ079-086>088-094>096. IA...Winter Weather Advisory from 6 AM Thursday to midnight CST Friday night for IAZ008>011-018-019-029-030. && $$ UPDATE...Boyne SHORT TERM...DAS LONG TERM...CA AVIATION...Boyne
National Weather Service Hastings NE
737 PM CST Wed Jan 13 2021 .UPDATE... Issued at 737 PM CST Wed Jan 13 2021 Quick note about the High Wind Warning going into effect later tonight: Everything outlined below by preceding day shift forecaster remains very-much on track. However, did opt to delay the "official start time" of the Warning from 9PM to 11PM, as it`s looking pretty unlikely that any intense winds will enter our north-northwest zones before the 11PM-Midnight time frame. Of course, even 11PM is still plenty early for especially the southeast half of the CWA (where winds will obviously arrive later), but at least it`s an improvement versus 9PM. Opted not to complicate matters by doing northwest vs. southeast segments, as this was not considered "worth it" for a wind-surge-arrival difference of only a few hours. && .DISCUSSION...(This evening through Wednesday) Issued at 350 PM CST Wed Jan 13 2021 Forecast concerns continue to center around severe wind, critical fire weather, and potential for snow/blowing snow...all within next 48 hrs. Changes with this forecast package: - Have upgraded High Wind Watch to High Wind Warning from 03Z tonight to 06Z Thu night (moved up start time to account for faster frontal timing) - Upgraded Fire Weather Watch to a Red Flag Warning for Thu aftn, and expanded aerial coverage - Maintained High Wind Watch for late Thursday night into Friday - Incr potential for snow and added small area of blowing snow for Fri across NE CWA. Main points of emphasis: - Confidence remains high for a prolonged high wind event, though true warning criteria may be less pervasive on Fri compared to tonight-Thu. The worst wind may be with the initial burst along and immediately behind the cold front tonight where isolated wind gusts of 65 to 70 mph appear possible. - Dangerous fire weather conditions likely over S third of CWA Thu aftn. A northward expansion of warning another tier of counties may be needed. - While not the most obvious aspect of this forecast, still looks like we could be teetering on a fine line between near-blizzard conditions vs. very little or no snow on Fri. This will all depend on location of closed upper low, but may need some sort of winter headline over far E/NE portions of CWA. Forecast Details: First with the wind... No major changes to the forecast, though did add some details to wind trends for tonight. The timing of the front appears a bit faster, and short term hi-res models have been persistent in showing a particularly intense burst of wind, lasting 30-90 min, immediately along and just behind the initial cold front. Seems reasonable given observed/forecast 3 hr pres rises on the order of 7-9+mb. HRRR and RAP forecast soundings both show 60-70kt between H9 and H8 just behind the front, so even modest mixing supports potential for 70mph gusts. Expect a lull from 09Z to 15Z before incr once again is mixing depth on GFS/NAM/RAP all reach at least H8, if not H7. Deep mixing of unidirectional flow, along with 10mb sfc press gradient across the CWA from SW to NE, suggest high likelihood for near 60mph gusts late AM thru late aftn or early eve. Decided NOT to carry warning all thru Thu night and Fri just yet as confidence is lower. Models indicate substantially more cld cover, less mixing, and slightly weaker sfc pres gradient ~8mb. Soundings also show deep layer winds not quite as unidirectional as upper trough stalls out, occludes, and gradually fills on Fri over Mid MS Valley. Didn`t want to cancel it either, though, given EC peak wind gusts still near 48-50kt over parts of area. Fire weather... Deep unidirectional, downsloping winds, and at least partial sunshine within area of subsidence argues strongly for anomalously low Tds by Thu aftn. We know the wind will be very strong. So not a surprise that HDWI values peak in the 90th to 95th percentile for areas along and S of the state line. As such, upgraded to Red Flag Warning with fairly high confidence, and expanded in areal coverage. One could argue, given magnitude of wind, to expand further and blur the strict RH criteria. Certainly something for later shifts to assess. More cld cover and cooler temps should keep min RH values quite a bit higher (30-40% plus) on Fri, but strong wind will keep fire concerns at least elevated. Precipitation chances... Have incr PoPs along the front tonight, as latest HRRR/RAP suggest a narrow band of QPF along the front. Most of this looks to remain rain, though brief wet snow may mix in. Temps should remain warm enough to prevent impacts. The bigger issue remains the potential for wrap around snow showers late Thu night into Fri as the upper low pivots near the Quad Cities. Model consensus is for very lgt QPF to graze E zones, with majority remaining JUST to the E/NE. However, any sort of wobble to the W will incr impacts dramatically, as it just won`t take much snow to cause poor visibility due to the strong wind. This makes for difficult messaging as it will be a fine line between next to nothing and near-blizzard conditions...and as of now...that line is very near or JUST off to the E. This will need to be monitored very closely. Very little time spent on the rest of the forecast, but the main message looks to be mainly dry with moderating temps this weekend into early next week. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday) Issued at 642 PM CST Wed Jan 13 2021 General overview: By FAR the main concern will be intense northwest winds (gusts of 50+KT possible at times), with an initial surge arriving overnight and then a more prolonged stretch late Thursday morning and through the afternoon. Despite the strong surface winds there will also be potential for at least periodic low level wind shear (LLWS) mainly between 03-16Z. Otherwise, confidence is fairly high in VFR ceiling/visibility through the period, although a brief period of scattered low-end VFR clouds cannot be ruled out around 06Z tonight (any other clodus through the period should be of the mid-high level variety). Precipitation-wise, the vast majority of the period will be dry, but have maintained a generic "vicinity shower" (VCSH) from 06-09Z to account for the possibility of a few passing rain showers. Read on for more wind-related details if interested... Surface winds: For sure the lightest winds of the period are right away these first few hours (under 10KT from the west-southwest). This changes big-time around 06Z as an initial surge of very strong northwest winds arrives behind a powerful front. This initial surge could easily feature a brief period of 50+KT gusts before winds temporarily settle back down somewhat during especially the 08-16Z time frame (but still gusting 20-35KT). After 16Z and through the rest of the period, expect fairly consistent very strong speeds sustained generally 30-40KT/gusting 45-55KT. LLWS: Although the magnitude of low level wind shear within the lowest 1-2K ft. will not be overly-intense for much of this time frame owing to the presence of strong winds in place at the surface, will officially advertise LLWS throughout the 03-16Z time frame as at least periodic shear magnitudes of 30-40KT will be possible. && .GID WATCHES/WARNINGS/ADVISORIES... NE...High Wind Warning from 11 PM this evening to midnight CST Thursday night for NEZ039>041-046>049-060>064-072>077- 082>087. High Wind Watch from late Thursday night through Friday afternoon for NEZ039>041-046>049-060>064-072>077-082>087. Red Flag Warning from 11 AM to 6 PM CST Thursday for NEZ082>086. KS...High Wind Warning from 11 PM this evening to midnight CST Thursday night for KSZ005>007-017>019. High Wind Watch from late Thursday night through Friday afternoon for KSZ005>007-017>019. Red Flag Warning from 11 AM to 6 PM CST Thursday for KSZ005>007- 017>019. && $$ UPDATE...Pfannkuch DISCUSSION...Thies AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Goodland KS
351 PM MST Wed Jan 13 2021 .SHORT TERM...(Tonight) Issued at 116 PM MST Wed Jan 13 2021 Satellite and 500 mb RAP analysis showed a closed low over Mississippi with ridging along the west coast. This pattern placed the High Plains under northwest flow aloft early this afternoon as a shortwave made its way from the Pacific Northwest to the northern Rockies. At 1:00 PM MST, mid to high level cloud cover built into the region from the northwest ahead of the advancing shortwave. Northwest winds gusted between 20 and 30 mpg across much of the area, with temperatures ranging in the upper 50s to upper 60s. For tonight, the aforementioned shortwave strengthens and becomes an upper closed low as it moves into the northern Plains. The cold front associated with the system enters the northern portion of the region around or shortly after midnight, progressing south through the remainder of the area by sunrise. An initial burst of strong northwest winds will be possible when the front first moves through, with the current forecast calling for gusts around 50 mph. However, gusts around 60 mph are not out of the question. Behind the frontal passage winds will stay strong through the rest of the nighttime hours. Otherwise, temperatures fall into the 20s and low 30s. .LONG TERM...(Thursday through Wednesday) Issued at 308 PM MST Wed Jan 13 2021 The forecast for Thursday and Friday is quite messy with lots of moving parts. Fire weather, high winds and dust will all be concerns through the end of the work week. Thursday, northwest flow aloft will be in place over the Tri-State area with an upper trough digging to the southeast and a closed low over North Dakota. At the start of the forecast period, a strong cold front will have already moved through the Tri-State area, ushering in a cool, dry airmass behind it. Winds will decrease slightly after the frontal passage, increasing again after sunrise. Stronger winds aloft (90-130kts) will move over the region as the trough moves in with winds mixing down. A tight pressure gradient over the area will also promote stronger winds. A High Wind Warning has been issued for the entire forecast area from early Thursday morning until Thursday evening. Northwest winds of 30 to 45 mph are expected with gusts to 70 mph. The High Wind Watch remains in effect from Thursday night to Friday evening. Strong and gusty winds are expected Friday, however, issuing additional products may cause confusion. Continue to monitor the forecast for updates. As the cold front swings through the region and in the hours following the frontal passage, blowing dust remains a concern, particularly for areas along and south of Interstate 70. Several days of warm and dry conditions prior to the frontal passage continue to be a reason for considering blowing dust. Despite the fropa being prior to sunrise, there is still concern that the passage will be enough to loft loose dirt into the air and blow it around. Surface winds will be exceeding 30kts at times in areas where the 0.5-1km winds will be in excess of 45kts. This is an indication of the possibility of blowing dust. Those needing to travel tomorrow, may encounter areas of reduced visibility due to dust. Finally for Thursday, the Fire Weather Watch has been upgraded to a Red Flag Warning, in effect from late morning to late afternoon. Relative humidity values will be in the 15 to 25 percent range. Given the prior mentioned winds of 30-45 mph gusting to 70 mph, any fires that are sparked will have the potential to grow very quickly. Winds are expected to relax slightly Thursday evening into early Friday morning. A second peak in the winds will be expected Friday morning and afternoon. The pressure gradient over the region will remain tight as the low continues to deepen to the east of the area. A jet max with winds up to 150kts will come over the Tri-State area. Once again, strong and gusty winds will mix down. A High Wind Watch remains in effect. Near-critical fire weather conditions will be possible on Friday with minimum relative humidity values ranging from the mid-teens to mid-20s across much of the area. Strong winds of 30 to 45 mph with gusts to 65 mph will be possible. This combination and dry fuels will result in any fires spreading quickly. Winds will decrease once again Friday evening as the trough moves out of the region. Behind the Thursday/Friday wind event, northwest flow persists between the backside of the upper low and ridging along the western CONUS. Although, the gradient and winds will have relaxed significantly. Over the weekend, a weak shortwave pushes through the northwest flow above the central Rockies, but no precipitation is expected at this time. A stronger wave advances from the Pacific Northwest southeastward towards the region on Monday. This generates some slight chances for rain and snow Monday afternoon and evening for the extreme southwest portion of the area. Late Monday into Tuesday, the wave develops into two branches: (1) the northern half continuing east to the Upper Midwest and (2) the southern half diving to the Four Corners region as a closed low where it lingers through midweek. With our area between these two disturbances, dry weather looks to prevail. Temperatures remain somewhat steady Saturday through Monday, with highs in the 40s to low 50s and lows in the upper teens to mid 20s. A slight cool down is forecast on Tuesday, with highs in the mid 30s to mid 40s and lows in the teens and low 20s. Wednesday looks a little warmer, with highs back in the 40s. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 351 PM MST Wed Jan 13 2021 Vfr conditions are currently expected at KGLD and KMCK through the TAF period. For this evening, light westerly winds around 10 knots begin to shift to the northwest and increase as a cold front approaches the region. The front is expected to come through the region around 06z with an initial burst of very strong winds before relaxing slightly. Then northwest winds strengthen through the morning, with gusts around 50 knots forecast. LLWS will be possible at both sites overnight before gusts fully mix down to the surface. Otherwise, am anticipating an increase in clouds overnight as the front moves through. Will need to monitor the potential for blowing dust occurring tomorrow. && .FIRE WEATHER... Issued at 308 PM MST Wed Jan 13 2021 A Red Flag Warning has been issued for late Thursday morning through the afternoon for the entire Tri-State area. Sustained northwesterly winds of 30 to 45 mph with gusts to 70 mph will be possible during this time. Minimum relative humidity values will range from 15 to 25 percent. High winds will result in rapid fire growth during this time. Near-critical fire weather conditions are expected Friday as winds similar to Thursday are expected. Minimum relative humidity values for much of the region will range from the mid-teens to mid-20s. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...High Wind Warning from midnight MST /1 AM CST/ tonight to 6 PM MST /7 PM CST/ Thursday for KSZ001>004-013>016-027>029-041- 042. Red Flag Warning from 10 AM MST /11 AM CST/ to 5 PM MST /6 PM CST/ Thursday for KSZ001>004-013>016-027>029-041-042. High Wind Watch from Thursday evening through Friday afternoon for KSZ001>004-013>016-027>029-041-042. CO...High Wind Warning from midnight tonight to 6 PM MST Thursday for COZ090>092. Red Flag Warning from 10 AM to 5 PM MST Thursday for COZ252>254. High Wind Watch from Thursday evening through Friday afternoon for COZ090>092. NE...High Wind Warning from midnight MST /1 AM CST/ tonight to 6 PM MST /7 PM CST/ Thursday for NEZ079>081. Red Flag Warning from 10 AM MST /11 AM CST/ to 5 PM MST /6 PM CST/ Thursday for NEZ079>081. High Wind Watch from Thursday evening through Friday afternoon for NEZ079>081. && $$ SHORT TERM...JBH LONG TERM...AW/JBH AVIATION...JBH FIRE WEATHER...AW
Area Forecast Discussion
National Weather Service North Platte NE
542 PM CST Wed Jan 13 2021 .SYNOPSIS... Issued at 400 PM CST Wed Jan 13 2021 H5 analysis this morning was highlighted by a closed low over northern Louisiana, a shortwave over eastern Ontario and a shortwave south of the Canadian Maritimes. Across the Western CONUS, high pressure was anchored off the coast of southern California. North of this feature, a potent shortwave trough of low pressure extended from southeastern British Columbia into northern Oregon. This feature shows up well on satellite imagery this afternoon and as of midday, this feature roughly extended from eastern Alberta into northern Montana. Very strong surface low pressure in association with this trough was noted over southwestern Saskatchewan AT 2 PM CT with a pressure of 883 mb noted. Trailing south of this low, a cold front extended across northwestern Montana. A surface trough of low pressure extended south of the low and was situated along the western borders of the Dakotas, as well as the Nebraska Panhandle. Winds west of the trough were very strong, especially over eastern Montana into eastern Wyoming and the far western Nebraska Panhandle. Over the past hour, some gusts topped 70 MPH in central Montana and were approaching 60 MPH in eastern Montana and eastern Wyoming. Across western and north central Nebraska, skies were mostly cloudy underneath of shroud of high cloudiness. Temperatures at 2 PM CT ranged from 49 at Gordon, to 60 at North Platte and Broken Bow. && .SHORT TERM...(This evening through Friday) Issued at 400 PM CST Wed Jan 13 2021 The main forecasting issues in the near term deal with high wind potential, precipitation chances tonight, and then again on Thursday night-early Friday. The before mentioned H5 trough, will close off over southern Saskatchewan this evening. The trailing trough of low pressure, now extending into the northern high plains, will force a cold front through the forecast area this evening. The short range models, most notably the HRRR, have this front approaching the NW forecast area around 02z this evening, pushing it through the forecast area by 06z. Very gusty winds will occur behind the front. Forecast sounding data, as well as the HRRR 2m wind gust product, indicate a 1-2 hour window behind the front with wind gusts to around 60 MPH. Based on what is occurring upstream, this looks like a good forecast ATTM. Winds will slacken somewhat overnight into Thursday morning. Winds will then rapidly increase Thursday afternoon as H850-H700 lapse rates approach 9-10C/KM. Forecast soundings from the GFS look down right nasty for the forecast area Thursday afternoon. At 3 PM CT in Thedford tomorrow, GFS Bufkit sounding winds are 60 KTS at the bottom of the mixed layer and 73 KTS at the top of the mixed layer. Winds are 50 KTS only 400 FT AGL at Thedford. With lapse rates that steep, we should have no problem hitting 60 MPH for wind gusts tomorrow afternoon and wouldn`t be surprised if we eclipse 65 MPH for wind gusts tomorrow afternoon, especially in open areas. With sunset Thursday, winds will slacken off slightly in the evening. Overnight, as the H5 low dives south into eastern Iowa, a shortwave trough on the northwestern periphery of the low will approach northeastern and north central Nebraska. This will force a secondary cold front through the area Thursday night into Friday morning. Winds will increase once again with this front. The latest 18z HRRR which runs out through 18z Friday, has 2m wind gusts in the 50 to 55 KT range Friday morning. These winds begin to diminish midday Friday. With strong forecast confidence in winds and wind speeds with this system, upgraded the high wind watch to a warning with this forecast package. I did start the high wind warning earlier based on the quicker frontal timing tonight. With respect to precipitation chances with this system. They will come in two episodes. The first will be along and post frontal this evening into the early overnight hours. The second will be in association with the arctic front Thursday night into Friday morning. For tonight, the models continue advertise strong lift from north central into eastern portions of the forecast area. The timing of the greatest lift will be along and immediately behind the front, which favors this evening. Looking at forecast soundings, most precipitation this evening will be liquid. There is a tight 1-3 hour window in the northwest where some snow could mix in with rain before changing over to all snow. This area is generally over western Cherry and Sheridan counties. The 12z NAM this morning, had a nice band of heavier precipitation across far ne Sheridan into western Cherry county with QPF`s approaching 0.4 inches. This was very similar to yesterday`s NAM12 forecast. However, this band is not found in the GFS, HRRR and WARW solns and was treated as an outlier soln. That being said, the highest QPF`s tonight will be over the northeastern forecast area and have painted the highest pops in these areas. Again with most of the lift this evening and temperatures being too warm, not expecting any snow accumulations. On Thursday night and Friday morning, light snow is expected to develop over the northeastern forecast area along the arctic frontal boundary. There continues to be weak lift noted across northeastern Nebraska during this period and the airmass should be saturated given the degree of cold air advection. QPF`s were increased in these areas with this package, in step with higher QPF`s noted in this mornings GFS and NAM12 runs. That being said, with the increased QPF`s, snowfall will increase as well. Combine the light snow with very strong winds, and we could see some potential blizzard conditions in the northeast. Went ahead and inserted a mention of blowing snow in these areas, as snowfall was increased to a half to an inch. We will need to monitor forecast trends closely in these areas as we could see blizzard conditions if enough snow falls. FWIW, the CIPS 2 hour blizzard product this morning increased to 20 to 30 percent for blizzard conditions Friday morning in our ne forecast area. This was an increase from 10 to 15 percent with yesterday`s run. .LONG TERM...(Friday through Wednesday) Issued at 400 PM CST Wed Jan 13 2021 The next chance for precipitation will arrive Monday into Tuesday as a mid level trough of low pressure carves a path across the central and northern plains. So far, this appears to be limited in its precipitation potential. For Saturday, Sunday, and Wednesday, dry conditions are forecast for now. Highs in the outer periods will be seasonal with readings in the upper 30s to lower 40s. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 540 PM CST Wed Jan 13 2021 Gusty northwesterly winds associated with the passage of a cold front are the main concern over the next 24 hours for western and north central Nebraska. Winds will increase through the evening before midnight with gusts up to 50 knots possible. Skies will become overcast at this time with the possibility of rain showers in northern Nebraska and the Sandhills, including KVTN, KGRN, and KTIF. Skies will become less cloudy tomorrow morning and afternoon, but wind gusts between 35 and 50 knots will continue. && .LBF WATCHES/WARNINGS/ADVISORIES... High Wind Warning from 9 PM CST /8 PM MST/ this evening to 6 PM CST /5 PM MST/ Friday for NEZ004>010-022>029-035>038-056>059- 069>071-094. && $$ SYNOPSIS...Buttler SHORT TERM...Buttler LONG TERM...Buttler AVIATION...Meltzer
Area Forecast Discussion
National Weather Service Pueblo CO
844 PM MST Wed Jan 13 2021 .UPDATE... Issued at 827 PM MST Wed Jan 13 2021 Main updates this evening were to expand the High Wind Warning, to include El Paso, Pueblo, Crowley, Otero, and Bent counties as damaging winds and gusts are expected late tonight into Thursday afternoon. Relatively quiet in the near term, with the dense cirrus which had been in place slowly pushing to the east. This trend will continue with clearer skies expected for most places tonight. The exception will be across the central mountains where the approaching system will provide a quick window of light to maybe moderate snow from late this evening through early Thursday morning. Highest/Focused ascent and moisture look to be brief, and still anticipate only light snow amounts. Some guidance showing some returning cloud cover and possible precip development over the far eastern plains in advance of this diving upper trough and strong cold front. Would anticipate a small window of more cloud cover then precip development later tonight, as focus looks to be stronger to the northeast of the area and have maintained no chance pops in this location. Main concern this evening will be with strengthening winds and gusts across parts of southern CO as this system pushes through. Rather potent system with very strong mid and upper level flow will move across the area later tonight into Thursday. An associated strong front and CAA will also push through after midnight, and expect northerly winds to quickly strengthen over the plains. Forecast still look to be on track for the eastern plains and even over the Sawatch mountains, though guidance was coming in stronger over the plains along and north of Highway 50. With sustained winds stronger and forecast soundings showing some rather strong speeds in the lowest levels, felt confident to expand the warning. Think there will be a strong push over the plains in the 2-5AM time frame, with gusts of 60 to 65 mph now expected. As gradient and flow look to relax, these may only occur for a few hour time frame though, and think there might be a lull in the highest speeds through late morning. However, flow and gradient will strengthen once again Thursday afternoon, with gusts of 55 to 60 mph likely returning. Have the Warning going through late Thursday afternoon, however, its possible that the warning may need to be extended into the evening. Guidance is varying right now, but it`s possible for gusts up to 60 mph to continue Thursday night and quite possibly into Friday. With lower confidence at this time, have not extended it further but will let later forecasts adjust as need be. && .SHORT TERM...(This evening through Thursday) Issued at 324 PM MST Wed Jan 13 2021 Strong upper jet over the nrn Rockies today will dip southward into Colorado tonight and Thu as upper level low deepens over the nrn plains. As trough passes tonight, may see just a few snow showers over the central mountains into early Thu morning, though accums will be minor and limited mainly to higher peaks. Main concern is high wind potential overnight and through the day Thu. HRRR and to a lesser extent the NAM, have been consistent with strong downslope winds developing late tonight in the lee of Pikes Peak/Cheyenne Mountain area, then a threat of strong winds downstream of the Continental Divide/Sawatch Range during the day Thu as winds near Pikes Peak subside by midday. While forward shear due to the upper jet migrating across the area would tend to argue against a strong mountain wave, model cross-sections/soundings suggest a brief window near Pikes Peak early Thu morning where mountain top inversion is strong and mid-tropospheric shear is neutral, which may be just enough for a brief downslope wind event. Not as much of a wave set- up farther west in the lee of the Sawatch, but 70 kt mid-level flow down below 700 mb suggests some strong gusts over the peaks and through downstream gaps during the day. Have hoisted a High Wind Warning for both Teller County/Pikes Peak region and the Sawatch Range for late tonight into Thu, though this is a low to moderate confidence event. Suppose some gusts near high wind thresholds could spill across Fort Carson and the west side of Colorado Springs as well as the upper Arkansas Valley Thu morning, but confidence is too low to include them in a warning at this point. As cold front races through the area overnight, N-NW winds will become gusty at many locations, with some gusts over 40 kts likely immediately following the fropa. Strongest winds will be near the KS border, and have started a High Wind Warning for Kiowa/Prowers counties after 09z, though winds through the morning may be just below criteria initially. During the day Thu, dry air mass spreads south across the state, with breezy to very windy conditions continuing. As mixing deepens in the afternoon, may see some 50 kt gusts appear over the eastern plains as winds just off the surface are in the 50-60 kt range, so will keep highlight going for Kiowa/Prowers through the day. RH falls below 20 percent over the plains for a few hrs Thu afternoon, but with cooler max temps, appears we`ll stay just above the 15 percent threshold, so no fire highlights issued. .LONG TERM...(Thursday night through Wednesday) Issued at 324 PM MST Wed Jan 13 2021 Thursday night and Friday...A strong low pressure system located over the upper midwest Thu evening will continue to produce strong northerly surface winds across the eastern plains through the evening, then again Fri aftn as the system gradually pulls away. Clearing skies will allow overnight minimum temps to drop into the teens to around 20F for the plains, and 0 to 15 above for the high valleys. However, brisk winds will produce wind chills of 0 to 10 above for the plains, and 5 to 15 below zero for the high valleys. Looking ahead to Fri, the stronger winds across the eastern plains combined with forecast low humidity values may produce some pockets of enhanced fire danger across Kiowa and Prowers Counties. No fire weather highlights at this time, but will let the following shifts have another look. Plan on highs in the 40s for the plains on Fri, and in the 30s for the high valleys. Saturday and Sunday...Long range models still point to an active weather pattern through the extended, with a couple of disturbances sweeping across the region on Sat as well as Sun night. Very little snow is anticipated across the central mts on Sat, with amounts less than an inch likely, and the greatest effect may be cloudy skies. The next system approaching for Sun night looks to be a much more significant system, initially affecting the central mts but carrying over into the next work week. Temps will remain somewhat steady both days, with highs in the 40s for the plains and 30s for the high valleys. Monday through Wednesday...GFS and EC models are agreeing that the upper trough of low pressure that pushes into the Great Basin late Sun will strengthen on Mon, as a closed low develops and pulls to the south southwest into AZ. This will produce snow across the higher terrain and adjacent plains Mon and Tue, possibly lasting into early Wed morning depending on how long the low lingers over AZ. The focus areas for higher snowfall amounts will be across the eastern San Juan Mountains, southern Sangre de Cristo Mountains and the Wet Mountains. Plan on high temps at seasonal normals on Mon, then slightly cooler for Tue and Wed, especially across the high valleys and westward where temps will drop by about 10 degrees. Moore && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 324 PM MST Wed Jan 13 2021 VFR at all taf sites the next 24 hrs. Winds at KCOS will stay rather erratic through the evening, becoming gradually NW 01-03z. W winds at KPUB will persist into the evening, with fewer/weaker gusts expected after 01z. Cold front passes through both terminals 08z- 10z tonight, with NW winds gusting to 40-45 kts following the fropa and continuing through much of the day on Thu. && .PUB WATCHES/WARNINGS/ADVISORIES... High Wind Warning from 2 AM to 5 PM MST Thursday for COZ081-082- 084>086-089-093-095>098. High Wind Warning until 5 PM MST Thursday for COZ060-061. && $$ UPDATE...RODRIGUEZ SHORT TERM...PETERSEN LONG TERM...MOORE AVIATION...PETERSEN