Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/14/21

Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
553 PM MST Sat Mar 13 2021 .UPDATE... Updated the Winter Weather Advisory to remove the western zones given current web cams showing little to no impact to roads, latest HRRR and HREF showing very little additional accumulation and our forecast of fairly low PoPs overnight. A couple northwest zones may need fresh advisories for Sunday morning given an 2nd round of snow developing on the backside of the then departing upper low. The northern mountains still look to benefit from this event, which will continue through Sunday, with over one foot possible on the peaks and higher west-facing slopes. 11 && .PREV DISCUSSION...436 PM MST Sat Mar 13 2021... .AVIATION... 00Z TAF CYCLE A mixed-bag of strong winds, dust and snow across our area this evening, with VFR to LIFR conditions and areas of mountain obscurations. IFR conditions at KROW in blowing dust are forecast to improve to VFR later this evening. LIFR conditions in snow at KFMN forecast to improve to MVFR early evening, but may dip back down to IFR Sunday morning with another round of snow forecast to move southeast around the backside of the slowly departing upper low. This second round of snow is forecast to impact KGUP Sunday morning as well, but with MVFR conditions. Otherwise, the big story is the strong winds that will continue overnight and through Sunday. Strong westerly winds may bring the redevelopment of blowing dust at KROW Sunday afternoon, but kept VFR for now. The northern mountains and portions of the western mountains will be obscured all day Sunday. 11 && .PREV DISCUSSION...325 PM MST Sat Mar 13 2021... .UPDATE... Update was made to add the Sandia/Manzano mountains zone as Wind Advisory for the overnight hours. 31 && .PREV DISCUSSION...313 PM MST Sat Mar 13 2021... .SYNOPSIS... As severe thunderstorms continue to shift east of the New Mexico/Texas border, the focus turns to the low pressure moving over the Four Corners Region. This winter storm will bring accumulating snow to the northern and western portions of the state, with a few inches expected across the lower elevations west of the Continental Divide and up to a foot or more total across the highest peaks. Stronger to potentially damaging winds are expected on Sunday with gusts of 60-65 mph possible, and rain and snow showers continuing through Sunday night. A brief break on Monday occurs, before another storm system brings windy conditions, cooler temperatures, and another round of snow for the northern mountains. Quieter weather is forecast for the remainder of the week. && .DISCUSSION... SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)... A broad and strong upper level low pressure system will continue to produce accumulating snow mainly over western and northern areas as it passes eastward along the CO/NM border tonight through Sunday. Wrap around moisture will cause showers to linger over the northern mountains into Sunday night as the system exits to the northeast. A few to several inches of additional snow accumulation are expected in the northern and western mountains, with the heaviest amounts of over 6 inches above 8500 feet in the northern mountains. Lower elevations of the north and west should also accumulate an inch or so of additional snow, except for up to 3 inches around Zuni and Fence Lake, as well as from Cuba to Dulce. The storm is also steering a strong speed maximum in the polar jet stream over the state with 700 mb winds expected to peak from 40 to 65 kt across western and central parts of the forecast area on Sunday. The flow will begin to strengthen over higher elevations tonight, so we will keep a Wind Advisory going through tonight over the central and south central mountains including Clines Corners. With the storm system passing eastward along NM`s northern border, a fair amount of cloud cover is expected on Sunday, which is known to inhibit atmospheric mixing and result in weaker winds, so we opted not to upgrade the High Wind Warning yet. Will let the nigh shift factor in the latest model data and sky cover forecast in the warning decision. At this time it does look like higher peaks and Clines Corners have the best chance of 60 mph gusts on Sunday. Initially these winds will blow out of the west, but they will shift out of the northwest as the day progresses. Winds will weaken as the jet migrates east of NM Sunday evening. LONG TERM...(MONDAY THROUGH SATURDAY)... As a shortwave ridge passes overhead on Monday, temperatures warm 5-10 degrees compared to Sunday`s highs. Breezy to locally windy conditions will continue, mainly east of the central mountain chain, as a leeside low develops over NE NM/SE CO. Another upper level low treks south and east from northern CA into the Four Corners region by Tuesday. While 12z models differ on the exact placement and timing of this system, this quick-hitter will bring light snow accumulations to the northern mountains, with a couple inches possible. In addition, soundings indicate strong mixing up to 500-600 mb and a 100+ kt 300 mb jet, so another round of strong westerly winds is possible Tuesday afternoon. 700 mb winds are highest over the Sierra Blanca Mountain Range, indicating speeds of 50-60 kts. The ECMWF keeps wrap around precipitation lingering across the northeast corner of the state through Wednesday morning and with higher QPF, while the GFS is quicker to exit eastward. Didn`t stray much from NBM POPs, keeping slight chance and chance for rain and snow showers Wednesday morning. A weak ridge begins to build to the west late Wednesday and shift over the state by Thursday, but temperatures aren`t forecast to warm to above normal across a majority of the state until Friday and Saturday. While wind speeds will be generally lighter than earlier in the week, breezy to locally windy conditions are forecast by Saturday afternoon, as southwesterlies strengthen aloft. There is the potential for another system to arrive late next weekend. Stay tuned. 44/31 && .FIRE WEATHER... A storm system will continue to bring accumulating snow to northern and western areas tonight through Sunday, as well as strong west and northwest winds to the entire forecast area on Sunday. Breezy southwest winds will return in the wake of the exiting system on Monday. Another storm system will move in from the west on Tuesday with more strong winds over a broad area. Temperatures will cool below normal Tuesday, except across the east where humidities will be low enough for fire weather concerns. The Tuesday system will probably bring more snow accumulation to the northern and western mountains. A ridge of high pressure will then cross from the west during the latter half of the week with warming temperatures, relatively light winds and dry weather. 44 && .ABQ WATCHES/WARNINGS/ADVISORIES... High Wind Watch from 6 AM MDT Sunday through Sunday evening for the following zones... NMZ206>208-219>224-226-233-239>241. Wind Advisory until 6 AM MDT Sunday for the following zones... NMZ223-226. Wind Advisory until 6 AM MDT Sunday for the following zones... NMZ221. Winter Weather Advisory until midnight MDT Sunday night for the following zones... NMZ210-211-213-214-227. Wind Advisory until 7 PM MST this evening for the following zones... NMZ233>240. && $$
as of this forecast discussion and it looks like how the system
is evolving we will probably see areas roughly from Liberal to
Pratt getting in on the slightly milder air this evening. Overall the heavy rain event with totals from 1 to 3 inches this evening and Sunday morning still looks to be a good bet for much of southwest Kansas. Detailing the severe weather threat this evening many of the CAM models are suggesting a fast growing upscale bow echo from around Lubbock, TX to Syracuse late this afternoon and racing eastward through this evening. 0-6 km bulk shear values from SPC mesoanalysis are high already (70-80 kts out of the southwest) and will continue to stay that way as this large dynamic system moves closer to the plains. From looking at forecast skew-t models the convection will have mainly elevated CAPE and the threat will be mainly strong winds and large hail. Tornado threat isn`t looking all that great outside of perhaps a brief QLCS tornado spin up...but even this threat remains low at this point as the forecast bow echo would be running pretty much parallel to the 0-3 km bulk shear direction. Storm motion will also be fast this evening going at about a 40 kt clip as it moves through southwest Kansas. The main upper low looks to move into southeast Colorado by Sunday morning and we should see a gradual ending to the rain from west to east after midnight tonight. With the large amount of rain and inversion with light winds I also included fog potential again for areas west of Dodge City which may need expansion depending on when the rain ends in our eastern zones. For Sunday it looks like a large dry slot on the southwest side of the low will move across southwest Kansas during the day clearing out most of the rain before noon and we could also see some sunshine breaking through. By the afternoon we could see some showers and thunderstorms develop with the lifting in the vicinity of the upper low in northwest Kansas. Overall should be a day where most of us will dry out and highs should reach into the 50s and 60s. .LONG TERM...(Sunday night through Saturday) Issued at 102 PM CST Sat Mar 13 2021 The storm system from the short term will slowly start to move northeastward on Monday and we could see some wrap around precipitation mainly for areas near I-70 Monday morning and by the afternoon the precipitation chances should exit the region. The upper level winds turn southwest for Tuesday ahead of the next upper level storm system which will be located near the four corners region. Next chance of rain will be with a closed low that moves from the four corners region into the Texas panhandle Tuesday night into Wednesday. Rain will overspread much of southwest Kansas Wednesday morning and we could see QPF values in the 0.50 inch or more range again with this mid week system. Colder air looks to wrap into the system Wednesday evening so the potential for snow will need to be monitored but at this point it looks like we should stay above freezing for the event. Once the storm system exits the region we should stay in a regime of colder air through the end of the week. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 503 PM CST Sat Mar 13 2021 Expect very poor aviation conditions to continue through 12z Sun. Widespread IFR/LIFR cigs and/or visibility will continue with stratus, areas of fog, and mist. Additionally, numerous showers and thunderstorms will impact all airports and all of SW KS through tonight. Rain will be very heavy at times. Following the HRRR on timing, the back edge of the rain/thunderstorm shield should reach GCK/LBL/DDC around 10z Sun, and HYS by 12z Sun. Expect VFR to quickly return after 12z Sun, continuing daylight Sunday. After 15z Sun, strong S/SE winds are expected at all airports, gusting 30-35 kts. && .PRELIMINARY POINT TEMPS/POPS... DDC 39 59 35 54 / 100 10 10 10 GCK 36 56 33 52 / 100 30 10 10 EHA 31 56 32 57 / 50 10 10 0 LBL 31 58 33 56 / 80 10 10 0 HYS 44 61 36 52 / 100 60 20 40 P28 48 65 39 59 / 100 30 10 10 && .DDC WATCHES/WARNINGS/ADVISORIES... Flood Watch through Sunday afternoon for KSZ030-031-045-046- 064>066-078>081-088>090. && $$ UPDATE...Turner SHORT TERM...Tatro LONG TERM...Tatro AVIATION...Turner
National Weather Service Hastings NE
608 PM CST Sat Mar 13 2021 .DISCUSSION...(This evening through Saturday) Issued at 415 PM CST Sat Mar 13 2021 Main concerns are rain amounts and strong winds over next 24-36 hours, then the potential for another storm system middle of next week. Rain has been on the incr during the day today, and even seeing some weak convection and lgtn per latest ENTLN plots. Can`t completely rule out an isolated strong storm with mainly a marginal hail threat given steep lapse rates/cool mid level temps and strong shear. SPC has southern areas clipped by Marginal risk. Short term hi-res guidance and 12Z HREF are in good agreement in bringing nearly continuous waves of shwrs/weak convection thru the area tonight and into Sun AM. Other than the small hail potential, main concern will be potential for areas of moderate or locally heavy rain given well advertised abundant deep layer moisture and persistence of rain. Latest NAEFS output places PWs near climatological max (above 99th percentile) and latest ECMWF EFI is nearly maxed out. Luckily MUCAPE values remain weak, which should help keep rates in check and allow dry soils to absorb much of the pcpn tonight. Winds will be on the incr as sfc low deepens over the High Plains, with gusts of 40-45mph possible overnight. The primary upper low will cross the Rockies onto the High Plains Sun AM, become vertically stacked, and move very little Sun thru Sun night. As the upper low occludes, expect the arc of moderate to locally heavy rn to gradually lift N/NE thru the day as dry air is wrapped in from the SW. Some guidance continues to indicate potential for some wet snow to mix in over the far N as early as Sun aftn. This seems a bit bullish, and even if this happened, wet sfc conditions and temps in mid to upper 30s would likely negate the potential for any snw accums. Further S, it`ll be interesting to see exactly where a potential clearing line and occluded bndry set up as, in theory, this could be a focus for widely scat low topped convection during the aftn. Latest HREF/SREF show the potential for as much as 500-750 J/kg of SBCAPE over KS zones by 21Z, in the presence of 30-45kt deep layer shear. Hodographs in this area are fairly straight or even a bit counter-clockwise in the 1-3km layer and WBZ levels are quite low. This suggests potential for small hail in the more sustained updrafts. Of course, this is conditional upon tstm development at all. It`s certainly a cold core system, so it just wouldn`t take much sfc clearing/heating to take advantage of steep lapse rates. Something to keep an eye on for tmrw aftn. The other issue for Sun will be strong winds. Latest guidance gives 25-30kt of sustained E-ENE sfc winds, with very strong winds in excess of 60kt in a layer between 2000-5000ft AGL. Obviously, mixing won`t be that deep given E component and thick cld cover, but mixing to even 1000 ft could result in some 40-45mph gusts, perhaps as high as 50mph, mainly along and N of I-80 during the daytime hrs. So certainly very RAW conditions given continued rain and cool temps in the 40s. Areas further S could rise into 50s to near 60F depending on aforementioned clearing. Pcpn rates will continue to decr Sun night as upper low fills and dry air continues to wrap in. Nonetheless, rain/snow chcs continue into Mon as core of upper low pivots NE right over the CWA. With the cold mid level temps overhead will still have potential for some wet snow mix in thru the AM for N/W portions of CWA, but again, not expecting any accums/impacts. Winds will be lighter and still be out of the E, so the upslope component and abundant low level moisture could support some fog development Sun night into Mon AM. Otherwise, below normal temps continue with highs in the 40s to near 50F. Yet another upper level disturbance will swing thru the Central Plains late Tue into Wed. This system has trended deeper and more closed compared to a couple days ago. Both EC and GFS track the upper low S of the area, from TX/OK Panhandles into the Ozarks, with the GFS it`s usual fast bias relative to the EC. Given the closed nature of the low, favor the slower EC. The current forecast track would place the deformation band over roughly S/SE half of CWA, and would typically expect this to be a band of heavy/wet snow. However, latest operational models show a distinct lack of negative H85 temp anomalies, suggesting little in the way of Arctic air in place ahead of system to work with. Thus, the system would need to create its own cold air to produce snow. This remains possible, but not overly likely attm. So forecast generally calls for cold rain or rain/snow mix. Should finally see some warmer and drier conditions return towards the end of next week into next weekend. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday) Issued at 603 PM CST Sat Mar 13 2021 Widespread heavy rainfall is expected through early Sunday afternoon. Even by later Sunday afternoon we could still be getting some decent rain, but the heaviest will likely fall between now and early Sunday afternoon. We are seeing some lightning around the area and that will likely continue for at least the next few hours with more isolated lightning as we get later into tonight. The wind will be rather strong and gusty out of the east especially Sunday morning with some gusts to around 45 mph. Strong low level wind shear is also possible at times Sunday morning. && .HYDROLOGY... Issued at 415 PM CST Sat Mar 13 2021 As mentioned above, still think most areas will be fine in terms of hydrological concerns given antecedent dry conditions and limited rain rates. However, latest HREF 48hr PMM and QPF output from longer runs of HRRR and RAP suggest localized areas could see total rain amounts as high as 4-4.5", esp. for areas from near GRI northeast towards OLU. There has also been a bit of an uptick in latest SREF means. As a result, overall total QPF has trended about 0.25-0.50" higher over past 12-24hrs. We have several river forecast points that forecast to reach action stage, with a few possibly rising into minor flood stage. This suggests to me that some localized minor flooding could occur over next 48hrs, mainly in known trouble spots for areas generally NE/E of the Tri Cities. Not enough has changed to go with formal Flood Watch, but did mention isolated minor flooding potential in latest HWO. && .CLIMATE... Issued at 435 AM CST Sat Mar 13 2021 How unusual is the March rainfall we have in the forecast over the next 2 days? Looking back, the largest 2 day totals for rainfall during the month of March are 3.12 inches in Hastings (1987) and 3.33 inches in Grand Island (1979). Given the current forecast, both these precipitation totals could be challenged over the next 48 hours, so this is a pretty significant event which could have very beneficial impacts on existing drought conditions. To put things in perspective, during a "normal" March, about 1.8 inches of precipitation is recorded in Grand Island. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ DISCUSSION...Thies AVIATION...Wesely HYDROLOGY...Thies CLIMATE...Rossi
Area Forecast Discussion
National Weather Service Grand Junction CO
450 PM MST Sat Mar 13 2021 .SHORT TERM...(Tonight through Sunday night) Issued at 251 PM MST Sat Mar 13 2021 As models had predicted, the mid-level low pressure system has closed on the Four Corners region early this afternoon and RAP analyses had the system`s center over Page, Arizona as of 20Z. Upglide and broad mid-level upward forcing depicted in q fields has resulted in snow and a rain/snow mix over southeast Utah with snow across elevations above ~5500 feet. Snow cams at the Telluride and Purgatory ski areas indicated light snow and 1 inch of new snow. The dry slot which was over the Rockies this morning largely kept snow out of those areas, but snow has begun to develop and will be increasing as the day progresses. Later this afternoon and tonight the low tracks eastward along the southeast Utah/southwest Colorado borders moving over the southern San Luis Valley, then to the southeast Plains of Colorado by morning. The moisture wrapped system will deepen moisture depth across the area while broad mid-level upward forcing persists. Consequently, precipitation will become widespread with areas of rain or mixed precipitation in the lower elevations largely changing over to snow. However, warm surface temperatures will cause some melting, limiting accumulations. Mountain snow, on the other hand, will begin to accumulate in earnest. The storm center moves little on Sunday so expect little change in conditions across the area. Daytime warming, however, will cause another shift in precipitation state for the lower elevations. Finally, on Sunday night, the storm center is expected to kick eastward over the central Plains which will result in a drying trend from west to east during the night. Latest highlights appeared to be on track, so will make no changes with this forecast package. Temperatures appeared too cold tonight and tomorrow night given cloud cover in the absence of cold air advection so raised them following MET/ECS guidance. Similar thinking and methodology applied to Sunday`s temperatures which are expected to run close to 10 degrees below normal. .LONG TERM...(Monday through Friday) Issued at 420 AM MST Sat Mar 13 2021 Lingering showers will taper off as the last of the current system drags across the divide on Monday. A second low pressure system will sit over northern California Monday morning and then slowly move eastward toward the four corners region on Tuesday. While some uncertainty remains as to the exact depth and timing of this system, models seem to be in better agreement this cycle. The trough axis then continues eastward...moving onto the plains by Wednesday. All said and done, it appears that this second system will bring very little QPF in the low valleys with around 3/10 inch to much of the high country...which translates to around 3-6 inches of new snowfall. With a large mid level low remaining in place off the Pacific Northwest, a ridge then builds in over the Intermountain West on Thursday and is expected to last through at least the first half of the weekend. Temperatures in the long term start out around 5 to 10 degrees below normal in the midst of the mid levels lows. Conditions will slowly warm moving toward the weekend as high pressure builds into the region. Highs will sit 5 to 10 degrees above normals by Friday (nearly 20 degrees warmer than today in many low / mid elevations). && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 450 PM MST Sat Mar 13 2021 Expect numerous amendments this evening as main part of this storm tracks across southwest Colorado into the northeast part of the State. MVFR or lower flight criteria will become more widespread as many snow form as moisture wraps around the system. MVFR or worse conditions will continue well into Sunday as cold air and light to moderate snowfall impacts flight conditions. Large spread in guidance for cigs and vsby by 12Z in many places for very low confidence forecast beyond 09Z. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...Winter Weather Advisory until 6 PM MDT Sunday for COZ003-017. Winter Weather Advisory until 6 AM MDT Monday for COZ018-019. Winter Storm Warning until 6 AM MDT Monday for COZ010-012. Winter Weather Advisory until midnight MDT Sunday night for COZ004-009-013. Winter Weather Advisory until noon MDT Sunday for COZ001. UT...Winter Weather Advisory until 6 PM MDT Sunday for UTZ025-028. Winter Storm Warning until 6 PM MDT Sunday for UTZ023. && $$ SHORT TERM...NL LONG TERM...KJS AVIATION...TGJT
Area Forecast Discussion
National Weather Service North Platte NE
539 PM CST Sat Mar 13 2021 .SHORT TERM...(This evening through Sunday night) Issued at 257 PM CST Sat Mar 13 2021 NDOR cameras on I-80 and elsewhere indicate snow levels this afternoon have dropped to 4000ft across the Panhandle and this progression is occurring from south to north; associated with the northward propagation of cold air aloft from the deep storm over Colorado. Excluding the warmer GFS model, time series plots of hourly temperatures Sunday across the Sandhills strongly suggest slowly falling temperatures throughout the day Sunday and on into the evening and overnight hours. Cold air aloft will continue to propagate north into Nebraska Sunday as an h700mb low across the Rockies moves east into KS. This should support a changeover to snow at elevations below 4000ft by morning and then down to 3000ft during the day Sunday. Coordination with neighbor offices suggest snow levels could drop a bit lower but remain mostly above 2500ft. The latest snow forecast uses 35F as a threshold for all snow which is probably correct for dynamic cooling events. This produced 3 to around 14 inches of snow from about midnight tonight through 00z Sunday evening. The models are in good agreement showing easterly 500m AGL winds around 25 to 35kt Sunday which supports sfc winds around 25 to 35 mph. If not for the heavy wet nature of the snow and temperatures near freezing, blizzard warnings would be obvious in some areas. Blizzard warning is now in effect across Sheridan county where temperatures will be below freezing Sunday morning. This warning may need to be expanded east into western Cherry county depending on the progress of the storm. For this forecast, an upgrade to a Winter Storm Warning is in place across Grant and Cherry counties and winter weather advisories are in place across much of the Sandhills. The new winter storm warning and weather advisories across the Sandhills are in place from 12z Sunday to 12z Monday. The most widespread accumulating snow should fall during the day Sunday but this weather system has been plagued with timing problems- the models have been too fast. The makes continuing the winter weather warnings and advisories until 12z wise. The spectre of this storm affecting the remainder of ncntl Nebraska Sunday night looms on the horizon as the GFS and ECM suggest the potential for significant wet snow in that area Sunday evening. Thus, depending on the progress of the storm winter, advisories may need to be extended east with later forecasts. The NAM and RAP model continue to show areas of a few hundred joules of elevated CAPE tonight and early Sunday morning. Isolated thunderstorms are in place across the southern Sandhills and southwest Nebraska during this time. .LONG TERM...(Monday through Saturday) Issued at 257 PM CST Sat Mar 13 2021 The last vestiges of the weekend storm will depart Monday morning with light snow ending across wrn and ncntl Nebraska. A second storm will be crossing the srn Rockies Tuesday, taking aim on the Central Plains Wednesday. The track of the storm for this forecast appears to be across KS and the midsouth. Chance POPs are in place across wrn and ncntl Nebraska Tuesday night through Wednesday night. Temperatures are very marginal for snow. The forecast is dry Thursday and beyond. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 539 PM CST Sat Mar 13 2021 A powerful springtime storm will continue to bring significant moisture to western and north central Nebraska. Rain will transition to snow in the northwest tonight, with the switchover moving east throughout the day Sunday. Multiple aviation weather hazards exist with this system, including low ceilings, strong winds, heavy precip, and reduced visby. Expect continued IFR cigs in the far west and south (KLBF), while conditions worsen tonight north central (KVTN). East surface winds will gust to 30 kts overnight and to 40 kts Sunday. && .HYDROLOGY... Issued at 257 PM CST Sat Mar 13 2021 The MBRFC ran a contingency forecast for the North Platte river at North Platte which predicts a near bankfull rise to just below action stage which is 5.5 feet. The forecast uses and expected rainfall of about 2 inches. Model QPF plumes at this location range from 2 inches in the 12z ECM to 4 inches in the down-scaled NAM. WPC has responded by raising storm total rainfall to 2 to nearly 4 inches with highest totals across ncntl Nebraska including Custer county. Hourly rainfall rates of up to 1/4 inch are likely tonight and Sunday. Wave after wave of moderate to briefly heavy rain should occur with breaks in between. This will likely lead to overland flooding in the valleys and low lands but not flash flooding. && .LBF WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning from midnight CST /11 PM MST/ tonight to 7 AM CDT /6 AM MDT/ Monday for NEZ005-023-094. Winter Weather Advisory from 7 AM CDT /6 AM MDT/ Sunday to 7 AM CDT /6 AM MDT/ Monday for NEZ006-008-024>026-035>037-057. Winter Weather Advisory from 11 PM MST this evening to 6 AM MDT Monday for NEZ022-056. Blizzard Warning from 11 PM MST this evening to 6 AM MDT Monday for NEZ004. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION...Snively HYDROLOGY...CDC
Area Forecast Discussion
National Weather Service Mobile AL
929 PM CST Sat Mar 13 2021 .NEAR TERM /Now Through Monday/...Upper level ridging fades away Sunday evening as an upper level trough swings negative and occludes over the central Plains into western Great Lakes. As this occurs, overall flow becomes westerly aloft through Monday. Surface high pressure gradually shifts east with a general pressure gradient setting up over the southeastern U.S. as low pressure begins to weaken and move into Missouri on Monday. A surface cold front moves into eastern Mississippi Monday morning becoming stalled out and serving as better focus for convective potential. The associated pressure gradient will promote continued southerly flow over the region, and continue to perpetuate warmer temperatures and higher moisture content across the area. A couple of notable weather features are worth noting, with most imminent being dense fog potential tonight, and the next being a non-zero threat for severe weather on Monday afternoon and evening. Both will be discussed below. Dense fog will likely develop again tonight with overall regime unchanged from last nights dense fog event. Expect fog to begin to develop across coastal areas shortly after midnight tonight, becoming more widespread and spreading inland through our coastal counties in Alabama and the Florida Panhandle, as well as far southeastern Mississippi counties during the overnight hours. A dense fog advisory is in effect for this area through 10 AM CDT Sunday. Dense fog will dissipate by mid to late morning, giving way to partly to mostly cloudy skies. Morning temperatures in the middle to upper 50`s will quickly rise once dense fog lifts, with daytime highs topping out in the upper 70`s and lower 80`s for most areas. Sunday night lows will be very warm with increased cloud cover and increasing low level moisture, with lows in the middle 60`s. Now we get into the more uncertain part of the forecast with Monday afternoon into evening. A low end chance for strong to severe thunderstorms exists Monday afternoon and evening. The aforementioned upper level trough and weakening surface low over Missouri along with stalled frontal boundary over eastern Mississippi stretching northeastward into central Alabama will provide for some modest large scale ascent over our area. This could foster the potential for shower and thunderstorm development Monday afternoon. Modeled soundings suggest that a moderately sheared environment will be present over the area, with general consensus of near 30 to 40kts of sfc-6km shear, and curved, elongated hodographs. In addition to this, it seems reasonable to believe that MLCAPE values will be generally on the order of 500 to 1000 J/kg. It is important to note, however, that hi-res guidance such as HRRR/NAM3KM support the higher range of MLCAPE nearer 1000J/kg, with HRRR even upwards of 1500J/kg. Despite the slight questions in CAPE, one persistent feature on forecast models is the presence of a 700mb EML (Elevated Mixed Layer) that could act as a cap that can limit convective coverage. This is especially noticeable on the hi-res guidance, and unsurprisingly they are rather meager on coverage of showers and thunderstorms Monday versus the global models that have better coverage without resolving the EML as clearly. All this considered, it seems evident that the ingredients are present for potential strong to severe thunderstorms, however to even realize that potential we need sustained updrafts associated with deeper convection over the area. For now, have opted to continue to keep chance to likely PoPs over much of the CWA, with better chances over the northern tier of counties in interior southwestern Alabama and interior southeastern Mississippi where forcing is a little bit more favorable for convection to fire in closer proximity to the stalled surface front. IF more robust, sustained updrafts can materialize, a low end potential for all severe hazards including isolated instances of large hail, damaging winds, and even a brief tornado are possible. This potential will continue to be monitored as we move forward. Otherwise on Monday, anticipate afternoon highs to top out in the lower 80`s for most locations, with upper 70`s along the immediate coast. Some patchy fog may be present early morning but will quickly lift as southerly low level flow increases with a tightening pressure gradient over the area. A HIGH RISK of rip currents continues through Monday evening. MM/25 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...Dense Fog Advisory until 10 AM CDT Sunday for ALZ261>266. High Rip Current Risk through Monday evening for ALZ265-266. FL...Dense Fog Advisory until 10 AM CDT Sunday for FLZ201>206. High Rip Current Risk through Monday evening for FLZ202-204-206. MS...Dense Fog Advisory until 10 AM CDT Sunday for MSZ075-076-078-079. GM...Dense Fog Advisory until noon CDT Sunday for GMZ630>636. && $$ This product is also available on the web at:
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
511 PM CST Sat Mar 13 2021 .SHORT TERM...(This evening through Monday Night) Issued at 149 PM CST Sat Mar 13 2021 The main takeaway of the forecast is that the best chances for snowfall remain the watch area, with the best chance for heavy snow in the watch area near the Iowa/Minnesota border. Areas to the northeast of the current watch, including the Twin Cities, have the greatest uncertainty where there will still be a sharp cutoff. Tonight and Sunday - high pressure will sag southward as the surface low continues across Colorado. This will cause the westerly winds to switch direction and become easterly overnight. The easterly winds will increase into Sunday ahead of the next storm system. Sunday night into Monday - The main impact in this period continues to be the large system impacting the central CONUS. Little has changed as the synoptic forecast of a large system with strong moisture transport remains high confidence. The lower confidence part remains how far north the QPF will go before the air dries out. As the low moves east and occludes moist air will be transported farther north into parts of the Upper Midwest. Model soundings in southern Minnesota show a well defined dendritic growth zone favoring higher snow ratios, although with the near freezing temperatures will counteract that to suggest near climatology snow ratios. One change since the previous forecast is a trend towards a slightly later start Sunday night which greatly increasing the chances that this will fall as all snow rather than rain near the start. The greatest challenge with this forecast remains in the northern extent of this precipitation. So where does the dry air win out and where do the precipitable water values, as seen in many model soundings of around 0.6 which is above the 90% for this time of year at MPX, lead to notable QPF? Ensemble data like the NBM and GEFS suggest that the best chances for accumulating snow remain south of the Minnesota River where the moisture is more certain. Farther north between the Minnesota River and I-94 there is much more variability between ensemble members and deterministic models moisture transport. Some guidance like the Canadian RDPS have little to no QPF in this area while others like the RAP take it farther north and even into parts of the southern Twin Cities metro area. On the ensemble side, GEFS members at MSP range from 0.05 to 0.9 inches in accumulation displaying continued high variability in the forecast here. Looking ahead, much colder air arrives Monday as the snow ends which will bring our streak of above average temperature days to an end with highs in the 30s. .LONG TERM...(Tuesday through Saturday) Issued at 149 PM CST Sat Mar 13 2021 Tuesday into the next weekend - a warming trend returns with temperatures back near normal by midweek and above normal by next weekend. This warming trend is supported by the lack of snowpack and warming ground temperatures such that once cold air masses move out we can warm back to at or above average temperatures much quicker. Tuesday into the end of the week is less certain on a precipitation front. As there is another upper wave moving across CONUS right behind Mondays system. Most deterministic and ensemble members keep this to the south of the Upper Midwest right now, but the interaction between the cutoff low from Mondays system and this advancing upper wave mid-week adds some uncertainty to the forecast. Bottom line: quieter weather most likely after Monday, but another round of precipitation is still possible. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 500 PM CST Sat Mar 13 2021 Very little impacts during this TAF period with winds becoming northeast/east during the next 6 to 12 hours, and gusty after 12z. Most of the MVFR/IFR conditions will occur after 06z/15. KMSP... No additional concerns. /OUTLOOK FOR KMSP/ Sun Night...VFR. Poss MVFR aft 09z. Wind E 10G20 kts. Mon...MVFR/IFR, mainly aft 15z. -SN likely. Wind SE 10-15 kts. TUE...MVFR cigs with IFR possible early. Wind Lgt and Vrb. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...Winter Storm Watch from late Sunday night through Monday afternoon for Blue Earth-Brown-Faribault-Freeborn-Le Sueur-Martin- Nicollet-Redwood-Renville-Sibley-Steele-Waseca-Watonwan-Yellow Medicine. WI...None. && $$ SHORT TERM...JRB/NDC LONG TERM...NDC AVIATION...JLT
Area Forecast Discussion
National Weather Service New York NY
957 PM EST Sat Mar 13 2021 .SYNOPSIS... High pressure over the region will give way to an approaching cold front late tonight. This cold front will move across during the day Sunday, followed by high pressure from Sunday night into Monday night. High pressure will then move out into the Atlantic Tuesday into Tuesday night. Meanwhile, a weak wave of low pressure will move off the Mid-Atlantic coast Tuesday night into Wednesday. A larger area of low pressure approaches Wednesday night and will move across Thursday night. The low will move east of the region on Friday with a strong high pressure area building in from the north and west going into next weekend. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Forecast is on track with only minor changes needed to reflect current observations. High pressure will slowly give way to an approaching cold front from the north and west. The pressure gradient will be weak this evening and winds will be decreasing into late this evening across the interior with a light breeze along the coast. Winds will slightly increase late tonight into daybreak Sunday as a cold front approaches from the north and west. Mostly clear skies will continue through tonight and temperatures will bottom out in the upper 20s across the interior to low to mid 30s closer to the coast and within NYC. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... A weak trough heads through the area on Sunday morning as high pressure builds into the Great Lakes. Winds will shift northwest and a pressure gradient again sets up across the region. A deep mixed layer, up to about 4k ft, is also progged to set up by mid morning as surface temperatures warm. This will increase the potential for strong gusts, with model soundings indicating near 50kts at the top of the mixed layer. HRRR 10m max wind gusts are also suggesting 35-40kts over land, with 40-45kts over the ocean waters. There is decent agreement amongst the models that this is a late morning through later evening event, with the strongest winds occurring mid afternoon Sunday. So, with this in mind, have collaborated a Wind Advisory for the entire forecast area starting at noon Sunday. The peak gusts will occur in the mid to late afternoon, when momentum transfer is maximized. Increased cloud cover in the afternoon is also likely, with a spotty shower possible across the interior as an upper trough swings through to the north. Confidence is very low in any sprinkle occurrence, however, given the depth the dry layer near the surface. Temperatures in the upper 40s and low 50s are expected with the good mixing, even with a bit of cloud cover in the afternoon. With the dry airmass in place with low RH values, gusty winds, lack of any recent rainfall and favorable vegetation state, fire weather concerns continue into Sunday for parts of the area. See the Fire Weather section below for additional details. && .LONG TERM /MONDAY THROUGH SATURDAY/... High pressure builds in from Southeast Canada Monday into Monday night with ridging aloft. The ridge will be flattening going into Tuesday and surface high pressure at that time will be moving out into the Atlantic. A series of shortwaves move across Tuesday night through Wednesday. At the surface, a weak wave of low pressure will approach from the west but will stay well south of the region. The precipitation associated with the wave may reach far enough north to get into the local forecast region Tuesday night into Wednesday. Chance POPs were shifted more towards Tuesday night with snow showers in the forecast. Slight chance POPs for rain showers are in the forecast for Wednesday. Overall though, the wave of low pressure is not expected to produce much precipitation so any precipitation is expected to be light. A weak pressure gradient resides over the area Wednesday before another area of low pressure approaches. This will be a larger area of low pressure with a deeper trough aloft associated with it. The low pressure area and trough continue to approach on Thursday and move across Thursday night into early Friday. Slight chance POPs are also forecast for Wednesday and increase to chance POPs for Thursday through Friday morning. Mainly a rain event expected with possible mixing with snow on the backside of the low on Friday with increasing cold air advection. The precipitation could linger into Friday afternoon so slight chance POPs are in the forecast for Friday afternoon. A return to dry conditions is forecast for Friday night and into next weekend as high pressure returns. A strong high will build in from the north and west. Regarding temperatures, below normal temperatures for highs are expected Monday (low to upper 30s) and Tuesday (mainly upper 30s). Temperatures forecast to rebound closer to normal values for Wednesday (mainly upper 40s) and even slightly above normal Thursday (mainly lower 50s) with slightly below normal values (mainly lower 40s) for Friday and next Saturday. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... High pressure weakens tonight as a deepening low moves into Northern New England. VFR through the period. West winds 10 kt or less overnight. Winds will then turn back to the northwest on Sunday with increasing speeds and gusts. Expect gusts 25-30 kt during the morning and 30-40 kt by mid to late afternoon. Gusts begin to diminish after 00Z Monday. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... No unscheduled amendments expected tonight. Amendments may be needed Sunday with start time of gusts and strength of gusts. .OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY... .Sunday night...VFR. NW 20-25kt with gusts 30-35kt in the afternoon, diminishing throughout the night. .Monday...VFR. NW 15-20kt. .Tuesday...MVFR. .Wednesday...MVFR early possibly becoming VFR late. .Thursday...MVFR or lower in rain. Detailed information, including hourly TAF wind component forecasts, can be found at: http:/ && .MARINE... Winds are expected to continue to diminish tonight with high pressure over the waters. This high will be giving way to an approaching cold front late tonight. This cold front moves across during the day on Sunday. NW Gales are likely on all waters Sunday afternoon/night, with sustained winds 20-30kts and gusts approaching 40kts. The peak winds will occur Sunday afternoon, and as a result a Gale Warning is in effect for all waters Sunday. Seas will build 4-7 ft across the ocean waters and 3-4 ft across the Sound on Sunday afternoon as well. Widespread SCA gusts Monday morning with possible gales on parts of the ocean waters. SCA gusts expected on all the waters Monday afternoon and just on the ocean east of Fire Island Inlet Monday night, mainly during the evening. Then, wind gusts are below SCA levels Tuesday through Thursday, with a return to SCA level gusts forecast Thursday night. For the seas, residual SCA seas on the ocean are forecast on Monday with ocean seas below SCA thresholds thereafter until Thursday late day and Thursday night, when ocean SCA level seas are forecast once again. && .FIRE WEATHER... Sunday afternoon into the evening could also see min RH values around 20-30% percent and NW winds gusting over 30 mph. As such, and after coordination with WFO PHI and state partners, have issued a Fire Weather Watch for northern NJ counties starting at 7am Sunday. With minimum RH values potentially increasing to over 30% on Sunday afternoon, will continue to treat the potential for enhanced brush fire spread with an SPS, elsewhere. && .HYDROLOGY... No hydrologic concerns are expected. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...Wind Advisory from noon Sunday to midnight EDT Sunday night for CTZ005>012. NY...Wind Advisory from noon Sunday to midnight EDT Sunday night for NYZ067>075-078>081-176>179. NJ...Wind Advisory from noon Sunday to midnight EDT Sunday night for NJZ002-004-006-103>108. Fire Weather Watch from 8 AM EDT Sunday through Sunday evening for NJZ002-004-006-103>108. MARINE...Gale Warning from 6 AM Sunday to midnight EDT Sunday night for ANZ330-335-338-340-345-350-353-355. && $$ SYNOPSIS...JM/DBR NEAR TERM...JM/JP/DBR SHORT TERM...DBR LONG TERM...JM AVIATION...JP MARINE...JM/DBR FIRE WEATHER... HYDROLOGY...JM/DBR
Area Forecast Discussion
National Weather Service Pueblo CO
353 PM MST Sat Mar 13 2021 .SHORT TERM...(This evening through Sunday) Issued at 228 PM MST Sat Mar 13 2021 Upper low over the 4 corners region continues to send rounds of rain/snow showers northward across the forecast area within the warm conveyor belt region of the storm. Rain-snow line has been wavering between 5000-6000 feet this afternoon. A quick 2 to 3 inches of snow has been reported across the Pikes Peak region and southern I-25 corridor as of early this afternoon. With another round of snow expected to move into El Paso county shortly, this area could end up with another 1 to 3 before 6 PM. Melting across the lower elevations has limited accumulations some, but as we head into the evening and temperatures cool...we should see some better accumulations across southern El Paso county and eastern Fremont county as the system crosses the mountains between 06z-09z and pulls wrap around precipitation back southward into the northern I-25 corridor and southeast mountains. Models keep slowing down the upper low, and EC and 18z GFS pull the wrap around precipitation farther south across the plains on Sunday as the low deepens across southeast Colorado. So there is still some uncertainty with how much additional snow will fall but forecast generally looks on track and will keep highlights as is for now as their is a chance that wrap around precipitation could be a little heavier than what grids portray. Winds increase Sunday afternoon so blowing snow will become more of a concern across northern El Paso county as the day goes on though it looks like heavier snowfall rates will be done by then, so strongest winds and heaviest snow are not quite as well juxtaposed for blizzard conditions. As for severe thunderstorm potential across the far southeast CO plains, this is looking less likely as the front has stayed well south of the area with dew point recovery only in the upper 30s so far. Latest HRRR keeps majority of stronger convection to the south of the forecast area which looks reasonable. Given shear and elevated thunderstorm possibility, can`t rule out a marginally severe storm with some small hail possible...but risk for stronger storms looks greatest to the south of the area. -KT .LONG TERM...(Sunday night through Saturday) Issued at 228 PM MST Sat Mar 13 2021 Precipitation still ongoing Sunday night across the plains and Continental Divide region but may be shutting down across the southeast mountains south of highway 50 a bit earlier as though EC and NAM which split the difference in the divergent tracks of the faster farther south GFS and farther north Canadian do hang on to some snow until 06z. Given the differences in the models kept the highlights unchanged for now. All highlights are set to come down at 12z Monday as the upper low pulls off to the east. Attention turns towards the next storm system which drops just south of the 4 corners region on Tuesday and moves across northern New Mexico Tuesday night. This system is more quickly moving but its farther south track could actually bring more snow to the plains than the previous one with its overnight timing and better chance for rain/snow switch over across all of the lower elevations of the plains Tuesday night. System could bring some significant snow to the southeast mountains and Raton Ridge if it maintains the more southerly track solution and potential for northeast upslope flow. There are some track differences however between the extended range models and with current storm still a factor in the shorter ranges, will need to address these details a bit later when things become more certain. For now grids are carrying generally advisory snowfall numbers for the southeast mountains and adjacent southern I-25 corridor in the Tuesday/Tuesday night. The weather dries out and warms up for the remainder of the work week with another storm system moving through the western U.S. for next weekend. -KT && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 228 PM MST Sat Mar 13 2021 IFR to LIFR conditions expected into the evening for KCOS and KPUB. As the upper low crosses the mountains this evening winds will shift out of the north for KCOS and KPUB with another round of snow this evening through the overnight hours. IFR VIS/CIGs will be possible through tonight with some improvement expected Sunday morning for both terminals. Winds will increase on Saturday with gusts up to 30-35 kts possible for KCOS and lighter gusts around 25 kts for KPUB. Could see another round of -SHSN though cigs though northerly winds off the Palmer Divide may keep cigs more in the MVFR range. KALS will see generally VFR conditions with periodic -SHRASN through the overnight hours. Cigs could briefly drop into the MVFR range. Winds will increase out of the northwest on Sunday with gusts to around 25 kts. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 6 AM MDT Monday for COZ058>063- 072>076-079>082-084. Winter Storm Warning until midnight MDT Sunday night for COZ077- 078-083-085. Winter Weather Advisory until 6 AM MDT Monday for COZ066-068. && $$ SHORT TERM...KT LONG TERM...KT AVIATION...KT