Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/23/17


Area Forecast Discussion
National Weather Service Bismarck ND
934 PM CDT Fri Sep 22 2017 .UPDATE... Issued at 934 PM CDT Fri Sep 22 2017 Shower activity centered on western SD as of 02 UTC is associated with the next impulse expected to move northeast into ND tonight. The forecast is generally on track, but once again we focused on refining PoPs with this update, particularly relying on iterations of the HRRR through its 01 UTC cycle since it appears to be doing the best job assimilating current radar returns in southwest ND. Lingering steep lapse rates aloft may still support thunderstorms in the southern James River valley as the impulse reaches there, but forecast soundings taken across Dickey County from the 00 UTC NAM and recent RAP cycles suggest MUCAPE will be limited to 200 to 700 J/kg, and that will be driven by parcels originating above 700 mb, with resultant small normalized CAPE supportive of only a low (though certainly non-zero) probability of a strong storm in that area. UPDATE Issued at 645 PM CDT Fri Sep 22 2017 Elevated convection increased in coverage from Stutsman into Foster Counties late this afternoon, on the nose of the strongest mid-level warm air advection centered near 850 mb per RAP-based guidance. That forcing is expected to be the primary driver of precipitation through the evening and so we refined PoPs slightly accordingly with this update, focusing on that area northward toward Rolla. Earlier brief subsidence in the wake of what appeared to be an eastward-propagating gravity wave per preliminary, non-operational GOES-16 visible satellite imagery has shifted eastward. The exit of that mesoscale subsidence also likely contributed to the convection, but the warm air advection is also forecast to refocus eastward by mid evening and so that will cause precipitation chances to dwindle until after 06 UTC, when another vorticity maximum embedded in southwest flow aloft will reach southern ND. Some recent HRRR simulations suggest a strong storm could affect Dickey and LaMoure Counties with that wave late tonight, where MUCAPE will likely still be sufficient for isolated stronger, elevated updrafts. && .SHORT TERM...(This evening through Saturday) Issued at 139 PM CDT Fri Sep 22 2017 Scattered showers and thunderstorms will continue through the evening hours for most of western and central North Dakota. Later tonight precipitation shifts south and east as the surface trough swings into Minnesota. With ample elevated instability, shear and a low freezing level, several storms could produce marginally severe hail this afternoon and evening. A very cool night is in store with northerly winds and temperatures in the 30s and low 40s for most. .LONG TERM...(Saturday night through Friday) Issued at 139 PM CDT Fri Sep 22 2017 The main focus for the Long term will be cooler temperatures with a good chance for showers Saturday and Sunday. The cool weather will last at least through next Tuesday. Highs during this period will be in the 50s and lows in the mid 30s to mid 40s. There could be some patchy frost during this period. Chances for showers will continue through Tuesday until the upper trough finally moves through. Then moderating temperatures at least into the 60s are expected with mainly dry weather for Wednesday and Thursday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 934 PM CDT Fri Sep 22 2017 MVFR ceilings are expected to become widespread across western and central ND tonight and Saturday morning. Local IFR ceilings are possible. Showers are possible in southwest and south central ND tonight, with a few thunderstorms also possible south of KJMS. A more widespread area of rain is expected to develop in southwest ND Saturday afternoon as a stronger disturbance approaches. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CJS SHORT TERM...AJ LONG TERM...AJ AVIATION...CJS
Area Forecast Discussion
National Weather Service Dodge City KS
615 PM CDT Fri Sep 22 2017 ...Updated aviation discussion... .SHORT TERM...(This afternoon through Saturday) Issued at 1235 PM CDT Fri Sep 22 2017 Atmosphere is more humid and unstable this afternoon compared to previous days, as the dryline has backed up to the CO/KS border vicinity. The dryline and its associated convergence will remain near these western zones through peak heating, where various models and CAMs including the latest iterations of the HRRR develop scattered convection by around 4 pm. Most activity is expected to remain west of US 83 through this evening. SPC 5% wind/hail probability is plausible, with marginal MLCAPE of 1000-1500 J/kg and marginal bulk shear around 30 kts. East of the dryline, the south to southeast winds will continue to blow this afternoon, in response to another round of lee cyclogenesis east of Denver. S/SE winds will again gust to near 40 mph through early evening. Temperatures still unseasonably hot, and approaching record levels again this afternoon, well into the 90s. Tonight...Breezy and unseasonably warm again. Any evening convection across the western zones will diminish rapidly with the loss of heating and convergence. Still, with various disturbances embedded in the SW flow aloft in proximity to Colorado, kept some pops going in the western zones all night. Locations east of US 83 expected to remain dry. S/SE winds will remain elevated and gusty again tonight in response to another low level jet. With winds keeping the boundary layer mixed and preventing radiational cooling, another unseasonably warm night is on tap, with temperatures struggling to get below 70 through sunrise Saturday. Saturday...Closed low in Nevada remains essentially stationary through the daylight hours. In other words, forcing for ascent needed to encourage convection will be in no hurry to come into SW KS. Still, 12z NAM and other guidance generate a line of showers and thunderstorms near/west of the CO/KS state line by 6 pm, with this convection making some slow progress eastward to near the US 83 corridor Saturday evening/night. Areas along and especially east of US 283 will have to be patient, as those areas are expected to remain dry through Saturday night. Otherwise, the persist strong south winds will blow yet again on Saturday, averaging 20-30 mph with gusts near 40 mph. Temperatures will begin to cool down, as 850 mb temps drop 2-3C, and models depict much more cloud cover (especially the western CWA). Afternoon temperatures will range from the upper 70s along the Colorado border, to the mid 80s at Dodge City, to near 90 eastern zones. Just the beginning of a cooling trend that will continue through the long term. .LONG TERM...(Saturday night through Friday) Issued at 208 PM CDT Fri Sep 22 2017 Still on track to pick up some sorely needed rainfall in SW KS Sunday and Monday. Closed low over Utah Sunday morning finally ejects slowly NE to southern Wyoming late Sunday. Forcing for ascent needed to generate precipitation will slowly progress west to east Sunday through Sunday night, with several rounds of showers and thunderstorms anticipated. Blended model pop fields continue in the likely category, and these were accepted. 12z ECMWF solution depicts showers and thunderstorms along and west of US 83 at sunrise Sunday, progressing west to east across SW KS daylight Sunday. QPF grids show 1/2 to 1 inch of rain possible daylight Sunday. With thick clouds and rainfall, temperatures will cool sharply Sunday, to 70s west and 80s east. Another round of rain and thunderstorms is expected Sunday night into Monday, as the associated cold front boundary sags into Kansas and frontogenetic forcing is enhanced. Another 1/2 to 1 inch of rain is forecast, and much of this rain will fall where it is needed the most, across the central and eastern counties. Winds will become northerly by Monday morning. Monday...Cloudy and much cooler, with afternoon temperatures holding in the 60s NW to the 70s SE. Frontal boundary will sink well south of SW KS, but models depict adequate moisture overrunning north of the boundary to keep rain and isolated thunder going much of Monday, particularly the SE zones. Another 1/2 to 1 inch of rain is possible daylight Monday. Storm total QPF grids continue to come up widespread rainfall amounts of 1-2 inches across SW KS. Of course, given the nature of convection, some areas will receive more than that, some areas less. Tuesday...Dry weather returns, as cool/dry high pressure sinks south into the central plains. Fantastic, crisp fall weather is on the way next week, with afternoon temperatures within a few degrees of 70, and lows down into the 40s. Wednesday through Friday...Dry. Let`s hope we get the rain Sunday and Monday. Models are consistent showing dry quiet weather late next week, with a weak cutoff low meandering over the Desert SW and weak dry flow over SW KS. Pleasant early fall weather on the way with highs only in the 70s. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 615 PM CDT Fri Sep 22 2017 Gusty surface winds will persist into the late evening hours at all the terminals. Through the overnight hours, LLWS will become more of an issue as surface winds diminish somewhat and 45-50 knots winds continue a few thousand feet AGL. Isolated to widely scattered thunderstorms currently forming over far southwest Kansas into the west Texas Panhandle should stay west of the Garden City and Liberal terminals this evening before dying out. There will be a slight chance for thunderstorms over far southwest Kansas late tonight into Saturday but will forego mentioning in the TAFs at this time given the sparse coverage. && .PRELIMINARY POINT TEMPS/POPS... DDC 70 86 66 80 / 10 20 30 60 GCK 67 84 62 76 / 20 50 70 70 EHA 62 79 58 75 / 40 60 70 60 LBL 68 84 65 76 / 20 40 60 70 HYS 72 87 68 80 / 10 20 30 60 P28 70 89 68 86 / 0 10 0 30 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Turner LONG TERM...Turner AVIATION...Gerard
Area Forecast Discussion
National Weather Service Hastings NE
713 PM CDT Fri Sep 22 2017 .SHORT TERM...(This evening through Saturday) Issued at 313 PM CDT Fri Sep 22 2017 Fire danger will remain near critical early this evening for western zones especially west of Kearney, to Franklin, to Osborne. The winds are very strong gusting into the 30 to 40 mph range. The only thing preventing a red flag warning this afternoon and evening remains the relative humidity values, which are near that critical 20 percent, but for the most part just above it. Am not impressed with thunderstorm chances this evening, but will allow the slight chances to remain across our far northwestern zones from Beaver City to Greeley and points west. The HRRR model, which typically over does convection is showing little to nothing happening with just a few warm sector heat of the day thunderstorms early this evening and then dry through the remainder of the night. The 12Z and 18Z NAM continue to highlight just a slight convective signature over our far west this evening. Therefore, will continue to go with our slight thunderstorm chances in our far west, but believe most folks will remain dry. There is modest instability and fairly high wind shear this evening so can not rule out a severe thunderstorm or two should thunderstorms form in the warm sector, but forcing is fairly weak in the warm sector. Saturday...There will be more in the way of cloud cover, which will knock a solid 5 to 10 degrees off of our highs. However, it will still be above normal for this time of year with our forecast area in the warm sector allowing highs to climb into the 80s and perhaps close to 90 in some eastern zones. The best chance for rain will be later in the afternoon and evening generally west of a Beaver City, Kearney, Greeley line. Can`t rule out an isolated shower or thunderstorm in the warm sector around the Tri-Cities, but likely not to big of a deal. Instability will be more limited and there is just a small chance of a marginally severe storm across our northern and northwestern zones. .LONG TERM...(Saturday night through Friday) Issued at 313 PM CDT Fri Sep 22 2017 Saturday night...Do not really expect the cold front to advance into our area until Sunday and thus the better rain chances will continue to be confined to our far northwestern zones with little change from Saturday afternoon into Saturday night. Sunday...The cold front should start to make that push further east and more into our western forecast area by afternoon and evening. Most of the rain will come along and behind the cold front. Expect rain will become more widespread and heavier across our western zones, generally west of the Hastings/Grand Island area. There could be a pretty good temperature contrast across our forecast area with mid to upper 80s in Hebron and Beloit to perhaps the 60s in Gothenburg. Sunday night...The front moves into the heart of our forecast area and this period currently is favored to be the wettest period for most of our forecast area. Monday...The cold front will pass to our east and the entire forecast area will be cooler with highs in the 50s and lower 60s over most of the area with a good deal of cloud cover and continued rain. The best bet for rain will now shift into our eastern zones. 3-day rain totals by the time it is all set and done will range from 1-3 inches across most of the forecast area. Tuesday through Friday...Cool and mainly dry with the cold front now well off to our east. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday) Issued at 712 PM CDT Fri Sep 22 2017 VFR conditions are expected to prevail. The cold front remains off to the northwest of the forecast area and south to southeasterly winds persist at both terminals. Winds are gusting 25 to 30 kts still and will continue until decreasing slightly overnight. Cloud cover is expected to increase, but with high clouds until later tomorrow afternoon/evening when mid-high clouds move in. Southerly wind will again increase during the afternoon hours Saturday. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ SHORT TERM...Wesely LONG TERM...Wesely AVIATION...Billings Wright
Area Forecast Discussion
National Weather Service Jacksonville FL
950 PM EDT Fri Sep 22 2017 .UPDATE... Isolated to scattered convection primarily driven by afternoon heating has now dissipated across much of the area. Only driver of convection overnight will come from low level convergence along the coastal areas...and current radar shows a few showers dotting the coastal areas south of Jacksonville and the marine zones. This trend is likely to continue...and will probably increase a bit toward the early morning hours after about 2 AM, as convergence increases. In addition...inverted low level trough noted in RAP guidance is forecast to push inland over central FL and into srn portions of the our area. This will usher in richer moisture and additional forcing for increased shower activity for the southeast zones. Thus have continued a trend of increasing rain chances again by sunrise on Saturday morning. Have inserted some patchy fog over inland southeast GA though probably not as much as what occurred Friday morning. Lows still forecast around 70 well inland...and closer to 72-76 near the coast. && .AVIATION... Few-sct cumulus around 1500-3000 ft through tonight for coastal TAFs though higher chance of sct-bkn cumulus at SGJ. VCSH still possible through the night...with possible TEMPO SHRA for SGJ. Winds northeast near 5 kt tonight...with near 8-12 kt at SSI and SGJ. Winds increasing Saturday to 10-16 kt and gusts around 20-25 kt. MVFR ceilings of 2000-3000 feet Saturday and good chance of showers affecting terminals with VCTS possible...except more vicinity shower activity at SSI. && .MARINE... Current forecast on track with winds of 10-15 kt...increasing to 15 kt/15-20 kt overnight. SCA continues for all waters. Only minor edits for initial conditions appear needed at this time. Rip Currents/High Surf: Prior discussion...High risk will be needed for all area beaches this weekend and early next week due to high surf and long period swells from Maria. A high surf advisory will likely be required for coastal locations beginning on Saturday for breakers in excess of 7 feet. Beach erosion will become an increasing concern during times of high tide late this weekend and early next week. && .PRELIMINARY POINT TEMPS/POPS... AMG 70 87 69 87 / 10 40 0 10 SSI 75 84 74 83 / 20 30 10 10 JAX 72 85 73 85 / 20 50 20 20 SGJ 76 84 75 84 / 30 50 20 20 GNV 71 87 71 87 / 20 50 10 20 OCF 71 87 72 88 / 20 50 10 30 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...Coastal Flood Advisory until 10 PM EDT Saturday for Clay-Coastal Duval-Flagler-Inland Duval-Putnam-St. Johns. GA...None. AM...Small Craft Advisory until 5 AM EDT Tuesday for Coastal waters from Altamaha Sound to Fernandina Beach FL out 20 NM- Coastal waters from Fernandina Beach to St. Augustine FL out 20 NM-Coastal waters from St. Augustine to Flagler Beach FL out 20 NM-Waters from Altamaha Sound GA to Fernandina Beach FL from 20 to 60 NM-Waters from Fernandina Beach to St. Augustine FL from 20 to 60 NM-Waters from St. Augustine to Flagler Beach FL from 20 to 60 NM. && $$ Shashy/Struble/Corless
Area Forecast Discussion
National Weather Service Marquette MI
757 PM EDT Fri Sep 22 2017 .SHORT TERM...(This evening through Saturday) Issued at 343 PM EDT FRI SEP 22 2017 Short term forecast complicated by MCS moving through the Upper Mi today. Latest radar imagery shows an intense line of strong to severe storms moving into the east half of Upper Mi with generally a weaker line of storms moving thru south central Upper Mi. Mixed layer CAPE values up to 2000 j/kg combined with effective shear values of 35-40 knots have supported isolated severe storms over the west half of Upper Mi earlier today. Convection and more clouds than expected have kept temps down cooler than forecast for many places over the west half so made some necessary adjustments downward. It will be tricky though if we see any partial clearing late afternoon behind the MCS over the west as it would not take much mixing to tap into much warmer air just off the sfc. Tonight, better performing experimental HRRR model indicates any remaining convection dissipating over eastern and south central Upper Mi early this evening as air mass dries and becomes increasingly capped by very warm 22-25c temps from 950-850 mb. With models showing the mid-level ridge strengthening and the sfc-850 mb warm front lifting north of Upper Mi, expect counties across Upper Mi to be dry tonight. There may be some isolated convection along the warm front over northern Lake Superior. Southerly gradient winds between high pressure centered over the eastern CONUS and low pressure and frontal system over MN will provide enough mixing to preclude fog development over land areas. Dewpoints in the lower to mid 60s however could support locally dense fog over marine areas, especially given the recent rainfall from today`s MCS. Min temps will stay well above normal given warm airmass and southerly winds. Expect many record high minimum temps to be set today into Saturday. Readings tonight will generally be in the upper 60s to lower 70s. Saturday, even with a strong subsidence inversion under the 590 DM ridge over the region, forecast mixing to near 800 mb with temps around 20C will support record to near record high temps in the upper 80s and possibly lower 90s over much of the area except downwind of Lake Michigan. Adding to the discomfort will be dewpoints into the mid and upper 60s. Capping should be strong to minimize shower/t-storm chances, per NAM/ECMWF/GEM keeping any convection to the north and west. However, the frontal zone over ne MN into western Lake Superior by late Saturday may allow some showers/t-storms to sneak into the far west from IWD to CMX toward evening. .LONG TERM...(Saturday night through Friday) Issued at 259 PM EDT FRI SEP 22 2017 Nam shows a deep 500 mb trough over the Rockies and a strong 500 mb ridge over the ern U.S. 00z Sun. Upper air pattern changes very little through 00z Tue with the ridge slowly moving east to New England by 00z Tue. What this will mean is warm and humid conditions will continue with summer like weather. Pops will remain mostly to the north and west of the cwa with area in the warm sector for this forecast period and some record highs are possible for this forecast period. In the extended, GFS and ECMWF show a 500 mb trough in the Rockies and northern plains 12z Tue with a ridge over the ern U.S. 12z Tue. This trough moves into the upper Great Lakes 12z Wed and this trough remains into 12z Thu. Starting on Wed, a cold front moves through and brings an end to the summer like temperatures with cooler air moving into the area. Temperatures will go from above normal on Tue to below normal for Wed through Fri. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 757 PM EDT FRI SEP 22 2017 VFR conditions are expected at all TAF sites. May see some fog near or at KCMX and KSAW, but not expected at this time. LLWS will be a factor at all sites through the night. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 343 PM EDT FRI SEP 22 2017 Low to mid 60s dewpoints sliding across Lake Superior are expected to linger into early next week bringing patchy to areas of fog for several days across the lake. Some of the fog could be locally dense at times, especially tonight considering today`s rainfall over the lake. Expect winds to generally be below 20 knots through the early part of next week under a weak pressure gradient. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...07 AVIATION...Titus MARINE...Voss
Area Forecast Discussion
National Weather Service Omaha/Valley NE
1101 PM CDT Fri Sep 22 2017 .SHORT TERM...(Tonight through Monday) Issued at 310 PM CDT Fri Sep 22 2017 Precipitation chances, precipitation amounts and temperatures are the main forecast concerns. Water vapor satellite imagery in combination with recent RUC model analysis showed a closed mid tropospheric low near the OR/ID/NV border area, which was part of a large trough that stretched from western Canada. A ridge extended from the eastern Great Lakes region down into northern Mexico. 12 hour height falls at 500 mb this morning were highest (around 60 meters) over northern AZ. Winds at 300 mb were strongest (100 knots or higher) from northern Baja CA up into WY. Thermal ridge at 700 mb (with temps as warm as 12 or 13 degrees C) extended from west TX into western and central SD. A ribbon of higher 850 mb moisture, with winds at that level mainly from 30 to 50 knots) was located just east of the mid level thermal ridge. At the surface, a cold front extended from low pressure over northeast SD down into southwest NE and northeast CO. Temperatures east of the front in our area at 3 pm were in the lower and mid 90s. Tonight, will maintain some 20-30 percent chance of thunderstorms in about the northwest half of northeast NE. There is a conditional threat for severe storms, with damaging winds and large hail. Chances are a bit higher prior to midnight. Southerly flow across the area tonight should hold temperatures up, with low expected to be mainly upper 60s and lower 70s. A few spots may only drop to the mid 70s. Frontal boundary will be nearly stationary near our northwest CWA from Saturday through Saturday night, generally stretching from southeast SD to southwest NE in that period. The chance for showers and storms will be highest along and northwest of that front. Temperatures ahead of the front should remain well above normal, and went a bit higher than MOS for Saturday afternoon. For Sunday, went mainly with highs of 85 to 90 ahead of the front and 70s behind the front. Precipitation should become likely Sunday in the northwest part of northeast NE, then chances increase for the rest of the area as the front slides to the southeast through Monday. Expect at least some areas of locally heavy rain, but with below normal rainfall recently, expect that if any flooding would develop that it would be minor (at least for now). Monday will be quite cool in northeast NE, with highs in the upper 50s to lower 60s, but ranging to 70s and lower 80s for the rest of the area. .LONG TERM...(Monday night through Friday) Issued at 245 PM CDT Fri Sep 22 2017 The chance for showers and thunderstorms will remain high for Monday night, but decrease on Tuesday from northwest to southeast. That is based on current model timing, which could change. At the start of this period, models are in good agreement that a positively tilted trough at 500 mb should extend from Manitoba to AZ. The northern end of that trough will trough to lift off to the northeast, while a closed low forms back toward AZ Wednesday and a ridge builds east from British Columbia. Right now, we will have a mainly dry forecast from Tuesday night into Thursday, then carry a low chance for showers around Thursday night. Temperatures will start out below normal Tuesday, but moderate back closer to normal by Thursday and Friday. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1100 PM CDT Fri Sep 22 2017 VFR conditions will continue through Saturday evening at all eastern Nebraska TAF sites. Cold front is forecast to remain well northwest of KOFK, allowing southerly winds near 15kt overnight, and gusting to 25kt during the afternoon hours, at all sites. Broken mid level clouds may move over KOFK, but only scattered high clouds are expected at KLNK and KOMA through the TAF period. && .CLIMATE... Issued at 616 AM CDT Fri Sep 22 2017 The records for today and Saturday are: Warm Max Warm Min Warm Max Warm Min 9/22 9/22 9/23 9/23 Omaha 99 (1937) 73 (2016) 96 (1892) 72 (1892) Lincoln 99 (1937) 75 (1937) 97 (1921) 72 (1930, 1892) Norfolk 96 (1940) 67 (2016, 92 (1921) 69 (1958, 1937) 1937) && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Miller LONG TERM...Miller AVIATION...Dergan
Area Forecast Discussion
National Weather Service Pueblo CO
728 PM MDT Fri Sep 22 2017 .UPDATE... Issued at 707 PM MDT Fri Sep 22 2017 Updated grids to take down the Red Flag Warning at its natural 7 PM expiration time. There is still a slight chance for a thunderstorm along the far eastern border...but latest HRRR runs are keeping most of the convection just east of the area until around midnight when a new round lifts northward into the area. Meanwhile best chance for showers overnight will continue along the Continental Divide with isolated to scattered showers spreading northeastward into the Sangre De Cristos at times. Snow levels will remain pretty high tonight...most likely above pass levels...but a couple inches of sloppy wet snow will be possible across the higher peaks. Best chance for showers and thunderstorms across the plains will spread in Saturday morning as energy lifts northeastward ahead of the approaching upper trof. Soundings moisten up quickly Saturday morning with scattered to widespread showers and a few embedded thunderstorms forming across the plains. Main question for tomorrow is how much will atmosphere destabilize across the southeast plains during the afternoon. Mid level lapse rates are not too impressive though depending on surface heating, there could be an axis of higher CAPE east of a line from approximately La Junta to Branson. Deep layer shear will be running around 40-50 kts...which is sufficient for rotating supercells. NAMNest appears to develop some stronger convection across the far southeast plains during the afternoon where atmosphere may destabilize a bit better. Will have to watch how this evolves in 00z runs. Overall grids appear to be in good shape for now. -KT && .SHORT TERM...(This evening through Saturday) Issued at 251 PM MDT Fri Sep 22 2017 ...Precip to return to most, if not all, of the region tomorrow... Currently... Breezy to windy over the area at 2 pm. Parts of the southeast plains are gusting to 40 to 45 mph while most other lower elevations regions are gusting to 25 to 35 mph. Red Flag conditions are marginal at best as most areas have RH values in the 15 to 20% range. Moisture in the midlevels is noted at mtn tops RH values are quite high, above 70% (most of the higher San Juan mtn areas are 100%), and quite a bit of mid lvl cloudiness is noted in teh water vapor imagery. In addition, showers with isold thunder has been going across the contdvd since earlier this morning. convective bubbles were starting to develop over far se CO, and SPC mentioned one or two stronger storms could form later this afternoon per latest SWOMCD. Rest of Today & Tonight... Isolated thunderstorms will be possible over far southeast Colorado this evening. As per latest discussion. one or two could be strong to marginally severe. The best chance will be over Baca county as best instability is located over this region. Later tonight showers with isold thunder will slowly increase over the far SE Colo plains. Showers with isold thunder will be possible this afternoon into tonight across the San Juan mountains. This activity will also increase at the night progresses. The best chance will be over the San Juan mtns. Over the rest of the area, it will remain primarily dry, Tomorrow... High amplitude 500 mb trough will continue to progress toward the region and this system will likely bring a good chance of precip to the area during this time period. Guidance is pretty insistent on bring bands of rain with embedded thunder across most if not all of the area during the day tomorrow. Two areas of activity will be across the Contdvd region. The 2nd area will be over the plains, with the overall best chance from central/eastern Las Animas county NNE up to La Junta/Lamar regions. A few strong storms could occur tomorrow as dwpts will be in the 50s and CAPE values will roughly be in the 1000 J/KG range, with deep shear about 30-40 knots. SPC currently does not have the area outlooked, but I would not be too surprised if parts of the se CO plains are outlooked in later SPC forecasts. As for QPF, several areas on the plains may see 0.50 to 0.75 inches of rain tomorrow. Snow will be likely across the higher elevations, with the accumulating snow mainly above 11000 feet. 1 to 4 inches of new snow will be possible at the highest elevations. Areas along the contdvd will have the best chance of snow. Temps tomorrow will be noticeably cooler than today, with highs mainly in the m60s to m70s plains, and 50s and 60s valleys. Breezy southerly winds will occur, especially over the far se plains and mtns and valleys. .LONG TERM...(Saturday night through Friday) Issued at 251 PM MDT Fri Sep 22 2017 Active and cooler weather is expected into early next week. Models are having a hard time through the middle of next week and there is a high degree of run to run inconsistency leading to lower forecast confidence. Ensembles spreads are high as well also leading to lower confidence in the later half of the extended period. Saturday night...the upper level low sitting over Utah will continue to lift energy northeast across Colorado Saturday night. Strong to severe weather will be ongoing across the far Eastern Plains and should push east into Kansas by midnight. Large hail, gusty winds in excess of 60 mph and heavy rainfall will be possible. For the rest of the area, showers and thunderstorms will be continuing over the mountains, spreading east into the Eastern Plains through the evening hours. Snow levels will lower some through the overnight hours down to around 10 kft, especially along the Continental Divide where a couple inches of snow are possible on area peaks. Sunday...currently this is where the most change looks to have occurred in the forecast. Models have the upper level low starting to track eastward into western Colorado through the afternoon. The current model runs bring dry air north out of New Mexico and dry slot southern Colorado. This has mixed the dryline further east, over western Kansas and would bring our severe weather risk down to zero through Sunday evening. This would also mean drier conditions across much of the region, with the exception of the mountain areas, where near continuous showers and thunderstorms are expected into Sunday night. Warmer afternoon highs are also expected with mid to upper 70s across the Plains. Low pressure is forecast to develop near Pueblo by Sunday afternoon, and move east to near Lamar overnight. This will send a cold front south across the CWA by Monday morning. A few model solutions to develop light precipitation across the Plains with the front late Sunday night. Snow levels over the mountains will also fall to around 9 kft with a few more inches of snow possible above that elevations. Monday and Tuesday...the upper low is forecast to split, with energy moving into the Northern Plains, and energy moving into Arizona. This will keep southern Colorado under cool conditions into early next week. Temperatures will be in the lower to mid 60s across the Plains. As far as precipitation, much will depend on energy moving across moving around the upper troughs. Southeasterly upslope flow across the region would favor the Eastern Mountains, into the I-25 corridor. But this time period is where uncertainty in the model solutions begins to develop. Wednesday through Friday...big model differences through the mid to late week period. The GFS keeps the split trough as such, with a longwave trough over the Northern Plains, and weak troughing over the Desert Southwest. Several disturbances would be forecast to lift north out of New Mexico and produce rounds of precipitation for the region. The ECMWF has the longwave trough to the north, but drops a strengthening disturbance south into the Great Basin through the end of the week. It has much better chances for precipitation, along with much cooler temperatures through the back half of the extended period than the GFS. Mozley && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 251 PM MDT Fri Sep 22 2017 VFR conditions likely tonight for all of the TAF sites (KPUB, KALS and KCOS). Gusty winds this afternoon will weaken by early to mid evening. For tomorrow, cigs will lower with a good chance or precipitation developing at all of the 3 taf sites by late morning or early afternoon. Some embedded thunder will also be possible. MVFR conditions will be possible due to low cigs, especially at KCOS. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KT SHORT TERM...HODANISH LONG TERM...MOZLEY AVIATION...HODANISH
Area Forecast Discussion
National Weather Service Shreveport LA
1007 PM CDT Fri Sep 22 2017 .DISCUSSION... Convection has diminished entirely this evening with mostly clear skies across the region. Falling temperatures are already nearing dew points at some sites south of I-20 so have expanded patchy fog coverage into much of north central Louisiana after midnight with more extensive coverage farther north of I-20 toward daybreak. The remainder of the forecast in on track for tonight with temperature trends in good shape. No other changes are needed at this time. Updated text products will be out shortly. /19/ && .PREV DISCUSSION... /issued 641 PM CDT Fri Sep 22 2017/ AVIATION... Isolated showers have dissipated across portions of North Central/ Northeast Louisiana with VFR conditions expected to prevail through the evening hours. Conditions should begin deteriorating in the form of patchy dense fog and IFR/LIFR ceilings across area terminals after midnight through the mid morning hours on Sat. The worst fog potential will likely be across the MLU/LFK/GGG terminals with low ceilings likely at those terminal in addition to the TYR terminal. Otherwise, IFR/MVFR ceilings will be possible shortly after sunrise at the remaining terminal locations for at least a couple hours through mid morning before ceilings scatter out and fog lifts areawide on Saturday by mid to late morning. VFR conditions should prevail beyond 17z on Sat through the afternoon hours. 13 PREV DISCUSSION... /issued 314 PM CDT Fri Sep 22 2017/ DISCUSSION... An UA ridge draped from the Great Lakes region southwest to across the majority of the Four-State Region has led to sea-breeze convection having a tough time making it to the region /versus what we have seen the last several days/. Only a few isolated showers were nearing/moving across Deep east Texas late this afternoon. However, a weak shear axis on the eastern periphery of the aforementioned UA ridge have aided in developing isolated showers across northeast LA and southwest AR, nearing Monroe LA and Texarkana AR respectively. Per radar analysis, the precip activity across all locations were not strong at all /which is not surprising given lack of UL support/ and per the HRRR solution, will diminish shortly after sunset. Furthermore, 21Z metars reported temps in the lower 90s, making it unseasonably warm for the first day of the Fall season. Tonight, clear skies, light southerly winds and moist sfc conditions /dewpoints in the 60s and 70s/ will result in another round of patchy fog mainly along and south of the Interstate-20 corridor. Portions of east TX and deep east TX may once again experience patchy dense fog, though confidence is not high enough to issue a Dense Fog Advisory attm. Will let later shifts see if dense fog comes into fruition. Slightly better chances for isolated to scattered showers and thunderstorms will occur this weekend, courtesy of a westward drifting weak UA disturbance, originating from the southeast CONUS. This disturbance providing for a bit of UL support will interact with a relatively moist low level atmosphere as southerly sfc winds ensue /PWATs on the order of 1-1.50 inches/. Attm, do not expect storms to reach strong levels given the that the disturbance is not overly strong by any means. This general weakness will remain nearby through Monday, before commencing to shift east and wane significantly by Tuesday. The eastward shift of the aforementioned weak disturbance is due to a longwave UA trough translating east across the Rockies. Long term solution hint at the longwave trough breaking into two defined pieces: the northern periphery ejecting quickly northeast to across the Northern Plains and into Canada by mid-week, whilst the southern periphery progresses much slower eastward across the Desert southwest/New Mexico Boot heel by late week. With a cold front expected to impact the Four-State Region from northwest to southeast on Wednesday, combined with a slow eastward propagation disturbance to our west, will result in much better chances for wetting rains initially across the northwest zones, then spreading to the remainder of the area throughout the week. This welcomed pattern change will result in daytime temps dropping from the lower 90s down into the 70s and 80s, with overnight temps cooling into the 50s and 60s by late week. 29 && .PRELIMINARY POINT TEMPS/POPS... SHV 73 94 73 92 / 10 20 10 20 MLU 71 93 71 91 / 10 20 10 20 DEQ 69 92 69 91 / 0 10 10 20 TXK 71 92 71 91 / 10 10 10 20 ELD 70 92 70 90 / 10 20 10 20 TYR 72 92 71 92 / 10 20 10 10 GGG 71 93 70 92 / 10 20 10 20 LFK 71 93 71 92 / 10 20 10 20 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 19/13/29