Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/22/19

Area Forecast Discussion
National Weather Service Amarillo TX
950 PM CST Sat Dec 21 2019 .AVIATION...06Z TAF... VFR conditions expected at all three terminals over the next 24 hours. Skies will be mostly clear with gradual increase in high clouds from west to east after 00Z Monday. Winds will be light, less than 10 kts, out of the south to southwest until 18Z Sunday. After 18Z winds should be out of the southwest around 10 kts. Hoffeditz && .PREV DISCUSSION... /Issued 514 PM CST Sat Dec 21 2019/ AVIATION...00Z TAF... VFR conditions expected at all three terminals over the next 24 hours. Skies will be mostly clear with surface winds less than 10 kts from the south, then southwest. Hoffeditz PREV DISCUSSION... /Issued 301 PM CST Sat Dec 21 2019/ SHORT TERM...Today through Tomorrow... Current mid-level water vapor satellite and RAP 500mb heights show the upper level closed low over southeastern Oklahoma with a ridge building over Baja California and southwestern Arizona. Dry air is wrapping around the back side of the closed low with clear skies across the forecast area today. Light winds and sunny skies make for a beautiful Saturday with temperatures getting up to around 60. The upper level ridge will build east over the Southern Plains through tomorrow night. Crisp low temperatures tonight with a continuation of clear skies and light winds. South southwest winds of 5 to 15 mph will prevail through tomorrow with high temperatures warming into the 60s and possibly the lower 70s in the far western Oklahoma Panhandle. The forecast area will continue to remain dry with no chances of precipitation today and tomorrow. Rutt LONG TERM...Monday through Saturday... Latest 21/12Z model and numerical data continue to show a dry start to the forecast period with possibly some fire weather conditions for parts of the region. This will be followed by a trend of cooling temperatures with our next chance of precipitation by the end of the forecast period. The main H500 ridge centered over western Oklahoma by Monday afternoon in-conjunction with a surface trough developing over SW KS/SE CO will help establish good southwesterly flow. With good adiabatic heating, temperatures will rise into the mid and upper 60s. Fire weather concerns are possible and will be further discussed in the fire weather section. Going from Christmas Eve Day into Christmas Day, the first mid level disturbance will move east across the Four Corners Region. By Christmas morning, as the system weakens quite a bit with limited moisture in-conjunction with fast forward prorogation, beside a light isolated shower, it will remain mainly dry with high temps on Tuesday and Wednesday ranging from the mid 50s to lower 60s. A second, and potentially stronger H500 level disturbance will move equatorward along the California coastline by Thursday before moving east across the far SW CONUS on Friday. Going past Thursday, latest 12Z model data are not in an accord. Stronger disturbance with further northern track illustrated by the GFS/CMC taps into Gulf of Mexico moisture, especially areas downstream of the main trough. This will help bring more moisture into the region starting Friday through Saturday. A second solution illustrated by the ECMWF showing the center of the upper level low further south moving east across northern Mexico displacing the moisture transport further to the east across Texas hill country north into central Oklahoma by the end of the forecast period. Precipitation type may follow diurnal trends with rain during the day and a wintry mix during overnight hours. Exact precipitation type is uncertain at this time, if precipitation makes it to the panhandles. Some guidance even shows some CAPE in the SE TX panhandle with some thunder possible as well. Will monitor and update accordingly as we get to the end of next week. Temperatures will drop to below average by the end of the forecast period, especially in the wake of a cold front moving through the region. Meccariello FIRE WEATHER... Elevated to localized near critical fire weather conditions are possible Monday mainly over the western and central Oklahoma Panhandle and the northwest Texas Panhandle. This is due to dry fuels, increasing southwest winds, and low minimum relative humidity values. Min RH values maybe as low as 9 percent with SW 20 ft winds of 15-20 kts. Meccariello && .AMA Watches/Warnings/Advisories... TX...None. OK...None. && $$ 36/98
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
728 PM CST Sat Dec 21 2019 .DISCUSSION... Updated forecast to add patchy fog to much of the CWA for the 09-15z Sunday period, despite a low risk for fog given recent SREF visibility probabilities. Considering the expected surface mininum temperatures and the most recent dew points, anticipate the development of near zero dew point depressions. Further, the NAM and RAP deterministic soundings at select locations suggest a nearly saturated surface with much drier aloft at 12z Sunday. The surface wind speeds are expected to be light/variable along with significant radiational cooling. && .PREV DISCUSSION... /Issued 524 PM CST Sat Dec 21 2019/ DISCUSSION... Note Aviation Discussion below corresponding to the 00z TAFs. AVIATION... VFR conditions during the period, except for brief MVFR visibilities during the 09-15z Sunday period. light north wind. PREV DISCUSSION... /Issued 259 PM CST Sat Dec 21 2019/ SHORT TERM (Tonight through Sunday Night)... Surface ridging continues to infiltrate the region with drier north winds. Although stratus should be scoured away from the region late this afternoon, a lingering subtropical plume of moisture high aloft will keep some high clouds intact before this plume departs after midnight. Not yet biting on the NAM`s radiation fog potential tonight even following the recent soaking rains over much of the area. Lower theta-e advection and steady north winds should tend to offset fog potential, but this will be monitored through the night. Full sunshine awaits tomorrow as the surface ridge axis arrives with very light north winds and highs closer to seasonal norms. LONG TERM (Monday through Saturday)... Warming trend continues Monday under surface high pressure and a mid- level ridge building in the from the west. Surface high pressure sliding east Monday night/Tuesday while an area of surface low pressure developing across the southern High Plains will result in weak to moderate onshore flow redeveloping by Tuesday. In the meantime, a mid-level longwave trough will begin to move inland along the Pacific coast and dig through southern California and Desert Southwest Tuesday, becoming slightly stationary. This trough will, however, nudge the mid-level ridge eastward, creating a southwest to northeast flow aloft across Texas. Embedded shortwaves in the flow aloft Thursday will introduce a slight chance for rain across the Brush Country. Moisture will continue to gradually increase through the week, so that by Friday, PWATs of 1.0 to 1.3 inches are to be expected. Rain chances will also increase for the latter half of the week. The longwave trough will move east late in the week, bringing a cold front through the region. Timing and development of the trough differ between the GFS/ECMWF long-term models, resulting in timing differences at the surface with regard to the front. GFS continues to run slightly faster, while the ECMWF is slower due to the model attempting to create a cut-off low which would slow any progression. Continued to lean with the GFS with timing of the fropa for Saturday, but will linger POPs through Sunday. Daytime highs are expected to warm into the upper 70s to lower 80s through the week. Overnight lows will also gradually warm into the 50s, although are expected to cool Saturday night in wake of the front. MARINE... Moderate northerly flow will continue tonight and reach SCEC levels by Sunday morning. As high pressure draws closer Sunday afternoon, offshore flow will gradually lessen. Weak offshore flow will become onshore by late Monday afternoon as the high pressure ridge moves to the east. A weak to moderate onshore flow will occur Tuesday through Thursday as a trough of low pressure forms over the southern high plains. Rain chances will increase late in the week as another cold front approaches the region. && .PRELIMINARY POINT TEMPS/POPS... Corpus Christi 42 65 40 68 43 / 0 0 0 0 0 Victoria 40 64 37 69 40 / 0 0 0 0 0 Laredo 39 69 40 72 43 / 0 0 0 0 0 Alice 40 67 38 70 41 / 0 0 0 0 0 Rockport 44 62 45 66 49 / 0 0 0 0 0 Cotulla 35 69 36 73 38 / 0 0 0 0 0 Kingsville 41 67 39 70 41 / 0 0 0 0 0 Navy Corpus 48 62 47 64 50 / 0 0 0 0 0 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ WC/87...SHORT TERM
National Weather Service Kansas City/Pleasant Hill MO
539 PM CST Sat Dec 21 2019 .Discussion... Issued at 229 PM CST SAT DEC 21 2019 Main challenge in the short-term continues to be potential for low clouds and fog development. Latest satellite imagery shows an area of low clouds and fog extending from south-central KS into parts of east-central KS that has been eroding around its edges. Models have really struggled with this low-level moisture the last few days. However, the NAM, ARW, NMM, and 3km NAM, are handling this area of clouds reasonably well. Where they`re failing is the eastward extent. The GFS, RAP, and HRRR are doing a better job with the moisture further east into our forecast area. Feel like with the clouds eroding that the GFS, RAP, HRRR will be a better choice for this afternoon into the overnight hours. So have generally clear skies forecast through the overnight. But I can`t rule out the possibility that the stratus deck builds east with time this evening and overnight. For Sunday - Wednesday, models have trended dry and as a result, warmer. We should see highs climb to near 60 degrees each day. Low cloud cover, like the NAM, ARW, and NMM show would keep hold temperatures back though. But for now, confidence is higher that we`ll be warmer like the GFS, Canadian and ECMWF show. It`s possible highs could get into mid 60s, especially across the southwestern quadrant of the forecast area. Records for the KC area are 67, 66, and 67 for 12/23, 12/24, and 12/25 respectively. These seem out of reach at this point given the latest suite of guidance. The next chance for any precipitation continues to looks like next weekend. Models move a strong trough through the middle of the country Saturday into Sunday. For now, this looks like primarily a rain event for the area as cold air lags behind until late, as the system is exiting, with only a brief wrap around chance for snow. && .Aviation...(For the 00Z TAFS through 00Z Sunday Evening) Issued at 538 PM CST SAT DEC 21 2019 Unfortunately the forecast for tonight is still a tough one regarding fog/low stratus potential. The NAM12 and NAM3km still have the entire area socked in with fog/low stratus. These models tend to go overboard with moisture though, so don`t feel comfortable leaning on them. The ARW is more in the middle with some patchy to areas of fog possible across the area. The RAP, HRRR, GLAMP, and GFS all show some low level moisture in the area, but not enough for fog/low stratus development. Given that the area of fog/low stratus that has been in eastern KS still looks to be eroding, going to lean on the conservative solutions. Therefore, have kept the one line TAFs going for now, but will continue monitoring for any signs of a change. Right now, if there are drops in visibility, they should stay above 6 SM. As for winds, they should stay light and out of the south-southwest. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Discussion...CDB Aviation...Atkins
Area Forecast Discussion
National Weather Service Grand Forks ND
934 PM CST Sat Dec 21 2019 .UPDATE... Issued at 930 PM CST Sat Dec 21 2019 Reports of BR and fog have been reported in Pembina, Cavalier, and Walsh counties this evening. Continued warm air advection over the snow pack will lead to continued chances for mist or patchy fog overnight, mainly for the northern portions of the Red River Valley, where temperatures remained lower today; lows here will fall into the middle to upper teens. Elsewhere, partly cloudy skies prevail with overnight lows falling into the lower to middle 20s. UPDATE Issued at 711 PM CST Sat Dec 21 2019 Made slight adjustments to temperatures within the Red River Valley through Sunday evening to reflect persistent southerly winds. Warmer temperatures remained outside the Valley through much of the day today. Looking at the latest guidance, we could see a similar setup for Sunday but with a slightly better chance of warming as west to southwest winds look to work slightly further eastward. && .SHORT TERM...(This evening through Sunday night) Issued at 259 PM CST Sat Dec 21 2019 Little to no impactful weather is expected through Sunday night, except for potential for fog during the overnight hours. The latest satellite imagery shows broken cirrus clouds continuing to stream eastward overhead amidst strong upper and mid level ridging. A stout inversion in the 850-925 mb layer will persist through Sunday. Given the heightened potential for snowmelt today and Sunday, snowmelt-enhanced moisture may become trapped in the near surface layer under this inversion prompting potential for fog development with nocturnal cooling tonight and Sunday night. Deterministic model soundings and the latest SREF and HRRR guidance suggest the best chance for fog development tonight would be in the northern Red River Valley and northeast ND where winds are progged to be weaker. Confidence is low regarding coverage and duration of potential fog, so will monitor overnight. Subtle daytime boundary layer mixing into the aforementioned inversion combined with WAA in westerly and southwesterly winds brought significant warming today, with temperatures climbing into the mid to upper 30s across portions of eastern ND along and west of the RRV escarpment. Further east along the Red River Valley, south winds and a persistent cold dense valley airmass have kept temperatures lingering in the mid to upper 20s. East of the valley across treed areas in portions of northwest and west central MN, lower albedo has allowed for temperatures to climb warmer into the mid 30s to near 40 degrees. Cirrus clouds are expected to persist overnight and into Sunday, tempering nocturnal cooling with lows expected to fall into the 20s. Assuming that any nocturnally developing low level stratus and fog do not linger for very long, localized temperature trends should be similar on Sunday, relying heavily on the solar radiative influences of terrain, land cover, and snowpack. However Sunday will be slightly warmer as even warmer 850-925mb air reaches the 10-15C range. .LONG TERM...(Monday through Saturday) Issued at 259 PM CST Sat Dec 21 2019 A return to seasonal temperatures is expected for Christmas week with snow chances Christmas night and into Thursday. Monday through Tuesday... A progressive upper level impulse propagating across southern Canada within a larger ridging regime is forecast to bring a weak attendant surface cold front through the region late Sunday into early Monday morning. This will bring increased cloud cover and cooler, more seasonal temperatures for Monday and Tuesday with highs in the upper 20s and possibly low 30s. There are some indications in recent guidance that boundary layer saturation may be sufficiently deep enough to promote patchy freezing drizzle at times during the Monday night/Tuesday morning time frame, but high variability between recent model runs yields low confidence in this occuring. While this appears to be a reasonable worst-case scenario for now, any freezing drizzle may cause local travel impacts. The most likely scenario is for cool and cloudy conditions to prevail. Christmas Day through Thursday... The first half of Christmas Day is expected to be dry and seasonable for the region with afternoon temperatures in the 20s. Snow chances will increase for the evening/overnight hours and into Thursday. As upper level ridging shifts eastward through mid week, a southwest flow regime is expected to be in place over the region by late Wednesday. A shortwave trough with an attendant surface low propagating into the central Plains are expected to deepen as they move northeastward towards the upper Mississippi valley region on Thursday. Widespread light snowfall is likely to begin Christmas night as broad-scale ascent associated with the approach of the upper level wave moves into the region. Stronger ascent due to mid level warm advection, and possibly areas of frontogenetical banding, will slowly move into the region through Thursday and may bring areas of higher snowfall amounts. Confidence in snowfall occurring is fairly high as most GEFS members show at least light snowfall during the Wednesday night/Thursday time period. However, confidence in amounts is generally low due to high ensemble spread and low confidence on the strength and placement of stronger ascent associated with warm air advection and possible frontogenetical banding. Looking through a historical lens, current guidance suggests that this storm will not be unusually strong for this time of year and so is not likely to bring high-end impacts to the region. However, even light to moderate snowfall during the holiday travel period may cause some travel concerns. Those planning on traveling on or after Christmas day should continue to monitor the forecast for potential travel impacts. Friday through Saturday... Generally quiet and cool weather is expected following the Wed night/Thursday system as surface high pressure builds over the region. Temperatures will remain fairly seasonal with highs in the 20s. There are some indications in ensemble guidance that a second upper level shortwave moving through the mean southwesterly flow aloft could bring snow chances to the central US late Saturday and into Sunday. While this potential will be monitored, there is currently too much ensemble spread to say for certain whether the region will see any impacts. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 516 PM CST Sat Dec 21 2019 VFR ceilings prevail this evening for most sites. For GFK, look for a broken stratus deck and a slight chance of mist or freezing drizzle. Westerly winds are expected to continue outside of the Red River Valley, with southerly winds persisting into Sunday for the Valley locations of KGFK and KFAR. This will create a tendency for LLWS beginning during the mid-morning, then persisting through much of the day as winds aloft will remain out of the west. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...Lynch SHORT TERM...BP LONG TERM...AM AVIATION...Lynch
Area Forecast Discussion
National Weather Service Key West FL
1023 PM EST Sat Dec 21 2019 .DISCUSSION... The next 48 hours will need to be watched for a few different types of weather-related hazards. These include heavy rain, severe thunderstorms, and rising tides within Florida Bay. The weather will be generally windy or breezy, but no more so than recent days. What will be causing this? A multi-lobed non-tropical area of low pressure is in the process of developing in the Central Gulf over the warm 80+ degree waters of the Gulf Loop Current. A warm front extends east from this feature near or just north of the Keys, with a weakly to moderately unstable air mass along and south of the warm front. A strongly veered wind profile has been in place, with easterly winds at the surface and west-southwest mid-level flow. Convection has not been able to root well into the boundary layer this evening, but that should be less of an issue on Sunday as surface winds veer more southeasterly and blow more directly off the 81-degree Gulf Stream waters south of the Keys. Interestingly, a persistent convective cluster has been continually re-developing in place this evening between the Marquesas Keys and the Dry Tortugas, perhaps where lift along the front has been maximized. Radar indicates a large area of storm- total rainfall of 3-6 inches today from the Marquesas Keys westward. What`s concerning is to see a couple of more reliable mesoscale models such as the HRRR and the ARW slowly gyrating and morphing this glob of heavy rain eastward across the Lower Keys sometime on Sunday. On one hand, some convective cells will be slow to move, but the veered wind profile will favor training and re-generation of convective cells. By Sunday night, the experimental Caribbean HRRR shows much of the Keys getting 5+ inches of rain, and the ARW shows a more splotchy and variable 2-8 inches of rain, heaviest over the Lower Keys. This raises a concern for localized flooding, especially if this develops in the more urban environment of Key West. This could make a drive on the Overseas Highway a slow, sloggy affair with hydroplaning and reduced visibility. On Sunday PM, a cold front trailing from the deepening low over the northeast Gulf will reach our western waters and move eastward. It appears that a frontal wave will develop along the advancing front as it crosses the southeast Gulf and crosses South Florida toward the northwest Bahamas. This sharpening of the front as it reaches our area could also sharpen a line of thunderstorms as it progresses across the Keys on Sunday evening. The 3km NAM and shows potential for discrete cells in advance of the main line. Any discrete cells preceding the main line of thunderstorms will have a favorable unstable and sheared environment for organization and rotation. This poses the greatest threat for severe thunderstorms. SPC currently has the Keys in a Marginal Risk for severe thunderstorms on Sunday and Sunday night, and their outlook discussion leaves room for a targeted increase to Slight Risk. The main severe mode will be damaging wind gusts, but a tornado cannot be ruled out. Once the front sweeps through late Sunday night, rain chances will drop significantly, with a few weak showers following the front. The main threat following the front will be a rise in tide levels over Florida Bay due to west winds pushing water into the basin. This threat should peak around late Monday. Many harbors in the Keys are on west-facing shorelines, which is good for our normal easterly trade winds. So the west winds on Monday will bring choppy and rough conditions into those harbors. && .MARINE... The Florida Keys and surrounding coastal waters are currently wedged between a developing low center over the Central Gulf and strong high pressure over the U.S. Mid- Atlantic region. This pressure gradient will continue to support strong breezes overnight. Low pressure will deepen as it moves through the northeast Gulf tonight and Sunday morning. Strong, thundery squalls will be possible across the coastal waters Sunday and Sunday night. A trailing cold front will cross the coastal waters of the Florida Keys Monday morning. Breezes will diminish Tuesday night and Wednesday. && .AVIATION... Through 22/24Z, prevailing VFR conditions are expected at both EYW and MTH. For overnight and Sunday morning, occasional MVFR ceilings are possible as fast-moving light rain showers move within the vicinity of EYW and MTH. The chance for thunderstorms and IFR ceilings and visibilities gradually will increase Sunday and Sunday afternoon as a frontal system approaches from the Gulf of Mexico. The best chance for a sub-VFR episode will be from 22/18Z-22/24Z. Finally, southerly crosswinds will increase throughout the day. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...Small Craft Advisory for GMZ031>035-042>044-052>055-072>075. && $$ Public/Marine/Fire...Haner Aviation/Nowcasts....Kasper Data Collection......KBL Visit us on the web at Follow us on Facebook and Twitter at: