Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/17/20

Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
600 PM CST Sun Feb 16 2020 .AVIATION... For the 00Z TAFs, areas of fog and low clouds are forecast to develop once again across eastern and northeast parts of the OK and TX Panhandles late tonight into Monday morning, dissipating thereafter. At this time, the low clouds and fog are expected to remain just east of KGUY and well east of KDHT and KAMA. Trends will be monitored closely this evening. A brief period of LLWS is also foreseen at KAMA late tonight. Finally, a cold front will move across the TAF sites late tonight through mid morning Monday with north and eventually northeast winds in its wake. 02 && .PREV DISCUSSION... /Issued 206 PM CST Sun Feb 16 2020/ SHORT TERM...Tonight and Monday Low clouds and fog lifted by 17Z/18Z today but likely will return after 06Z Monday through 16Z Monday across much of the northeastern portions of the Panhandles. The NAM and HRRR are once again forecasting fog and low clouds advecting north and west across most of the eastern Oklahoma and also the northeastern and far eastern Texas Panhandles late tonight into Monday morning. Dry northwesterly upper flow across the Panhandles tonight will transition to zonal upper flow by 12Z to 18Z Monday. High level cloudiness will continue to track southeast across the forecast area tonight into Monday. A cold front front will push across the Panhandles late tonight through Monday morning shifting the winds to the north and northeast becoming breezy by early Monday afternoon. Highs on Monday will remain above normal but slightly cooler from Sunday`s high temps. No precipitation is expected through Monday. Schneider LONG TERM... Tuesday will start out fairly close to normal, with low temperatures in the lower 30s, but the highs won`t get much higher than the mid 40s. There remains a small chance for a few snowflakes to fly in the far northwest, mainly in the Oklahoma Panhandle. Have reduced our PoPs even more, as snow chances through the day on Tuesday will be decreasing. CLoud cover and north winds remain during the day on Wednesday, keeping temperatures well below seasonable normals. For the second straight day, high temperatures will struggle to break 40 degrees across much of the area. Thursday will be the coldest day of the week, with highs struggling to get above the freezing mark. At least the current trend of warming up over the weekend looks to remain intact, with temperatures rebounding into the 60s by Saturday and Sunday. Precipitation chances increase somewhat during the middle part of the week as well, with the best chances for snow begin on Thursday. By Tuesday, the medium range models are in decent agreement in developing a strong, but narrow band of mid level frontogenesis to our south, keeping precipitation chances mainly to our south until the next short wave trough moves through late Wednesday/early Thursday. By this time, chances for snow remain for much of the area, yet at the moment, we`re talking about a 1 in 3 chance of light snow. We will continue to refine the forecast through the week. While the prospects look pretty good for some sort of precipitation on Thursday, keeping the 1 in 3 potential for a variety of reasons. The first is the inherent lower confidence of a day 4 forecast and secondly because of the subtle, yet important differences in the guidance. GFS and ECMWF deterministic 12Z runs appear to be in close agreement with the large scale pattern by 00Z Friday (Thursday evening) with short wave ridging just to our west and troughing to the east. The GFS ensemble mean 500mb flow shows the ridging will be much farther to the west, as a result of about half of the GFS ensemble members showing a much slower solution. Depending on exactly what happens with the speed and strength of said system, this brings in uncertainty for day 4. The uncertainty is necessarily in the chances for snow, but the timing of the snow. Fox && .AMA Watches/Warnings/Advisories... TX...None. OK...None. && $$
Area Forecast Discussion
National Weather Service Columbia SC
1034 PM EST Sun Feb 16 2020 .SYNOPSIS... Low pressure will lift northeastward and farther away from the forecast area tonight. Ridging will briefly dominate Monday. A slow moving frontal system will be in the region Tuesday through Wednesday. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Lingering light rain should end from west to east as low pressure shifts farther away from the area. High-level moisture will continue with stratus and fog through the night. Dense fog may occur but have held off issuing a dense fog advisory for now. The fog may be limited by cloudiness. The HRRR suggested the lowest visibilities mainly northwest of the forecast area closer to more shallow moisture and greater cooling. Cloudiness will limit net radiational cooling overnight. The guidance was close with lows ranging from the upper 30s north to mid 40s southeast Midlands and lower CSRA. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... A brief return to zonal flow Monday will cut off the deep moisture from the Gulf of Mexico. With weak high pressure ridging conditions remain mostly dry. High temperatures will be return to above normal with highs in the low/mid 60s. Clouds will be on the increase Monday night as high pressure retreats to the northeast and low-level flow becomes more southeast and southerly. This will keep low temperatures up into the upper 40s to lower 50s. With an increasing southerly flow ahead of an approaching cold front deeper moisture will return to the region by Tuesday. The cold front from this system will stretch into the southeastern US. Models have come into better agreement with moisture overspreading the area Tuesday/Tuesday night. Rainfall amounts look to range from one half inch up to one inch across the region through Tuesday night. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Rain is likely again Wednesday with moisture remaining plentiful and the front crossing the forecast area. Temperatures will be closer to normal in the northern Midlands to above average in areas that remain on the warm side of the front longer during the day Wednesday. Lingering moisture Thursday could lead to additional chances for showers. The frontal boundary will slow across the region as it becomes parallel to the mid/upper flow. Both the GFS and ECMWF show another wave moving along the boundary Thursday with low pressure developing along the Southeast Coast. The models however differ on how far southward the boundary will sink south/east. The GFS is more robust with the boundary remaining farther northward and higher pops across the region, the ECMWF is a bit farther south with most of the precipitation along the coast. The GFS has been more consistent from run to run with the system Thursday. Will lean toward higher pops for the period. With the boundary to our south and high pressure building in from the north, expect temperatures to average below normal Thursday through Saturday. Once again, over the next 5 days, some areas of the Carolinas into Georgia will see rainfall totals ranging from 1 to 2 inches. This will affect the area rivers, which remain higher than normal. Expect additional river flooding or current river flooding persisting. Strong high pressure will begin to ridge into the area behind this front ushering in a dry and colder air mass for Friday through the weekend. Gusty winds from the north contribute to cold air advection Thursday keeping highs below average across the forecast area. This high pressure will hang on through the end of the week promoting clear skies and below average temperatures. && .AVIATION /04Z MONDAY THROUGH FRIDAY/... IFR restrictions in stratus and fog overnight and into early Monday. Some improvement expected on Monday. Regional radar still showing a few light rain showers across the area. Trends indicate some weakening, so not confident that any showers will reach the terminals. Shower activity will continue to diminish and move out of the area by 06Z as low pressure along the coast lifts northeastward. Ceilings have generally dropped to IFR levels and should remain IFR/LIFR through the overnight period and into Monday morning. Visibilities are a little less certain, but generally expect MVFR visibilities in fog overnight with potential to drop to IFR. Ceilings and visibilities should improve some with heating and mixing by late morning, but still expect MVFR ceilings to hang around for much of the day. Winds will be light through the period. EXTENDED AVIATION OUTLOOK...Showers and associated restrictions Tuesday and Wednesday. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$
Area Forecast Discussion
National Weather Service Cheyenne WY
421 PM MST Sun Feb 16 2020 .SHORT TERM...(This evening through Monday) Issued at 200 PM MST Sun Feb 16 2020 Lots going on weather wise across southeast Wyoming. Forecast challenges range from strong winds to headline level snow in the short term. Water vapor imagery showing a shortwave tracking into our western counties this afternoon on the nose of a 115kt jet max over southwestern Wyoming into northwestern Colorado. Has been snowing very heavily over the Snowy and Sierra Madre Ranges with well over a foot of snow widespread. SNOTELS at Blackhall Mountain...and Little Snake River in the Sierra Madre Ranges are reporting Snow Water Equivalent well over an inch as of noon. Snowy Range SNOTEL at Medicine Bow closing in on 1.5 inches of SWE. WYDOT webcams out near Arlington this afternoon showing quite a bit of snow has fallen with I-80 snow covered. With that area in the upward lift of the strong jet...winds have come down...with gusts in the low 40 mph range at County Road 402 and Halleck Ridge. Needless to say...WYDOT has I-80 closed at this time and would not expect it to open any time soon. Good agreement in short term models bringing the upper shortwave into east central Wyoming this evening. HRRR and Hires mesoscale guidance showing precip blossoming across Converse and Niobrara Counties after 00Z as the shortwave lift moves over the area. At the same time...snow out west begins to decrease quite a bit. Only change with the afternoon package was to add central Laramie County to the High Wind Warning. GFS 750 and 800mb winds over Cheyenne this evening pick up to 50-55kts as winds shift northwest behind the surface trough. Expecting enough subsidence behind the shortwave to mix some of these winds down to the surface. Some concern for the Arlington area tonight for possible blizzard conditions with increasing winds. But given the decrease in snow seen on mesoscale models for this evening...decided to stick with the Winter Weather Advisory and High Wind Warning. Evening shift will need to monitor closely. WOuld also advise to watch Converse and Niobrara Counties as we are getting quite an increase in snow totals up there for tonight. Precip and winds begin to decrease Monday as shortwave exits east. Snow ends from west to east through the afternoon Monday. .LONG TERM...(Monday night through Sunday) Issued at 200 PM MST Sun Feb 16 2020 Still looking at better conditions after Monday with lighter winds and drier weather. Do have a dry shortwave that moves through the area Wednesday that will likely bring us another shot of cold air. Those trying to make plans late in February...we are starting to see the GFS and ECMWF coming together on a potential winter storm around the 24th of February. GFS further south...thus less snow while the latest ECMWF hitting us with a classic Colorado low with over 1 inch liquid equivalent. Stay tuned as the event draws closer as this could be our next significant winter storm. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 421 PM MST Sun Feb 16 2020 IFR conditions expected at KRWL for low cigs and snow into Monday morning before improving during the day. VFR elsewhere this evening then some mainly MVFR cigs should develop over KCDR and KAIA after 06Z with snow showers around. Otherwise some gusty winds through the period especially over the se Wy terminals. && .FIRE WEATHER... Issued at 200 PM MST Sun Feb 16 2020 Minimal fire weather concerns as heavy mountain snow expected through Monday afternoon. Even lower areas expected to pick up accumulating snow...especially along and west of the Laramie Range. A drier less windy pattern sets up after Monday for southeast WYoming and Nebraska Panhandle...but colder temperatures and favorable less wind should keep us from seeing critical fire weather issues through the upcoming week. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Winter Weather Advisory until 8 PM MST Monday for WYZ101>105-109- 113-116. High Wind Warning until 8 PM MST Monday for WYZ106-110-116-117. High Wind Warning from 6 PM this evening to 8 AM MST Monday for WYZ118. Winter Storm Warning until 5 PM MST Monday for WYZ112-114. Winter Weather Advisory until 7 PM MST Monday for WYZ110. NE...Winter Weather Advisory until 8 PM MST Monday for NEZ002-003-095. && $$ SHORT TERM...GCC LONG TERM...GCC AVIATION...RE FIRE WEATHER...GCC
National Weather Service Sioux Falls SD
828 PM CST Sun Feb 16 2020 .UPDATE... Issued at 815 PM CST Sun Feb 16 2020 A few modifications made to the ongoing forecast overnight and into Monday. First of all, easterly flow over the lingering snowpack has allowed stratus to thicken and lower tonight. In some areas along the edge of the cloud layer, fog has increased and visibilities may drop below 1 mile at times. Latest RAP CPD plots suggest that winds within the high RH layer will begin to turn more southerly after midnight, which may allow this moisture to advect northward slightly. Other concern is a shift towards more liquid precipitation into Monday morning away from snow. High-resolution model data through the afternoon and early evening continue to emphasis stronger warm advection in the 900 mb layer overnight, pushing temperatures aloft between +2 to +3 along and south of interstate 90. We`re still expecting light precipitation to develop over northern Nebraska late this evening and move eastward into western Iowa after midnight. Models show increasing frontogenesis within the 700:750 mb layer pivoting back northward after daybreak as the subtle shortwave arrives. This should assist in developing a narrow corridor of light precipitation along and either side of the Interstate 90 corridor through mid-morning. Boundary layer temperatures will hold near to slightly below freezing, but may attempt to rise in areas along and just north of Highway 20 through morning. Thermal profiles indicate that there will remain a stout melting layer AOA 900 mb, which should should promote a mixture of sleet and freezing rain. This idea has been supported by simulated p-type data from HRRR/RAP along with the latest 00Z runs of the ARW/NMM. The 00Z NAM remains an outlier solution, this evening, with it`s QPF likely overly influenced by the presence of minor convective elements. All that said, modified forecast suggested the need for a winter weather advisory for portions of southern Minnesota and northern Iowa into mid-day Monday for up to a half inch of snow, potential for a tenth of an inch of ice, and sleet. && .SHORT TERM...(This Evening through Monday) Issued at 344 PM CST Sun Feb 16 2020 Complex, low confidence forecast in the near term with many variables still in play. Models are offering a variety of solutions, but have sided with a GFS/HRRR/RAP blend. Trough of low pressure is expected to work out of the intermountain west this evening and work into the plains overnight. Low level warm air advection leads to weak isentropic lift on the 290K surface after 06Z along the South Dakota/ Nebraska extending into northwest Iowa, however, models are disagreeing on amount of low level saturation. If ample low level saturation develops, then could see drizzle or light precipitation develop, but CAMs are suggesting low level saturation would be a struggle. Therefore, may have to wait till upper wave approaches from the west towards 12Z. At that point, upper jet streak noses into southern Iowa. Forecast soundings are suggesting a dry wedge from just above the surface through 700 mb, with the warm nose well above freezing. Models suggest band of 700mb frontogenetic forcing across northwest Iowa, but with upper level div Q focused further south, may trigger closer to the 800-850 mb front which is just south of the forecast area. If that occurs (as the CAMs suggest), there is a question as to how much precipitation will fall in the forecast area. Have therefore trended down in precipitation amounts. Surface temperatures at the time appear to be in the low to mid 30s, favoring either rain or snow. Could be an area where conditions set up just right for a brief period of freezing drizzle, but precise location is a bit uncertain. As cooler air collapses southward tomorrow afternoon, mid levels of the atmosphere dry out fairly quickly. Therefore, there is a fairly confined window of precipitation from approximately 09-19Z Monday, but precipitation type is really uncertain. Best chance for precipitation looks to be mainly across northwest Iowa, where up to a 0.10" of an inch of precipitation will result in a light mixture of rain/snow. Snow amounts are expected to be fairly light totaling around an inch or less. With minor amounts of precipitation, will not issue any headlines at this time, but will need to keep a close eye on model trends in case icing potential increases. .LONG TERM...(Monday Night through Sunday) Issued at 344 PM CST Sun Feb 16 2020 Low level temperatures continue to fall into Tuesday morning behind the departing wave. Colder air surging south Tuesday evening may produce additional light snow. With a deep dendritic layer near the surface across eastern South Dakota, have raised pops with surrounding neighbors. Amounts look to be light, but snow ratios will be near 20:1. Extended forecast looks to be mainly dry. Have not made any changes beyond Tuesday night with challenging forecast in the near term. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 519 PM CST Sun Feb 16 2020 Bit of a tricky aviation forecast this evening. IFR ceilings over the snowcover areas will continue into the evening and early overnight hours as easterly winds remain. However, precipitation does begin to increase across Nebraska and slides east towards Sioux City after midnight. This will likely fall in liquid form with a cold rain expected. Further north, as ceilings improve slightly (still IFR along the Buffalo Ridge), mid- lvl frontal forcing begins to develop after 3am and could yield a mixture of snow/sleet/freezing rain along the I-90 corridor and into portions of northern Iowa. Confidence too low to indicate in current TAF, but may amend this evening if guidance continues to hint at this development. Anticipating some improvement in ceilings by mid- morning but still anticipating MVFR to high IFR ceilings through the day. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...Winter Weather Advisory from 3 AM to noon CST Monday for MNZ080- 081-089-090-098. IA...Winter Weather Advisory from 3 AM to noon CST Monday for IAZ001>003-013-014. NE...NONE. && $$ UPDATE...Dux SHORT TERM...BT LONG TERM...BT AVIATION...Dux
Area Forecast Discussion
National Weather Service Key West FL
1013 PM EST Sun Feb 16 2020 .DISCUSSION... A mild and dry evening is underway across the Florida Keys. Radar detects just a few showers well west and southwest of the Dry Tortugas, while satellite imagery shows only thin cirrus passing overhead. Very light winds of 5 mph or less to calm have allowed temperatures to drop down to around 70 degrees at some sheltered interior locations, and even down to 67 degrees as of 9 PM at the usual cool spot on North Big Pine. Temps are holding in the mid 70s at more exposed and waterside locations. Surface analysis depicts a weak high pressure ridge extending from the western Atlantic across the Florida peninsula and into the central Gulf of Mexico, while a stalled frontal boundary lies to the north of this ridge axis. The 00Z Key West sounding measured only a slight reduction of PW to 1.50 inches, but did show a weak inversion developing near 2500 feet. Recent MIMIC-TPW imagery shows a drier airmass, with estimated PW values around 1.2 inches, spreading NW from the Florida Straits across the Keys. This drier airmass, along with the very weak low level flow, is likely responsible for the lack of shower activity across our area this evening. Overnight, the pocket of dry air currently moving through the area should prevent any shower activity along the Keys. Although some of the CAM guidance including the HRRR does depict scattered showers developing near the Keys after midnight, it seems more likely that any such activity would remain over the Straits and south of the island chain. The lack of any shower activity or even clouds over the Straits at present also brings into question the accuracy of the CAM guidance forecast. Otherwise, expect clear to partly cloudy skies due to the passing high clouds, with light winds allowing temps to drop into the lower 70s for most areas. Some sheltered interior locations, mainly in the Lower Keys, will cool off a bit more into the upper 60s to near 70 by morning, as has already occurred at North Big Pine. Have made minor adjustments to the gridded forecasts, but no updates are planned for the zone forecast this evening. && .MARINE... Evening observations show benign conditions across the Keys waters, with NE to SE winds of 10 kt or less prevailing. Similar conditions are expected to continue through the rest of the night. No significant changes are planned for the late evening forecast issuance. && .AVIATION... VFR conditions will prevail overnight and Monday at the EYW and MTH terminals. A brief episode of MVFR ceilings cannot be totally ruled out during the late night and early morning hours, but the probability is much too low to mention in the terminal forecasts. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...Jacobson Aviation/Nowcasts....Jacobson Data Collection......DR Visit us on the web at Follow us on Facebook and Twitter at:
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
719 PM EST Sun Feb 16 2020 .UPDATE... Latest RAP model has a subtle short wave trough...with a weak surface reflection...tracking across across the northern part of the state tonight then exiting to the Atlantic Mon morning. During Mon zonal aloft begin to return to the region while Atlantic high pressure ridges westward...through FL to the Gulf of Mexico. A swath of deep moisture...model PWAT values up to up 1.8 inches... with the short wave trough/surface reflection sweeps across the area over night with considerable cloudiness and patchy fog. This system will support slight chance to likely showers but mainly north of the I-4 corridor. These showers exit to the east early in the day. The clouds and fog begin to lift and clear by mid-morning although some cloudiness will linger. && .AVIATION... 17/00Z TAFs. Anticipate VFR clouds giving way to prevailing MVFR VSBY and CIGS AFT 06-08Z and lifting/clearing by 15-17Z. LCL IFR VSBY and CIGS PSBL 09-13Z mainly at inland and southern terminals where winds are expected to become calm. Otherwise light and VRBL winds become SE in the morning and SW for the afternoon. Afternoon SHRA which hit some of the airports have exited to the east. Associated SHRA with system moving by to the north overnight is expected to stay north of terminals. && .MARINE... High pressure building across the waters will result in east and southeast winds...but with an onshore shift near the coast in the afternoons...through midweek. A front moves through the eastern Gulf toward the end of the week with high pressure behind it...increasing winds to 15 to 20 knots. && .Preliminary Point Temps/PoPs... TPA 65 79 67 82 / 20 10 0 0 FMY 66 84 67 85 / 20 10 0 0 GIF 64 83 65 86 / 40 20 0 10 SRQ 65 81 66 82 / 20 10 0 0 BKV 61 82 63 84 / 40 10 0 0 SPG 66 80 67 79 / 20 10 0 0 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...None. Gulf waters...None. && $$ UPDATE/AVIATION/MARINE...09/Rude UPPER AIR...04/Sobien DECISION SUPPORT...69/Close
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
856 PM MST Sun Feb 16 2020 .UPDATE... Issued at 847 PM MST Sun Feb 16 2020 03z surface analysis had broad low across east central WY into south central SD with weak cold front behind it into western WY. Water vapour showed well-defined shortwave zipping through eastern ID/southwest MT. Activity looks bumpy on satellite with KRIW/KTFX soundings showing steep lapse rates from 800-500mb. Lightning strike detected over eastern ID a bit ago. 00z KUNR sounding showed a lot of dry air, which will impede initial lift ahead of shortwave. Late afternoon RAP was a bit concerning with a further north depiction of accumulating snowfall, but after ingesting 00z sounding data, latest runs keep pushing main snowfall southwest, inline with current forecast across northeast WY into southwest SD where best synoptic lift combines with 850-700mb frontogenesis. Wild card for tomorrow afternoon will be combination of steep lapse rates and downstream convergent flow over far southwest SD. Might be a band of several inches of snow, but temperatures in the 30s may keep impacts low. Current forecast updated a couple of times to reflect latest trends and current thinking. && .DISCUSSION...(This Evening Through Sunday) Issued at 149 PM MST Sun Feb 16 2020 General WNW flow will persist through the week. Shortwave traversing the northern Rockies will advect ESE tonight into Monday and support light snow over the SW third. Best overlap of forcing and FGEN will occur over far SW Campbell county and south with 2-3 inches possible there, and lesser amounts of an inch or 2 expected mainly from the Black Hills and SW through Monday morning. Precip will then become more convective in the afternoon as FGEN wanes and diurnal heating interacts with a weak cold pool aloft. This will support snow shower activity over NE WY and the Black Hills, with more persistent snow expected over the southern Black Hills and SE onto the plains where NW flow will support eddy convergence. An inch or 2 of snow will be possible if and where this band develops. However, with highs expected in the 30s, accums will be limited mainly to grassy sfcs, with limited road impacts, esp on the plains. Arctic front will begin to settle into the region Tues morning, with temps likely falling over northern areas through the day. The speed of the front will dictate how high temps rise in the southern half, with cooler highs certainly possible. Expected FGEN band along the arctic front may result in a high qpf low pop event with an inch or 2 of snow possible along and just behind the front. This is esp the case in the Black Hills (esp along the eastern slopes) where ENE flow will enhance snow production in the afternoon and evening. Have increased pops/qpf there for this. Arctic high will settle south with cold temps expected Wed morning. Arctic airmass will be short lived as dry conds with a warming trend can be expected the remainder of the week, with much warmer conds expected by next weekend as shortwave ridging occurs ahead of a digging eastern Pac trough. && .AVIATION...(For the 00Z TAFS Through 00Z Monday Evening) Issued At 417 PM MST Sun Feb 16 2020 Light snow will develop across northeast WY this evening and spread into southwest SD overnight persisting Monday, although the snow will become more showery in the afternoon. Expect MVFR/IFR conditions with the snow. The SD plains north/east of the Black Hills will see snow, but MVFR/IFR stratus/fog will develop overnight into Monday. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ Update...Helgeson DISCUSSION...JC AVIATION...Helgeson