Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/18/20

National Weather Service Wakefield VA
827 PM EDT Sat Oct 17 2020 .SYNOPSIS... Cool and dry conditions will prevail through tonight as high pressure builds in from the west and settles across the area. The high becomes centered from Atlantic Canada to the local area from Sunday through Tuesday, bringing dry weather with gradually warming temperatures to the local area. && .NEAR TERM /THROUGH SUNDAY/... As of 815 PM EDT Saturday... Latest RAP analysis shows surface high pressure over the MD lower eastern shore early this evening. Overnight that surface high will shift up to New England, while another surface high from the west settles over the area. Skies are mainly clear this evening, with calm winds over the interior and 5-10 mph near the coast. Ideal radiational cooling conditions tonight over inland portions of the area will allow temps to fall steadily. Will continue to go lower than guidance for low temps, with mid to upper 30s inland, and lower 40s to low 50s closer to the coast where the light onshore wind will keep temps up a bit. Frost Advisory continues for the far W/NW sections of the CWA where confidence is highest for overnight lows into the mid 30s (with a few of the coldest spots potentially near freezing). Patchy frost is also expected in far western and northern Richmond suburbs, along with the Salisbury to Dorchester areas, although coverage is not expected to be widespread enough to warrant headlines. On Sunday, a weak sfc trough moves into ern NC and SE VA and will increase clouds such that skies avg out partly sunny (and possibly mostly cloudy for a few hrs). Not enough deep moisture to include any PoPs. Highs will be a little warmer, mainly from around 70F SE to the mid 60s NW. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... As of 345 PM EDT Saturday... The center of the high will be well to our NE by Sun night. With weak return flow, lows won`t be quite as cold with mid 40s inland and 50s near the immediate coast. The latest 12z/17 model guidance continues to show a cold front approaching the eastern states from the west on Monday but parent low pressure becomes increasingly removed from the boundary well to the north into Canada. As such, the boundary is forecast to assume an east-west orientation across the Ohio Valley with little to nothing to push the boundary toward our area. Upper ridging builds toward the region from the SW Atlantic on Monday resulting in continued dry weather and afternoon highs in the low-mid 70s. Similar conditions for Tue, with highs trending up another degree or two with some upper 70s possible under partly/mostly sunny skies. Given the gradual increase in low level moisture, some patchy fog/low clouds will be possible early Tue AM. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 345 PM EDT Saturday... Latest models remain in decent agreement that a fairly strong upper level ridge will remain anchored along the SE US coast through the mid to late week timeframe, with sfc high pressure over the local area and all systems staying off to our NW (with a potential tropical system also staying well offshore to our E). Temperatures will be above normal with highs mainly from 75 to 80F Wed-Fri with lows in the 50s to lower 60s. The ridge gradually breaks down late Fri into next weekend, with the typical differences in the models by that point. For now, will have the forecast partly to mostly sunny/dry through Fri, with more clouds and a low chance for showers by Fri night/Sat. Cooler Sat with highs in the mid 60s to mid 70s. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... As of 700 PM EDT Saturday... VFR conditions to start the 00Z TAF period. Mostly clear skies overnight. A light onshore flow at ORF/ECG around 5 kts, with calm winds at RIC/SBY/PHF. Low level moisture increases Sunday morning. This will result in clouds developing first over the SE and then spreading N/NW throughout the morning. MVFR ceilings are possibly by Sunday afternoon at ORF/ECG, while remaining terminals are more likely to remain VFR. Winds after 15Z Sunday will be E/SE 5-10 kts. OUTLOOK...Mainly VFR conditions with little to no chance for rain Sun night through Thu. With the onshore flow, some flight restrictions will be possible in low clouds/patchy fog early each morning from Mon-Thu however. && .MARINE... As of 305 PM EDT Saturday... Afternoon surface analysis shows 1028mb high pressure centered over north-central VA with north and NNE winds continuing across the waters. Waves are 2-3 ft in the bay with seas generally 4-6 ft offshore. Despite a weakening pressure gradient as high pressure nears the region, winds over the waters have been quite stubborn to subside across the Ches bay this afternoon. Dry and cool air contacting the still relatively warm bay/ocean waters has led to efficient mixing of higher momentum winds aloft. Winds will slowly subside from west to east through the remainder of the afternoon so have allowed most bay headlines to expire on schedule but have extended SCA flags for the mouth of the bay and the Currituck Sound until 7pm. Buoy 44009 off Ocean City continues show seas 5-6 ft so will extend this area a few more hours as well. Seas will be slowest to subside across the southern coastal waters south of the VA/NC border where SCA headlines remain in effect through 4am. High pressure moves away to the NE on Sunday but an elongated ridge remains across the area with onshore winds 10-15 knots expected to continue into the late afternoon before falling to 5-10 knots. Much of the same is expected for the mid-week period with sub-sca onshore flow and seas 3-4 ft. && .TIDES/COASTAL FLOODING... As of 305 PM Saturday... Large amplitude astronomical tides will continue this weekend into early next week along with light to moderate onshore winds. This combination will result in periods of mostly nuisance to minor tidal flooding. Tonight`s high tide is lower than the one earlier today so not expecting many coastal flood issues other than some potentially low-end nuisance flooding. The next high tide cycle on Sunday could be more problematic with minor and potentially moderate tidal flooding in a few spots. && .EQUIPMENT... As of 115 AM EDT Saturday... KDOX radar will be down until 10/21 for a scheduled generator replacement. See FTMDOX for details. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...Frost Advisory from 2 AM to 9 AM EDT Sunday for VAZ048-060>062- 069-509-510. MARINE...Small Craft Advisory until 10 PM EDT this evening for ANZ656. Small Craft Advisory until 4 AM EDT Sunday for ANZ658. && $$ SYNOPSIS...LKB NEAR TERM...CMF/LKB SHORT TERM...ERI/LKB LONG TERM...LKB/RHR AVIATION...CMF/LKB MARINE...RHR TIDES/COASTAL FLOODING... EQUIPMENT...
Area Forecast Discussion
National Weather Service La Crosse WI
1042 PM CDT Sat Oct 17 2020 .SHORT TERM...(Tonight through Monday) Issued at 200 PM CDT Sat Oct 17 2020 Cold front sweeping in from the northwest this afternoon with RAP pointing to fairly decent frontogenetic forcing along it. The bulk of the associated saturation is mostly in the mid/upper levels, but ample to support shower production. Rather dry sub cloud layer but warmer wet bulb temps per bufkit soundings would suggest rain will be the the pcpn type at the outset. Can`t rule out a brief swing to more of a wintry mix (or just snow) later into the night...although sfc temps and soundings suggest is a small chance at this time. Meanwhile, that dry layer will enhance already gusty winds around any shower. Speaking of those winds, pressure gradient gets a little baggy as the cold front moves in, but tightens later in the evening as the front exits east. Will continue Wind Adv for small portion of south west Wisconsin into the evening, but anticipation is that the rest of the local area (while blustery) will stay below criteria. A blast of cold air follows in the wake of the front and Sunday and Monday are looking rather chilly as a result. 850 mb temps as cool as -7 C while NAEFS 850 mb temp anomalies near -2. Highs in the 40s will be the result while some locations in the north could struggle to even reach that. Weak high pressure builds in Monday, but models also point to a ripple in the upper level flow sliding west-east across the region. Some frontogenetic forcing with the shortwave, with models generally favoring along/south of I-90 for the better lift. Time/height x-sections point to enough saturation to fuel some pcpn chances. Mostly just rain, light with minor accumulations (where it falls). Some snow potential early and/or late...depending on how the timing of the shortwave shakes out. .LONG TERM...(Tuesday through Saturday) Issued at 205 PM CDT Sat Oct 17 2020 Swift northwest to zonal flow a loft will slide various shortwave troughs across the region, resulting in periodic precipitation chances. Some differences between the GFS and EC on placement and timing, especially in the smaller scale features, but latest runs do agree on a couple periods: Tue and Thu. Temperatures look to be cold enough that snow will be possible, moreso north of I-90...and dependent on timing of the systems. Way too early to sketch out possible/if any accumulations...but both models suggest minor snow accums (mainly cold, grassy surfaces) are in play for the local area north of I-94 later in the day Tue. Tis the season... As for temperatures, after the cold Sun/Mon the flex in the upper level flow will promote a bump up in temps, although still likely 5 to 10 degrees below the mid October normals. No significant warmup in sight. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1040 PM CDT Sat Oct 17 2020 The band of showers has diminished quite a bit, and dry conditions are expected through this period. MVFR ceilings will linger for awhile early this morning with the low clouds expected to erode before daybreak. Lingering mid clouds through the morning give way to nearly SKC in the afternoon, followed by increasing high clouds in the evening. Northwest winds will lighten a bit late tonight before turning breezy again in the afternoon. Winds then become light and westerly in the evening. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Rieck LONG TERM....Rieck AVIATION...Kurz
National Weather Service Hastings NE
954 PM CDT Sat Oct 17 2020 ...Short Term Update... .UPDATE... Issued at 953 PM CDT Sat Oct 17 2020 After "playing around" with various short term model data sets (including latest HRRR/RAP/NAM), ended up making fairly minimal change to the inherited forecast for overnight. If nothing else, am feeling a bit more confident that any narrow frontogenetic snow band that could potentially "zing" us with perhaps greater-than- expected snow amounts in the 1-2" range would focus pretty solidly north of the I-80 corridor, and would be most favored within our far northern few counties (Valley/Greeley/Nance). South of there, odds are that most places between Highway 92 and I-80 will see little to no snow (mainly just a dusting), while areas south of I-80 and especially down into KS stand almost ZERO chance of accumulating snow overnight. Have updated our Hazardous Weather Outlook (HWOGID) to tweak this latest thinking a bit, but again, the overall message from the earlier day shift forecast package remains largely unchanged. This is not a major snow event by any means, but especially our far north could easily see its first accumulation of the season by sunrise. && .DISCUSSION...(This evening through Saturday) Issued at 344 PM CDT Sat Oct 17 2020 The primary forecast concerns centered around the chance for accumulating snow tonight, and then another chance for light snow tomorrow tonight along with possible subfreezing temperatures for areas that have yet to have a freeze. Tonight...We will see strong cold air advection tonight along with a decent frontogenetic precipitation band. Forecast models are pretty consistent in showing banded precipitation stretching from west to east across Nebraska tonight. However, there are subtle model differences regarding the exact location of this narrow precipitation band as well as differences in how quickly the rain will change over to snow. Our higher resolution models such as the HRRR and RAP tend to be the furthest south with this precipitation band, with recent 18Z runs placing some of the heaviest rain and snow centered over the Grand Island area. We`ll see if that pans out or if it moves a bit one way or the other. The overall 00Z and 12Z model consensus is for the heavier rain/snow band to be just north of the Grand Island area. My feeling is that this may end up trending just a bit further south and I`m leaning towards the more southern solution with the heavier snow running from northern Dawson County to around Grand Island to York County. This is the kind of set up where the snow band could be very narrow, only 25 to 50 miles in width. We are officially calling for around one inch or less within this snow band due to marginal temperatures right around or just above freezing. Most of any snow accumulation will be on grassy surfaces. However, given the nature of this band, and favorable diurnally cool time of the morning, can not rule out a 10 to 20 mile wide 1-3 inches of snow on grassy surfaces in a few spots. I could see this snow band shifting one way or the other by perhaps up to 25 miles. Temperatures tonight should only bottom out right around freezing in areas that see the change over to snow, while areas along and south of the Neb/Kansas border should remain just a bit above freezing. Sunday... It will be a raw/cold day with breezy north winds and highs only in the 40s. Any snow should end by around mid morning. Sunday night... There is some uncertainty here, but we could see another round of light rain/snow across southern Nebraska, although it would likely be lighter than tonight. There will be a good deal of clouds, but temperatures do not have to fall off much for some folks to catch their first freeze. We are currently forecasting lows to be right around freezing, but clouds could play into which side of freezing we end up on. With the forecast uncertainty Sunday night and the snow to worry about tonight, decided to hold off on any Sunday night frost/freeze headlines for now. Monday through Saturday... Did not make many changes from the overall forecast blend of models during this outer forecast period, which continues to indicate cool and mainly dry conditions. The big story will be the below normal temperatures with highs in the 50s to lower 60s and lows a few degrees either side of the freezing mark most every night. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday) Issued at 721 PM CDT Sat Oct 17 2020 General overview: High confidence in VFR ceiling/visibility both right away this evening and then through much of the latter half of the period Sunday daytime. That leaves the late-evening through early-AM hours (particularly 06-11Z) as the main time frame of concern, as much of this time is expected to feature MVFR ceiling and at least an off-and-on rain possibly transitioning to outright-snow for a time. Wind-wise, the overall-strongest winds of the period are right away this evening (sustained northerly 15-20KT/gusts to around 25KT), with a gradual decrease in speeds then occurring late tonight into the daytime Sunday as direction gradually starts turning more easterly especially late Sunday afternoon. Read on for more details regarding ceiling/visibility and precipitation potential. Ceiling/visibility and precipitation details: Confidence is medium-high that much of especially the 06-11Z time frame will feature quite a bit of MVFR ceiling, but the "exact details" are still a bit murky, as probably cannot rule out a brief period of IFR at some point, and at least high-end MVFR could move in slightly before 06Z and perhaps linger until around 14Z. As for precipitation/visibility, confidence is fairly high that a period of light rain will affect both sites overnight, which could mix with some wet/slushy snow at some point. Have indicated -RASN as the main prevailing type overnight, as expect rain to be the predominant type overall. That being said, there is an outside chance that a light coating of slushy snow could materialize (slightly favoring KGRI versus KEAR). Once any light precipitation moves out Sunday morning expect a return to VFR especially beyond 14Z, although a considerable amount of mid-high cloud cover will likely persist through the day. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...Pfannkuch DISCUSSION...Wesely AVIATION...Pfannkuch
National Weather Service Jackson KY
1025 PM EDT Sat Oct 17 2020 .UPDATE... Issued at 1025 PM EDT SAT OCT 17 2020 The valleys continue to drop off quick this evening so have taken their lows and hourly T grids down into Sunday morning. Also beefed up the frost in the weather grids as a result. Finally, adjusted the near term T and Td grids per the latest obs and trends. These updates have been sent to the NDFD and web servers along with a forthcoming ZFP and SAF update. UPDATE Issued at 740 PM EDT SAT OCT 17 2020 23z sfc analysis shows high pressure off to the east of Kentucky and the light winds are starting to respond in its wake - swinging around to the southeast. Skies remain mostly clear and dewpoints are rather dry which should allow for another night of good radiational cooling and a moderate ridge to valley temperature split. This is already underway with the sheltered spots already in the mid 40s while low to mid 50s are noted on the hilltops. Dewpoints are generally in the low to upper 30s with most of the variance found in the valleys. We are looking at some of those valleys falling into the mid 30s by early morning with patchy frost a good possibility for those locations. This potential is featured in the grids, zones, and HWO. With this update have mainly fine tuned the sky cover, T, and Td grids per the latest obs and trends but also tweaked the fog potential. These updated grids have been sent to the NDFD and web servers. && .SHORT TERM...(This evening through Sunday night) Issued at 347 PM EDT SAT OCT 17 2020 The afternoon surface analysis reveals an area of surface high pressure is parked to our east along the Central Apps. The flow around the high is weak out of the south to southeast. The upper levels we are seeing zonal pattern as yesterdays shortwave is now in Maine. The zonal flow is bringing in a little smoke aloft from the western states this afternoon based on the satellite and HRRR smoke product. This is leading to a quiet forecast for tonight under mostly clear and calm conditions. Despite the return flow, a few of the cooler eastern valleys will see some patchy frost tonight and perhaps a few locations see some valley fog. The warming trend will continue Sunday, with partly sunny skies and return flow leading to highs in the mid to upper 60s. The NAM is depicting a decent low level jet kicks up in the afternoon and provides the shot for a few showers in the Lake Cumberland and perhaps the Bluegrass. However, most other guidance keeps it dry and hold any precipitation until Sunday night. Did keep some slight PoPs to account for this, but then all attention will be on the baroclinic zone to the north. At the surface, we see a weak boundary from a front that is disconnected from the parent low across Canada. This will remain mostly to the northwest, as upper level ridging to the southeast keeps this system from making much headway east and southeast. This system will bring increasing clouds at a minimum, but some showers will be possible mainly in the Bluegrass regions nearer the I-64 corridor. This seems to align well with the GEFS and EPS chances of seeing measurable rainfall around that 24 hour period. .LONG TERM...(Monday through Saturday) Issued at 425 PM EDT SAT OCT 17 2020 Models are generally in better agreement today compared to yesterday, at least in respect to frontal feature timing/location and associated precip coverage and how it affects the state. That being said, it will be a fairly active period, with generally S to SW flow and temperatures moderating warmer. That part has remained certain. The precip and fronts will continue to be the varying factor. To start the period Monday morning, Kentucky will find itself on the SW flow side of a deep and large trough that will be encompassing much of the U.S. Meanwhile, a pretty stout frontal boundary will be progressing eastward, making its way across the Ohio Valley and infringing on the Ohio River at 12Z. At this point the front will stall, being partially slowed by a strong area of high pressure across the Mid and Southern Atlantic States, and as the surface low continues to become more occluded and wrapped up. The presence of this stationary boundary will keep pops centered along its axis, including increased pops across the northern portion of the CWA, generally north of the I-64 corridor. By Tuesday, the stalled front will begin to weaken and will eventually dissolved upon the progression of the next frontal boundary and upper level system. As the boundary fades, so too will the precip chances...with both the GFS and ECMWF dissipating throughout the afternoon. High pressure will then build in from the east for Tuesday evening and into the day Wednesday. Meanwhile, a surface low will develop and strengthen across the Central Plains by Tuesday evening, as a shortwave begins to develop within the axis of the trough. This low will continue to quickly project northeastward, with a frontal boundary extending SW from this. This will bring about another center of instability and precip, along with a developing line of precip along the frontal boundary. The ECMWF keeps this boundary and associated precip north of Kentucky through the day Wednesday and well into Thursday, lifting it back north as a warm front, while high pressure continues to strengthen and dominate much of the SE. The GFS on the other hand does bring precip associated with this front through the state briefly WEdnesday night, before it dissipates. Yet another, stronger system, and upper level shortwave, will develop late in the work week. This surface low will be located over the southern/central Plains Thursday afternoon. And will quickly follow the height falls NE, reaching the Upper Midwest by Thursday night, and SE Canada by Friday. Models come into much better agreement again for this system, as it drags a potent cold front eastward towards the MIssissippi and Ohio Valleys Thursday night and Friday. Both models have precip overspreading the state and into eastern Kentucky Friday afternoon and Friday night, continuing through the day Saturday as the front slows and gradually pushes eastward through the state. The deep SW flow in place ahead of this system could also be enough to muster up some instability, and soundings did show the potential of some thunder during this time. Will note that based on the GFS and ECMWF, pops should be fairly substantial. However, given that it is heading into Day 7, kept with the NBM, which seems quite a bit overdone with only slight and low end chance pops. Expect these to increase in the coming runs unless the pattern changes for some reason. As mentioned, the SW flow in place across the region through much of the period will keep a warmer airmass in place. Mondays highs will range from the low 60s in the north (where the rain will be focused) to the low 70s in the south. By Thursday and Friday, highs will be in the mid and upper 70s. Temps will then cool for Saturday as the front begins to move over, along with continued precip and clouds. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 800 PM EDT SAT OCT 17 2020 An area of high pressure to the east will provide VFR skies through the period, with perhaps a smattering of high clouds at times becoming more substantial late. There is the potential for some valley fog, but overall this should be of limited extent and will not affect the TAF sites. There could be some low level wind shear at the SME site, owing to a low level jet skirting the Lake Cumberland region later tonight. The surface winds will be at 5 to 10 kts or less through the period generally from the south. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...DJ LONG TERM...JMW AVIATION...DJ/GREIF
Area Forecast Discussion
National Weather Service North Platte NE
640 PM CDT Sat Oct 17 2020 .SHORT TERM...(This evening through Sunday night) Issued at 253 PM CDT Sat Oct 17 2020 A cold front is surging southward across western and north central Nebraska this afternoon. Downslope west to northwest winds will allowed temperatures to warm up just ahead of the front with lower 70s observed across southwest Nebraska. The front pushes south into KS and eastern CO this evening. There will be a period of north to northeast winds of 15-25 mph with gusts to near 30 mph for a couple of hours this evening after the frontal passage across southwest Nebraska. Mid-level FGEN begins to develop quickly around sunset in an west to east band across the area. Available moisture looks decent with mid-level Pacific moisture in place. PWATS in the NAM rise to around 0.65" prior to any precipitation development early this evening. This is above normal for the date in the 75th percentile range with normal values right near 1/2 inch. Short term models are not in good agreement on the placement of a concentrated band of precipitation. There continue to be hints of it, but overall confidence has decreased in the development of a narrow band of heavier precipitation. The HRRR hints that it could set up for a few hours after midnight just north of I-80. Meanwhile the NAM is up north near the SD border. Other solutions keep precipitation more scattered and no concentrated band. Due to all of this will not be increasing snow totals any. In fact with such model spread the totals have went down a little. The exception is across Sheridan County where 1-2 inches still seems likely. Timing would be from around 10p Saturday night to 10a Sunday morning. The system quickly moves east of the area Sunday afternoon with another quick moving system arriving Sunday night. A warm front will lift northward Sunday night, and as lift overspreads the area some light precipitation will again be possible. Again, lots of model spread with this too, and confidence is low on much snow accumulation. Right now looks to be less than 1/2 inch and primarily across eastern portions of north central Nebraska. .LONG TERM...(Monday through Saturday) Issued at 253 PM CDT Sat Oct 17 2020 A Hudson Bay low pattern develops next week. A series of weak shortwaves and cold front will cross the region. Little precipitation is currently expected with the passage of these fronts, but some very light precipitation could occur across portions of north central and north west Nebraska.. Highs next week generally look to average in the 50s to mid 60s...warmest southwest Nebraska. The pattern next week is the result of strong high pressure ridging across the eastern pacific and the upper low near Hudson Bay which carves out deep troughing across the eastern U.S. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 639 PM CDT Sat Oct 17 2020 Lowered ceilings will create MVFR conditions across western and north central Nebraska through the evening and into tomorrow morning. Snow showers will continue in northern Nebraska including KVTN through the early evening, then become sporadic through the rest of the night. Winds in northern Nebraska will be out of the north, shifting to the west by tomorrow afternoon. Snow is expected to impact KLBF later in the evening around midnight. Winds near KLBF will remain northerly into tomorrow afternoon, when they will begin to shift to the southeast. Gusty winds across the area will decrease during the early evening. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Taylor LONG TERM...Taylor AVIATION...Meltzer