Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/13/17

Area Forecast Discussion
National Weather Service Duluth MN
915 PM CST Tue Dec 12 2017 .UPDATE... Issued at 901 PM CST Tue Dec 12 2017 Latest water vapor imagery showed a strong shortwave diving southeast through southern Saskatchewan this evening. This feature is expected to move southeast through the Northern Plains toward the South Dakota/Minnesota/Iowa border region by 12Z Wednesday. A surface low was in southern Manitoba and will move into southeast Minnesota by 12Z Wednesday then continue southeast through the day. Light snow was falling from near Crane Lake southeast into northern Wisconsin. Another area of precipitation was over southern Manitoba/Saskatchewan/northwest North Dakota and was moving southeast. The latest NAM has a narrow ribbon of 0.20 to 0.35 inches of precipitation after 06Z from southern Cass County southeast through southern Sawyer Counties. However, several of the higher resolution models including the latest HRRR, NMM, ARW, and RAP all have this band either further south or lower amounts of precipitation. We did make some adjustments up to the depth of the saturation, temperatures aloft, and QPF. What this did was lower the icing a bit and increase snowfall some from Walker southeast through Hinckley and points south. We`ve tossed around the need for an advisory but decided not to issue there yet. We will continue to highlight in an SPS. Further north, the Winter Weather Advisory for the Arrowhead still looks on track. Lake enhancement will occur there and 3 to 6 inches looks likely, with some locally higher amounts in the higher terrain. The Twin Ports may get into some lake enhancement late tonight into Wednesday morning as winds veer to east then northeast as the low departs through the day. && .SHORT TERM...(This evening through Wednesday) Issued at 328 PM CST Tue Dec 12 2017 At 3 PM, light snow was falling across much of northeast Minnesota. Snowfall amounts up to this point have been light based on reports and a survey of web cams across the area. Much of the moisture at this point has gone into saturating the drier low levels of the atmosphere. Temperatures ranged from the single digits in the Minnesota Arrowhead to the teens elsewhere. The focus for tonight and Wednesday will be the evolution of the incoming clipper system. While the models are generally in decent agreement, there are some differences in synoptic and mesoscale handling of the system. The initial band of light snow will continue to move eastward across the region late this afternoon and evening, helping to saturate the low level environment. The question is with regard to where the main axis of precipitation will pivot across the region. The HRRR supports more of an opportunity for snow accumulation than the NAM for the Duluth/Superior area. Nearly all of the deterministic models support a solid advisory across the Minnesota Arrowhead, so we did issue an advisory for the entire Arrowhead starting at 9 pm tonight and ending at 4 pm Wednesday. Easterly winds will likely contribute to locally higher amounts, up to 6 inches in spots. Based on current thinking, we should see a widespread swath of 2 to 4 inch snow accumulation from north central Minnesota, near the International Border, down through the Twin Ports and into northern Wisconsin. The greatest amounts are expected further east. Duluth is still a bit of a tricky one, as some of the models only support about an inch of snow, while others would indicate the 2 to 4 inches. So we should fall somewhere in that range. Generally expecting a couple here. The least snow accumulation is expected in the Brainerd Lakes, although they are the ones that may see a bit more mixed precipitation, and possible freezing drizzle overnight and early Wednesday. Will issue an SPS for areas outside of the advisory, and would not be surprised to see some modifications to the current advisory for the overnight hours into Wednesday due to the possibility of mixed precipitation and some west to east convective banding. We may need to expand the advisory beyond it`s current area, but will start with the most likely scenario at this point. The precipitation focus will then shift southward on Wednesday, as the low slides southeast, and brings the main area of wrap around precipitation southward with it. .LONG TERM...(Wednesday night through Tuesday) Issued at 328 PM CST Tue Dec 12 2017 The persistent northwest flow of the past seven days will finally give way to a small pattern change late-week into the weekend leading to slightly warmer temperatures this weekend into early next week. A continued chance for snow showers most days through the long term period, with the best chance for accumulating snow Friday night into Saturday when around an inch or so is possible. Highs in the teens to 20s through the rest of the week and into the weekend, then warmer Monday with highs in the 30s across much of the Northland. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 543 PM CST Tue Dec 12 2017 Light snow was moving through central portions of the Northland toward the east. Low pressure will move from southwest Manitoba this evening toward southeast Minnesota by 12Z Wednesday, then continue to move away from the region on Wednesday. Warmer air will move into portions of the area this evening, especially the Walker, Brainerd Lakes, Aitkin, and Hinckley areas. Precipitation will redevelop tonight after the band of snow moves through and may be a wintry mix in southwest/southern areas including freezing drizzle. Steady snow is expected across the Arrowhead into Wednesday morning and an enhanced band of lake enhanced snow will be possible further south to the Twin Ports area and along the South Shore late tonight into Wednesday morning as low level winds back. Ceilings will lower tonight to low MVFR or IFR for most areas with some LIFR possible. As the low pulls away from the area Wednesday, the precipitation will end for most areas, except along the South Shore, and ceilings will gradually lift. && .PRELIMINARY POINT TEMPS/POPS... DLH 11 22 9 19 / 80 80 20 10 INL 12 20 5 15 / 80 70 10 20 BRD 19 27 13 22 / 40 30 10 10 HYR 11 21 10 20 / 70 80 40 20 ASX 8 22 13 20 / 80 90 70 30 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...Winter Weather Advisory until 4 PM CST Wednesday for MNZ012-020- 021. LS...None. && $$ UPDATE...Melde SHORT TERM...DAP LONG TERM...JJM AVIATION...Melde
Area Forecast Discussion
National Weather Service Wilmington OH
1004 PM EST Tue Dec 12 2017 .SYNOPSIS... High pressure will briefly build into the area tonight and early Wednesday. Later in the afternoon, low pressure will track southeast and into the Ohio Valley, crossing east through northern Ohio in the evening. A ridge of surface high pressure oriented west to east will bring dry weather for Thursday and Thursday night. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Lake effect snow band continues to weaken as the flow backs from Lake Michigan. This trend will continue and the snow should be over by 06Z. The lake effect clouds band will also see a dissipating trend through the night. Some mid clouds ahead of the next storm system will work into the region after midnight. Low temperatures will range from 15-20 degrees. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... A slight warmup is expected tomorrow as southerly winds will pick up and a warm front sets up north of the CWA. Warm is still a relative term, with upper 30s expected sw of metro Cincy and around 30 over and ne of metro Columbus. Low pressure will track into the area late in the day, and an upper level shortwave will be the kicker to provide enough lift ahead of the surface low to initiate snow showers, primarily for the northern half of the CWA. A secondary shortwave will follow the first in the evening, bringing another potential round of snow and then ending any snow threat as it exits the area. Highs may be warmer tomorrow in the southwest if the sun is more abundant. Regardless of the surface temperatures, the cold nature of the atmosphere above it will only permit snow to be the weather type of the day. Significant accumulations are not expected, though an inch or two will remain possible for the northern half of the CWA tomorrow afternoon and evening. While the snow potential remains higher over the next few days, snow totals in the forecast appear to be too high and could be realistically shaved by half. Adding up 2 and 3 tenths in several 6 hour blocks given the presence of snow was putting a higher total in place than what is actually expected. A more realistic expectation for Wednesday`s snow would be on the order of an inch in central ohio and maybe a half inch northeast of metro Cincinnati. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Northwest flow aloft with surface high pressure building across the region Thursday. This high will offer dry weather conditions and cold temperatures. Expect Thursdays temperatures to be 10 to 15 degrees below normal, with highs from the lower 20s northwest to the lower 30s southeast. Surface low to track through the northern Great Lakes Friday. Best precipitation to stay to ILN/s north closer to the surface wave. Will carry low chance pop of snow showers north. Temperatures look to be around 10 degrees below normal, with highs Friday ranging from the upper 20s north to the mid 30s south. Upper level flow backs westerly with ridge building into the region. Southerly low level flow develops Saturday with temperatures warming to near normal. Expect highs Saturday to range from the mid 30s northeast to the mid 40s southwest. Mid level flow backs southwesterly with moisture spreading back into the area early next week. ECMWF appears to be an outlier with GFS/Canadian solutions weaker and more progressive. Will continue chance pops with the best chance southeast Sunday. Based on thermal profiles, across the north expect rain and snow during the day changing to snow Sunday night with mainly rain south. Temperatures Sunday look to be above normal with highs from 40 north to the upper 40s south. This pcpn event looks to be progressive with pcpn ending early Monday. Temperatures looks to be close to normal with Mondays highs ranging from the the upper 30s north to the mid/upper 40s south. Model solution spread increases by the middle of next week, so confidence decreases. Using a blended approach will continue a dry forecast Tuesday into Wednesday with surface high pressure over the area. Temperatures to moderate a little with highs Tuesday from the around 40 north to the upper 40s south. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... Low level flow is beginning to back off of Lake Michigan. This means the snow showers will continue to lift northeast, and will be limited to CMH/LCK for the first few hours of the taf period. At CVG/LUK, sc is already coming to and end. The southern edge of the sc will see a gradual progression to the ne through 06Z. Models and satellite loop is showing an area of AC over WI/IL that will swing in overnight ahead of a digging H5 s/w. Forecast for Wednesday is still up in the air. The bulk of the synoptic models are keeping the overrunning pcpn north of the fa for period. This is now being supported by the latest runs of the RAP and HRRR, which now reach out until 18Z. The two WRFs and the 18Z Canadian regional have more isentropic lift ahead of the low and are bringing a swath of snow into the tafs between 15-18Z. Decided to lean towards the former solution, but even this solution is showing a chance of snow at CMH/LCK during the morning and lasting into the afternoon. For the other tafs, the chance of snow will wait unto; the sfc low gets closer to the region. OUTLOOK...MVFR ceilings and visibilities along with wind gusts to 25 kt possible Wednesday night. MVFR ceilings and visibilities possible Friday and Sunday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Franks/Sites NEAR TERM...Sites SHORT TERM...Franks LONG TERM...AR AVIATION...Sites
Area Forecast Discussion...UPDATED
National Weather Service Memphis TN
944 PM CST Tue Dec 12 2017 .UPDATE... Clear, calm and cold conditions prevailed across the Midsouth at midevening. 9 PM CST temps had cooled into the mid 20s near the TN River, while mid 30s prevailed over east AR. Latest HRRR and other short term guidance shows winds may edge up a bit over east AR prior to sunrise, which should be enough to level off the cooldown during the overnight. Forecast was recently updated to lower overnight lows over most of west TN and northeast MS, inclusive of the outlying Memphis suburbs. PWB && .PREV DISCUSSION... /issued 549 PM CST Tue Dec 12 2017/ UPDATE... Updated for 00z TAF discussion PREV DISCUSSION... /issued 334 PM CST Tue Dec 12 2017/ DISCUSSION... A deep trough continues to affect the eastern CONUS with an upstream Rex Block in place across the west. This pattern will persist for a few more days but the ridge will gradually shift west over the Pacific, signaling a synoptic pattern change. Until we see this shift occur, we`ll continue to see fast-moving, moisture-starved weather systems. Fortunately, this change looks to occur by the end of the work week with rain chances appearing more likely during the latter half of the weekend, potentially lingering into early next week. Looking back at the short-term, winds today were a bit stronger than suggested by NWP but are finally beginning to decrease. With relative humidity falling into the range of 30-40%, fire danger was elevated but Red Flag criteria were never threatened. Wind speeds will quickly decrease after sunset, setting the stage for a cold night across the Mid-South. Dewpoints are currently in the teens and lower 20s and skies are mostly clear. This will promote strong radiational cooling. The caveat is that southerly winds will begin to increase late which may prevent temperatures from dropping too low, especially along/west of the Mississippi River. Winds will continue to increase on Wednesday as a deepening surface low tracks ESE near the western Great Lakes. Southwest winds are forecast to increase to 15-25 mph, with gusts potentially exceeding 30 mph at times, especially across the northwest half of the CWA. Temperatures will rebound into the 50s, pushing relative humidity down to 35% or less by peak heating. Should dewpoints mix more readily than anticipated, relative humidity could approach Red Flag criteria. It`s worth noting that the Energy Release Component is in the 97th percentile across west TN and above the 90th percentile in east AR and north MS. This suggests a good amount of dry fuel in an area that has seen well below normal rainfall the past 30-60 days. In summary, fire danger will be elevated area wide and may approach critical thresholds in some areas. Another cold front will move across the area Wednesday evening, ushering a cooler Continental Polar air mass back into the region for Thursday and Friday. Highs will largely be in the 40s with overnight lows in the upper 20s to lower 40s. A positively-tilted shortwave trough will traverse the area Thursday night into early Friday, resulting in increasing cloud cover. While mid-level moisture will increase, it remains scant in both the low-levels and aloft (specifically in the dendritic growth zone). This indicates a low potential for rain/snow with this passing trough. While a few sprinkles and/or flurries cannot be ruled out, the potential really isn`t worth mentioning in the 5th/6th periods as no impacts are anticipated. Southerly winds are expected to resume on Saturday, concurrent with the shifting synoptic pattern. The eastern CONUS trough is progged to move east with a flat shortwave ridge over the Ohio Valley (and Mid-South). The GFS and ECMWF are in fair agreement that a southern stream shortwave trough will lift northeast across TX Saturday night into Sunday morning. This will be the trigger for the enhanced rain chances through the day on Sunday. However, the models quickly diverge for early next week. The GFS is slow in departing this trough, keeping it west of the CWA through Monday night while the ECMWF is about 24 hours quicker. Should the ECMWF verify, the low PoPs for Monday may need to be removed. Regardless, with this being a Pacific trough, we`re not anticipating much of a cool-down in its immediate wake. Johnson && .AVIATION... 00z TAFs VFR conditions to prevail, with light and variable winds expected at all TAF sites overnight. Southwest winds will pick up quickly by late morning with a surface low pressure system dropping out of the northern plains. Sustained winds will approach 20 kts with gusts close to 30 kts at all sites but KTUP where the pressure gradient will be a bit weaker. WLC && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$
Area Forecast Discussion
National Weather Service Marquette MI
630 PM EST Tue Dec 12 2017 .SHORT TERM...(This evening through Wednesday) Issued at 337 PM EST TUE DEC 12 2017 WV imagery and RAP analysis indicated a mid/upper level trough over the wrn CONUS and a trough from nrn Quebec into the Ohio Valley resulting in nnw flow through the wrn Great Lakes. A vigorous upstream shortwave trough was located over cntrl Alberta. Cold air with 320-340 low level flow prevailed across Lake Superior producing multiple wind parallel LES into the cwa. Radar indicated a steady diminishing trend this afternoon with mainly just light and less organized bands remaining. Winds were also weakening. So, the LES headlines were cancelled. Radars also showed light snow advancing through nrn MN in a strengthening WAA pattern. Tonight, the remaining LES into the n cntrl cwa will continue to diminish this evening as a weak sfc ridge moves in with diminishing winds and inversion heights falling to 3k-4k ft. As the clipper approaches and the sfc low and warm front move into MN the light snow will increase over the sw with an around an inch possible overnight. LES will also move offshore as winds become se. Tuesday, the models have trended slightly farther north with the path of the clipper and associated mid level fgen and isentropic ascent over the region. Although moisture is modest with around 2 g/kg available, the dynamics should squeeze out a band of moderate snow. With SLR values near 20, the system should bring snowfall amounts of 1 to 3 inches near the WI border with higher amounts over the far south toward Menominee where amounts up to 4 inches are expected. In addition some ene to ne flow lake enhancement may add to the totals at MNM. However, confidence in the development/location of enhanced bands is low. Farther north, 850 mb temps remaining around -16C with convergent ese flow will bring some LES back into the Keweenaw and as winds back further in the afternoon into nrn Marquette county, especially north of M-28. Accumulations north of 1 to 3 inches will also be possible with some locally higher amounts. .LONG TERM...(Wednesday night through Tuesday) Issued at 312 PM EST TUE DEC 12 2017 Typical winter time scenario with snow in some portion of the forecast area at all times in the extended, but the only significant impacts from weather are late Thu through Fri with moderate LES. With NW flow, 850mb temps from -15C to around -20C, and a shortwave dropping through, late Thu through Fri will see moderate to potentially heavy (at times) lake effect snow. Have total snowfall (30 hours) of 5-8 inches in the NW wind snowbelts, but that may need to be increased once we can look at some higher res models. Doesn`t look all that windy, so impacts shouldn`t be all that great for a lake effect event. Otherwise, not seeing anything significant within reasonable predictability, so let the blended initialization remain untouched for other time frames. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 630 PM EST TUE DEC 12 2017 Lake effect snows have pushed east of the TAF sites however more snow will move in from the west overnight. MVFR ceilings will prevail for a time tonight once the low clouds at KCMX lift, but MVFR will return as the snow arrives ahead of the clipper system, with the lowest ceilings expected during the late night and early daylight hours. Ceilings will improve a little during the afternoon but will stay in the MVFR range. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 337 PM EST TUE DEC 12 2017 NW winds to 25 knots will decrease to less than below 20 knots by Wednesday morning. Winds will then increase to 15 to 25 knots late Thursday and into Friday as the next system approaches from the west. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Weather Advisory from 3 AM to 6 PM CST Wednesday for MIZ012. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...Titus AVIATION...RJT MARINE...JLB