Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/26/19

Area Forecast Discussion
National Weather Service Boston/Norton MA
1032 PM EDT Fri Oct 25 2019 .SYNOPSIS... A weak low pressure traveling along a front crosses through our area late tonight, bringing a few showers mainly to areas north of the MA Turnpike. High pressure brings dry and seasonable weather Saturday.Low pressure will bring a widespread soaking rain to the region on Sunday. Scattered showers and an abundance of clouds will linger Monday, Tuesday and possibly into Wednesday but a washout is not expected. Onshore flow and high astronomical tides will likely result in pockets of minor coastal flooding along the eastern Massachusetts coast early next week. A cold front may bring a steadier/heavier period of rain sometime later Thursday and/or Friday. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Made some tweaks to the forecast this evening. Last several runs of the HRRR have been matching up with the observations rather well. These runs have been suggesting measurable rainfall remains confined a little farther north, so tightened up the gradient for rainfall chances towards the MA Turnpike overnight. Minor tweaks to temperatures to reflect observed trends. Still expecting rainfall to move offshore after midnight, with clearing arriving from west to east late tonight. Previous Discussion... A weak low pressure system travels along a cold front will cross the region overnight. The best lift and moisture should remain to our north into NH/VT, however some light showers are expected mainly north of the MA Turnpike later this evening. Precip chances end from W to E after midnight as the low moves offshore and high pressure brings a dry NW flow. Decreasing cloud cover is expected after midnight from W to east. Overnight lows will generally be in the low to mid 40s across the interior, and mid 40s to low 50s along the coastal Plain. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... Saturday... High pressure brings a reprieve, with mostly sunny skies. NW breeze prevails through midday. Then as high passes overhead low level winds become light. This may enable local sea breezes to develop by mid afternoon. Highs in the mid 50s to low 60s, though a few typically warmer locales may see mid 60s. Saturday night... Transition period as the surface high pressure pushes to the NNE into ME and eastern Quebec, and moisture-rich low pressure system emerging out of the Gulf Coast region Fri night/Sat tracks into the Great Lakes Region. While surface and mid level ridging keeps our area dry to start the night, the low approaching from the west, accompanied by a negatively titled trough, will send an increase in moisture our way. For Sat night across southern New England, this will mean increasing cloudiness, with showers/rain moving into at least western portions of our area before daybreak Sunday. In that area, have likely to categorical pops for late Sat night, and a chance/slight chance before daybreak across eastern MA and RI. An easterly breeze should allow surface dew points to rise by a few degrees, then as we wet bulb as the rain moves in. Expecting overnight lows mainly in the 40s. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Highlights... * Widespread/soaking rainfall Sun with chilly temperatures * Considerable cloudiness along with scattered showers Mon & Tue * Unsettled weather at times Wed into Fri, but the best chance for a period of widespread/heavier rain will be late Thu and/or Fri * Above normal temps much of the next work week, especially at night Details... Sunday... A widespread/soaking rainfall will impact the region Sun. Strong shortwave energy across the eastern Great Lakes early Sun morning will lift northeast into northern New England and Quebec by afternoon. This will induce a modest southerly LLJ/Pwat plume that is to 2 to 3 standard deviations above normal. There are still some timing differences, but the widespread rain probably overspreads most of the region Sun morning. If some of the slower solutions verify, its possible that dry weather could persist into the mid afternoon along the southeast New England coast. Either way, the heaviest rain looks to occur Sunday afternoon. A secondary low will develop near the south coast, which may result in heavier amounts in that region. We also can not rule out a rumble or two of thunder near the south coast, but probably not worth inserting into the forecast at this point. Rainfall amounts Sunday should range from 0.50 to 1.50 inches across the region. Bands of heavier rain may result in the typical ponding of water on some roadways, but no significant flooding issues are expected. The modest southeast LLJ will allow for some gusty winds along the coast to develop, but at this time do not expect the need for any wind headlines. Temperatures will be quite cool most of Sunday, mainly in the upper 40s to lower 50s with even middle 40s in the higher terrain. A secondary low pressure system developing on the south coast may allow the warm sector to flirt with the south coast Sun evening. If that happens, some of those locations might spike into the lower 60s but probably not until the evening hours. Sunday night... Steady rain will continue into part of Sunday evening, especially across eastern New England. Otherwise, scattered light showers and patches of drizzle may linger overnight at least along the coast with onshore flow. Low temps will mainly be in the middle 40s to the lower 50s. Monday and Tuesday... High pressure across the eastern Canadian Maritimes with weak low pressure offshore will result in moist onshore flow. The result will be an abundance of clouds and scattered showers at times with drizzle possible too. While the entire period will not be a washout, rather gloomy conditions expected. Overall, mild temperatures will persist. Highs mainly between 55 and 65 with the coolest readings likely along the coast. Low temps will be significantly above normal given the clouds and onshore flow, generally in the middle 40s to the lower 50s. Wednesday through Friday... There remains some uncertainty in the timing of a highly anomalous trough that will develop over the western and central U.S. and how quickly that moves east. Given the upper level ridging off the southeast coast and a general agreement between the ECMWF/UKMET and GGEM going with the slower solution. The GFS seems to be lost the last few days and way too progressive given the above factors. With that said, relatively mild temps may continue into Friday (especially at night). The best chance for a period of widespread showers may be sometime late Thu or even Fri, but the exact timing is uncertain. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Saturday Night/...High Confidence. Tonight... Mainly VFR with a few showers likely through early morning Saturday north of the MA Turnpike. May also see some patchy fog develop toward daybreak. So while VFR conditions dominate, may see some localized MVFR to perhaps even localized/brief IFR conditions overnight. Saturday... Any lingering lower CIGS along the coast should improve to VFR during the morning. NW winds 5-15 kts becoming light from a NNE direction during the afternoon. Local sea breezes probable during mid to late afternoon. Saturday night... Thru midnight Sat night, VFR with increasing/lowering clouds. Then for late Sat night MVFR/IFR conditions possible across interior MA and northern CT with low ceilings and rain developing. E/SE winds 5- 10 kts. KBOS Terminal...High confidence in TAF. Potential for renewed sea breeze development during Sat afternoon. KBDL Terminal...High confidence in TAF. Outlook /Sunday through Wednesday/... Sunday: Mainly IFR, with local MVFR possible. Windy with gusts up to 30 kt. RA, patchy FG. Sunday Night: Mainly IFR, with local MVFR possible. Windy with gusts up to 35 kt. RA likely, slight chance SHRA, patchy FG. Monday: MVFR/IFR conditions possible. Breezy. Chance SHRA. Monday Night through Tuesday: Mainly MVFR, with areas IFR possible. Breezy. Chance SHRA. Tuesday Night: Mainly MVFR, with local IFR possible. Chance SHRA. Wednesday: Mainly VFR, with areas MVFR possible. Chance SHRA. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Saturday Night/...High confidence. Tonight and Saturday... Relatively light winds and seas across the coastal waters through Saturday. As a result, local sea breeze development is possible once again during Saturday afternoon. A weak low pressure crosses the water tonight. Showers will be most likely across the waters east of MA, while the waters near and south of the Cape/Islands may remain dry. Could see briefly reduced visibility if any heavier showers develop. A few lingering showers possible around daybreak Sat, otherwise dry weather expected. Saturday Night... E/SE winds developing, with gusts around 20 kts possible along the southern waters. Slight chance of rain. Outlook /Sunday through Wednesday/...Moderate to high Sunday: Small Craft Advisory to marginal Gale Force wind developing. Rough seas. Rain, patchy fog. Areas of visibility 1 to 3 nm. Sunday Night: Moderate risk for gale force winds with gusts up to 35 kt. Rough seas up to 10 ft. Rain, chance of rain showers, patchy fog. Areas of visibility 1 to 3 nm. Monday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Rough seas up to 10 ft. Chance of rain showers. Monday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Rough seas up to 10 ft. Chance of rain showers. Tuesday: Winds less than 25 kt. Rough seas up to 9 ft. Chance of rain showers. Tuesday Night: Winds less than 25 kt. Areas of rough seas. Chance of rain showers. Wednesday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers. && .TIDES/COASTAL FLOODING... * Pockets of Minor Coastal Flooding Likely Mon & Tue along the eastern MA coast High astronomical tides may result in some splash over or perhaps very minor coastal flooding on Sunday with onshore flow associated with our rain event. However, the potential for more widespread minor coastal flooding will be around lunch time on Mon, Tue and perhaps even Wed along the eastern MA coast. Boston has an 11.9 foot astro tide Mon and a 12.0 on Tue. This coupled with onshore flow and 5 to 10 foot seas just offshore will likely result in pockets of minor coastal flooding during these astro tides. Coastal Flood Advisories will likely be needed. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Gale Watch from Sunday afternoon through Sunday evening for ANZ231>234-254>256. Gale Watch from Sunday afternoon through late Sunday night for ANZ250. && $$ SYNOPSIS...Frank/NMB NEAR TERM...Belk/NMB SHORT TERM...NMB LONG TERM...Frank AVIATION...Belk/Frank/NMB MARINE...Belk/Frank/NMB TIDES/COASTAL FLOODING...Staff
Area Forecast Discussion
National Weather Service Caribou ME
1026 PM EDT Fri Oct 25 2019 .SYNOPSIS... Low pressure will track eastward across the Gulf of Maine overnight. High pressure will return Saturday into early Sunday. Another area of low pressure from the Great Lakes will approach Sunday afternoon and track well south of the Gulf of Maine Sunday night. High pressure builds westward into the area Monday into Tuesday. A cold front will approach Wednesday. && .NEAR TERM /THROUGH SATURDAY/... 1030 PM Update... Only significant adjustment was to the temps to adjust them downward a degree or two across the wnw areas where clearing has allowed temps to drop in the upper 20s. Clouds are filling back in per the IR satl imagery. Daycrew had this handled quite well. Radar showing the highest returns along the coast attm ahead of that weak low. KBHB(Bar Harbor) reported light rain in the last hr. The HREF and RAP handling things quite attm. Minor tweaks were done to the precip chances to account for the latest radar and HREF/RAP blend. The rain is expected to shift quickly to the ese overnight and remain light. Previous Discussion... An upper level trough in the northern stream is approaching from the Great Lakes region tonight. This trough will induce weak cyclogenesis along a stalled frontal boundary tonight. The baroclinic zone and resultant weak low will pass to the south of the forecast area tonight. The low will generate rain in southern zones late this evening through the night. The most precipitation will occur along the Hancock County coast where total amounts may exceed a quarter inch. Further north, the passage of the upper trough could generate a few snow showers towards daybreak in northern Aroostook County. While upper levels are cold, boundary layer temps are marginal and deeper moisture will only last an hour or two. As such, it`s difficult to foresee any widespread measurable accumulation. As the upper trough exits, gusty northwest winds will commence. Gusts may briefly reach 25 mph in the morning, but will quickly subside as high pressure builds through Saturday. The high and associated subsidence is expected to produce clearing during Saturday...especially in southern zones. There is good cold air advection tonight into Saturday with H850 temps dipping towards minus 6C on Saturday. Even with less cloud cover than today, highs will several degrees cooler than today`s readings. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... A high pressure ridge will be in place over our area at the start of the period. A low in central Illinois with a warm front extending east to the coast of New York and a cold front extending south to the Gulf of Mexico will be the next system to affect our area. By late Sunday morning the high will build east as the low and associated front move east. The low moves northeast to Eastern Lake Huron. The warm front into SW Maine, and the cold front south along the East Coast. Sunday evening the low continues to move Northeast into Southwestern Quebec. A new low forms on the front over Eastern New York. The warm front extend into Eastern Maine. Early Monday morning, the energy from the parent low transfers to the new stronger low now over Cape Cod. This low is forecasted to move SE well away from our area. Higher pressure will ridge back across the area for the end of the period. Loaded a blend of the GFS/NAM/ECMWF/GEM to smooth out the minor differences in the models. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... A high pressure ridge will be in place across the area at the start of the period. A trough across Quebec north of the ridge will be the next system to affect our area. A low will develop along the trough and move east across Quebec pulling the trough into NW Maine Wednesday morning. The trough will interact with a low moving north along the Atlantic Seaboard. The trough will become a warm front and remain across Maine, as the low continues to track north along the coast. The low will track across Maine Thursday evening, then on into the Maritimes Friday morning. Higher pressure will ridge into the area through the end of the period. Loaded a blend of models to smooth out the minor differences. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... NEAR TERM: VFR conditions will continue until later tonight when MVFR will become the predominant condition into Saturday morning. Can`t rule out a brief snow shower with IFR vis at sites such as FVE, Clayton Lake and CAR towards daybreak Saturday. By late Saturday morning through the remainder of the day, VFR is expected at all terminals. SHORT TERM: Saturday evening through Sunday afternoon...VFR with increasing clouds and decreasing ceiling beginning Sunday morning. Sunday afternoon through Monday morning...MVFR falling to Low MVFR to IFR conditions in rain Sunday evening. Monday morning through Monday evening...MVFR with scattered showers, becoming VFR Monday evening. Monday evening through Tuesday morning VFR becoming MVFR in showers Tuesday morning. Tuesday morning through Wednesday...MVFR to Low MVFR with showers. && .MARINE... NEAR TERM: Light winds and seas decreasing towards 1 to 2 feet will be the story into tonight. Rain will develop later this evening and continue into late tonight. The end of the rains will correspond with a sharp wind shift to the northwest and a few gusts could reach 25 kt, but will not be issuing an advisory at this time as the duration of 25 kt gust potential is very brief. The northwest winds will keep gusting to 20 kt into Saturday afternoon. SHORT TERM: Winds and seas below SCA Saturday evening through Sunday afternoon. Winds and seas building to Small Craft Advisory levels Sunday evening. Winds and or seas will remain above SCA criteria through Tuesday evening. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...Hewitt
Area Forecast Discussion
National Weather Service Goodland KS
511 PM MDT Fri Oct 25 2019 .SHORT TERM...(This evening through Saturday) Issued at 109 PM MDT Fri Oct 25 2019 Water vapor imagery and 500mb height RAP analysis showed a closed low slowly tracking east-southeast today along the Oklahoma/Texas border. Sunny skies and light winds prevailed across the tri-state region on the backside of the system. At 1 PM MT, temperatures ranged in the upper 50s to low 60s. Weak ridging extends across the area overnight while the OK/TX low moves slightly east. Clear skies and light winds are expected to continue across the region as temperatures fall into the upper 20s to low 30s. Westerly downslope flow helps temperatures climb into the 70s on Saturday. Enjoy the warmth while you can. A cold front is set to move through during the evening hours and it will be the start of much cooler weather for the area. This looks to be a dry frontal passage; however, breezy north winds are expected behind the front overnight. Meanwhile, an upper trough digs towards the Central Rockies from the Pacific Northwest. This disturbance generates some light snow chances that start to enter the forecast area from the northwest late Saturday night as temperatures fall into the 20s and low 30s. .LONG TERM...(Saturday night through Friday) Issued at 200 PM MDT Fri Oct 25 2019 Focus for this period will be the two rounds of snow that will move across the forecast area before the middle of next week. For the first round, latest guidance continues to show a deepening trough over the western CONUS through early next week. As this trough deepens then swings across the Plains, it will bring heavy snow to the Central Rockies. The higher snowfall amounts continue to be over the mountains in CO where the lift will persist longer, with much lower amounts on the Plains. Am not very impressed/concerned about the potential for no more than a few inches of snow occurring, with the highest amounts occurring in western parts of Yuma, Kit Carson, and Cheyenne counties. Due to orographic effects, there may be a localized area of higher snowfall amounts in western Kit Carson County. The rather broad, fairly quick moving trough from the west is not supportive of warning snow amounts. Looking at the CIPS Analogs the probability of receiving 2"+ is less than 30% for the forecast area. The 90th percentile (10% chance of occurring) is low end warning criteria. The majority of the snow is not forecast to occur until Monday, as the trough swings across the Plains and continues east. Bottom line, there will be low snow amounts in East Central Colorado as early as Sunday, spreading across the rest of the forecast area Monday, ending Monday night. The second round of snow will move through Tuesday into Wednesday as another broad trough moves across the Plains along a similar path to the previous one. There is disagreement as to how quickly this second trough will move across the Plains. The GFS has the trough moving quickly across the Plains, similar to the speed of the prior trough, and keeps the trough as an open wave. The ECMWF lingers the trough over the Four Corners region and deepens the trough into a closed low. As the closed low tracks east, it moves across KS. By the time the ECMWF moves the closed low east, the GFS has its open wave over the Ohio River Valley. The last three runs of the ECMWF favor the trough tracking across KS, and the last 6 runs of the GFS (which all have an open wave) show a similar trend. Even though there is still a question about how quickly the second trough will move across the forecast area, model trends point toward a more favorable path for precipitation than with the first round of snow to move through. Aside from snow, the big change for upcoming weather is the drastic drop in temperatures behind the cold front Saturday night. Once that front moves through highs may not even approach normal for a week. The current temperature forecast for the first part of next week is more likely to trend cooler over the coming days. Wind chills by mid week will fall to the single digits above and below zero during the night/early morning hours. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 511 PM MDT Fri Oct 25 2019 High pressure expected to dominate the region`s weather thru the forecast period. A cold front is expected to traverse the area near the end of the forecast period...affecting KMCK before 00z Sunday. VFR conditions until then. Winds for KGLD, light/variable thru 03z Saturday, then SW around 10kts. By 14z, SW 10-20kts becoming SE around 10kts by 22z just ahead of the frontal passage. Winds for KMCK, light/variable thru 07z Saturday, then SW around 10kts. By 21z, N 10-20kts due to front pushing thru the area. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...JBH LONG TERM...JTL AVIATION...JN
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
850 PM CDT Fri Oct 25 2019 .UPDATE... Updated for evening discussion. && .DISCUSSION... Shortwave ridge in advance of TS Olga has diminished the precipitation considerably over southern portions this evening. This will not last long, though, as Olga makes landfall around midnight and quickly pushes northward overnight. So, an increase in showers will be seen after midnight with some thunderstorms, as well. Enhanced wind fields around the center of circulation will lead to strong convergence, strong shear and possible severe convection with wind and tornadoes being the primary threats. Latest HRRR data showing some interesting convective structures around and to the east of the circulation center./GG/ Prior discussion below: Through Saturday... A rather wet pattern will continue through much of the short term. Warm front still remains close to the coast with lower to mid 70s dewpoints remaining in this part of the state. Dewpoints have been slowly increasing across portions of our forecast area with readings in the mid 60s. As the low pressure system in the Gulf continues to move north through the remainder of the afternoon and evening, this warm front is expected to also move north, bringing a bit more moisture and instability further inland. Models tend to agree that this low will move north in the vicinity of the I-55 corridor this evening and overnight. As it does, the best parameters for strong to severe storms, including better shear profiles, will be across the east and southeast parts of Mississippi, potentially reaching as far west of the I-55 corridor. It is in this region where we previously expanded both the slight and marginal risks for severe weather. The main concern will be from damaging winds and tornadoes, coming roughly from 3am through daybreak. A fly in the ointment may come in how far north this more unstable air is able to go. The other concern will be from flash flooding potential. Most locations have seen steady moderate rain for most of the day with around 1 to 2 inches common but some locations in the east have seen amounts upwards of 3 inches. Another 1 to 3 inches will occur through tonight into tomorrow before all is said and done. Some rates will be higher/heavier rainfall in convective bands later tonight into tomorrow and going Flash Flood Watch seems good for now. As the surface low deepens and moves inland, given the tightened pressure gradient, there may be some gusty winds not associated with more robust convection. Winds will be out of the south/southeast during the night but will hold off adding anything to the HWO this afternoon for this threat. Models continue to quickly push convection out of the region by early afternoon or perhaps even by noon. Clearly should come gradually from west to east through the afternoon and evening. Temperatures have been and will continue to be tricky given rain and cloud cover. Of course with a northward advancing cold front, temperatures will remain steady to increase overnight tonight. Highs tomorrow will roughly be in the 60s and lower 70s. /28/ Saturday night through next week... A cooler airmass will filter into the region Saturday night as the surface front pushes east of the region and the upper low ejects to the north. Some moisture will remain in the lower levels as surface high pressure increases. Some fog will be possible throughout the region on Sunday morning. Temperatures will be slightly below average on Sunday as dry conditions prevail. Monday will remain dry with temperatures closer to average as the surface high remains parked over the area. As with the last several forecast packages, there is still little agreement amongst guidance moving into midweek. As a trough over the Rockies deepens on Monday, SW upper flow will begin to increase over the lower MS River Valley in response. As the trough begins to migrate eastward on Tuesday, a weak disturbance embedded in the pattern will help to push a weak front towards the region. This is where the agreements end. The GFS still holds on to the drier solution with only light PoPs in the region on Wednesday into Thursday with cooler air filtering into the region behind the front. The Euro`s solution continues to be the wetter of the two through the period as a deep upper closed low crosses the Rockies and approaches the MS River, keeping rain, storms, and warmer temperatures in the region through early Friday. We will continue to lean towards the warmer, wetter midweek solution due to the performance of the Euro so far in this transitional season but the forecast remains low confidence until there is more consensus amongst guidance. && .AVIATION... 00Z TAF discussion: Mostly IFR/LIFR conditions will continue through the night with widespread rain and isolated thunderstorms. After sunrise Saturday, conditions will slowly improve to MVFR as the widespread rain tapers off to showers. East and southeast winds will prevail at 10 to 20 knots with gusts around 25 knots tonight eventually becoming more south to southwest after sunrise./GG/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 64 68 50 71 / 90 72 12 4 Meridian 62 75 50 70 / 95 96 18 5 Vicksburg 60 65 50 71 / 93 57 12 3 Hattiesburg 66 72 50 71 / 92 82 12 4 Natchez 59 63 50 71 / 88 49 12 2 Greenville 58 64 50 68 / 96 60 12 3 Greenwood 60 68 50 69 / 95 76 12 3 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...Flash Flood Watch through Saturday afternoon for MSZ018-019- 025>066-072>074. LA...Flash Flood Watch through Saturday afternoon for LAZ007>009-015- 016-023>026. AR...Flash Flood Watch through Saturday afternoon for ARZ074-075. && $$
Area Forecast Discussion
National Weather Service Paducah KY
1011 PM CDT Fri Oct 25 2019 .UPDATE... Issued at 1011 PM CDT Fri Oct 25 2019 Forecast remains largely on track. However, some concern remains with regard to exactly how much rain will fall and where. The models have largely been off with respect to convection over the Deep South this evening, with the NAM and GFS depicting a bullseye of higher QPF much further west than reality. Meanwhile, the ECMWF and RAP seem to have a better handle on current conditions. What impact this will have on conditions going forward remains unknown. However, even the ECMWF and RAP both develop a swath of heavy rain across the region late tonight into Saturday morning, with the heaviest rain still within the Flash Flood Watch area. As a result, will keep the watch and QPF forecast as is for now. Another concern remains strong winds on Saturday in response to the tightening gradient in the vicinity of a low pressure system forecast to track northeast into the lower Ohio Valley. Increased the strongest wind gusts into the 35 to 40 mph range across much of western Kentucky, southwest Indiana, and southeast Illinois during the late morning and afternoon. These estimates may be a bit conservative, depending on the amount of low level mixing that occurs. A broken line of showers and isolated storms may bring even stronger wind gusts to that region during the late morning through mid afternoon, with some gusts of 50 to 55 mph or greater possible. The issuance of a Wind Advisory may eventually become necessary on Saturday, but will ultimately leave that up to the midnight shift to make the final call. && .SHORT TERM...(Tonight through Saturday night) Issued at 309 PM CDT Fri Oct 25 2019 The current weather system pushing rain northward from the Tennessee Valley this afternoon continues to hold surprises, especially in the spatial location of the heaviest QPF (forecast rainfall amounts) and rainfall rates tonight and early Saturday. In coordination with the NWS Forecast office in Memphis, introduced a Flash Flood Watch for late this evening through midday on Saturday. It was a toss up between going with a Flood Watch versus a Flash Flood Watch, but it looks like there may be a roving 3-4 hour period within a deformation zone with the upper low that efficient rainfall rates may exceed established short term flash flood guidance. The Flash Flood Watch falls within WPC`s Day 1 (tonight) and Day 2 (Saturday) Slight Risk for Excessive Rainfall. There is lower confidence in the duration and intensity of rainfall north of Route 13 in southern Illinois, so keep the watch generally south of that area. Utilized WPC Rainfall as primary QPF focus, which has lowered precipitation amounts markedly Saturday afternoon and dropped overall storm total rainfall amounts down by at least an inch. The mesoscale challenge will be determining the intake of drier air into the low from the west in the 15z-18z Saturday time frame. This will also be key as to the potential for overturning of theta-e air in the mixed layer and the capability of downward mixing of air and the stability of the boundary layer with its gradient winds around the low. Do have a mention of up to 40 mph winds over west Kentucky in the gridded forecast Saturday afternoon. Will not rule out some damaging wind potential for any convective line segments that develop along the eastern half of the WFO PAH forecast area Saturday afternoon. Will be a close call. At this time, SPC has our area only outlooked for general Thunderstorms for Saturday. Utilized a blend of the HREF, RAP, ESRL HRRR, and NAM high resolution guidance, overlaid with NAM-WRF (ARW version) and Canadian Guidance for sub-synoptic sensible weather features. .LONG TERM...(Sunday through Friday) Issued at 309 PM CDT Fri Oct 25 2019 There are two primary targets of opportunity for forecast adjustment in the long term. The first is with a weak frontal/system passage Monday night. This system is scarce of mean moisture and depth in the atmospheric column over the PAH FA. Its best and deepest pool of moisture stays catafrontic to our north, where the dynamical energy associated with its passage is also better. And the thermal profile, while cooling post frontally, remains just warm enough to preclude mention of anything other than liquid pcpn. The Builder`s use of the blend did output slight chance pops, mainly for our northwest-most counties, Monday evening...which stands for this writing...pending collaboration. If trending continues, however, removal of these pops altogether may be warranted with this first/weak system`s passage. The 2nd and better target of opportunity for forecast adjustment occurs 24-48 hours later, with another frontal/system passage. This system will introduce a little better moisture, a little better lift/via dynamical energy, and a little better thermal profile (favoring a potential wintry mix), to make things a little more interesting. That said, we are not ready to go out on a limb just yet with a Tuesday night/Wednesday morning event, other than it would appear confidence is increasing in a pattern change that favors the late week cooldown that the extended range outlooks have been hitting upon. It appears the collaborative strategy for now is to mention the brief/wintry mix chance pop late Tue night-early Wed., with a system passage sometime Wed night-Thursday. This ending time period is also an area that may be looked at for future forecast adjustment, as some deterministic runs suggest ending pcpn much earlier, like by Wed evening, versus 6-12 hours later. This could be the blend averaging the runs, so we`ll wait til more member agreement comes into play before changing the ending time. As for temps, we`ll see 60s early in the week, fall into the 50s, then thru the 50s, with even some 40s by the end of the week (in our northwest) for highs. Lows will follow a similar course, from the 40s into/thru the 30s, with some 20s showing up (along with their killing freeze potential) by the end of the week. && .AVIATION... Issued at 628 PM CDT Fri Oct 25 2019 Significant impacts to aviation anticipated. Through the evening, cigs will gradually lower across the area to MVFR to local IFR, with MVFR vsbys as rains increase from south to north across west KY and southeast MO, into southern IL and eventually southwest IN. Overnight, east winds will increase with some gusts to or above 20 kts with time, and MVFR to IFR cigs and vsbys due to widespread showers. LLWS may become an issue late tonight into Saturday morning as strong winds just off the surface from the southeast increase to 35 to 50 kts. Showers will continue Saturday, with some decrease in coverage with time, as winds veer more south, southwest, with gusts 20 to 30 kts expected, highest over west KY into southwest IN. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...Flash Flood Watch through Saturday afternoon for ILZ088>090- 092>094. MO...Flash Flood Watch through Saturday afternoon for MOZ086-087- 109>112-114. IN...None. KY...Flash Flood Watch through Saturday afternoon for KYZ001>009. && $$ UPDATE...RJP
National Weather Service Charleston WV
1021 PM EDT Fri Oct 25 2019 .SYNOPSIS... Light rain spreads from south to north along a warm front Saturday. A cold front sweeps across the region Sunday with more beneficial rain. The area gets a break until midweek. && .NEAR TERM /THROUGH SATURDAY/... As of 1020 PM Friday... Blended recent HRRR guidance into POPs in an effort to better reflect current radar trends. The current band of light rain stretching from the Tug Valley into the central WV mountains should taper off as an upper level ripple pulls away and the focus for precipitation transitions closer to the surface low crossing the Gulf Coast. As of 140 PM Friday... Clouds will continue to thicken through the overnight hours in response to approaching increasing mid-level moisture associated with southern stream low currently stationed over eastern Texas. Think a bulk of overnight activity will be limited to very light precipitation or virga, mainly across the southern coal fields. Increasing moisture/forcing for ascent associated with strengthening southerly-southeasterly H850 flow around the east side of the aforementioned low will provide a focus for rain Saturday morning with the heaviest accumulations across eastern Kentucky, western West Virginia, northwestern Virginia and southeastern Ohio from late morning into early afternoon with mostly light accumulations further east away from the nose of the jet and closer to the influence of downsloping winds off the higher terrain. H850 strengthens further through Saturday afternoon/evening exceeding 50KTs for a bulk of the region by 00Z. With warm air advection, do not see any large scale mechanisms to transport enough of this momentum to the surface to support any wind highlights for the lowlands, but will certainly be breezy downwind of higher terrain. For the higher elevations, do look to approach wind advisory criteria along the highest ridgetops Saturday evening and especially early Sunday morning as H850 flow approaches 70KTs. Will highlight this risk in the HWO for now and allow the midnight shift to evaluate. Despite freight train of low level moisture, PoPs through the afternoon mostly fall into the slight chance/chance category without a strong focus for ascent. This will change significantly as a cold front slams into moisture laden profiles late Saturday night/early Sunday morning with continued strong moisture advection into the frontal zone. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... As of 235 PM Friday... For the start of this FCST period models are picking up on the downslope effect for the western slopes of the mountains and lowlands. Possible lighter rain showers will exist in these areas, however will pick up in intensity through the night into Sun. The bulk of the rainfall from the system to the west will drop over the Ohio River Valley. The lowlands will see more rain as the surface low moves north and drags a cold front through early on Sun. Generally around 1 inch in total rain is expected although the lowlands may struggle to squeeze out even 3/4 of an inch. Southeasterly flow along with downsloping and a tight pressure gradient across the mountains will create strong winds areawide and a low level jet as high as 75kt. Therefore, expecting very gusty winds along the front picking up late Sat. night and persisting into Sun. morning. The strongest winds will be along the mountains and their western slopes, however areawide will endure gusty wind which could cause downed trees, isolated power outages and flying debris. Holding off on a wind advisory for now since soundings are saturated with warmer air being advected in which will prevent the majority of the strongest winds from mixing down to most areas ahead of the cold front through Sunday morning. Mentioned strong gusty winds in the HWO for now. Models are now slower with the exit of the cold front than previous runs since a system that was suppose to help push it along quicker did not really pan out, so the area will experience rain showers into Sun. afternoon with possible lingering showers in the mountains until the evening. With drought conditions still in effect, not expecting any flood issues although any prone flood or low lying areas are at slight risk of experiencing issues. This cold front is fairly weak as far as temperature gradients are concern. Temperatures will not fall that much overnight Sun. so basically went with central guidance, however guidance is banking on clouds hanging around which I believe will clear out sooner. For this reason I nudged temperatures down slightly. Temperatures will then stay seasonable for the next few days with a nice break from unsettled weather. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 235 PM Friday... A nice break from unsettled weather continues through this period, but unfortunately a fairly active weather pattern will set in starting around midweek. A broad and deep upper level trough will slide east over the area and create numerous short waves with potential to spawn a few surface lows. These features are forecast to affect the area in one way or the other through Friday, possibly longer, as a vort max is prog to impact the CWA into the weekend. The aforementioned feature will bring in cold air starting Thurs. Since models diverge slightly around this time frame, went with guidance and left in chances for rain since timing and location is uncertain. Contrary to guidance, decided to bump temps down since confidence is high in the trough sweeping over the area and advecting Canadian air to the region. Some of the models are in unison with my decision leaning towards a colder bias for Thurs. and Fri. morning presenting the chance for snow flakes in the air during these periods, especially in the higher terrain. Central guidance added some frost into the forecast for Fri. morning and opted to leave it in since temps should get down to around freezing. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... As of 720 PM Friday... Rain making it to the ground a bit sooner than previously expected, so main change to TAFs was to add light rain showers across the south this evening. Still have a dry layer of air near the ground and an overcast sky, so not expecting much fog to form following this rain. Rain will remain light, so VFR expected through the night. More widespread rain expected to move from south to north on Saturday morning. For now kept this VFR, but some dips into MVFR will be possible. Winds will pick up out of the southeast Saturday, with gusts of 15-30 kts. This could also lead to LLWS Saturday afternoon/evening as a strong southerly low level jet noses through. With gusty surface winds expected, and fairly unidirectional flow in the low levels, did not include LLWS in the TAFs right now. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SUNDAY... FORECAST CONFIDENCE: High. ALTERNATE SCENARIOS: Patchy fog may form tonight. MVFR visibility possible in rain showers Saturday. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE SAT 10/26/19 UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 00Z SUNDAY... IFR or worse conditions Sunday along a cold front with heavy precipitation. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...JP/JZ NEAR TERM...MZ/JP SHORT TERM...JZ LONG TERM...JZ AVIATION...MZ
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
853 PM MDT Fri Oct 25 2019 .UPDATE... Issued at 842 PM MDT Fri Oct 25 2019 02z surface analysis had low over central SK with cold front into northwest MT with 5-8mb/3hr pressure rise bubble behind it. 00z KUNR quite dry giving us a glorious Friday. Water vapour showed upper trough moving across southwest Canada into the northwest US. Two main pockets of energy, one spinning over southern AB and another pushing into WA/OR per 90kt jet streak. This trough will progress east/southeast through Saturday pushing the cold front into the CWA very late tonight and out of the CWA Saturday afternoon. Cold air advection will be fairly robust with 3-5mb/3hr pressure rises per latest RAP forecast, but rises will weaken throughout the day. Result will be a period of gusty winds for the northern squeeze areas northeast/east of the Black Hills. Attention then turns to lift with southwest jet steak as it dives into the central Rockies. Guidance depicts a moderate band of 850-700mb frontogenesis from central WY into far southwest SD by 00z Sunday. At the same time low level dry air continues to advect into the CWA with Td/s dropping into the teens. This will be the battle in place for accumulating snow. HREF guidance shows highest probabilities for 0.25-0.50" QPF near the far southwest SD/NE state line. Tweaked the forecast for latest thinking through 12z Sunday and came up with near winter weather advisory amounts for Fall River/Oglala Lakota areas and marginal wind advisory conditions for Rapid City and the surrounding squeeze zones. So, yeah. Lots of text to basically say will hold onto headline-less forecast until full suite of new data arrives overnight. && .DISCUSSION...(This Evening Through Friday) Issued at 207 PM MDT Fri Oct 25 2019 Deep NW flow upper trough will dig into the central CONUS this weekend, supporting very cold conditions across a large portion of the country by the end of the weekend. Warm SW flow has supported a WAA regime and has allowed for a mild fall day across the region, with most places on the plains in the 60s. Strong cold front will quickly move through the region Sat, with gusty NW winds expected by afternoon on the plains. Frontside impulse will support increasing chances for snow over the SW third Sat afternoon, best chance over far SW SD into NE WY where 1-3 inches looks likely Saturday afternoon into Sunday morning. Southward bias of best FGEN per faster frontal surge has continued to shift the best snow chances south as drier air will work into the region quicker. An adv may be needed for Fall River county if snow amounts remain around forecast values. Otherwise, gusty NW winds will likely support wind adv winds in the lee of the Black Hills Sat afternoon. Will defer any headlines to the next shift when a good handle on timing and hazards should be attained. Very cold unsettled NW flow will dominate through early next week, with re- enforcing rounds of CAA expected per clipper systems. This will support temps 20-40 degrees below seasonal norms Sunday through Tues (coldest over the far west), with the coldest day being Tues where many places will struggle out of the teens and 20s in the western half. Slow warming trend expected afterward, with mainly dry conds and below normal temps continuing. && .AVIATION...(For the 00Z TAFS Through 00Z Saturday Evening) Issued At 529 PM MDT Fri Oct 25 2019 VFR conditions expected through tonight. Gusty southwest winds are expected tonight over northeast WY and the higher Black Hills. A sharp cold front will move through the area from northwest to southeast starting late tonight, exiting the area Saturday afternoon. Behind it, conditions will deteriorate. Expected widespread MVFR CIGS by afternoon with local IFR/LIFR conditions over northeast WY into the Black Hills due to clouds and then increasing coverage precipitation. Precipitation will start as rain, but change to snow most areas by the end of the period. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ Update...Helgeson DISCUSSION...JC AVIATION...Helgeson