Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/01/23


AREA FORECAST DISCUSSION
National Weather Service Albany NY
1025 PM EDT Sun Apr 30 2023 .SYNOPSIS... Periods of rain, heavy at times, will continue through tonight before tapering off from south to north toward daybreak Monday. It will remain cool and showery for much of the upcoming week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Flood Watch in effect through 2 am for Ulster and Greene Counties... Wind Advisory has been cancelled... .UPDATE...As of 1025 PM EDT, an upper-level low continues to slowly track eastward across the Great Lakes while a potent, upper-level shortwave rotates around the main low across the northeast. A rather seasonably strong area of low pressure (986 hPa per latest RAP analysis) is tracking northward toward Long Island. An inverted trough is located just to the west of our area closer to the I-81 corridor. Overall, strong forcing from all of these features is resulting in widespread rainfall, which will continue through much of the overnight hours. A convective band of showers and thunderstorms is lifting northward and approaching Long Island and will then move into southern areas around and shortly after midnight. Here, rainfall rates may increase to 0.50 to 1.00 inches per hour for a short time and may result in some localized minor flooding in urban and poor drainage areas. Despite a decrease in precipitation intensity, we have extended the current flood advisory for portions of the mid-Hudson Valley and eastern Catskills as we anticipate this convective band to impact the area shortly, which could increase minor flooding problems in the area once again. We will also keep the flood watch as is until it expires at 2 am, though, areas across Dutchess and Litchfield counties should be on alert for some possible minor flooding with the approaching convective band. Elsewhere, we still expect this rainfall to lead to little if any hydrological issues. Wind speeds across portions of western New England and the Taconics of eastern New York have generally been in the 30 to 40 mph range. With the nose of the low-level jet now lifting northward out of our area, wind speeds are expected to slowly trend downward through the remainder of the night. As we have not observed any wind advisory criteria winds (46 mph or greater), we have cancelled the wind advisory an hour earlier than its original expiration time. Precipitation will begin to taper off from south to north during the overnight and early morning hours on Monday. With the clouds and the rain, temperatures will hold fairly steady tonight in the 40s with some upper 30s across some of the higher terrain. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... Monday, subsidence behind the shortwave trough rapidly translating north of the area, combined with midlevel dry air, should result in a dry start to the day. However, the combination of midlevel cold advection and diurnal heating should allow showers to quickly develop during the afternoon hours as shallow instability develops. The most widespread showers will be located north of I-88 and west of I-87 where the midlevel cold pool will be strongest (700 mb temps falling to minus-10C). Equilibrium levels will be rather high at around 15 kft, so isolated thunderstorms producing graupel or small hail will be possible. Highs are expected to range from the upper 40s to low 60s. The showers and isolated storms are expected to wane Monday evening, but coverage will likely increase again late Monday night as a shortwave trough pinwheels into the area around the upper low wobbling around just north of Lake Ontario. Lows Monday night should range from the mid-30s to mid-40s with a few snowflakes possible in the higher elevations. Tuesday, the upper low will remain rather stationary in the vicinity of the local area thanks to an evolving omega block over the CONUS. Associated midlevel cold pool combined with diurnal heating will result in numerous to widespread showers and isolated storms, with coverage likely better than Monday over most areas. It should be cooler than Monday with highs only reaching the mid-40s to mid-50s. Scattered rain and high- terrain snow showers will continue Tuesday night with lows in the low 30s to low 40s. Little to no accumulation is expected. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Upper cutoff low and associated midlevel cold pool are expected to remain over the local area at least Wed/Thu thanks to an omega block over most of the CONUS, keeping temps on the cool side and showers prevalent. Numerous to widespread showers expected again on Wednesday, especially during the afternoon and evening as weak diurnal instability develops. 700 mb temps continue to average around minus-10C, which is -1 to -2 standard deviations. The midlevels may warm slightly Thursday as the core of the cutoff low shifts east, so showers may be a bit less widespread compared with Wednesday, but scattered to numerous showers can still be expected. Highs both days are likely to be in the 40s and 50s. For Friday into next weekend, there are some signals that the blocky pattern breaks down somewhat, with higher midlevel heights gradually building in. There is uncertainty as to how quickly this happens, however. At least isolated to widely scattered showers remain possible Fri/Sat, and will trend the forecast mainly dry by Sun. Temps will increase as well, possibly back to near seasonal normals over the weekend with highs mainly in the 50s and 60s. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... Through 00z Tuesday...While there are a few pockets of VFR vsbys/cigs this evening, seeing mostly MVFR and some IFR conditions. Expecting conditions to deteriorate over the next few hours as additional moderate to heavy rain moves in from the south. GFL may stay low-end MVFR, but expecting IFR vsbys/cigs with moderate to heavy rain at ALB/POU/PSF from late this evening through around 8- 10z tomorrow morning. Rain tapers to showers late tonight/early tomorrow morning, and improvement back to VFR conditions is expected after 12z tomorrow at ALB/POU/GFL and after 15z at PSF. VFR conditions prevail through the rest of the day, although additional scattered "pop-up" showers are expected tomorrow afternoon. Will use VCSH and prob 30 groups at all TAF sites to highlight brief MVFR vsby and possibly cig restrictions in these showers. Winds will be at 5-10 kt from the east/northeast tonight, with some gusts of 15-20 kt possible. Between 6-9z, winds switch abruptly to the west/southwest behind a frontal passage. Note that there is some uncertainty in the exact timing of the wind switch, and it is possible this wind shift could occur an hour or two earlier than the current TAFs indicate. Tomorrow morning, winds will be at around 10 kt with some gusts to 20 kt from the southwest. Winds become more southerly tomorrow afternoon still at around 10 kt with some 20 kt gusts. Included low-level wind shear at POU and PSF this evening with a strong low-level jet overhead. ALB and GFL will come close, but likely fall just short of LLWS criteria. However, at these sites winds between 2000-3000 ft will likely be at 40-50 kt from the east/southeast this evening through 3-4z before diminishing afterwards. Outlook... Monday Night: Moderate Operational Impact. Likely SHRA...TSRA. Tuesday: High Operational Impact. Definite SHRA...TSRA. Tuesday Night: Moderate Operational Impact. Chance of SHRA. Wednesday: High Operational Impact. Definite SHRA. Wednesday Night: Moderate Operational Impact. Chance of SHRA. Thursday: Moderate Operational Impact. Chance of SHRA. Thursday Night: Low Operational Impact. Slight Chance of SHRA. Friday: Low Operational Impact. Slight Chance of SHRA. && .HYDROLOGY... A stronger storm system will bring moderate to possibly heavy rainfall through tonight. It appears this next round will bring 0.75 to 2.00 inches of rain in most areas, with higher amounts of 1.50 to 3.00 inches over easterly aspects of the eastern Catskills and southern Greens. Furthermore, elevated instability will cause brief heavy downpours this evening. This rainfall could result in minor urban and poor drainage flooding. Most rivers are forecast to crest below flood stage on Monday, but a few spots along the Schroon, West Canada, Schoharie, Esopus, Rondout, and Housatonic may get close to minor flood stage. A Flood Watch was issued for Greene and Ulster Counties to account for the heavy upslope rainfall in the Catskills and rises on the creeks and streams draining the Catskills. This area was preconditioned a bit by 1-1.5 inches of rain over the last 48 hours. Overall, do not expect this to be a major or widespread flood event, but at least some flooding is possible, especially in small creeks and streams, urban areas, and typical low lying spots. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...Flood Watch until 2 AM EDT Monday for NYZ058-059-063-064. MA...None. VT...None. && $$ SYNOPSIS...Thompson/Rathbun NEAR TERM...Thompson/Rathbun SHORT TERM...Thompson LONG TERM...Thompson AVIATION...Main HYDROLOGY...Thompson
Area Forecast Discussion
National Weather Service Cheyenne WY
530 PM MDT Sun Apr 30 2023 .SHORT TERM...(This evening through Monday) Issued at 300 PM MDT Sun Apr 30 2023 Forecast challenges deal with precip chances the next couple days. Currently...surface low in central Colorado with a stationary front extending north into Albany County near Laramie...north northwest to Casper and then northwest into western Montana this afternoon. Winds northeast east of the front...westerly to the west of the front. Surface ridge of high pressure extends south out of Saskatchewan Canada...south to western South Dakota...all the way down to the Oklahoma/Texas Panhandle area. Radar has been PPINE so far this afternoon with a few mid and upper level clouds. Most areas are clear. RAP and HRRR mesoscale simulated radar continues to remain dry this afternoon. Went ahead and removed PoPs from the forecast this afternoon and early evening. Real nice day Monday across the CWA as upper ridge axis begins to move into Carbon County. Seeing 3 to 6C warming of 700mb temperatures over the next 24 hours...so afternoon highs Monday likely to be several degrees warmer over todays highs. Ridge axis right over eastern Wyoming Tuesday morning...with afternoon highs in the mid 70s in the Panhandle and near 70 west of the Laramie Range. By Tuesday afternoon...ridge axis forecast to be near the Nebraska Panhandle. GFS/ECMWF/NAM/SREF guidance all in agreement with showers developing over the western half of the CWA west of the Laramie Range. So continued high end chance PoPs from Cheyenne to Elk Mountain Tuesday afternoon. .LONG TERM...(Monday night through Sunday) Issued at 330 PM MDT Sun Apr 30 2023 As the calendar flips to May, the weather looks likely to reflect the changing seasons. The primary focus of this outlook is a period of unsettled weather increasingly likely for Thursday through Saturday, that will bring daily chances for showers and thunderstorms. The synoptic pattern this week will be dominated by an omega-block, with a narrow but amplified ridge over the Rockies/central Plains sandwiched in by two stubborn upper level lows meandering near each coast. Expect warm temperatures underneath the ridge, with Wednesday likely the warmest day of the week. GEFS mean 700-mb temperatures maximize around 00z Thursday at about +8C likely supporting widespread 70s to 80s across the area. Wednesday is likely to continue the pattern of isolated afternoon convection, but this is not expected to be widespread or organized. By Thursday, however, models continue to show a weak point in the middle of the ridge over our area developing. This will allow a series of vort-maxes rotating around the west coast upper level low to push through the area from southwest to northeast. Simultaneously, the break in the ridge may allow deeper southeasterly flow to develop on the southwest flank of the lobe of the ridge left to our north over Canada. The result of this will be fairly deep moisture advection through the day on Thursday into the high plains. GEFS mean dewpoints at KBFF exceed 50F by 00z Friday. Moreover, the NAEFS mean and ECWMF ensemble mean precipitable water and 700-mb specific humidity values both approach or exceed the 99th percentile of climatology. With plentiful moisture present, all we would need is some lift to get precipitation going. One piece will come in the form of the positive vorticity advection from the vort-max aloft. Additionally, the GFS depicts a mid-level convergence boundary developing between southwest flow over the mountains and southeast flow over the high plains, producing significant frontogenesis and vertical motion in the 700 to 500-mb layer. Modest instability will also be present, indicating the possibility for thunderstorms. The ECMWF is not as aggressive with the convergence boundary and thus still produces numerous showers and storms, but with a bit less QPF. Additional vorticity lobes moving through are likely to additional rounds of scattered to widespread showers and thunderstorms on Friday. Finally, models are in fairly good agreement of a more significant shortwave passing through on Saturday. This activity is reflected in the forecast with widespread PoPs in the 40 to 60% range each afternoon and evening with rounds of precipitation developing over the higher terrain and moving off to the northeast through the overnight. This overall pattern has fairly strong ensemble support, with almost all members showing widespread precipitation. The highest confidence in higher rainfall totals is further off to the east, whereas Carbon county will likely receive less. The GEFS 50th percentile total QPF exceeds 1.25" at KCYS by Saturday evening, while the ECMWF ensemble 50th percentile is a little more modest at 0.75". Observed precipitation will likely depend on mesoscale features, so may be quite a bit more variable than what is depicted in an ensemble mean, but this is where the confidence is right now at several days lead time. Temperatures look to cool down a bit for Thursday-Sunday as model mean 700-mb temperatures drop to the +2 to +4C range. As far as the severe potential goes, we will have modest instability and some vertical wind shear, but parameters look on the low end for what could produced organized severe convection. However, we still are likely to see isolated to scattered strong convection with gusty winds and small hail. It`s a little early to be going into the details on storm type and threat though, so this will be ironed out in the coming days. We will also need to closely monitor snow levels with this event. Substantial snowpack remains as low as 7500 ft in some areas, and current best estimate snow levels for the late week precipitation are around 9000 ft or higher. Warm rain on snow could lead to accelerated runoff and the potential for flooding. Thus, the main takeaway here is to expect a period of unsettled weather from Thursday through Saturday, with scattered to numerous showers and thunderstorms likely each afternoon extending into the overnight, though details on rainfall totals, severe potential, and flood potential remain uncertain. && .AVIATION...(For the 00Z TAFS through Monday afternoon) Issued at 530 PM MDT Sun Apr 30 2023 A weak convergence boundary will remain near the Laramie Range this evening before weakening tonight. Shower activity associated with this boundary has mainly been confined to the mountains and even there has been short-lived. Expect SCT to BKN skies around 6k feet agl this evening to dissipate. HAZARDS/WEATHER TRENDS: VFR conditions are expected with probability of fog or low CIGS near zero percent tonight and into Monday morning. && .FIRE WEATHER... Issued at 300 PM MDT Sun Apr 30 2023 Stationary front currently lays from Laramie to just south of Casper...west northwest to Riverton and then north into western Montana this afternoon. East of this front...northeasterly winds are common...while west...westerly winds prevail. Minimal fire weather conditions with above critical afternoon humidity and light winds this afternoon. Warmer Monday as upper high pressure builds into the area from the west. Again...afternoon humidity expected to stay above critical levels. By Tuesday...upper ridge moves east into the Panhandle with chances for showers and thunderstorms developing along and west of the Laramie Range. May see critical afternoon humidity Wednesday...but strong winds are not expected. && .HYDROLOGY... Issued at 310 AM MDT Sun Apr 30 2023 Warmer temperatures this week will produce snowmelt runoff into the Little Snake River and Upper North Platte River basins. The CO Basin RFC is still forecasting the Little Snake River to climb above action stage near Dixon by the middle of next week. We will also need to keep an eye on snow levels later this week as the closed low approaches from the southwest. If snow level stays above 9000 ft we may be looking at the potential for rain on snow, which may ripen the snow pack more or cause faster snowmelt. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...GCC LONG TERM...MN AVIATION...TJT FIRE WEATHER...GCC HYDROLOGY...MJ
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
605 PM CDT Sun Apr 30 2023 .Discussion... Issued at 259 PM CDT SUN APR 30 2023 Key Messages: - Breezy Through Monday - Seasonable Temperatures - Next Precipitation Chances: Thursday/Friday Discussion: 500mb pattern currently dominated by a closed-low system over the Central Great Lakes Region with open short-wave trough axis through the southeast Atlantic Coast. An amplified ridge axis currently sits over the Intermountain West. This has left our forecast area in mid to upper-level northwesterly flow, forcing the cold front that passed through last night well south of the Ozarks. At the surface, low pressure is directly underneath the closed H5 low over the Central Great Lakes. There is a stronger high pressure over the Canadian Prairie Provinces with inverted ridge extending into the Central High Plains. With stronger AVA and subsidence over the central CONUS, would anticipate for the surface high pressure to strengthen over the next 12 to 18 hours, and with the exiting low over the Great Lakes Region should maintain a stronger pressure gradient across the region. This along with stronger mixing this afternoon will continue gusty northwesterly winds up to around 35 kts. Locally higher gusts are possible, especially in northeastern portions of the forecast area where winds at the top of mixed layer are progged around 37 kts. This afternoon, GOES 16 satellite imagery has shown the development of a cumulus field across most of the forecast area. With steeper boundary layer lapse rates and weak lift still on the backside of cyclonic flow, expect this to continue through the afternoon and dissipate after peak insolation is lost. The boundary layer is quite dry after yesterday`s FROPA, and will prevent any precipitation that may try to form from the cumulus field. For Monday, subsidence downstream from the H5 ridge axis will continue to keep skies mostly clear. Additional clouds are possible in our far east and northeast which may be on the very edge of the cyclonic flow from the closed-low system to the east. Most of the moisture though is being held east of that system, which should inhibit broken or overcast skies. Another breezy day may be in store for eastern Kansas into east-central Missouri with strong gradient flow still in play, and boundary layer mixing through afternoon again. Current RAP soundings indicate 30 to 35 kts toward the top of the mixed layer again, especially east of Interstate 35. Temperatures will be in the lower to mid 60s. Cooler temperatures possible in the far northeast if cloud cover from central Illinois drops southwestward into our area. A quick note on fire weather conditions for Monday: RH values may drop below 30 percent in northwest Missouri with wind gusts 20 to 25 MPH. Wind gusts above 30 MPH are favored more for northeast Missouri, where temperatures should be cooler and not nearly as dry. Therefore, no fire weather headlines were issued, but will need to watch the winds closely in northwest Missouri. An increase in winds could increase fire weather concerns in northwest Missouri on Monday. Tuesday and Wednesday, a PV anomaly over the eastern Pacific develops a strong closed-low at H5 over the west coast and results in an Omega Block pattern for most of the CONUS, as the closed-low system currently east of the area slides into the eastern Great Lakes Region. The back-edge of the cyclonic flow should just exit out of our area. Meanwhile, low-level flow across the central CONUS turns southerly in response to the PV anomaly over the west coast, and helps to amplify the H5 ridge across the central CONUS. While we will not be in a predominant WAA regime, the nose of the warm air will attempt to push up against our forecast area. With the mid to upper-level flow northwesterly and AVA downstream from the ridge axis, skies should remain clear enough to allow stronger isolation on Tuesday and Wednesday, increasing temperatures into the upper 60s and maybe lower 70s, most likely lower 70s for southern reaches of our forecast area. The winds should also be lighter, as the center of the high pressure moves over the area and the pressure gradient slides east of the Mississippi River. The stronger meridional flow will be confined to the Central and High Plains over the next couple of days, therefore will not a see a great deal of moisture return as the access to Gulf moisture will be greatly limited. For Tuesday afternoon high temperatures, current inner-quartile spread is between 60 and 68 degrees for most locations, and on Wednesday between 64 and 72. Temperatures very seasonable for the start of May. With clear skies and light winds, expecting overnight lows in the mid to upper 30s. Current model guidance keeps frost/freeze conditions out of the forecast area, but will need to monitor diurnal trends closely for the middle part of this week. Early Thursday, the closed-low over the west coast has most of its vorticity wrapped around it and will be slow to propagate eastward. However, there is another H5 wave in Central Canada that is developing on the backside of the Great Lakes system that has better flow, but because of the blocking pattern is forced southward into the upper Midwest. This de-amplifies the H5 ridge across the Central CONUS, and sends a weak shot of vorticity across the forecast area. The kinematic lift with this along with the WAA allows a surface cyclone to develop in the High Plains, and looks to back surface winds more toward the southeast. This should provide more moisture transport Thursday morning and into the afternoon. With the combination of the mid-level vort max and surface response, seeing a signal for Q-vector convergence across the forecast area that will help lead to rain shower activity. GFS deterministic solution depicts around 1000 J/kg CAPE developing as the H5 ridge breaks down, which may support thunderstorm development. With the better flow wrapped up with the two closed-low systems, the environment may not be greatly sheared, thus limits organization potential and could hinder severe potential. If model guidance is forcing the eastern low eastward too quickly in this blocking pattern, there may be slightly better shear. Once the west-coast wave comes ashore, should be able to better refine the forecast for thunderstorm potential. Even if instability is not fully realized, still looking at showers across the area Thursday, with ensemble probabilities for at least one-tenth of an inch over 90 percent along Interstate 70 and southward, and between 50 to 60 percent elsewhere. Shower potential continues into Friday as another vort max breaks away from the west coast PV anomaly and creates another period of stronger convergence, as well as return moisture flow into the region. There again is some signal for instability to develop with stronger theta-e advection into the region, but deep layer shear again may be displaced from the better lift and instability. Medium to high confidence in rain activity on Friday across the forecast area, with potential for embedded thunderstorms. Like with Thursday, if our area is able to tap into stronger mid to upper level flow, perhaps wind shear becomes more prominent to support more organized activity. As for QPF, ensembles maintain probabilities above 80 percent for at least one-tenth of inch of QPF for our central and above 50 percent northward. And for half an inch of QPF, looking at probabilities above 60 percent southward and 30 percent northward. For next weekend, lower confidence in how the large scale synoptic pattern evolves with the break down of the blocking pattern. A ridge likely sets up somewhere over the CONUS that could give us dry conditions, but there also solutions that send another vort max across the region bringing more rain shower activity. NBM guidance has placed some low end POPs across the forecast area for next weekend. With overall low confidence, will not make any drastic to changes to this forecast for next weekend. && .Aviation...(For the 00Z TAFS through 00Z Monday Evening) Issued at 605 PM CDT SUN APR 30 2023 VFR conds will prevail thru the pd as sct clouds around 8kft becomes clr skies by 02Z with just ocnl passing high clouds poss. The main concern for aviators will be the gusty NW winds. Winds btn 15-20kts with gusts to 30kts will diminish by 02Z to around 10kts before increasing again btn 14Z-16Z to 15-20kts with gusts to 30kts. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Discussion...Krull Aviation...73