Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/25/17

Area Forecast Discussion
National Weather Service Taunton MA
1019 PM EDT Mon Apr 24 2017 .SYNOPSIS... Low pressure will slowly track up the east coast Tuesday and Wednesday, bringing periods of rain, gusty winds and the risk of minor coastal flooding. Drier and milder conditions will briefly return Thursday. A cold front may bring scattered showers and possibly a few thunderstorms Friday into early this weekend, but may waver across the region into early next week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... No major changes to the forecast this evening. Mainly had to tweak rainfall chances this evening, as a precursor band of very light rainfall made it all the way to the southern coast of New England. Latest few runs of the HRRR seemed to have the best handling of this light rainfall heading into early Tuesday morning. Dew point depressions across the northern half of MA remain large, and will take some time to overcome. Thus, still thinking rainfall will hold off across most of our region tonight. Minor tweaks to temperatures and dew points to reflect observed trends. 650 PM Update... Northern fringe of high cloud deck moving slowly across southern areas at 22Z as seen on latest IR satellite imagery as well as OBS. Thin band of precipitation seen across S coastal areas on NE regional 88D radar mosaic, but no rain is reaching the ground due to continued very dry low level layer across the region. Dewpts at 22Z were in the lower-mid 30s across N central and NW Mass with temps hovering at 70-75 degrees. Very high dewpt depressions indeed. With E-SE winds in place, T/Td spreads along the S coast are much lower, though still dry enough to allow for evaporation of the precip aloft before reaching the ground. Have updated to bring conditions current and incorporated trends into the evening forecast. This did lower dewpts a bit, but should start to see them rise during the night. Previous Discussion... Deep moisture plume will slowly lift northward into SNE tonight resulting in lowering cigs. Band of light rain across northern NJ and NYC area will struggle to move north through this evening due to presence of dry layer in the low levels so expect dry conditions into this evening. Eventually expect some spotty light rain to move up from the south and west after midnight as low level jet moves into the region along with increasing low and mid level frontogenesis which induces modest forcing for ascent. Best chance of rain will be from western New Eng to the south coast region where low levels eventually moisten up. However, it may remain dry through the night further north across northern and especially NE MA where low level dry air persists through 12z. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Tuesday into Tuesday night...Closed/vertical stacked low off the SC coast lifts slowly northward to the Mid Atlc region Tue night. With high pres locked over the north Atlantic, this results in a deep moist easterly flow into New England with low level wind and PWAT anomalies increasing to 2-3SD above normal. This will bring periods of rain, heavy at times through Tue night. The rain will gradually spread north across SNE through the morning and into the afternoon as low levels moisten and easterly low level jet moves north across the region. Rainfall during Tue should be mostly light to moderate. But a second period of heavier rainfall is likely Tue night, as a SSE low level jet approaches with increasing PWATS over 1.5". Expect a period of heavy rain along with chc of a few thunderstorms along the coast after midnight as elevated instability increases at the nose of the low level jet. Rainfall of 0.75-1.5" is expected with locally up to 2 inches in any heavier convective rain/t-storms. This will not produce river flooding but minor urban and poor drainage flooding is possible, especially Tue night. It will be a chilly and raw day Tue with gusty NE winds and temps in the mid 40s to lower 50s, mildest near the south coast. NE winds will occasionally gust to 20-30 mph near the coast with highest gusts over the Cape/Islands. Temps should rise into the mid 50s Tue night across RI and SE MA, with slowly rising temps overnight in the interior. Gusty easterly winds will continue Tue night along the coast. 50+ kt low level jet approaches the south coast late Tue night but inversion will likely prevent these winds from mixing down. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Overview... As cutoff H5 low pres and associated surface system moves up the eastern seaboard Wed, it will slow and tend to weaken near or just S of the region through Thu night. Band of heavy rain moves across through midday Wednesday ahead of this system, along with gusty E-SE winds that will slowly shift to S as remnants of the surface low linger. Will likely see lingering light showers, areas of drizzle and fog. Can not pinpoint when or where the showers will occur, but suspect mainly across central and eastern areas with the good low level moisture will continue to feed into these areas with the onshore winds, albeit diminishing as the low weakens. Digging H5 trough across the Plains states will slowly shift E as large subtropical high pres (Bermuda high) looks to set up off the SE U.S. coast by the end of the week. This will make the progression of the H5 trough difficult while mainly zonal flow sets up across New England N of the high. A cold front may try to make a run across the region, but appears will get hung up in the W-E flow. Not seeing a whole lot of moisture or instability with this front, especially as it wavers across the region by this weekend. Will likely see S-SW winds late this week through the weekend, which may shift to W at times depending where the front lies. A lot of uncertainty with this portion of the forecast. Details... Wednesday...Moderate confidence. As weak low moves up the eastern seaboard, heaviest precip will occur during the morning into midday hours. Some question as to how quickly the precip exits the region late Wed into Wed night. 12z NAM/GFS tend to be quickly in pushing heavier precip out, while the GGEM/ECWMF linger it a bit later as the low lingers S of the region. With the low lingering, could see some marginal instability work into S coastal areas. Noted LIs around zero to -1 along the S coast and over the southern waters, as well as K indices around 30. Have kept mention of isolated thunder across the immediate S coast and adjacent coastal waters through midnight, but not confident. The more certain part of this forecast will be the lingering showers, areas of drizzle and fog through Wed night. May see visibilities locally reduced below 1 mile, less along the immediate coast early Wed morning and again Wed night. Will also see E-SE winds gusting up to 25-30 mph mainly across Cape Cod and the islands where a strong low level jet will pass across. Winds at 2Kft running in the 50-60 kt range, but not seeing a lot of good mixing with an inverted layer aloft. Winds will diminish as pres gradient slackens and winds start to shift to more southerly during the afternoon or Wed night. Thursday...Low to moderate confidence. As weakening surface and upper low meander near or just off the coast, will see some more scattered showers, patchy drizzle and fog in place. The drizzle and fog will mainly occur during the overnight and early morning hours, then return late Thu night. With the lack of a strong onshore flow, though, looks like temps should become milder as winds start to shift to a more southerly direction, though they will remain light. Just seeing a lot of low level moisture lingering through Thu night. Friday...Low confidence. Will start to see a more S-SW wind flow in place as surface and upper low finally flattens out and a cold front starts to approach. However, noting the SW H5 steering currents tend to become more W-SW during the day and especially Fri night. So, as the front approaches, will get caught in this flow and slow its progression. Some showers may move into N central and western areas ahead of this front as it tries to sag S across the region Fri night or early Sat morning. Saturday-Monday...Low confidence. A lot of uncertainty with remnants of the front lingering across the region. At this point, have kept slight chance to low chance POPs across the region. Exact timing and position of the precip still in question though. As the H5 long wave trough tries to shift E, may see the front lift around the late Sunday or Monday timeframe, but this timing is uncertain. Temperatures should run warmer than seasonal normals for late April. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday Night/... Through tonight...High confidence. VFR cigs trending downward to MVFR/IFR along the south coast towards daybreak with patchy -RA developing. Tuesday and Tuesday night...Moderate confidence. Conditions lowering to IFR/LIFR in the morning with widespread rain, stratus and patchy fog, lingering through Tue night. E wind gusts to 25 kt developing over Cape/Islands Tue with winds veering to SE Tue night with similar gusts. LLWS developing Cape/Islands after midnight as SE/S low level jet at 50+ kt develops. KBOS TAF...Moderate confidence. KBDL TAF...Moderate confidence. Outlook /Wednesday through Saturday/... Wednesday...Moderate confidence. MVFR-IFR CIGS with -RA/RA and patchy fog. Reduced VSBYS likely, down to IFR in spots. May see areas of LIFR CIGS across the higher inland terrain and along the coast. SE winds gusting up to around 25 kt mainly across Cape Cod and the islands Wed, should diminish Wed night. Low risk of TSRA along S coastal terminals. LLWS impacts for coastal terminals with 40-50 kt S winds 2 kft agl, possibly approaching 60 kt on the outer Cape and Nantucket, shifts offshore late in the day. Wednesday night...Moderate confidence. Mainly IFR in areas of -RA, -DZ and FG. Areas of VLIFR along the coast and across higher terrain. Light/variable winds, except SE-S up at 5-10 kt across Cape Cod and the islands. Thursday-Thursday night...Low to moderate confidence. Drizzle and fog move offshore early Thu, but isolated showers linger with local MVFR VSBYS. CIGS should improve to VFR across western terminals, but will likely remain MVFR-IFR for central and eastern areas. IFR-LIFR conditions may return in patchy fog and low clouds Thu night with light winds. Friday-Saturday...Low confidence. Brief MVFR-IFR VSBYS early Fri, then improving. May see scattered -SHRA across N central and W Mass early Fri. CIGS should be mainly VFR, though areas of MVFR return Fri night and early Sat. SW winds shift to W late Fri or Sat, though timing very much in question. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday Night/...High confidence. Tonight and Tuesday... Increasing pressure gradient between low pres to the S and high pressure to the N will lead to increasing easterly winds spreading north across the waters late tonight and especially Tue. Gusts to 25-30 kt expected with building seas. Reduced vsbys in rain and fog Tue. Tuesday night... E winds veering to SE overnight. Wind gusts may briefly diminish for a time Tue evening but increase again after midnight with gusts 25-30 kt, especially south coastal waters as SSE low level jet approaches. Reduced vsbys in rain and fog. Outlook /Wednesday through Saturday/... * Small craft advisories likely for a majority of the period. Wednesday...Moderate to high confidence. E-SE winds at 15-20 kt will continue, with gusts up to around 30 kt during the day. Seas continue to build up to 8-12 ft during Wed, highest along the outer waters south and east of Cape Cod and Nantucket. Winds and seas will slowly diminish Wed night, though wind will remain onshore. Reduced visibilities possible during the day, more likely at night in patchy rain, drizzle and fog. Low risk of thunderstorms on the southern waters through midnight Wed. Thursday-Thursday night...Moderate confidence. Light winds in place, mainly S across the southern waters and E-SE on the eastern waters. Seas remain high, up to 6-8 ft on the outer waters early and slowly subsiding but remain at or above 5 ft over the open waters. May see local visibility restrictions in patchy fog mainly after dark. Patchy rain and drizzle may also linger. Friday-Saturday...Low to moderate confidence. Light S-SW winds early Fri will increase, gusting up to around 20 kt. Winds may shift to W as a cold front may approach sometime Sat. Seas remain around 5 ft on the outer waters Friday, though may subside Fri night or early Sat. Patchy fog with locally lower visibilities early Fri. May see a few showers late Fri into Sat if cold front approaches. && .TIDES/COASTAL FLOODING... * Potential minor flooding impacts during astronomically high tides Tuesday night through Wednesday along the east and south coasts Not anticipating any flooding impacts for the Tue high tide as winds, surge and seas will not have built up enough. Minor flooding possible during the Tue night and Wed high tide cycles along both coastlines. A storm surge around 1 ft with low risk of 1.5 ft surge on top of high astronomical tides and building seas may lead to minor inundation of vulnerable shoreline roads. Some beach erosion is also possible, especially for east and SE facing beaches. Boston High Tides (flood stage 12.5 feet)... 11.47 feet / Tuesday 11:20 pm 11.15 feet / Wednesday 11:50 am Providence High Tides (flood stage 7 feet)... 5.98 feet / Tuesday 8:11 pm 5.53 feet / Wednesday 841 am && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 4 AM Tuesday to 8 AM EDT Wednesday for ANZ232>235-237-255-256. Small Craft Advisory from 8 AM Tuesday to 8 AM EDT Wednesday for ANZ231-250-251-254. && $$ SYNOPSIS...KJC/EVT NEAR TERM...Belk/KJC/EVT SHORT TERM...KJC LONG TERM...EVT AVIATION...KJC/EVT MARINE...KJC/EVT TIDES/COASTAL FLOODING...Staff
Area Forecast Discussion
National Weather Service Billings MT
828 PM MDT Mon Apr 24 2017 .UPDATE... Latest upper air analysis shows 100+ kt H3 jet nosing from the great basin toward the central Rockies, with increasingly divergent flow extending thru WY into our cwa. The combination of increasing synoptic scale ascent and deepening upslope winds in a moist and unstable airmass has allowed for plenty of showers across our western cwa this evening. There has been some lightning but that is diminishing since sunset. Cold advection associated with Canadian surface high to our northeast has dropped temps to the 40s...with low-mid 30s noted in NE MT already. Upper and surface lows will become stacked later tonight in northeast WY, allowing for significant precipitation along the easterly upslope side of the Bighorns, extending across our far southeast. Trailing convergent axis in central MT will keep pcpn going in our west tonight into early tomorrow as well. Our northeast parts from Miles City to Baker will remain dry with this system. Have made no changes to the inherited winter highlights, which include a Winter Storm Warning for the Beartooth/Absarokas and advisories for the Sheridan Foothills and across our far southeast zones. Low level cooling will be a result of advection and dynamics, and latest RUC wet bulb zero height forecasts suggest a change to snow overnight, perhaps not til after 09z for the lower elevations of Sheridan County. So, these areas will see a good dose of rain before snow becomes a concern. Further west, the Beartooth/Red Lodge foothills will also see a change to wet snow late tonight or early Tuesday, but moisture will begin to lessen by then. So although some wet accumulation is possible in the Paradise valley and at Nye and Red Lodge, believe these areas will see most of the precipitation in the form of rain. Melville on the east side of the Crazy Mtns should also see some wet accumulation. Accumulations of 3-6 inches still seems a good call for our far southeast, especially over the hills and near the WY border. Will need to keep an eye on Sheridan County per the upslope. If Sheridan/Dayton/Big Horn change over earlier than expected, higher snow amounts are possible. Also, the Bighorns will see heavy snowfall and this looks to be a high end advisory with up to a foot of snow above 6kft. Travel on I-90 thru Sheridan and on Highway 212 thru southeast MT will be messy tomorrow morning. JKL && .SHORT TERM...valid for Tue and Wed... A few showers were moving E through the forecast area early this afternoon. Abundant cloud cover was keeping thunder at bay. A Pacific jet, seen on water vapor, was diving SE into the four- corners region and will bring upper divergence to the region through Tuesday as it carves out a deep trough. An upper low will form over NE WY by 12Z Tue. and will push E into the Dakotas Tue. evening. Associated surface low will deepen over E WY tonight. Models agreed that a bullseye of QPF would develop N of this low and affect areas from the Sheridan Foothills N and NE into SE MT tonight through Tue. morning. Strong ENE winds will wrap around this low into the forecast area. Backdoor cold front will push W into the area bringing negative 850 mb temperatures as far W as Yellowstone and Musselshell County Tue. morning. QPF amounts will be greater than a half inch in some areas around the low. Soundings showed the precipitation changing to snow around the low by 12Z Tuesday. Snow ratios combined with expected QPF will allow for several inches of snow. The snow, although wet, will combine with the winds to support Advisory conditions. Therefore will have an Advisory for snow tonight through Tuesday in SE MT and the Sheridan Foothills. Time-height cross sections continued to support high snowfall amounts in the Beartooths/Absarokas and NE Bighorns into Tuesday. The Bighorns may see Warning criteria snow, but will leave the Advisory in place for now. Otherwise, rain will mix with snow across the area overnight through Tue. morning. Some rain/snow mix will linger in the SE Tue. afternoon. Snow amounts looked too light to support an Advisory over remaining areas, but this will need to be watched in subsequent shifts. Highs will reach only the 40s on Tuesday. Did mention some thunder over western zones Tue. afternoon and evening with LI`s below zero degrees C. Precipitation winds down Tue. night into early Wednesday under WNW flow/weak ridging. Another Pacific jet dives SE into the western U.S. Wed. afternoon through the end of the period, lowering heights and bringing more showers. Wednesday will be a bit warmer than Tuesday with highs in the 50s. Arthur .LONG TERM...valid for Thu...Fri...Sat...Sun...Mon... Extended period Thursday and Friday is cool with upslope flow with low heights aloft but fairly disorganized structure to the upper trough over the region. This will yield a couple of days with modest precipitation and persistent cold temperatures with accumulating mountain and likely foothill snowfall. But accumulation rates will be slow and daytime melting could occur below 6000 feet so impacts may be limited from a winter perspective. The amount of precipitation will cumulatively cause sloppy conditions for non paved roads and will continue to increase the amount of moisture in the ground and in the snowpack so streams and rivers will remain at elevated levels for this time of year. Upslope flow breaks on Saturday and a transition to an unsettled northwesterly flow sets up for the remainder of the extended. This will allow for a minor warmup but with still below normal temperatures and more shower chances but amounts will not be as great as the early week or late week events. borsum && .AVIATION... Increasing upslope flow this evening and overnight will cause widespread low clouds and a mix of rain and snow. Mountain and foothill obscurations will become widespread and all terminal sites will encounter IFR conditions or worse tonight in low cigs and reduced vis. AAG/borsum && .PRELIMINARY POINT TEMP/POPS... Tue Wed Thu Fri Sat Sun Mon ----------------------------------------------------------- BIL 037/047 035/056 039/049 036/046 034/052 036/058 040/058 85/O 32/T 45/W 75/R 32/O 11/B 33/R LVM 036/050 032/054 035/047 030/046 029/051 030/056 034/055 87/T 46/T 75/W 55/O 42/O 22/R 33/R HDN 037/049 034/058 039/050 037/048 035/054 035/060 039/060 85/O 21/E 45/W 56/R 32/R 11/B 33/R MLS 033/046 031/055 036/053 036/050 035/055 036/060 041/060 11/E 11/B 23/W 33/R 21/B 11/U 23/R 4BQ 033/044 027/053 032/048 034/046 032/050 033/057 037/059 77/O 11/B 24/W 44/O 33/O 21/B 33/R BHK 027/043 024/051 028/051 030/050 031/053 031/057 035/057 01/E 11/B 12/W 12/O 11/B 11/B 24/R SHR 034/043 030/052 035/045 034/042 030/046 030/053 036/054 ++/O 22/T 45/W 66/O 43/O 11/B 32/R && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...Winter Weather Advisory in effect until 6 PM MDT Tuesday FOR ZONES 36>38-58. Winter Storm Warning in effect until 6 PM MDT Tuesday FOR ZONE 67. WY...Winter Weather Advisory in effect until 6 PM MDT Tuesday FOR ZONES 98-99. && $$
Area Forecast Discussion
National Weather Service Charleston SC
1127 PM EDT Mon Apr 24 2017 .SYNOPSIS... A low pressure system will affect the area tonight, before pulling away Tuesday. Although a short wave could impact the area late Thursday, high pressure will prevail most of the time into the weekend. A cold front could affect the area early next week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... The Flash Flood Watch for Inland Berkeley County will be allowed to expire at midnight. Showers will continue to diminish through the night. Updated pops to reflect current trends. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... Tuesday: The separation between the surface low and it`s accompanying cyclone aloft with shrink as the associated surface warm and cold fronts occlude and the resulting vertically stacked low pulls away to the NE. The last lobe of vorticity spinning counter-clockwise will pull through the area in the morning, and with considerable wrap-around moisture to continue across our northern zones, we still have a slight chance to chance of showers for the Charleston quad-county area through 1-3 pm. Widespread low stratus to start the day will lift into an extensive cumulus deck, and will be slow in diminishing in coverage until late morning south and not until mid to late afternoon north. Depending upon this transition, it will have huge implications on max temps. For now we have mid 70s north of I-26 where cloud cover will last longest, upper 70s over the rest of SC, and 80-83F across our GA counties where insolation will b most prevalent. Tuesday: Mid and upper level will develop and the W-NW extension of Atlantic high pressure pokes in behind the departing stacked low pulling through the Great Dismal Swamp and VA Tidewater to the nearby Atlantic off the Delmarva. Winds will decouple and with mostly clear skies south and partly cloudy north, there will be enough radiational cooling to get lows down to the upper 50s-lower 60s inland from the warmer beaches. Wednesday: Deep-layered high pressure with rising surface pressures and climbing heights aloft will provide the region with plentiful sunshine and dry conditions. Temps at 850 mb are as high as 14-16C, or between the 75th and 90th percentile for late April, and equates to temps reaching the mid and upper 80s. Coastal sections will experience a resultant sea breeze, so highs will generally be held below 80F. Thursday: Sub-tropical ridging at the surface and low levels, and a W-SW flow aloft will dominate. The resulting subsident cap around 5- 6K ft looks to keep the majority of the area rainfree, but a dampening mid level short wave situated in the Pacific NW as of late Monday, will skirt the region late in the day, actually taking on a slight negative tilt. This could spark a few showers and t-storms far inland sections before dark. Despite a little greater cloud cover than Wednesday, similar 850 mb temps will produce highs again the in the mid or upper 80s inland from the barrier islands. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... A strengthening upper ridge and strong Atlantic high pressure will maintain above-normal temperatures and mainly dry weather. Friday and Saturday will probably reach the lower 90s across inland southeast GA with upper 80s elsewhere. A cold front is expected to approach next Monday, possibly bringing some rain. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Expect IFR cigs to fill in behind the upper low tonight, especially at KCHS. KSAV is a bit more questionable as to how low cigs will get. Latest RAP soundings suggest low-end MVFR, but IFR is possible. Expect prevailing IFR or lower at KCHS, but opted to limit cigs to alternate minimum thresholds for now. Extended Aviation Outlook: No significant concerns. && .MARINE... Tonight: Winds expected to turn westerly behind departing low pressure, mainly reaching 15-20 kt with seas 3-5 feet, except up to 6 feet in the Charleston County waters and the outer Georgia waters where an Advisory remains in effect. Tuesday: There remains a cyclonic flow around low pressure off to the north through the day to hold any resultant sea breeze circulations at bay until maybe late in the day. Winds and seas will be below any advisory levels on all waters, with one exception, the outer GA waters, where the SCA continues into the afternoon. Wednesday through Saturday: Atlantic high pressure will dominate with a S-SW synoptic flow to prevail. Despite some boost from the sea breeze, winds won`t be any higher than about 15-18 kt and seas will be capped at 3 or 4 ft. && .TIDES/COASTAL FLOODING... Astronomically high tides will prevail during the middle of the week due to the Perigean Spring Tides, likely resulting in the risk for shallow coastal flooding along at least parts of the coast with the evening high tides Wednesday and Thursday. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...Small Craft Advisory until 2 PM EDT Tuesday for AMZ374. Small Craft Advisory until 6 AM EDT Tuesday for AMZ350. && $$
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
705 PM CDT Mon Apr 24 2017 .AVIATION.../00Z TAFS/ VFR conditions are expected to continue at all sites until MVFR ceilings develop at the I-35 sites around 11Z as southerly 10 knot winds bring Gulf moisture back into the region. Some models are indicating that ceilings may lower to IFR at SAT/SSF, but given that this is the first day of moisture return we have stuck with higher ceilings for now. Ceilings should lift to VFR by 17Z at all sites with southerly winds gusting to 20-25 knots tomorrow at AUS. && .PREV DISCUSSION... /ISSUED 256 PM CDT Mon Apr 24 2017/ SHORT TERM (Tonight through Tuesday Night)... A compact mid level impulse crossing the Mexican mountains will generate isolated showers and thunderstorms there this afternoon. Only the HRRR shows any of this moving across the Rio Grande into our area this evening. Also, previous runs of TTU-WRF showed some moving into our far western counties. Have a 5 POP for Maverick and Dimmit Counties where steering flow would take them. As an upper level trough moves across the Rockies and out into the High Plains, a surface low drifts to the northeast across the Southern Plains. South to southwest lower level flow will result. This increases moisture for stratus formation later tonight into Tuesday morning, then it mixes out by midday. The main impact of this will be a rapid strong warmup as 850 MB temperatures warm to 21C-27C and 925 MB to 27C-33C on Tuesday. High temperatures Tuesday will be about 10 degrees above normal, with some approaching 100 along the Rio Grande. A dryline moves into western areas late Tuesday night. There may deep enough moisture below a strong cap for patchy drizzle along and east of Highway 281 by Wednesday morning. Have silent 10 POPs for this. LONG TERM (Wednesday through Monday)... The upper level trough moves out across the Plains on Wednesday with the dryline moving across the remainder of our area by midday. In spite of a right entrance region of an upper level jet passing overhead, moisture will be confined to below a strong cap with only patchy drizzle for only silent 10 POPs east of I-35. Should moisture become deeper and linger longer, then isolated showers and perhaps a thunderstorm are possible along the Highway 77 corridor around midday. Downslope flow will keep temperatures above normal Wednesday. Strong mixing and a tight pressure gradient will result in breezy conditions. Some guidance shows speeds near advisory levels. Low humidities combined with the winds mentioned above will create elevated to near critical fire weather conditions with best chances for these conditions west of San Antonio along and southwest of the Escarpment to the Rio Grande. A cold front moves across our area late in the afternoon into evening after peak heating. No rain is expected with the front as moisture will have been scoured out by the dryline. Cool surface high pressure settles into our area Wednesday night for a return to below normal low temperatures. Cool down will be short lived as south to southwest lower level flow quickly returns on Thursday with high temperatures back above normal. The surface high moves off to the east as surface pressures lower in the Plains as an upper level trough takes shape over the western states. Another strong warming trend is expected for late week into next weekend as 850MB and 925MB temperatures rise again. There are good chances for 100 degree high temperatures along parts of the Rio Grande on Friday and Saturday as 925MB temperatures near 35C. The western states upper level trough moves across the Plains next weekend with a dryline/pre-frontal trough and a cold front moving across South Central Texas. Timing and consistency issues have been noted in the models and run to run. The 12Z runs show slightly better agreement and for now, have gone with a Saturday night frontal passage and a Sunday upper trough passage. Expect isolated showers and thunderstorms on Saturday to become more numerous Saturday night and then end on Sunday. There is a potential of strong to severe storms as forecast soundings indicate high CAPE and shear. Temperatures fall below normal in the wake of the front and remain below normal into next Monday due to cool surface high pressure. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 63 89 72 89 55 / 0 - 10 10 - Austin Bergstrom Intl Airport 61 88 72 88 52 / 0 - 10 10 - New Braunfels Muni Airport 61 88 71 90 53 / 0 - 10 10 - Burnet Muni Airport 60 89 68 84 51 / 0 0 10 - - Del Rio Intl Airport 62 97 67 91 58 / 0 0 0 0 0 Georgetown Muni Airport 63 88 71 86 52 / 0 - 10 10 - Hondo Muni Airport 60 92 66 91 53 / 0 0 0 - 0 San Marcos Muni Airport 61 88 71 89 53 / 0 - 10 10 - La Grange - Fayette Regional 61 87 72 89 54 / 0 - 10 10 - San Antonio Intl Airport 63 89 72 90 55 / 0 - 10 - 0 Stinson Muni Airport 62 90 71 91 56 / 0 - - - 0 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Mesoscale/Aviation...LH Synoptic/Grids...05 Public Service/Data Collection...Treadway
Area Forecast Discussion...UPDATED
National Weather Service GLASGOW MT
832 PM MDT Mon Apr 24 2017 .SHORT TERM...for northeast Montana...tonight through Wed... Sent an update tonight to fine tune the immediate near short term grids to fall more in line with recent observations and satellite and radar trends. Precipitation will continue to be shunted away, barely clipping our CWA along our west and southwest edges. Will be a cold night with persistent cloud cover and breezy easterly winds. BMickelson Previous short term discussion: Following a thunderstorm that developed east of Flatwillow, MT just after noon today, convective showers have continued across the southwest zones of the CWA this afternoon. Additional convective development appears to be occurring based on radar reflectivity across Fergus County with a few lightning strikes, just upstream of the forecast area. As RAP analysis shows MUCAPE supportive of thunder in the southwest zones this afternoon and perhaps early evening, thunder was maintained in the weather grids for now. Additional support does come from mesoscale simulated reflectivity over the next few hours. This seems collaborated with SPC which has a general thunderstorm outline for portions of Petroleum County. The actual forecast brings slight chance of thunder a little further north and east based on radar trends. Cloud cover from incipient showers may be a limiting factor however, and conditions will continue to be monitored over the next few hours. An upper level shortwave tracking across southern Alberta and Saskatchewan into Tuesday will provide enough forcing for ascent to justify at least slight chance to chance pops in western portions of the CWA through this time period. Thus, a continued cool and active weather pattern looks to prevail into the short term period. Maliawco .LONG TERM...Wed night through Mon... System that brings showers over central Montana should weaken and not affect our western zones late Tuesday/Tuesday Night but left higher pops for mainly collaboration purposes. Rest of forecast looked good and agreed with model consensus. TFJ Previous Discussion... Longwave trof over the western/central CONUS will dominate the weather pattern for the extended period. Shortwaves diving into the trof will generate showers along the front range, and possibly extending into the plains through the middle of the week. With the cold trof overhead and plenty of cloud cover, temperatures will remain below normal, with showers turning to snow in the overnight periods possible. Late in week the development of a stronger storm system in the desert southwest will cut off much of the moisture into the northern plains. Should see showers ending and some sun peeking through to warm temperatures closer to normal for the weekend. As a storm system lifts toward the Great Lakes early next week, showers are expected to return to the state with next shortwave diving into the lingering trof. Ebert && .AVIATION... SYNOPSIS: SFC High pressure will bring a dry and stable ENE flow to NE MT over the FCST period. Due to a departing low over the Great Lakes and another low over E WY, most of the area will be covered in low stratus for the next couple of days. Flight Conditions: MVFR CIGS. CIGS: Generally 1500 to 2500, with CIGS slowly rising farther west into Philips County. Cigs are FCST to gradually improve toward the end of the FCST period, 00z 4/26. Weather: No SIG WX FCST thru the period. tec && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$
Area Forecast Discussion
National Weather Service Green Bay WI
1032 PM CDT Mon Apr 24 2017 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Tuesday Issued at 255 PM CDT Mon Apr 24 2017 The latest rap analysis and satellite/radar imagery show a surface warm front losing definition over central Wisconsin early this afternoon. Despite a influx of dry air above the inversion and increasing south winds aloft, relative humidity values have been behaving so far, with only a few locations over north-central WI below 25 percent. Will still have a few hours to tap into the vast reservoir of dry air above the inversion, but southeast winds will likely prevent that from happening over eastern WI. Looking to the west, a cold front is traveling east over the eastern Dakotas, while a shortwave is producing showers from eastern Nebraska into southern Minnesota. Forecast concerns revolve around precip chances as moisture pushes in ahead of the cold front and shortwave trough. Tonight...As a shortwave trough swings northeast across the region, a cold front will slowly slide into the northern Mississippi Valley. Southerly flow aloft and southeast winds at the surface will provide a steady influx of dry air below 10 kft which should hold off precip. Could be some virga though over north-central WI as the shortwave moves through. Otherwise the combo of mid and high clouds overhead and a breezy southeast wind should keep temperatures mild. Went slightly above the multi-model blend with low temps mainly in the middle to upper 40s. Tuesday...The cold front will not make much progress eastward, but will see a weak shortwave impulse move across the state during the afternoon. This shortwave will have more moisture to work with than the impulse arriving tonight, so will see the first decent chance of showers over central and north-central WI, mainly during the middle to late afternoon hours. Eastern WI should remain protected by lingering dry air. Otherwise, should see periods filtered sunshine and broken cloud cover through the day. Temps warming into the middle 60s to near 70 degrees. .LONG TERM...Tuesday Night Through Monday Issued at 255 PM CDT Mon Apr 24 2017 Southwest upper flow and lots of upper jet action will provide at least a few periods of significant precipitation this week. It will also turn much cooler with some chance of winter precipitation across northcentral Wisconsin late Wednesday night and Thursday, and again possibly Saturday. The first round of precipitation will begin Tuesday afternoon or evening and continue into Thursday as upper troughs approach from the northern and southern Plains. They will combine to produce surface lows that track northeast along a nearly stationary front from Oklahoma to Lake Michigan. As colder air arrives late Wednesday night the rain may change to freezing rain or sleet in the far north. WHile not a climatologically favorable time of the year for freezing rain, forecast soundings support it as the most likely precipitation type if the temperatures aloft are as forecast. Another synoptic scale weather system with possible significant precipitation will arrive at the end of the week. A 1032mb surface high is forecast to be north of the Great lakes, which could deliver enough cold air in the low levels to produce some winter precipitation in the far north, depending on the track and timing of course. Rains from these systems will likely cause rivers and streams to rise again later this week, with possible minor flooding i some areas. && .AVIATION...for 06Z TAF Issuance Issued at 1024 PM CDT Mon Apr 24 2017 LLWS will continue overnight, then subside toward daybreak. Otherwise, broken mid-level clouds and virga can be expected through Tuesday morning. A cold front will approach the region Tuesday afternoon and evening, and bring rain showers and lowering ceilings. Flight conditions should deteriorate to MVFR over much of central, north central and far northeast WI Tuesday evening. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......RDM AVIATION.......Kieckbusch
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1050 PM EDT Mon Apr 24 2017 .SYNOPSIS... A deep and vigorous low pressure system will slowly move from the South Carolina coast to near Cape Hatteras by late Tuesday. Expect drier and warmer weather Tuesday and Wednesday. A dissipating cold front crosses our region Thursday and Friday. && .NEAR TERM /THROUGH TUESDAY/... As of 1040 pm EDT, recent HRRR runs continue to bring the relatively good coverage of persistent light to moderate showers westward into the I-77 corridor from the NC central piedmont through the early overnight hours. The current FFA will be maintained although the threat of additional flooding continues to slowly diminish as rates fall and the banding focuses more on I-40 than CLT metro late this evening. Otherwise, the forecast remains generally on track with the area entrenched in an unseasonably cool wedge, well removed from the sfc based unstable air which is mainly east of I-95. Banded forcing northwest of the departing low pressure circulation will keep intermittent bands of showers pivotting west into the Piedmont overnight. An additional half inch to inch of rain will be possible in some areas east of I-77 through the early morning hours. A much improved day is on tap for Tuesday with the flow through a deep layer backing to the NW as the sfc/upper flow wobbles toward the mid-atlantic. Maximum temperatures are expected to be 12-15 deg F milder than today`s chilly readings. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 100 PM Mon: Heights rise Tue night and Wed as a shortwave upper ridge moves overhead. A strong subsidence inversion accordingly will develop. With weak warm/moist advection occurring in the low levels, as well as saturated soils across the area, there is potential for low stratus and perhaps some dense fog to develop early Wed morning, particularly over the Upstate and NE GA. That afternoon, the same inversion should be strong enough to stifle convection across the whole CWFA, so PoPs will be kept below slight chance. Max temps are expected to be 6 to 9 degrees above normal. Wed night into Thu, the upper ridge axis will be just to our east. A full-latitude trough will be hot on its heels, centered near the Mississippi River at 12z Thu. This trough will be associated with a low over the western Great Lakes, and a frontal zone that will impinge on the western CWFA by 00z Fri. A plume of midlevel moisture preceding the trough suggests increasing clouds/PoPs. Elevated tstms will be possible in the aftn, but sfc-based convection continues to be suppressed by poor lapse rates resulting from either the ridge or from the moisture aloft. The best-verifying blend of guidance suggests max temps will top out 5 to 8 degrees above normal, held down a bit more by the cloud cover. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 200 PM Mon: Friday and Saturday will see the resurgence of a late-spring pattern over the Carolinas and Georgia, as the upper pattern amplifies. Temps will trend upward under continued southwesterly flow; the warmest day looks to be Saturday, when a few spots may hit 90. Convection will be limited by a weak capping inversion on Friday, but the warming temps overcome that Saturday. By Sunday the ridge will have drifted east slightly, allowing slightly better lapse rates and still greater instability. Given the pattern, we`ll maintain diurnally driven PoPs, with chances trending up from day to day. As one might expect, weak wind profiles result in little shear, and sfc-to-midlevel theta-E differences are high. Together these findings suggest pulse storm threats from the stronger cells. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... At KCLT: Occasional showers will impact the airfield through the early overnight before gradually becoming more scattered in nature through daybreak. Ceilings have bounced around quite a bit this evening in the MVFR range but should settle quickly back into the IFR to LIFR range overnight. Expect slow recovery through the day on Tuesday as abundant low level moisture persists and the departing, stacked low pressure system wobbles only slowly to the coastline. NNE winds will vary back toward NW through the period, generally at less than 10 kt going forward. Elsewhere: Shower coverage will steadily diminish across the mountains and foothills as the low pressure system migrates toward the coast through the period. Shower chances will be best at KHKY through the early morning hours. Ceilings may bounce around a bit this evening but should settle into IFR then LIFR most areas overnight. Slow recovery is expected Tuesday morning, but weak downsloping will aid lifting and scattering through Tuesday afternoon. Expect northerly winds to turn more NW with time, and possibly WSW at KAND late in the period. Outlook: Conditions should continue to improve through Wednesday dry air works in behind the departing low. Return flow moisture ahead of the next system will develop late in the week. Confidence Table... 03-09Z 09-15Z 15-21Z 21-00Z KCLT Low 51% Med 66% Med 72% High 83% KGSP Med 70% Med 70% Med 66% High 85% KAVL Med 66% Med 72% Med 78% High 100% KHKY Low 53% Med 66% Med 61% Med 77% KGMU Med 66% Med 64% Med 61% High 85% KAND High 85% Med 61% Med 70% High 85% The percentage reflects the number of guidance members agreeing with the scheduled TAF issuance flight rule category. Complete hourly experimental aviation forecast consistency tables and ensemble forecasts are available at the following link: && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...Flood Watch until 8 AM EDT Tuesday for NCZ035>037-056-057- 069>072-082. SC...Flood Watch until 8 AM EDT Tuesday for SCZ009. && $$ SYNOPSIS...DEO NEAR TERM...CSH/HG SHORT TERM...Wimberley LONG TERM...Wimberley AVIATION...HG
Area Forecast Discussion
National Weather Service Jacksonville FL
920 PM EDT Mon Apr 24 2017 .UPDATE... For tonight...deep west to northwest flow will continue as the large low pressure just to our north slowly lifts out to the northeast. Wrap around clouds will continue tonight...over parts of northeast FL through late this evening and continue on and off over southeast GA. Smoke from the West Mims wildfire expected to move into portions of Nassau and Duval County tonight through Tuesday under the prevailing westerly flow. May need a special weather statement for low vsby and smoke potential tonight into Tue morning. Otherwise...only slight tweaks to the cooler overnight lows in the lower to mid 50s...with upper 50s to near 60 northeast and eastern most areas. && .AVIATION...VFR conditions will prevail through the period though some caveats due to smoke from wildfire. Smoke may move into the Duval County TAF sites overnight or Tuesday morning first with scattered deck at 1-2 kft. Some light smoke mentioned for KJAX, KCRG and KVQQ tonight for into Tuesday for the expected smoke. Certainly can`t rule out lower conditions briefly down to IFR at JAX but more likely MVFR vsby/cig. Westerly winds about 5-10 knot winds tonight. Westerly winds around 8-12 knots gusting up to 17-20 kt forecast on Tuesday. && .MARINE...SCEC headlines continue tonight and Tuesday due to strong pres gradient south of primary sfc low located off the coast of SC. Only slight tweaks to winds and seas for the update. Rip Currents: Low to Moderate risk of rip currents through Wednesday. && .FIRE WEATHER...Light westerly flow tonight with LVORI values possibly around the 6 to 9 range after 4 am. Smoke from West Mims fire will be pushed east-southeast tonight through early Tue morning based HRRR guidance and model trajectories. && .PRELIMINARY POINT TEMPS/POPS... AMG 56 84 60 88 / 0 0 0 0 SSI 60 79 66 80 / 0 0 0 0 JAX 57 85 62 86 / 0 0 0 0 SGJ 55 82 64 81 / 0 0 0 0 GNV 52 83 58 85 / 0 0 0 0 OCF 53 82 59 85 / 0 0 0 0 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$ Shashy/Peterson/Corless
Area Forecast Discussion
National Weather Service North Platte NE
629 PM CDT Mon Apr 24 2017 .SHORT TERM...(This evening through Tuesday) Issued at 255 PM CDT Mon Apr 24 2017 The latest NAM12, GFS and HRRR solutions develop some convection into the Panhandle and western Nebraska this evening, lifting it to the east and northeast overnight. Main area of precipitation should track as far south as the the I80 corridor. The mention of thunder maintained overnight mainly near and south of highway 2. Looking at instability, lifted indices, both surface based and elevated, were slightly negative within this area. Overnight lows will range from the upper 30s in the north to mid 40s south. On Tuesday, much cooler with rain showers likely east of Cody through Broken Bow. Still a chance for isolated thunder south of highway 2 until 10 am cdt. Still a chance for showers for western sandhills and southwest with chances decreasing through the day. Models have been fairly consistent in tracking a 500 mb low center from northeast Wyoming across South Dakota. Cold air aloft will push southward Tuesday afternoon, with highs nudged colder due to influence of stratus from only the low to mid 40s north central to the mid 50s southwest. .LONG TERM...(Tuesday night through Monday) Issued at 255 PM CDT Mon Apr 24 2017 A 20 to 30 percent chance for lingering showers Tuesday evening. 850 mb temperatures fall to 0 to -5 degrees Celsius. Lingering light rain may mix or change to wet snow n the north central, but precipitation by this point will be very light and no accumulation is expected. Some clearing late to allow lows to fall below freezing from the upper 20s to lower 30s. Wednesday will be a breezy and continued chilly day. Northwest winds of 15 to 25 mph are expected. 850 mb temperatures do recover to around 8C across southwest Nebraska by afternoon, but remain below zero all day across the northeast portion of the forecast area. Some sun will help highs climb into the 50s across southwest Nebraska, but across north central Nebraska, lingering clouds and colder air aloft will limit highs to the upper 40s. The next chance for showers will arrive Thursday afternoon, continuing Thursday night and Friday. This will be in response to an upper trough pushing into the Central Plains. Likely pops most areas during this timeframe. With colder air aloft, and temperatures falling into the low to mid 30s in the northwest, some snow may mix in. Highs Friday only in the 40s to low 50s. For Friday night through Saturday night, there will be a continued chance for rain showers, and even a chance for snow showers on the backside of the system Saturday night. Operational models have been struggling with the evolution of this system. Model consensus is for the main system to track from Colorado and Kansas into central and eastern Nebraska, where the higher chances to reside. Highs in the 40s to lower 50s Saturday, moderating to the lower 50s Sunday, and upper 50s to lower 60s Sunday, as northwest flow still influences the region. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 625 PM CDT Mon Apr 24 2017 Models in good agreement with high confidence clouds will lower overnight and beyond 09z marginal visual flight rules to be expected west of Highway 83, east through north central visual flight rules overnight with clouds lowering beyond 12z to marginal visual flight rules throughout. Clouds will lower further across the far north overnight to include KVTN where overnight Instrument Flight Rules will be seen into the afternoon Tuesday. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Roberg LONG TERM...Roberg AVIATION...Keck
Area Forecast Discussion
National Weather Service Marquette MI
750 PM EDT Mon Apr 24 2017 .SHORT TERM...(This evening through Tuesday) Issued at 317 PM EDT MON APR 24 2017 12Z raobs/latest wv imagery and RAP analysis show a wsw flow alf over the wrn Great Lks to the e of upr troffing dominating the wrn CONUS/sw Canada. The ese flow arnd a retreating sfc hi pres rdg extending fm nw Ontario into the se Great Lks is advecting dry llvl air shown on the 12Z APX, GRB and MPX raobs into Upr MI. But there are plenty of hi clds streaming into the cwa ahead of a shrtwv/sfc lo pres in the nrn Plains lifting toward MN within the wsw upr flow. Despite this hi cld, temps have risen well aoa normal, especially over the w with downslope flow away fm lk moderation. Tngt...Shrtwv in the ncentral Plains will move ne, reaching wrn Lk Sup late tngt. Since this disturbance is fcst to shear out a bit as it enters a more confluent upr flow and the ssw lo-mid flow wl still be tapping the dry air to the s, the bulk of the models indicate no more than isold-sct showers wl impact only the nw portion of the cwa. Plenty of hi clds and steady winds wl limit the diurnal temp fall. Tue...A shrtwv rdg axis is fcst to aprch following the exiting shrtwv to the ne. So any pops over the nw cwa wl tend to diminish until later in the day, when another shrtwv and some large scale forcing/hier pwat aprch fm the sw as the lo-mid flow grdly taps a moister airmass. The best chc of some showers mainly in the 21-24Z time frame wl be over the w closer to the aprchg forcing/deeper moistening and along a slow moving frontal bndry that wl push slowly into the far w during the day in the wake of the first passing shrtwv to the ne. Many of the short term guidance also indicate the llvl moistening wl be sufficient to bring a return of some lo clds over at least the e half. Despite the incrsg clds, expect temps to top out as hi as the 60s, warmest over the central away fm Lk MI moderation and some thicker clds/late arriving cold fnt over the w. If there is more sunshine, a few places in the downslope regions near Baraga could see 70 degree max temps. .LONG TERM...(Tuesday night through Monday) Issued at 337 PM EDT MON APR 24 2017 Still expecting an active weather week with multiple chances for precipitation across the area. As longwave troughing digs across the plains, numerous weak shortwaves embedded within the southwest flow aloft will traverse the area. This will also allow warm and moist air to stream northeast ahead of the slow moving surface trough expected to extend northeast into western portions of Upper Michigan by Tuesday night. The combination of increasing upper-level support and warm air advection should allow for fairly widespread rain showers to spread across the much of Upper Michigan Tuesday night through the day on Wednesday. With the first round of moisture transport lifting northeast across the area, expect the focus for moderate to heavy rain to remain across the west and central, where surface convergence will be maximized. During the day on Wednesday, expect rain showers to linger across the area as moisture transport continues to linger. There are some differences among the model QPF, likely due to how they each are handling the timing and strength of the mid-level baroclinic zone. Therefore, there is some uncertainty as to what locations will see the highest rainfall totals during the day on Wednesday, but some locations may see over an 1 inch of rain. Impact wise, Wednesday is a challenge. We could be looking at a day where we have showers and thunderstorms across the central and east, and wintry precipitation across the west. It will all be dependent on how the surface trough traverses Upper Michigan, and on how much unstable air can lift northward and how much shallow cold air can undercut the warm, moist air ahead of and behind the surface trough, respectively. Based on the current model guidance and trends, looks like the potential for any freezing rain across the west will be Wednesday night into Thursday morning. As colder air arrives into Thursday morning, cloud ice will dissipate and leave behind freezing drizzle before possibly transitioning over to snow in the west. Ice accumulations from the forecast builder are showing upwards of a quarter of an inch in some locations across the far west in the higher terrain. Thinking this is overdone a bit considering the increasing ground temperatures over the past few weeks. While ice accumulations will be possible, elevated surfaces should have much better chances at seeing any accumulations. The big question on Thursday will be if any locations see any system snow. There is still quite a bit of uncertainty in regards to the track of low pressure with the Canadian now tracking the low north across western and central Upper Michigan, leaving any chances for system snow across the far southwest. The GFS is the most progressive and lifts the low across eastern Upper Michigan and up into Southern Ontario. Precipitation wise, the models remain different, with the GFS being the less robust QPF wise as the system is less wrapped up compared to the other deterministic models. Therefore, confidence still does not remain high in regards to where precipitation will track on Thursday. However, given the fact that upper-level energy is progged to become negatively tilted, as a stout shortwave lifts across the region, leaning towards the ECMWF/Canadian solutions at this time. That being said, we`re still looking at the potential for freezing rain to transition over to snow across the far west and additional rainfall across the central and east on Thursday. Depending on when the system lifts out of the area, precipitation will come to an end sometime Thursday night through early Friday from south to north. We will see a break Friday and Saturday from precipitation chances as high pressure clips the region. However, towards the end of the weekend and into the beginning of next week precipitation chances will return across Upper Michigan as yet another system ejects out of the Plains and up across the Great Lakes. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 749 PM EDT MON APR 24 2017 Under considerable mid and high clouds, a dry low-level air mass will dominate the area thru Tue aftn, allowing VFR conditions to prevail at KIWD/KCMX/KSAW. As near sfc layer cools this evening and increases low-level stability, LLWS will develop at all terminals. Just beyond this fcst period, conditions will deteriorate as a sfc trof settles se across the Upper Lakes. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 337 PM EDT MON APR 24 2017 Ese winds up to 25-30 kts will prevail into this evening under the tight pres gradient between hi pres retreating to the e and a lo pres moving into MN. Although there could be some gale force gusts mainly in a ribbon from Isle Royale to the tip of the Keweenaw and the ne portion of the Lake, overall hi stability over the relatively chilly waters will limit the potential for a more widespread gale and the need for headlines. As the gradient slowly weakens overnight into Tue, especially over the w half, winds will diminish. Stronger se winds up to about 25 kts will persist over the e thru Tue. Tuesday night northeast winds will increase to gales of 35 knots across the west and north central portions of the lake as a surface trough pushes east across the area. A few locations may see gusts upwards of 40 knots. Through the day Wednesday, gales to 40 knots will persist across the west and central, with winds 20 to 30 knots across the east. A few gale force gusts will be possible across the east. By late Wednesday night into Thursday morning winds will begin to subside to 20 to 30 knots as winds become northerly. Late Thursday through Friday, winds will further decrease to 10 to 20 knots as winds become westerly. Winds of 10 to 20 knots are expected through the weekend and into early next week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Watch from Tuesday evening through Wednesday evening for LSZ162-263. Gale Watch from Tuesday evening through late Wednesday night for LSZ264. Lake Michigan... None. && $$ SHORT TERM...KC LONG TERM...Ritzman AVIATION...Rolfson MARINE...Ritzman
Area Forecast Discussion
National Weather Service Sacramento CA
331 PM PDT Mon Apr 24 2017 .SYNOPSIS... Weak weather systems will bring light precipitation through Wednesday. Gusty north winds likely to develop Friday. && .DISCUSSION... A weak weather system is currently skirting across the far northern portions of California. A few light showers have been detected by radar through the course of the day. The HRRR model is showing some modest instability toward the Northern/Central Sacramento Valley this afternoon and tonight, so have included slight chance wording for thunderstorms there. Snow levels are projected to fluctuate between 5000 and 7000 feet through tonight, with a few inches of snow accumulation possible over the higher elevations. Additional weak weather systems are forecast to move through the region on Tuesday, and again on Wednesday. Both of these will again bring only precipitation totals to the region. Snow levels will also be a fair bit higher, so little to no impact expected to the mountains. Breezy north winds along with warming and drying conditions commence Thursday. Dang $$ .EXTENDED DISCUSSION (Friday THROUGH Monday) Dry northerly flow expected over the weekend as an upper ridge builds inland over interior NorCal. This will lead to dry conditions and temperatures trending upward across the forecast area. Daytime highs could be around 5-8 degrees above normal this weekend, with Valley temperatures reaching the lower 80s. Periods of gusty northerly winds are expected Friday into Saturday as pressure gradient tightens, with 35-45 mph gusts in the Valley. && .AVIATION... Local MVFR/IFR conditions possible with isolated LIFR in shower activity this evening. Isolated thunderstorms possible through 06z Tuesday from KRDD southward to near KOVE. Improving conditions expected overnight as shower activity ends. Gusty winds will be decreasing this evening, with additional gusts up to 20 kts mainly south of KSAC after 18z Tuesday. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
834 PM MDT Mon Apr 24 2017 .UPDATE... Issued at 828 PM MDT Mon Apr 24 2017 00z KUNR sounding showed steep lapse rates, but some dry air to work on via lift ahead of shortwave energy spinning over southwest WY per latest water vapour movie. Latest KUDX radar loop showed drier air as precipitation struggling to make it east of the Black Hills at this point, but raining nicely over the higher terrain. Forecast updated earlier for quicker movement of precipitation shield. 01z RAP showed upper low moving into southwest SD by Tuesday morning with well-defined band of 850-700mb frontogenesis across far northeast WY into the Black Hills. Forecast wet bulb zero suggest changeover over the highest elevations by 06z and then above 4500 feet by 09z and then on the adjacent plains between 09z-12z. Forecast snow amounts tricky, but feel current headlines depict best potential. Will be watching snowfall rates overnight from northern Campbell into Butte County and then south into the northern Black Hills. && .DISCUSSION...(This Evening Through Monday) Issued at 335 PM MDT Mon Apr 24 2017 Current surface analysis shows frontal boundary remaining from northeast WY through southern SD, with colder air across northern and eastern portions of the forecast area. Upper level analysis shows low pressure over the Pacific NW, with trough digging south and east across the western US. Skies are variably cloudy across the area. KUDX radar showing isolated showers over the southern Black Hills area, with regional radars showing showers and isolated storms expanding across central into eastern Wyoming now. Current temps in the 50s and lower 60s, warmest across far southwest SD. North-northwest winds remain brisk across portions of northwest into central SD. All medium range models in good agreement on an unsettled and very cool week ahead as the large upper trough to the west digs and settles over much of the western and central US over the next couple of days. A series of systems will move through the trough, bringing near daily chances for pcpn through the weekend. For late today and this evening, the first of these systems will approach the area, bringing increasing chances for rain showers across northeast WY and into western SD. Upper low will develop across northern WY tonight and slowly track east into northeast WY by morning, before sliding slowly southeastward and weakening as it moves into the plains. As colder air sinks south into the area to the northeast of the low, pcpn will start to change over to snow generally from north to south and from higher to lower elevations across northeast WY and western SD. NAM, GFS, and EC are bulls- eyeing the most pcpn later tonight/early Tuesday over far northeast WY, generally near and just north of the track of the upper low. If the low ultimately tracks this way, the Bear Lodge Mts would likely see the most snowfall, while the Black Hills would not see as much pcpn and somewhat lower snowfall amounts later tonight into Tuesday. Have decided to issue winter wx advisories for most of the area covered by the watch, except for the Wyoming Black Hills/Bear Lodge Mts zone, where a warning has been issued. Also included Butte County and the foothills zones from Spearfish to Sturgis and Piedmont in the advisory. Looking for mostly 2 to 6 inch amounts across much of the advisory area, with 1 to 4 inch amounts across southern Campbell County, the Weston County plains, and southern Black Hills. Over the Bear Lodge Mts, it looks like amounts to around 8 inches are likely, especially across the higher elevations. Any adjustments in the track and strength of this system late tonight and Tuesday morning, or changes in timing of a switch to snow, would alter pcpn and snowfall amounts across these areas. Rain and snow will taper off in the afternoon, with pcpn mostly over by late afternoon. Highs on Tuesday will mostly be in the 30s, with some lower 40s over far eastern portions of the CWA. Skies will stay mostly cloudy Tuesday night, with some clearing possible over western and northern areas toward morning. Lows will be chilly, mainly in the 20s. Wednesday looks to be the one dry day of the week before the next system moves into the high plains. Highs will be in the 40s. The next system will dig south into the Central Rockies Wednesday night and Thursday, then slowly track across the Central Plains through Friday. Pcpn chances look rather widespread, with the better chances and more significant pcpn likely from northeast WY through southern SD. With some colder air being drawn in on the north side of the system, some snowfall looks likely across at least the higher elevations of the area during the overnight/morning hours. Latest models, especially the EC, have trended a bit further south and west with the system, so will see if that trend continues over the next day or two. The weekend looks mostly dry at this point, but still cool, as the broad upper trough remains across the region. A stronger upper low is progged to remain mostly south of the region as it tracks across the plains. Highs will be in the 40s and 50s. Some unsettled weather could return Monday as trough moves further east and northwest flow on the back side of the trough brings additional energy across the area. .AVIATION...(For the 00Z TAFS Through 00Z Tuesday Evening) Issued At 531 PM MDT Mon Apr 24 2017 A storm system will move across WY into SD tonight. It will spread widespread rain into the area from southwest to northeast. Precipitation will change to snow from north to south overnight as colder air moves south, and from higher elevations to lower elevations. Areas MVFR CIGS will transition to widespread IFR conditions after 06z with areas LIFR conditions with the heaviest snow bands, especially near the Black Hills. Conditions may start to slowly improve late Tuesday afternoon. .AVIATION...(For the 00Z TAFS Through 00Z Tuesday Evening) Issued At 531 PM MDT Mon Apr 24 2017 A storm system will move across WY into SD tonight. It will spread widespread rain into the area from southwest to northeast. Precipitation will change to snow from north to south overnight as colder air moves south, and from higher elevations to lower elevations. Areas MVFR CIGS will transition to widespread IFR conditions after 06z with areas LIFR conditions with the heaviest snow bands, especially near the Black Hills. Conditions may start to slowly improve late Tuesday afternoon. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...Winter Weather Advisory from midnight tonight to 3 PM MDT Tuesday for SDZ012-024-025-028-029-072. WY...Winter Storm Warning from midnight tonight to 3 PM MDT Tuesday for WYZ057. Winter Weather Advisory from midnight tonight to 3 PM MDT Tuesday for WYZ054-056-071. Winter Weather Advisory from 6 AM to 3 PM MDT Tuesday for WYZ055- 058. && $$ Update...Helgeson DISCUSSION...26 AVIATION...Helgeson