Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/09/18

Area Forecast Discussion
National Weather Service La Crosse WI
637 PM CDT Tue May 8 2018 .SHORT TERM...(Tonight through Thursday) Issued at 226 PM CDT Tue May 8 2018 Another nice day ongoing out the office window today with enough thinning of the cloud cover early on to allow for a very warm day near and east of the Mississippi River, along with one more day of elevated fire weather concerns. However, big changes are lurking just to the west, as evidenced by thickening cloud cover making inroads across the local area. Those come courtesy of burgeoning warm advection and moisture transport into the region in advance of a shortwave trough meandering east across the Dakotas, while another upper wave is transiting eastward through southern Saskatchewan. That latter feature is forecast to link up with the lead wave and slow the eastward progression of an upper trough across our area through tomorrow, with persistent warm advection ascent and moisture transport into the region supporting increasing coverage of showers through the evening and night, gradually exiting east into Wednesday. Overall instability isn`t anything terribly impressive, but elevated CAPE values pushing 500 to maybe 1000 J/kg (NAM highest) is certainly enough to deliver some thunder, especially across northeast Iowa into southwest Wisconsin closer to the nose of strongest moisture transport. Severe threat very low given elevated nature of convection and lack of any organizing shear but some small hail isn`t totally impossible given low freezing levels of 9-10kft. As alluded to above, the majority of precip should swing east of the area by midday Wednesday, though can`t rule out a smattering of additional showers and thunderstorms into the afternoon beneath the upper trough axis, especially near and east of the Mississippi River with sharper low level convergence along a cold front. Some of that will also hinge on how much instability we can generate within what should be fairly widespread lower cloud cover. Otherwise, we`ll have to see how those clouds trend into Thursday but most of the day should end up dry and fairly pleasant as low level ridging and drier air briefly nose down into the region from Manitoba. With that said, will have to watch late day shower potential possibly north of I-94 within an blossoming axis of frontogenetical forcing, though most of that should hold off until Thursday night and beyond. .LONG TERM...(Thursday Night through Tuesday) Issued at 226 PM CDT Tue May 8 2018 Active period of weather set to arrive Thursday night through Saturday as a fairly stationary frontal boundary lays out somewhere from Nebraska through the lower Great Lakes while various pieces of shortwave energy emanating from a cutoff western CONUS upper low get kicked eastward. Those waves will interact with modest moisture given a wide open Gulf of Mexico and building instability to the south to deliver several rounds of showers and potential thunderstorms into the first half of the weekend. As mentioned yesterday, confidence in the exact placement of the heaviest rainfall and timing remains on the lower side, but the general trend for another very wet period of weather remains intact. Highest confidence is on Thursday night-Friday with an axis of strong and deep layer frontogenesis developing near the I-90 corridor and lifting north through the northern Great Lakes. That strong forcing should result in a band of heavier rainfall traversing the area, though there remain some subtle differences among guidance regarding the actual placement of that heavier QPF axis (GFS persistently farther north while ECMWF/NAM/GEM bullseye near the I-90 corridor). The setup actually isn`t all that dissimilar from the one we saw last Thursday which resulted in a band of 2-4" of rain across northeast Iowa in an axis of strongly sloped FGEN forcing, so we`ll have to keep a close eye on the potential for some flooding pending where said rain band ends up. Forcing looks to briefly wane later Friday before returning Saturday with another wave riding along the frontal boundary just to our south. Very tricky temperature forecast during the Friday/Saturday timeframe, with some hints that temps may be stuck only in the 40s (maybe even upper 30s?) in some areas north of the warm front with clouds while areas farther south may spike into the 70s if that boundary can briefly flex northward (a big "if). Regardless, it does appear we`ll finally dry things out just in time for Mother`s Day and into early next week with a return to high pressure and much drier air working back into the region. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 637 PM CDT Tue May 8 2018 Some scattered moving across the area this evening in association with a short wave trough moving into northern Wisconsin. This activity will continue to lift northeast through the evening and should primarily stay north of both airports or at worst produce some additional sprinkles at KRST. By late evening, a stronger short wave trough will be approaching from the west. The low level jet will form ahead of this wave and will be in position to produce some low level shear for a short period at both airports. It will also increase the moisture transport into the area that will cause additional showers to form and move east across the area through the night. There will also be enough instability to produce a few rumbles of thunder. The main concern behind these showers will be how low the ceilings will drop. Both the 08.18Z NAM and 08.21Z RAP forecast sounding suggest the overnight rain will be enough to saturate the low levels and allow IFR ceilings to develop at KRST and MVFR at KLSE. This is a rather low confidence forecast and will maintain continuity with previous forecast of going to MVFR and keeping KRST just above IFR. Yet another short wave trough will swing across the area Wednesday afternoon and could produce a few more showers. Confidence on placement is not high enough to include a VCSH at this point for either airport. && .HYDROLOGY... Issued at 226 PM CDT Tue May 8 2018 Minor flooding continues along the Yellow River at Necedah (almost done), Kickapoo River at Steuben (done later this evening) and Mississippi River at McGregor and Guttenberg. Another round of rain will arrive this evening and tonight, with additional showers possible on Wednesday. In general, rainfall amounts around one- half inch are expected, though with any convective (thunderstorm) elements, locally heavier amounts are possible. At this time, the threat for additional flooding tonight is low but will have to watch to make sure storms don`t line up over the same areas for too long (looks pretty progressive). More rounds of rain are likely Thursday night into Saturday, with some potential for additional heavy rainfall of 2+ inches in some areas. Right now, the threat appears highest near and north of Interstate 90 but will need to watch forecast trends the next few days to nail down the details. Should those amounts be realized, additional flooding will be possible. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Lawrence LONG TERM...Lawrence AVIATION...04 HYDROLOGY...Lawrence
Area Forecast Discussion
National Weather Service Green Bay WI
1104 PM CDT Tue May 8 2018 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Wednesday Issued at 243 PM CDT Tue May 8 2018 The latest RAP analysis and satellite/radar imagery show high pressure centered over the east coast and an area of weak low pressure over northeast South Dakota. In addition, a shallow cold front has dropped into far northern WI where winds have shifted to the north. A few showers have popped up along this boundary over Marinette county early this afternoon. A few more showers will be possible in this general area through the rest of the afternoon with decent low level convergence. Meanwhile, additional showers are pushing across the Mississippi River and the latest short- range models have some of these showers moving into north- central WI by 5-6 pm, despite widespread relative humidities between 20 and 30 pct. As this low moves east, forecast concerns mainly revolve around rain chances over the next 24 hours. Tonight...The first round of showers is expected to move across northern WI this evening as clouds increase across the rest of the region. After a relative lull, the main area of showers, currently over southern Minnesota, will lift northeast and into north-central WI late tonight. Not much of a chance of thunder, though cannot necessarily rule out an isolated storm. Warmer lows ranging from the mid 40s over Door County to the mid 50s over central WI. Wednesday...The low pressure system will push a band of rain across the region from west to east during the morning. With MU capes upwards of 500 j/kg, some embedded thunderstorms appear possible within the rain band. Even though this rain band is expected to exit the NE WI shoreline in the afternoon, some additional showers and isolated storms could also develop in its wake if any heating can occur due to the close proximity of the surface low and mid-level trough. Highs mainly ranging from near 60 degrees in Vilas county to the mid or upper 60s over the southern Fox Valley. .LONG TERM...Wednesday Night Through Tuesday Issued at 243 PM CDT Tue May 8 2018 Precipitation trends Wednesday night, and Thursday night through Saturday night periods, are the main forecast concerns. Models have sped up the system a little bit for Wednesday night, so it looks like most of the precipitation will be out of the region by 06z/Thu. Will keep likely pops over our eastern counties in the evening, as well a chance of thunderstorms. Generally dry conditions are anticipated on Thursday into Thursday evening as Canadian high pressure passes through. Forecast confidence has increased a little bit for the end of the week, as models generally agree on a couple rounds of moderate to potentially heavy rainfall moving through during the Thursday night through Saturday period. A strong frontal boundary will set up just south of the region, with periods of moderate to strong overrunning occurring at times. Still think that the best chance of heavy rainfall will occur over central and east central WI, due to the closer proximity of the 850 bm front and deeper moisture. There will also be a small chance of thunder over our southern counties during this period. The bottom line is that a round or two of significant rainfall is possible later in the week, which could cause flooding concerns to flare up again. Temperatures will be below normal, especially Thursday night into Friday. Cannot rule out a rain/snow mix over far northern WI late Thursday night, though confidence is low, and temperatures may not even reach 50 degrees in the forecast area on Friday. Generally dry conditions are anticipated for the end of the weekend and beginning of the next work week, along with warming temperatures and another round of low relative humidity over northern WI. && .AVIATION...for 06Z TAF Issuance Issued at 1104 PM CDT Tue May 8 2018 While VFR conditions should hold for most of the overnight period, flying conditions are forecast to gradually deteriorate Wednesday morning as an area of low pressure/associated cold front and a mid-level shortwave trough move into the western Great Lakes region and brings showers and a slight chance of thunderstorms to northeast WI. Anticipate cigs/vsbys to drop into the IFR/MVFR range pretty much for the entire day on Wednesday with little improvement until later Wednesday night when high pressure begins to build southeast from Canada. There may also be a brief period of LLWS late tonight. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......Kieckbusch AVIATION.......AK
Area Forecast Discussion
National Weather Service Wichita KS
645 PM CDT Tue May 8 2018 .DISCUSSION... Issued at 315 PM CDT Tue May 8 2018 20Z water vapor imagery shows an upper level shortwave trough moving across the northern and central plains. At the surface a trough of low pressure extended from the southern high plains through the eastern Dakotas. For this evening and overnight, models continue to bring the upper wave through eastern KS as well as the surface trough. Forecast soundings keep a surface parcel capped, but there is some elevated instability progged. Models have been mixed on the idea for convection this evening and while the HRRR has been one of the more bullish in developing precip, the last couple runs have back off on coverage. With the potential for some forcing and the elevated instability, have kept a 20 to 30 percent chance POP across the forecast area in case some isolated convection pops. Deep layer shear is not all that impressive any storms that develop may be multistorm with cold pools dominating. An isolated wind gust may not be out of the question but overall conditions for severe storms do not look favorable. Lows tonight are expected to range from the mid 50s over north central KS to the mid 60s across southeast KS. The daytime Wednesday is shaping up to be fairly nice with mostly sunny skies. Models keep the surface trough axis across the area and think this may limit afternoon mixing. Additionally 850MB temps suggest adiabatic mixing would only yield highs in the upper 80s. So have trended highs a coupe degrees cooler, especially for central KS where there may be an east wind through the day. For Wednesday night, there are some signs of a vort max rounding the upper ridge and propagating across the forecast area. This could cause some scattered storms to develop through the night and have some 20 to 30 percent chance POPs. For Thursday through Saturday, the pattern looks to flatten out somewhat with energy moving mainly north of the forecast area. There are some concerns with the placement of the surface trough over central KS and whether convection could focus along this feature. But GFS forecast soundings show a strong elevated mixed layer advecting over the region and capping the boundary layer. So for now have mainly a dry forecast save for a few slight chances skirting the northern counties. Highs are expected to trend warmer with the thermal ridge leaning over into central KS and we could see some locations have highs in the mid 90s. By Sunday the the surface trough is progged to push further south and bring cooler weather to the area. Monday and Tuesday are looking unsettled as an upper low moves into the southern Rockies and eventually lifts out on Tuesday. Persistent southerly flow in low levels is likely to bring a moist airmass into the region. Depending on what the inhibition is like, there could be a couple chances for showers and storms Monday and Tuesday due to weak perturbations within the southwesterly flow aloft. Because of this there are some chance POPs in the forecast. Have kept temps close to seasonal normals with lows in the 50s and 60s and highs in the 80s. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 630 PM CDT Tue May 8 2018 Aviation concerns look to be minimal through the next 24 hours. Water vapor imagery shows an impulse approaching the northern Mississippi Valley with some of this energy extending down across eastern KS. At the surface, a weak cold front extends from eastern Nebraska through central KS. This front isn`t expected to progress much further east before washing out. An isolated storm will be possible east of the KS Turnpike but confidence in development isn`t high enough to insert into KCNU`s TAF. Confidence is high in mostly clear skies on Wed with light winds. && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 62 91 64 89 / 10 0 20 10 Hutchinson 60 89 63 88 / 10 0 20 10 Newton 61 89 63 87 / 10 0 20 10 ElDorado 61 89 63 87 / 20 0 20 10 Winfield-KWLD 62 91 64 88 / 20 0 20 10 Russell 57 88 62 91 / 10 0 30 10 Great Bend 58 89 62 91 / 10 0 30 10 Salina 60 89 62 90 / 10 0 30 10 McPherson 59 89 62 88 / 10 0 30 10 Coffeyville 65 90 63 88 / 20 10 10 0 Chanute 64 89 63 86 / 20 10 10 10 Iola 63 89 63 86 / 20 10 10 10 Parsons-KPPF 65 90 63 87 / 20 10 10 0 && .ICT WATCHES/WARNINGS/ADVISORIES... None. && $$ AVIATION...RBL
Area Forecast Discussion
National Weather Service Jacksonville FL
752 PM EDT Tue May 8 2018 .UPDATE...Widely scattered convection diminishing just N of our forecast area...otherwise mostly clear skies and light winds are expected Tonight. Latest HRRR guidance suggests potential for fog and low clouds to develop over inland areas late Tonight, but SREF probabilistic guidance only has low probabilities for fog/low clouds. Will include patchy fog W of I-95 corridor late Tonight. Made just minor tweak to low temp forecast based on latest consensus temperature guidance. && .AVIATION...VFR expected next 24 hours. Patchy fog possible late Tonight for TAF sites W of I-95 corridor...and included light fog at KGNV/KVQQ for now. && .MARINE...No significant changes planned for next CWF issuance. High pressure will develop over the marine area by Wednesday resulting in light winds and fairly low seas. Headline criteria is not anticipated through the remainder of the week. Rip Currents: Onshore winds and a persistent 8-9 second period from an east-southeasterly ocean swell will keep a moderate risk in place at area beaches through at least midweek. && .PRELIMINARY POINT TEMPS/POPS... AMG 59 87 60 89 / 0 0 0 0 SSI 65 79 68 85 / 0 0 0 0 JAX 61 86 64 91 / 0 0 0 0 SGJ 65 80 66 82 / 0 0 0 0 GNV 59 87 59 87 / 0 0 0 0 OCF 60 89 60 91 / 0 0 0 0 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$ Wolf/Nelson/Bricker
National Weather Service Jackson KY
1130 PM EDT Tue May 8 2018 .UPDATE... Issued at 1120 PM EDT TUE MAY 8 2018 Hourly grids have been updated based on recent observations which led to colder temperatures over the next 2 to 3 hours for some of the valley locations. Overnight lows still look on target, however. As valleys continue to cool overnight, fog should develop around or after 2 AM and could be dense in a few spots. UPDATE Issued at 827 PM EDT TUE MAY 8 2018 A few showers linger mainly in Harlan and Letcher counties and these should diminish with the loss of daytime heating and departing trough. Otherwise, a few cumulus and ac linger. As the ridging moves into the area tonight, these clouds may be slower to dissipate or even linger through late evening, especially in the east. Forecast soundings indicate some moisture remaining between 850 and 700 mb. Chances for valley fog still look on target at this point with some locally dense fog possible in typically more favored locations. && .SHORT TERM...(This evening through Wednesday night) Issued at 440 PM EDT TUE MAY 8 2018 19z sfc analysis shows some weakness in the pressure field over far eastern Kentucky while high pressure controls most of the weather through the Ohio Valley. Enough low level moisture and cooler air aloft in the southeast again encouraged convection and a decent cu field to develop over eastern Kentucky this afternoon though nowhere near as extensive as yesterday with any storms so far staying outside the state lines. Still expect a few to pop up near the ridge lines into the first part of the evening. Meanwhile, temperatures are running in the upper 70s to lower 80s across the area - overachieving from guidance again this afternoon. Dewpoints dried out a bit this afternoon with values currently in the upper 40s to lower 50s and winds mainly light and variable. The models remain in good agreement aloft through the short term portion of the forecast. They all depict a weakening trough departing to the east with rebounding heights into Wednesday morning as ridging passes over the state. This is in advance of a larger trough shifting east out of the Midwest and over the Great Lakes into Thursday morning. Plenty of energy will accompany this trough and spread toward Kentucky early Thursday. Given this agreement have favored a general model blend as the starting point for the grids with emphasis on the HRRR and NAM12 in the near term. Sensible weather will feature another night of moderate - large ridge to valley temperature disparity owing to good radiational cooling conditions of light winds and clearing skies. Do expect some patchy fog to form in the river valleys late - locally dense but not any worse than the limited amounts we saw this morning. Wednesday will be another warm and pleasant day, though clouds will be on the increase in the morning with a potential for showers and thunderstorms in the afternoon ahead of the sfc low moving into the Upper Midwest. Western convection may be on the wane as it spreads into our part of the state in the afternoon keeping the activity less organized while the better mid level support is found well off to the northwest. Expect a lull in any activity into the evening with additional showers and storms expected later in the night as the system`s cold front stalls out overhead. Again used the CONSShort and ShortBlend as the starting point for the grids with adjustments to go a notch warmer Wednesday and also to include terrain based differences tonight and to a lesser extent Wednesday night. As for PoPs - beefed them up in the southeast through early evening and also kept them a bit lower than guidance on Wednesday. .LONG TERM...(Thursday through Tuesday) Issued at 435 PM EDT TUE MAY 8 2018 A bit of an unsettled pattern during the extended portion of the forecast. Still tracking an upper level trough moving across the lower Great Lakes on Thursday, as it continues to lose strength and become absorbed into the larger upper level trough over Canada. A surface cold front will be shifting SE towards the region, but latest WPC analysis still shows the front shearing out by the time it reaches eastern Kentucky. Soundings are also showing a very dry airmass in place as it moves over, with generally only speed shear, though instability during the day is still quite decent. As a result, kept only chance pops in the forecast with isolated to scattered thunderstorm potential during the afternoon, as any pockets of moisture could easily result in rapid storm development. Storms that do develop could result in some gusty conditions given the parameters in place. Once this system has passed, backing winds and drier air will quickly cut off precip potential for Thursday night. More zonal westerly flow will take hold aloft for much of the remainder of the forecast period, with the previous frontal boundary pushing north as a warm front, placing Kentucky in the warm sector through the weekend. Several weather systems will move north of Kentucky, keeping the bulk of precip potential away from the CWA. However, our location in the warm sector will keep generally S to SW flow in place across the JKL CWA, allowing for warm and moist air to pump into the region. Temperatures will modify warmer each day, with mid and upper 80s forecast for highs Friday through Sunday. Afternoon heating will lead to some instability and the potential for isolated or scattered showers Friday afternoon, though storm potential should remain on the leeward side of the Appalachians away from our CWA. By Sunday into Monday, the zonal flow will begin to break down and allow for some height falls across the CWA. In turn, a frontal boundary located just north of the Ohio River (oriented WSW to ENE) will begin to propagate farther southward, impacting much of Kentucky Sunday night into Monday as it becomes stalled. This will provide us our next epicenter for more widespread shower and thunderstorm chances both Sunday and Monday. Thunderstorm potential will be best during the afternoon and evening with peak heating. The increase in cloud cover will also limit temperatures on Monday, with highs in the low 80s forecast. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) ISSUED AT 820 PM EDT TUE MAY 8 2018 Some diurnally driven cu and lingering ac remain at this time, with VFR observed across the area. Winds are generally light and should remain so tonight. VFR conditions area expected to continue at the TAF sites. However, the deeper river valleys where MVFR or lower fog is likely to develop between 6Z and 9Z and dissipate by 13Z. The nocturnal inversion should dissipate by 15Z with sustained winds picking up from the southwest at generally 5 to 10 KT. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...GREIF LONG TERM...JMW AVIATION...GREIF/JP
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
811 PM CDT Tue May 8 2018 .UPDATE... 806 PM CDT Only a few minor updates to the forecast this evening. With thick cirrus already blanketing the area and expected to continue to filter overhead through the night, made an upward adjustment of a degree or two to min temps. Regarding thunderstorm potential late tonight into Wednesday morning, bumped up chances an hour earlier per late afternoon and early evening high-res guidance. Start times for a one to possibly two hour period of showers and thunderstorms should be around 5am CDT for the western CWA, and around 7-8am CDT for the Chicago metro. See the short term forecast for more details on convective mode and strong/severe storm potential. Kluber && .SHORT TERM... 105 PM CDT Through Wednesday... Short term focus is on several rounds of thunderstorms late tonight into early Wednesday, and then redevelopment Wednesday afternoon. Details added focused on honing in on the more favored times for thunderstorms by location. Near term weather has been a continuation of the splendid spring weather of late across the Great Lakes with plentiful sunshine and temperatures around 80 with comfortable humidity readings. A lake breeze has formed and will cap the warming lakeside areas to the upper 60s. The signs of change are evident in the sky and on satellite as higher clouds have continued to fill in from the north and west head of a series of disturbances in the mean trough across the central and northern Plains. Tonight, warm air advection driven elevated showers and t-storms are expected to blossom over Missouri and Iowa late this evening in the vicinity of several shortwaves in the mean trough axis upstream. As the low level jet strengthens, these will gradually spread east into western IL after midnight and likely into our western CWA prior to 12z. NAM and GFS and now the RAP are in good agreement in showing strengthening shear profiles late tonight into Wednesday morning in response to tightening height gradient ahead of lead shortwave currently over central High Plains, and drive an elevated instability axis and a modest to somewhat steep lapse rate environment. MUCAPE of near 1000 J/kg per the RAP, suggest thunderstorms with some marginally severe hail are still possible very late tonight into early Wednesday morning and storms move across the CWA. This convectively driven wave will likely spread across the Chicago area in the morning, so while the severe threat is lower, thunderstorms are likely to spread northeastward embedded in the wave of showers. The most likely period for a break in showers and storms will be mid morning into the early afternoon in wake of this first wave. Both NAM and GFS do show decent atmospheric recovery will take place on the advection of moisture on continued southwesterly winds, though the degree and northward extent is still a bit in question. The weather story issued earlier today is fairly well in line with the updated SWODY2 which brings the slight risk along the I-57 and eastward corridor, It is this corridor that the suite of convective allowing models initiate convection ahead of the approaching surface trough where the highest likelihood of a moist and unstable airmass will be. A marginal risk will continue farther west given the uncertainty in recovery farther northwest before the surface trough comes through, and due to the fact that some CAMs do initiate more robust convection (briefly) farther west over the Chicago metro area. Damaging winds are the main driver for the Slight risk given forecast shear profiles favoring a multicell mode, though a marginal hail and tornado risk will exist as outlined in SWODY2. KMD && .LONG TERM... 259 PM CDT Wednesday night through Tuesday... The main weather concerns during the period will be temperatures along with the chances and timing of thunderstorms across the region, particularly Thursday night through Saturday night as a quasi-stationary frontal boundary sets up near the area. Thursday looks to be a nice day across the area in the wake of Wednesdays active weather. However, this looks to be a short break in the weather, as an upper trough begins to dig over the northwestern CONUS Thursday night into Friday. Overall, this will induce down stream upper-level height rises and increasing warm air advection across the central CONUS into Friday. Meanwhile, the surface boundary is only gradually expected to shift northward into Central IL Friday, before possibly shifting towards the I-80 corridor on Saturday. The favored area for periods of showers and storms will generally be on the cool side of this boundary, as the warm sector looks to remain capped. Therefore, the exact placement of this boundary will be important in determining where the heaviest rainfall will occur. Given that the outflow from the convection itself could lead to a farther south position of the front then guidance currently suggests, just could mean that portions of northern IL or southern Wisconsin ends up in the strike zone for a few periods of showers and thunderstorms through Saturday night. At some point on Sunday it appears the surface frontal boundary will be driven back to the south as high pressure builds over the Great Lakes. This should bring an end to the threat for storms over the area into early next week. After a couple of quiet and pleasant days early next week, it then appears that the weather pattern may turn active again by the middle of next week. KJB && .AVIATION... For the 00Z TAFs... The aviation forecast concerns for the Chicago airports into Wednesday are: - Two windows of thunder likelihood - the one with the higher confidence being in the early morning, and the other mid-late afternoon - Gusty south-southeast winds Wednesday morning turning southwest Wednesday afternoon - Possibility of MVFR ceilings Wednesday morning After a quiet evening locally, thunderstorms are anticipated to increase across the Mississippi Valley region early overnight and push east-northeast over the airports early Wednesday morning. The thunderstorm activity may not be too wide, thus only two hour TEMPOs for ORD and MDW, but some shower activity and possibly thunder may linger into mid/late morning. Confidence in this first round timing is medium-high. These storms are not anticipated to have much effect on the surface winds, though cannot rule out some convectively-induced gusts. South-southwest wind speeds at 1500-3000 ft will be 40-45 kt with the low-level jet in the early morning, possibly creating brief LLWS depending on surface conditions. The surface winds will turn more south-southwest, and the confidence in that being during midday/early afternoon is medium. While MVFR ceilings are probable in the wake of the storms, especially over northern airports, the potential for IFR looks low for the Chicago airports. Clouds will initially limit destabilization into Wednesday afternoon and as such early afternoon is not expected to have much for showers or storms. Even partial thinning of these clouds though will likely create enough instability for redevelopment of storms, and that is expected, especially from ORD to BMI and eastward during the mid-late afternoon. Thunderstorms may only be isolated/scattered in coverage near the airports and that is why have maintained a VCTS for ORD and MDW at this time. MTF && .MARINE... 313 PM CDT An area of low pressure will shift from the northern Plains over Lake Michigan by Thursday evening. This will result in some stronger Southerly winds (15 to 25 kt) on Wednesday followed by a cold frontal passage and a period of northwest winds for Wednesday night and Thursday. Also expect showers and thunderstorms to impact the lake late Wednesday into Wednesday evening with the approach of this low. Another area of low pressure is forecast to take shape over the central Plains on Thursday. As this occurs, the winds over the lake will trend towards an easterly direction and increase into Saturday. This will likely set up waves supporting small craft advisory conditions along at least portions of the western and southern near shores of Lake Michigan this weekend. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...Small Craft Advisory...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...9 AM Wednesday to 7 PM Wednesday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Blacksburg VA
918 PM EDT Tue May 8 2018 .SYNOPSIS... High pressure will be in control through Thursday before a front passes through the region. After the front passes through ridging over the area will bring warmer and humid conditions to the area for the weekend. && .NEAR TERM /THROUGH WEDNESDAY/... As of 918 PM EDT Tuesday... High pressure will control our weather tonight into Wednesday. Diurnal showers have ended for our forecast area this evening with the loss of heating. Removed mention of convection from ISC grids tonight. This evening 00z RNK raob captured the light easterly winds from the surface up to around 3000 ft. The combination of low level moisture and light winds will result in patchy fog overnight into Wednesday morning. Adjusted temperatures with the latest surface observations, their trends and leaned toward GLAMP for overnight. Lowered low temperatures a few degrees overnight. As of 730 PM EDT Tuesday... Made a quick update to adjust temperatures and cloud cover tonight. Modified temperatures with latest surface observation and their trends for this evening. Showers are diminishing with the loss of heating. Thus decreased pops for this evening into tonight. Shaped cloud cover and weather overnight to capture river valley fog late tonight into Wednesday morning. More changes later this evening. As of 315 PM EDT Tuesday... A weak 500mb low centered over the region per the 12Z analysis is forecast to slowly move east of the region during the forecast period. At the surface, high pressure to the north is providing a weak, generally easterly flow. This flow is clearly visible on METSAT where a cu field and some isolated showers are popping up along the ridges. The past few runs of the HRRR suggest the best chances for precip this afternoon exist mainly around the Alleghany Highlands, but smaller chances throughout the mountains, mainly east of I-77. Chances for showers and increased cloud cover will drop off significantly after sunset with loss of diurnal heating. Expect skies should be mostly clear by around midnight allowing for ample cooling and a decent chance for fog, particularly in the valleys. Wednesday will be similar to Tuesday as we will be in between systems. Surface high pressure will remain the dominant player allowing the air mass to modify a bit for slightly warmer and drier conditions than the previous day. Chances for some afternoon showers in the mountains will again exist, with latest GFS and Conshort guidance indicating that the best chances will be in northwest NC into the New River Valley. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... As of 315 PM EDT Tuesday... The upper pattern will become progressive through the latter portion of the workweek as a trof digs over the western US and we get into some low amplitude flow in the east. One low will move through the Great Lakes and push a trailing cold front through the Appalachians and central mid Atlantic region on Thursday. The best dynamics will slide by to our north but there will be ample instability and some shear present to favor something more that garden variety convection, but parameters do not support widespread severe weather. The current marginal risk advertised by SPC looks good to cover the situation and will monitor later model runs to see how the situation evolves. A warm front will then move through on Friday with some scattered showers/thunder possible, with perhaps some better coverage west of the Blue Ridge due to orographic forcing. With no significant push of cooler air behind the front on Thursday, expect temperatures to remain above normal through the period with highs generally in the low to mid 80s east of the Ridge, and mid/upper 70s to the west. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 315 PM EDT Tuesday... Summer-like pattern with a flat upper ridge in the east and a Bermuda high off the coast will bring warm and humid conditions to the region this weekend with an isolated shower/storm in the mountains. However a frontal boundary will sink into the region from the north later on Sunday, then wash out just to our south. This will bring a better chance for showers/thunderstorms to the region into the first part of next week. Temperatures will remain above normal this weekend, though the increase in clouds associated with the frontal boundary will bring a moderating trend closer to seasonal norms early next week. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... As of 744 PM EDT Tuesday... Patchy fog and isolated convection will hinder aviation operations tonight into Wednesday. Isolated showers in the mountains will diminish during the next couple of hours with the loss of solar heating. Reduced visibilities may be possible in these storms but otherwise, VFR conditions should prevail this evening into tonight. After sunset, skies will clear out and temperatures will be cool, setting up a situation for some patchy fog. The best chance for fog will be in the mountain valleys where the greatest radiational cooling will occur. Morning low clouds and fog will lift by mid morning. Drier air as winds turn more southerly and the weak wedge breaks down should allow for improvement to VFR on Wednesday. Winds during the forecast time frame will be mostly variable, favoring an easterly component tonight and southerly component Wednesday. High confidence in ceilings, visibilities and winds during the taf period. .Extended Aviation Discussion... VFR conditions will continue Wednesday night. Warm front brings another round of showers Thursday, followed by a cold front into Friday, though best threat of sub-VFR could be Thursday, with overall VFR for the weekend as high pressure aloft strengthens over the region. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JR NEAR TERM...JR/KK SHORT TERM...MBS LONG TERM...MBS AVIATION...KK