Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/19/18

Area Forecast Discussion
National Weather Service Albuquerque NM
530 PM MDT Fri May 18 2018 .AVIATION... 00Z TAF CYCLE Stronger winds aloft will mix down to the surface until around sunset this evening across much of northern and central NM. West to southwest winds will gust from 20 to 30 knots through 02Z. A few stronger gusts will be possible near virga across central and northeastern NM early this evening. Winds will decouple by mid evening with wind speeds generally less than 11 knots overnight. Winds will become lighter aloft Saturday, and afternoon winds will range from 8 to 12 knots from the southwest and west with a few gusts to near 20 knots possible. Dry southwest flow aloft will maintain VFR conditions across the region through Saturday afternoon. A backdoor cold front will move into the northeastern plains late Saturday afternoon with a wind shift to the north northeast and a slight chance of thunderstorms from the Sangre de Cristos to the northeastern plains. 28 && .PREV DISCUSSION...315 PM MDT Fri May 18 2018... .SYNOPSIS... Temperatures will be closer to normal, or even a few degrees below, for mid May, through the middle of next week. Low level moisture will gradually increase from the east slopes of the central mountain chain over the eastern plains, thanks to a couple of cold fronts this weekend. Gusty east winds may develop into the Rio Grande Valley Saturday and Sunday nights, pushing some of the moisture westward. Chances for thunderstorms trend upward through the weekend and early next week in the central and east, while isolated activity with little to no rain and gusty winds will prevail in the west. Chances for thunderstorms diminish by the middle of next week, with drier and windier weather forecast. && .DISCUSSION... Convection increasing in southeast CO this afternoon as RAP13 and HRRR predict a surface boundary will sag into ne NM this evening and overnight. Think this boundary may make more progress towards I-40 thanks to the CO convection at this time, but not much impact if it does, with small pops over the ne tonight. The boundary mixes out Saturday with a stronger one Saturday night, reaching the east slopes of the central mountain chain and pushing an east wind into the Rio Grande Valley. Yet another round of moisture sloshing westward occurs Sunday night, and this may produce a stronger east wind into the Rio Grande Valley as the westward push is assisted by an approaching upper low. Unfortunately, the low is forecast to lift to the northeast early next week, bypassing NM, but not before potentially drawing up some deeper moisture at least temporarily Monday into Tuesday. Upshot is there will be increasing chances for showers and thunderstorms from the central mountain chain eastward over the weekend and into early next week before a drying trend commences. The west will remain mostly dry though, with potential for some dry showers and storms with little to no rain and gusty winds. However, another front could replenish moisture across the east in time for the early part of the Memorial Day weekend. Guidance temperatures at odds with Sunday`s highs. MET and MAV are up to 15 degrees different with forecast highs over the eastern plains with MET guidance being cooler. Leaned toward the ECMWF guidance, which was more similar to the MAV. && .FIRE WEATHER... There will be a break in critical fire weather conditions after today as an upper level trough exits from the central Rockies northeastward onto the Great Plains this weekend. As the system exits, a back door cold front will sag into northeast and possibly east central areas tonight with an increase in humidities. A stronger back door cold front will push through eastern areas late Saturday afternoon and night with wind gusts potentially reaching 40 to 50 mph along NM`s eastern border. The front will also push into the Middle Rio Grande Valley with a gusty east canyon wind Saturday night into Sunday morning. Peak gusts could reach 45 mph below Tijeras Canyon, but probably only around 35 mph farther south and around Santa Fe. Moisture will increase enough with the front for a chance of showers and thunderstorms along and east of the North Central Mountains Saturday afternoon, but any wetting precipitation will probably favor lower elevations of the northeast. The back door cold front should push all the way to the AZ border, or at least the Continental Divide, Sunday night. The moisture with the front may be fairly shallow in the west, so it could mix out by Sunday afternoon. However, there is a slight chance that the moisture will be deep enough for a few gusty and dry thunderstorms west of the central mountain chain to the Continental Divide Sunday afternoon. Spotty wetter variety thunderstorms are expected along the central mountain chain and across the east central plains Sunday afternoon and especially Sunday evening. Sunday and Sunday night, an upper level low pressure system will move over the Great Basin from the west and stall there. It will draw a moist low level return flow into the state from the south and southeast Monday through Tuesday. There will be a healthy chance of wetting showers and storms along and east of the central mountain chain both days, with spottier, drier thunderstorms westward to the Continental Divide. Ahead of the upper low, winds will become breezy over western NM with critical fire weather conditions possible for the Northwest Highlands, and locally critical conditions elsewhere along and west of the Continental Divide, both Monday and Tuesday afternoons. The upper low will eject gradually northeastward across the northern Rockies Wednesday through the end of the week, ushering a mid level dry slot over NM from the southwest in the process. This will cause a downtick in thunderstorm activity Wednesday, when spotty cells will probably favor locations along and east of the central mountain chain. The weather will probably be dry areawide by Thursday. && .ABQ WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 9 PM MDT this evening for the following zones... NMZ103-104-108. && $$
Area Forecast Discussion
National Weather Service Charleston SC
1007 PM EDT Fri May 18 2018 .SYNOPSIS... Low pressure will linger just west of the area through Saturday. Atlantic high pressure will then build in from the east and likely prevail through the upcoming work week. && .NEAR TERM /THROUGH 6 AM SATURDAY/... A closed mid level low in the mid MS valley will open up into a wave by late tonight as its negatively tilted short wave pivots toward the southern Appalachian and SE states. At the surface is extensive high pressure from the Atlantic positioned underneath a 591 meter anticyclone centered near Bermuda. A deep and rich tropical plume of moisture will extend into the region from the Caribbean, allowing for PWat is reach as high as 150-170% of normal. For early tonight the lingering isolated showers due to boundary remnants will fizzle out by, then we`ll keep an eye on a few mid level perturbations within the southerly flow that will advance toward the area by late tonight and closer to daybreak. Low level convergence and isentropic ascent will support increasing coverage of showers and t-storms, especially after 4 or 5 am. We do remain concerned that the reliable HRRR continues to depict very little convection, but since the equally dependent NARRE-TL shows more coverage and is in line with our previous forecasts, we have made few changes in regards to convective coverage. This still points toward the greatest chances over the Charleston and eastern Berkeley counties, where we have 60-70%, while chances drop off to 30-50% to the E of I-95 in SC and to less than that elsewhere. Locally heavy rains will continue to be the main concern as bands of convection could train over the same area, especially over the Charleston tri-county district. We did tweak a temps down about 1-2F most places to account for earlier rain-cooled conditions and the expected increase in convective rains late. But even so, temps will again be well above normal. && .SHORT TERM /6 AM SATURDAY THROUGH MONDAY/... Saturday and Saturday night: Expect the pattern to continue to produce unsettled weather as the area remains between an upper trough to the west-northwest and a building Atlantic ridge to the east. Models keep the deepest moisture over the northern 1/3 of the area, which is where we kept likely PoPs. Chance PoPs rest of the region, for mainly afternoon and early evening showers and some thunderstorms. Highs will be held closer to normal in the lower to mid 80s due to cloud cover and precipitation coverage. Slightly lower values of deep layer moisture push in from the west-southwest Saturday night as the upper trough pulls off to the northeast. Kept slight chance to chance PoPs through the night. Lows in the upper 60s to lower 70s. Sunday and Monday: Atlantic high pressure continues to build from the east. The GFS and NAM are now indicating a surface low center/easterly wave feature moving well south of the region into the eastern Gulf of Mexico Sunday, and toward the northern Gulf coast Monday. This could bring higher tropical moisture across the area on Sunday and possibly into Monday. Due to uncertainty, have kept high end chance PoPs Sunday, then chance for Monday. Highs continuing in the mid 80s and lows in the upper 60s to lower 70s. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Upper low pressure will linger mainly just west of the area through the period. By the end of the period surface low pressure could develop near the western Caribbean Sea and track northeastward toward Florida. Way too early to tell if this low will become a tropical cyclone but we`ll definitely keep an eye on it for a potential track near the Southeast U.S. Coast next weekend since the GFS and ECMWF have been pretty consistent for a while now suggesting such potential. In general it looks like temperatures and rain chances will stay fairly close to or even slightly above normal. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... KCHS: Ceilings at the airfield will teeter between low-end VFR and MVFR through the night. A deep plume of moisture from off the ocean will move through during the morning on Saturday, resulting in at least MVFR ceilings and visibilities. TSRA cannot be ruled out, but probabilities are too low to include at this stage. A return to VFR conditions is then expected in the afternoon as the sea breeze pushes further inland and things stabilize. Moderate wind gusts will occur much of Saturday. KSAV: Isolated SHRA will skirt the area this evening, and any direct hit would be too brief to include anything more than VCSH. MVFR will prevail tonight, although VFR can return from time to time, and IFR is even possible for a few hours late tonight into Saturday morning. Scattered SHRA/TSRA and periodic flight restrictions are possible late Saturday morning into the evening, so we have VCSH and VCTS for now until trends are better defined. Extended Aviation Outlook: Periods of mainly afternoon flight restrictions expected on Sunday, especially over Charleston where deeper moisture exists. Expect a return to more typical scattered afternoon showers/thunderstorms Monday through Wednesday with brief flight restrictions possible each day. && .MARINE... Overnight: The far western portion of sub-tropical Atlantic region will be situated the coastal waters, with enough of a gradient to support SE to S winds as high as around 15 kt. There has been several days with an onshore fetch, enough so that seas will remain elevated. For early tonight those seas will be as high as 3-5 ft, then build about a foot overnight to allow for some 6 footers to move into the outer Georgia waters and the Charleston County oceanic waters. It is across these two marine zones where we have Small Craft Advisory headlines in effect. The bulk of convection early tonight will be out near the Gulf Stream, but eventually they will develop and/or advance in closer to shore and into Charleston Harbor by late. Some storms could produce heavy rains, lightning strikes and strong winds. Saturday through Wednesday: An upper level trough will be departing well north of the area later Saturday, then Atlantic high pressure will gradually build from the east Sunday through mid next week. Marginal Small Craft conditions for seas around 6 feet are expected to continue through early Sunday morning for the offshore waters. Sunday and beyond, no highlights are not expected with southeast winds of 15 knots or less and seas 3 to 5 feet. Winds near the coast could be a bit strong each afternoon with the sea breeze. Rip Currents: Lingering swell combined with a modest onshore flow will continue to support a moderate risk for rip currents through Saturday. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...Small Craft Advisory until 8 AM EDT Sunday for AMZ350-374. && $$ NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE...
Area Forecast Discussion
National Weather Service Cheyenne WY
916 PM MDT Fri May 18 2018 .UPDATE... Issued at 910 PM MDT Fri May 18 2018 WSR-88D reflectivity from Cheyenne and nearby radars indicates widespread showers and isolated thunderstorms across southeast Wyoming along and east of a Douglas to Cheyenne line and over the northern Nebraska Panhandle. The 00Z NAM progs the upper trough over northern Colorado to move slowly eastward to far northeast Colorado by daybreak with a cold front plunging southward across our counties as winds turn to the north and increase in speed. NAM QPF indicates the bulk of precipitation falling overnight across our northern counties of Converse and Niobrara and also over our southern Nebraska Panhandle counties with the bulk of QPF due to the mid level trough moving across northeast Colorado. Have therefore adjusted rain chances, POPs for the rest of the overnight hours. Our Flood Watch is in decent shape and no changes are needed at this time. && .SHORT TERM...(This evening through Saturday) Issued at 202 PM MDT Fri May 18 2018 In the very near term, we will need to be on the lookout for a few stronger storms initially developing across the higher terrain west of I-25 where steeper midlevel lapse rates could result in some larger hail and strong wind gusts. This potential for stronger storms will edge east onto the plains through the late afternoon and early evening hours, but overall threat not as high as what we saw yesterday. A large, negative tilt upper trough will continue to push across the central Rockies through Saturday with a deepening upper low still projected over northeastern Colorado late tonight through Saturday. The NAM, GFS and ECMWF have the band of heaviest rainfall on the north side of the upper low a bit farther west along I-25 late tonight into Saturday, while the latest HRRR continues to advertise the heaviest rainfall axis to be across the southern Nebraska Panhandle into eastern Colorado. With the uncertainty in play as to exactly where the heaviest precip axis will set up, we decided to extend the watch farther west to highlight the potential threat for areas along and east of the south Laramie Range. As for other hazards, we continue to advertise 8 to 12 inches of new snowfall tonight above 9000 ft elevation on the west facing slopes of the Snowy Range and will continue to Winter Weather Advisory that area tonight through Saturday. .LONG TERM...(Saturday night through Friday) Issued at 202 PM MDT Fri May 18 2018 As the upper low deepens, it will stall late Saturday along the Colorado, Nebraska border then will make slow progress northeastward into the northern Plains through late in the weekend. We start ti taper PoPs down Saturday evening keeping chance PoPs going over the Nebraska Panhandle, then we see a drying trend Sunday into Monday. Another slow moving upper low deepens over the desert southwest by Tuesday with several shortwaves ejecting northeastward into our area mid to late week, bringing increased chances of showers and thunderstorms starting Tuesday. && .AVIATION...(For the 00Z TAFS through Saturday afternoon) Showers and thunderstorms will continue to develop across southeast Wyoming and eventually across western Nebraska this evening. CIGS will trend lower through tonight with IFR or near IFR CIGS across most terminals by midnight. Periods of moderate to heavy rainfall are expected through Saturday, resulting in VIS down to 2 miles at times. Mainly IFR conditions are expected Saturday with numerous showers and isolated thunder showers. && .FIRE WEATHER... Issued at 202 PM MDT Fri May 18 2018 Driest areas this afternoon where green-up has been delayed a bit would be around zone 306, however winds and RH values remain outside critical thresholds for Red Flag Warnings. Fairly wet pattern expected over the next 24 hours with numerous showers and isolated thunderstorms moving across the districts...with high elevation snow expected for the Snowy Range and parts of the Sierra Madre Range this weekend. Drier conditions expected for Sunday into Monday, however increased chances for showers and thunderstorms return by Wednesday. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Winter Weather Advisory until midnight MDT Saturday night for WYZ114. Flood Watch through Saturday afternoon for WYZ106>108-116>119. NE...Flood Watch through Saturday afternoon for NEZ019>021-054-055. && $$ UPDATE...Rubin SHORT TERM...JG LONG TERM...JG AVIATION...TJT FIRE WEATHER...JG
Area Forecast Discussion
National Weather Service Dodge City KS
716 PM CDT Fri May 18 2018 ...Updated aviation discussion... .SHORT TERM...(This evening through Saturday) Issued at 354 PM CDT Fri May 18 2018 Severe weather event getting ready to unfold across southwest Kansas late this afternoon and evening. As of mid afternoon, surface low pressure was centered over southeast Colorado near KSPD. A stationary front/outflow boundary extended from the low into west central and central Kansas. Farther south, a dryline was becoming more pronounced from the low into the Texas Panhandle. The atmosphere continues destabilize across the area this afternoon per the SPC Mesoanalysis page. MUCAPE values are increasing to 2000+ j/kg. In addition, 0-6 km shear has been slowly ramping up to around 40 kts. A special 19z sounding from KDDC is verifying this and is also showing a capping inversion at 700 mb which was a little more pronounced than the RAP13 soundings were depicting it earlier today. Per recent runs of the HRRR/RAP models, storms should develop along the front and dryline mainly after 4 pm. Storms will initially be discreet with a greater threat for large hail. Think there will be a window of opportunity for a few storms developing along the old outflow boundary in west central Kansas to become briefly tornadic given the enhanced low level shear along and north of the boundary. The models have been consistent in showing the storms growing upscale into a convective line as they move out of far southwest Kansas and the northeast Texas Panhandle early this evening with the severe weather threat will switch from large hail to strong/damaging winds as the storm cluster moves northeast. Most of the thunderstorm activity will be moving out of central Kansas around or after midnight. The HRRR has been hinting at storms redeveloping over southwest Kansas later tonight. Not real confident this will happen but it will have to be watched. On Saturday the stationary front is progged to move into south central Kansas as the remains of the upper low move out into far northwest Kansas. A fairly cold airmass aloft related to the upper system will keep some instability in place over the region. A stronger cold front is expected to move southeast through western Kansas during the afternoon with widely scattered thunderstorms developing along it. A few severe storms could develop along the front over south central and parts of southwest Kansas along the front, as well as some storms up along I-70 under the colder air aloft. .LONG TERM...(Saturday night through Friday) Issued at 354 PM CDT Fri May 18 2018 The medium range models are showing another upper low developing over the western states early next week. This will keep the central High Plains under a general southwesterly flow aloft pattern through mid week. The models show subtle disturbances moving out over the region but the strength and timing of these features is uncertain. Forecast Builder has some slight chance to chance pops through the week which looks good for now. An upper level ridge builds over the central CONUS later next week which should result in daytime high temperatures back up into the 90s. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 716 PM CDT Fri May 18 2018 Scattered strong to severe thunderstorms will develop and move northeast across portions of southwest into central and south central Kansas through this evening. The Dodge City and Hays terminals will likely be the most impacted by these storms with hail up to golf ball size and strong winds at Dodge City. Strong thunderstorm wind gusts and heavy rain may the be main impacts at Hays. Conditions should be improving across the area after 04-06z. Some MVFR stratus could impact Hays and possibly Garden City later tonight. && .PRELIMINARY POINT TEMPS/POPS... DDC 61 82 51 73 / 50 20 20 10 GCK 57 78 48 71 / 40 20 10 10 EHA 56 81 47 73 / 10 20 20 10 LBL 60 82 49 74 / 20 20 20 10 HYS 61 79 51 70 / 60 20 20 10 P28 66 91 57 78 / 40 20 40 10 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Gerard LONG TERM...Gerard AVIATION...Gerard
Area Forecast Discussion
National Weather Service Hastings NE
640 PM CDT Fri May 18 2018 .SHORT TERM...(This evening through Saturday) Issued at 254 PM CDT Fri May 18 2018 Have been running behind from the word go this shift...primarily due to dissipating MCS and the wake low that occurred behind it. Due to on-going tstms...this will be a shorter AFD than normal. SW flow is over the Cntrl Plns. A potent trof was over the Desert SW. This trof will lift NE and cross the rgn thru tomorrow. The rgn will be in the favorable LFQ of the fairly modest 60 kt upr- lvl jet streak. Expect multiple rounds of shwrs/tstms thru tomorrow. Given that 1-2" of rain fell over parts of Valley/Sherman/Buffalo/Dawson counties... issued a Flood Watch up against the one issued by LBF. CAMs line up with pattern recognition that numerous tstms will develop invof sfc low over SE CO...including SW the unmodified air S of the outflow boundary. They should form a common cold pool. The 06Z/12Z NAM Nest and latest HRRR agree that a sqln will form and lift NE into the CWA. It`s unclear if the remnant cold pool will inhibit its impacts. Vis satellite shows stable wave clds over N-cntrl KS. Believe it won`t matter. Continued S flow above the cold pool should replenish/maintain elevated instability. Svr wind/hail could occur until midnight...mainly SW of the Tri- Cities. Be sure to monitor for svr tstm watch issuance early this eve. This sqln will move thru tonight. Should see a relative break behind it...especially S of Hwy 6. Extensive stratus will form late tonight behind the tstms as the Nrn Plns cool front sags thru the CWA. That will lead to low-lvl saturation as the cool air undercuts rich moisture. Where daytime heating occurs tomorrow...expect renewed tstms development near the upr-lvl vort max...possibly as early as midday. These storms should become elevated as they move NE into the stratus. These storms could be hailers...but can`t rule out an isolated downburst or two. For more details on the meteorology...please see SPC outlooks and MD`s. .LONG TERM...(Saturday night through Friday) Issued at 254 PM CDT Fri May 18 2018 Did not have much time to examine these timeframes due to short- term wx concerns. Sun-Tue are looking fairly uninteresting and quiet. Then more tstm activity appears possible Wed-Thu as rich moisture advects back N and the area remains on the fringe of an EML. Chilly Sun. Then back to much warmer than normal Tue-Fri. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday) Issued at 630 PM CDT Fri May 18 2018 Showers and thunderstorms are continuing to develop to our southwest and are expected to expand in coverage and affect both terminals during the evening through overnight hours. Expect CIGS to gradually lower as clouds thicken over the next couple of hours...with MVFR CIGS encroaching from the west and southwest by late evening at KEAR...and around midnight at KGRI. At the same time...expect some TSRAs to move into the local area...with the strongest storms expected between 19/03Z and 19/09Z. Thereafter...TSRAs will become more scattered and generally weaker in nature...but IFR or lower CIGS will filter in across the area associated with a cold front tomorrow...making for a dreary day with low CIGS and reduced VSBYS in areas of BR. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Flood Watch through Saturday evening for NEZ039-046-060-061. KS...None. && $$ SHORT TERM...Kelley LONG TERM...Kelley AVIATION...Rossi
Area Forecast Discussion
National Weather Service Goodland KS
621 PM MDT Fri May 18 2018 .UPDATE... Issued at 603 PM MDT Fri May 18 2018 Just completed an update. Main reason was to expand the severe thunderstorm watch. Also raised pops and raised rainfall amounts based on high resolution/CAMs have a very good handle on what is going on. && .SHORT TERM...(This evening through Saturday) Issued at 209 PM MDT Fri May 18 2018 Forecast still looks on track for this afternoon/evening with convection expected to form vicinity of leading edge of outflow boundary. Latest GOES imagery suggests boundary lies along convergent zone of stable wave clouds and cumulus streets over northern Greeley and Wichita counties extending up toward Gove and over to Wakeeney. HRRR has been very consistent last 6 runs or so with timing of storm initiation around 4-5 pm MDT and location around highway 96. Latest SPC mesoanalysis suggests there may be a couple more hours before CINH is overcome. Guidance points to storms quickly developing upscale with discrete storms existing in a narrow time window early on. Not thinking much of a tornado threat given weak 1 km bulk shear and SRH values, but best chances would likely be across far southern part of our forecast area late this afternoon. Given mean wind flow and high precipitable water values, potential for heavy rainfall exists in areas which experience training cells, perhaps with better chances over our north and northeast counties. On Saturday, cold front will push through the area with GFS a bit faster than NAM, accompanied by showers. Current forecast has Saturday high temps ranging from low 50s NW to low 70s SE, but frontal timing may require refinement. .LONG TERM...(Saturday night through Friday) Issued at 245 PM MDT Fri May 18 2018 Long range guidance suggests that split flow aloft will prevail over the western CONUS through next week -- and that shortwave energy digging ashore the PAC NW on Sunday will amplify into a closed low that stalls over portions of the Intermountain West Mon-Wed. W-SW flow aloft is expected downstream over the Rockies and High Plains. Given a complicated synoptic pattern characterized by split flow and a cut-off low -- confidence is very low w/regard to sensible weather over the Tri-State area next week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 603 PM MDT Fri May 18 2018 Widespread thunderstorms that will be severe and producing heavy rainfall are developing and expanding over the area. Prevailing conditions will be Mvfr with occasional ifr conditions through this period. Winds will be gusty and variable. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...BULLER SHORT TERM...DLF LONG TERM...VINCENT AVIATION...BULLER
Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
903 PM CDT Fri May 18 2018 .SHORT TERM...(This evening through Saturday) Issued at 346 PM CDT Fri May 18 2018 Trend of decreasing precip potential with the incoming front continues. The problems this front are encountering include weak forcing in split flow, with the MPX area stuck between the northern stream up in southern Canada and the southern stream down across the srn/central Plains. We also lack much in the way of instability thanks to dewpoints only in the 50s and meager mid level lapse rates. And finally, the low levels remain quite dry ahead of the front. Based on what we are seeing with the HRRR and other CAMs, looks like we`ll see only scattered showers developing along the front as it moves through tonight, with precip amounts for where it does rain rather meager. What we do look to get with the front is a good dose of post frontal stratocu as what we see up in NODAK today moves through here tonight and Saturday. This cloud cover along with CAA behind the front will help hold highs back a good 10 degrees from what we are seeing today. They also look shallow and unlikely to provide us with much, if any precipitation. .LONG TERM...(Saturday night through Friday) Issued at 346 PM CDT Fri May 18 2018 The long term will start with southern stream wave currently coming out of the 4-corners region slowly making a trip across Iowa and the WI/IL border Sunday and Monday. There will be several bouts of showers and storms beneath this wave, but those will stay largely south of us. Our problem is the northern stream wave going across southern Canada on Saturday will drop an area of high pressure over central MN/northern WI. Dry air associated with the high will limit the northern extent of precip Sunday/Monday, with the I-90 corridor looking to have the best shot at seeing rain. Current PoPs probably still spread precip chances too far north Sunday and Monday, but we did see a southward contraction with this forecast update. Behind this system it`s back to more of the same for what we`ve been dealing with much of May. With the northern stream retracting well north into Canada as an upper ridge builds from the northern high Plains up toward eastern Alaska. A weak southern stream under-cuts the ridge, coming out across the southern/central Plains. This means highs in the 80s return Tuesday and will stay with us for the rest of the work week. As heat/moisture slowly build next week, models show increasing instability and start generating qpf based on diurnal destabilization and nightly increases in the strength of the LLJ. Current forecast is probably overdoing the endless precip chances that start Wednesday as at some point Wednesday thru Saturday you can find a model giving us precip, hence the forecast that sounds a lot more active than it will really be. Best precip chances look to come Friday/Saturday when there is at least some agreement on a system working across the upper MS Valley, though it does not look overly strong, with severe weather or even healthy rainfall amounts looking unlikely. && .AVIATION...(For the 06Z TAFS through 06Z Saturday evening) Issued at 903 PM CDT Fri May 18 2018 MVFR and some IFR cigs will progress eastward behind a cold front overnight. MVFR cigs are expected area wide Saturday morning with conditions improving again to VFR during the afternoon from west to east. Expecting a mostly dry forecast, with only a few showers near the front tonight. KMSP...MVFR cigs arrive by Saturday morning. Cannot rule out a few showers nearby late this evening through the overnight. /OUTLOOK FOR KMSP/ SUN...VFR. Wind ENE 5-10 kt. MON...MVFR. Chc -SHRA. Wind E 5-10 kt. TUE...MVFR cigs early, then VFR. Wind lgt and vrb. && .MPX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. && $$ SHORT TERM...MPG LONG TERM...MPG AVIATION...BORGHOFF
Area Forecast Discussion
National Weather Service Marquette MI
716 PM EDT Fri May 18 2018 .SHORT TERM...(This evening through Saturday) Issued at 354 PM EDT FRI MAY 18 2018 WV imagery and RAP analysis indicated a ridge from NY/PA into the northern Great Lakes and a troughs from Manitoba into the nrn Plains and from ern Missouri into Alabama. At the surface, moderate south to southeast winds of 10-15 mph gusting to 20-25 mph prevailed across Upper Michigan between high pressure over Quebec and an inverted trough into nw MN. Dewpoints in the 25-30F range with temps from the 60s east to 70s west have dropped RH values into the 20-25 percent range over much of the area. The breezy, warm dry conditions have resulted in an elevated wildfire risk. Since winds are expected to remain below Red Flag criteria, an SPS was reissued to highlight the risk into this evening. Tonight into early Saturday, models have trended significantly farther west with a shortwave trough lifting to the nne from IL. As a result, rain chances have increased over the southeast half of Upper Michigan from late tonight into Saturday morning. However, rainfall amounts should remain light, at or below a tenth of an inch. Temps dropping into the 40s along with some additional low level moisture, will aid RH recovery into the 70-80 pct range. The Manitoba/nrn plains shrtwv will slide to the east dragging a cold front through Upper Michigan. Although the 700-300 qvector conv and fgen with this feature is relatively modest, it should still be able to generate sct -shra advancing through the west half of Upper Michigan by late afternoon into the evening. Again, any rainfall amounts will be light. Temperatures will drop substantially by mid to late afternoon into the 40s over the north as onshore nrly winds develop off of Lake Superior. .LONG TERM...(Saturday night through Friday) Issued at 320 PM EDT FRI MAY 18 2018 The main forecast concern in the extended will be the elevated fire weather potential for much of next week as little to no rain is expected. Beginning Sat night, there could be an isolated shower along/behind exiting trough/cold front mainly over the se portion of the fcst area. Otherwise, expect decreasing clouds from the north and west late Sat night. Much of next week will be dry as models maintain split flow pattern across the western half of the CONUS and a confluent nw flow into the Upper Great Lakes region. Although winds will remain fairly light across the area under persistent sfc high pressure, daytime minimum RHs will continue to be fairly low (20-30% range) through much of the week, heightening fire weather concerns in this persistent dry pattern. Unfortunately, the next best chance of rainfall looks like it won`t be until late next week (at the earliest) as a shortwave trough moves in from the Northern Plains. At this point, there`s plenty of model uncertainty on the strength of this wave and whether there will enough available moisture to produce any meaningful rainfall. A few of the recent model runs suggest a shortwave from the Plains could bring some light rain into the southeast fcst area on Monday, but again even if this happens, it will do little to quell fire weather concerns over the next week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 715 PM EDT FRI MAY 18 2018 VFR conditions will prevail overnight at all terminals, along with the loss the gusty winds as we lose sunlight this evening. Ahead of an advancing cold front, a low-level jet will track across western Upper Michigan tonight introducing low-level wind shear at KIWD/KCMX as flow just off the surface increases to 35 to 40 knots. Early Saturday, cloud cover will be on the increase as the above mentioned cold front moves west to east across the area. Ahead of this front, a shortwave lifting north towards KSAW could bring light rain through the morning hours. Confidence isn`t high as to how far west this initial chance for rain will get during Saturday morning, so have opted to only mention VCSH for now. Further west, chances for rain showers will not arrive until Saturday afternoon as the cold front arrives. Also, as this front moves through winds will become northwest to northerly with gusty winds expected on the backside. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 354 PM EDT FRI MAY 18 2018 Southeast winds of 15 to 25 knots will persist over eastern Lk Superior tonight, before diminishing late. Winds will be less than 20 kts to start day on Sat but will shift north 20 to 30 kts in the aftn and evening behind a front dropping across Lk Superior. Winds will diminish to less than 20 kts late Sat night through the rest of the forecast period as high pressure parks itself over the Upper Great Lakes. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...Voss AVIATION...Ritzman MARINE...JLB
Area Forecast Discussion
National Weather Service Nashville TN
825 PM CDT Fri May 18 2018 .DISCUSSION... After a late afternoon burst of convection in the Nashville area, we are now watching the main batch of thunderstorms working their way northward into Kentucky. Latest HRRR indicates that convection should continue to exhibit the regular nocturnal decrease in activity, with, perhaps, a late night regeneration over eastern areas. Current overnight grids look good, but will run a new set of zones to eliminate the pre-first period. && .AVIATION... 00Z TAF DISCUSSION. BNA/MQY/CKV/CSV...An upper low continues to circulate near STL this evening with a shortwave more or less bisecting Middle Tennessee, leaving us with plenty of moisture and an unsettled weather pattern. Radar shows widely scattered convection persisting as we head into the evening, although this activity will diminish as we lose our surface heating. Look for for mainly light radiation fog overnight, with low ceilings developing at CSV toward morning. We are expecting another round of active weather tomorrow, mainly along the Cumberland Plateau. && .PRELIMINARY POINT TEMPS/POPS... Nashville 67 86 69 90 69 / 40 40 10 30 20 Clarksville 65 84 68 88 68 / 40 30 10 30 20 Crossville 64 78 64 82 65 / 60 60 20 40 20 Columbia 64 86 67 88 67 / 40 30 10 30 20 Lawrenceburg 65 85 66 88 66 / 50 30 10 30 20 Waverly 65 86 69 89 69 / 30 20 10 30 20 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......19 AVIATION........08
Area Forecast Discussion
National Weather Service Paducah KY
916 PM CDT Fri May 18 2018 .UPDATE... Issued at 916 PM CDT Fri May 18 2018 Cleaned up the forecast a bit to catch up to the most recent observational trends. The thunder/heavy rain threat is over, as most of the instability over the region has been expended. Isolated thunderstorms will remain possible over portions of the region for the remainder of the night, as the upper low moves through the region. They should be short-lived with just sporadic lightning and a brief heavy downpour. The other concern is fog development which is already underway over much of the region. At this time much of southern Illinois, west Kentucky and southeast Missouri have MVFR level fog with KCGI already to IFR levels. Most of the area is near saturation already this evening, as winds remain nearly calm, and some clearing develops, dense fog is not out of the question. Added areas of fog to the forecast, mainly over southeast Missouri where the more persistent clearing is likely. We will continue to monitor the dense fog potential for the remainder of the night. UPDATE Issued at 745 PM CDT Fri May 18 2018 Updated aviation discussion. && .SHORT TERM...(Tonight through Sunday night) Issued at 339 PM CDT Fri May 18 2018 The negatively tilted closed low centered just northwest of St. Louis Missouri, with an axis stretching down into the Missouri Bootheel at 230 pm CDT, will continue to slowly drift northeast this evening and overnight. The highest rain chances will continue to the east of the low/trough axis, where enhanced lift in the moist adiabatic environment will produce effective rainfall amounts with a minimum of 3/4 of an inch or higher per hour. Given the extremely isolated nature of the pockets of heavy rainfall, will just utilize hydrological advisories for local drainage/minor flooding issues. With the sharper vorticity gradients aloft, non-supercell based landspouts will be possible again, especially over southeast Missouri this afternoon and this evening. We have been carrying statements the last couple of days hinting at that potential. The 13km RAP and 12km NAM-WRF continue to perform rather will in placement and general intensity of afternoon convection within the favorable isentropic lift zone. With the loss of daytime heating, any convection should be limited to the very narrow zones of enhanced lift aloft overnight. With near calm and saturated condition at the surface, added a mention of fog for the western sections of the WFO PAH forecast area (mainly southeast MO and southwest IL) late this evening and overnight. A very narrow ridge will continue to move in behind the closed low tonight and Saturday, capping the coverage of convective activity across most of the WFO PAH forecast area on Saturday and Saturday evening. Worked to keep as much of the area dry as possible, limiting any spurious model generated pockets of rain chances. Rain chances will initially develop late Saturday night and early Sunday along an impressed surface (warm frontal) boundary along the interstate 64 corridor, then expand southward as diurnal heating generates scattered convection over the remainder of the area ahead of channeled vorticity in the southwest flow ahead of a closed low in eastern Nebraska and western Iowa. .LONG TERM...(Monday through Friday) Issued at 339 PM CDT Fri May 18 2018 Have rather low forecast confidence in the coverage and timing of the precipitation through the work week next week. The previously mentioned closed low over Nebraska and Iowa is forecast to move little on Monday, with minor ridging possible early in the day. The placement of the PoPs/Weather seem a little too far west into the WFO PAH forecast area, but for collaborative and regionally blended model guidance initialization purposes, left a low chance PoP across most of the area. There is a disparity among the ECMWF, GFS, and the Canadian medium range guidance on how dominant the ridge building will be along and west of the WFO PAH forecast area. The GFS and Canadian generate a low over the southeast U.S., southeast of the central U.S. ridge. With the significant uncertainty associated with this forecast low, leaned toward lesser PoPs/Weather for the latter half of the week. Temperatures were a blend of the regional model initialization, the national blend of models, and the Canadian guidance. && .AVIATION... Issued at 745 PM CDT Fri May 18 2018 As an upper low centered just to our northwest migrates east- northeastward, and a weak surface low over our eastern sections moves generally north overnight, most shower and tstm activity is expected to diminish in the evening hours, since much of it is diurnally-driven. However, better mid level vorticity will be concentrated in the eastern half of the region late in the night, and this may enable re-ignition of shower and tstm activity there, lingering well into the morning hours. As a result, there should be an accompanying decrease in cig heights to MVFR and possibly IFR mainly east of the MS River. Light winds overnight will be conducive to fog formation. Noticeably improved conditions will be noticed by late morning/afternoon Sat. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...DRS SHORT TERM...Smith LONG TERM...Smith AVIATION...DB