Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/12/19

Area Forecast Discussion
National Weather Service Huntsville AL
713 PM CDT Fri Oct 11 2019 .UPDATE... For 00Z TAFS. && .NEAR TERM...(Tonight) Issued at 713 PM CDT Fri Oct 11 2019 The dearth of instability over northern Alabama was ultimately the downfall of the line of showers and thunderstorms that approached the area this evening. A few lingering showers will continue, but have removed any chance for thunderstorms this evening. Rainfall amounts will be negligible from this line. The HRRR shows another line of showers developing overnight along the surface frontal boundary, which is currently stretched from the southwest corner of Mississippi northeast toward just west of Nashville. Northwesterly winds behind the front can already be seen just northwest of Florence and Muscle Shoals. As this front moves through, there will be a noticeable drop in temperature and increase in northerly winds. Cloud cover and wind should help to keep temperatures from dropping too low tonight, but temperatures will fall into the mid to upper 40s across most of the area, making for the coldest night of the Fall so far. .SHORT TERM...(Saturday through Sunday) Issued at 245 PM CDT Fri Oct 11 2019 Northerly flow and continued cloud cover (maybe a few showers) should keep highs in the lower to mid 60s. If cloud cover dissipates sooner than expected, insolation could keep highs a tad warmer. Most guidance weakens and pushes the front southeast into central/southern Alabama during the late afternoon hours. Very light winds and the very dry air being advected in the area should allow temperatures to drop into the upper 30s to mid 40s primarily. Some models show dewpoints actually in the mid 30s Saturday night. If this occurs, not sure lows couldn`t drop a bit lower and we could see some frost in NW Alabama and portions of southern middle Tennessee. Leaving that out for now and keeping lows in the upper 30s due to uncertainty with this possibility. Expect the weak boundary to push back to the north into central Alabama Sunday morning. There looks to be just enough lift and moisture for some isolated to scattered precipitation to return to the area. At this point, not expecting any thunderstorm activity with little if any instability shown in guidance. However, could cover associated with this boundary should keep highs cooler, despite some warmer 925 temperatures and thickness values moving into the area. Highs in the mid to upper 60s look reasonable given cloud cover and the expected cold start to the morning. This activity should dissipated with the loss of daytime heating by the late evening hours, but cannot rule out an isolated shower lingering towards Cullman or Dekalb county. Warmer conditions are expected on Monday, as more sunshine and zonal flow aloft should help temperatures to climb into the lower to mid 70s. .LONG TERM...(Monday night through Thursday) Issued at 245 PM CDT Fri Oct 11 2019 A brief dry spell on Monday will come to an end Monday night into Tuesday, as the frontal boundary that passed across the area on Friday night heads back northward as a warm front. The returning front/moisture from the south, along with another cold front moving in from the northwest, will bring more clouds and chances for showers and thunderstorms to the Tennessee Valley. The forecast upper air pattern between the various upper air model camps begins to vary towards the mid/latter part of next week --- especially in the way they handle an upper system moving ESE from the Gulf of Alaska to the Great Lakes region. The ECMWF more strongly develops it, with the Canadian in-between and the GFS the weaker solution. The stronger EC solution with this low brings higher rain chances and more QPF for the Tennessee Valley, with the GFS and Canadian a bit lighter. The system next week should swing to the east of the area during Wednesday, with rain tapering off in a west to east manner. Cool high pressure to our NW will build somewhat to the SE, bringing another cooler change for the mid/latter half of next week. Highs on Wed/Thu should range in the mid/upper 60s to around 70. Low temperatures Wed night will cool in the low/mid 40s. A few readings in our normally cooler spots could chill into the mid/upper 30s, making light/patchy frosting a possibility. A zonal flow and quick moderation should bring low/mid 70s for high temperatures on Friday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 713 PM CDT Fri Oct 11 2019 VFR conditions persist along the line of showers ahead of the front. Showers are weakening and dissipating. The surface front is just to the northwest of MSL, and should move through by 02Z. With that, expect cigs to plunge and northerly winds to increase behind the front. Cigs behind the front right now at SNH are bkn009, and CRX is ovc004. Expect this trend to continue eastward with low IFR conditions making it to HSV around 05Z. Cigs should improve right around sunrise around 12Z, and be VFR by 15Z at the latest. Clouds decreasing Saturday morning means VFR conditions through Saturday evening. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...McCoy SHORT TERM...KTW LONG TERM...RSB AVIATION...McCoy For more information please visit our website at
Area Forecast Discussion
National Weather Service Indianapolis IN
1146 PM EDT Fri Oct 11 2019 .UPDATE... The AVIATION Section has been updated below. && .SYNOPSIS... Issued at 204 PM EDT Fri Oct 11 2019 A strong cold front will exit Indiana this evening. Rain showers will sweep across Indiana early this evening ahead of the front. In the wake of the front...the coldest air thus far of fall will arrive in Central Indiana for the weekend. Saturday through Monday night...dry and cool weather will be expected with below normal temperatures as high pressure moves across the area. More rain chances will return to the area on late Tuesday into Wednesday as an area of low pressure is expected to push across the area. && .NEAR TERM /Tonight/... Issued at 841 PM EDT Fri Oct 11 2019 Cold front has cleared the eastern zones, with areas of rain within the post frontal zone. Short term model guidance and extrapolation suggests the rain should pass off into Ohio around 120400Z or so. Clearing line currently approaching the western border zones at this time, so skies should start to clear out from the west over the next couple of hours. Made some minor adjustments to the PoPs for the rest of the evening, based on above, otherwise current forecast still looks good for the most part. Previous discussion follows. Surface analysis early this afternoon shows a cold front over the Wabash...quickly moving east across Indiana. GOES16 shows an abundance of cloud cover and moisture ahead of the front across Indiana. Surface flow was southerly with dew points in the mid 60s. A very different air mass was found in the wake of the the front as temperatures in the middle 40s were found across Illinois. Radar shows scattered showers over SW Indiana...poised to push across Central Indiana through the afternoon. HRRR suggests the cold front will continue to push across Indiana this afternoon exiting the state near 00Z. Still some light showers look to be possible in the wake of the front...and time heights and forecast sounds keep some lower level moisture lingering between 00Z-03Z. Thus will keep some some lower chance pops for the first part of the evening as the lingering moisture departs. By 06Z forecast soundings and time heights dry out dramatically amid northwest winds and strong cold air advection. 850mb temps fall to near 0c by 12Z. Of note...people outside this evening will note falling temperatures and very changeable conditions from 6pm to 11PM with temperatures falling to the lower 40s by late evening. So, if you are going to be outside this evening... listen to your mom and wear your coat. Winds overnight should not fall to calm overnight as a significant pressure gradient will remain in place. Surface ridging and strong subsidence should allow for clearing through. Thus will trend lows close to the NBM. && .SHORT TERM /Saturday through Monday/... Issued at 204 PM EDT Fri Oct 11 2019 Through Monday the GFS and NAm continue to keep a strong area of low pressure in place over Ontario. This results in cyclonic flow aloft over Indiana along with cooler NW flow. At the surface strong high pressure looks to be in place stretching from the northern plains to the Tennessee Valley. Time heights and forecast soundings show a dry column through the period. Thus will trend toward mostly sunny and cool days and mostly clear and cool nights. Will trend temps at or below the NBM given the cooler air mass in place across the area. && .LONG TERM /Monday night through Friday/... Issued at 310 PM EDT Fri Oct 11 2019 The long term will keep near to below normal temperatures in place, with some chances for rain and an isolated storm on Tuesday. Otherwise dry conditions will be the rule with a surface high moving across the area and relatively flat upper flow Wednesday through Friday. Right now Wednesday night/Thursday morning lows dip into the middle 30s and may have to monitor for frost as we get closer. && .AVIATION /Discussion for the 120600Z TAFS/... Issued at 1144 PM EDT Fri Oct 11 2019 Some limited cloud cover around 050 expected overnight, but the more extensive cloud cover and associated ceilings, look to stay north of the terminals tonight. Surface winds 270-300 degrees at 6-9 kts overnight will gradually back around to 240-260 degrees by midday Saturday. Occasional surface gusts around 20 kts possible by then as well, especially in the KLAF area. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Puma NEAR TERM...Puma/JAS SHORT TERM...Puma LONG TERM....CP AVIATION...JAS
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1003 PM CDT Fri Oct 11 2019 .UPDATE... Updated for evening discussion. && .DISCUSSION... Mid evening surface analysis had the cold front nearing the Interstate 59 corridor. Very little precipitation was noted along and ahead of the cold front and satellite imagery showed very little cloud cover in our west with drier air filtering into our CWA. Latest HRRR also shows the precipitation tapering off the next several hours. Have updated cloud cover and removed pops after midnight. Otherwise, much cooler and drier air will continue to filter into the CWA with morning lows in the 40s across the delta and in the 50s to the southeast. /22/ Prior discussion below: This Evening through Tomorrow Morning: The well advertised and much anticipated cold front is currently working its way southeastward across our forecast area this afternoon. It was stretched from roughly Starkville to Natchez as of 330 PM. Modest instability and wind shear ahead of the cold front have been able to sustain a few stronger thunderstorms in addition to scattered warm advection showers so far today. Expect the front to continue its eastward journey through the evening, with the chance for thunderstorms mostly dropping off by sunset. Some thunder will linger in the Pine Belt in southeastern MS through early tonight before drier and more stable air moves in behind the front. Some light showers/sprinkles will continue to be possible across the forecast area through early Saturday morning, and then drier air will prevail in the lower levels as the post- frontal air mass builds in. Low temperatures tonight will range from 30 to 40 degrees cooler than what we observed for high temperatures today. Temperatures could be as cool as near 40 degrees in the Delta by sunrise tomorrow. /NF/ Saturday through Friday: Much drier air will filter into our forecast area by tomorrow afternoon, with relative humidity expected to be as low as 30-40 percent across much of the area. A Limited threat for fire weather conditions has been added to the Hazardous Weather Outlook text and graphics for areas generally north and west of a line from Natchez to Greenwood, MS tomorrow. Despite the rainfall across parts of the area today and the last few days, be sure to obey local burn bans as low humidity and north winds of 5 to 10 mph may still make grass and brush fires a concern in these areas. Some modification of the air mass will occur through early next week as high pressure builds in at the surface and flow aloft becomes zonal, but with the old frontal boundary hanging near the Gulf Coast, isentropic lift over the cooler air mass will keep some cloud cover and a chance for showers in the forecast into early next week. Model guidance remains in fairly decent agreement for increasing chances for showers and possibly some thunderstorms from Monday night through Tuesday night as a southern stream shortwave slides east across the Gulf Coast region. A powerful jet streak just to our north will aid in isentropic lift and moisture advection as a developing low pressure system over east TX/OK lifts a warm front north through our area on Tuesday. This frontal boundary may serve as a focus for a corridor of heavier rain during that time, with guidance continuing to point to an area just north of the Interstate 20 corridor. A surge of anomalously deep moisture associated with tropical activity in the eastern Pacific will be lofted northeast by the westerlies, and this deep moisture interacting with the front will likely result in locally heavy rainfall rates. Westerly flow at in the low levels may support some training along the front as well. Therefore have added a Limited threat area for Flash Flooding north of I-20 to the HWO. Another cold front will dip south as the low pressure system moves eastward Wednesday night into next Thursday. /NF/ && .AVIATION... 00Z TAF discussion: A cold front was moving across east Mississippi at 2330Z. Scattered TSRA/SHRA will precede the cold front and may reduce flying conditions but after fropa, MVFR cigs wl develop and continue most of tonight in west and cntrl MS but take until Saturday aftn before improving to VFR in the east and se. VFR conditions wl prevail areawide Saturday evening. /22/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 53 68 52 69 / 9 7 10 52 Meridian 53 70 54 72 / 13 12 9 52 Vicksburg 50 68 50 68 / 5 7 11 53 Hattiesburg 58 71 58 77 / 20 11 5 34 Natchez 52 68 53 72 / 8 7 9 41 Greenville 43 65 46 67 / 4 1 12 48 Greenwood 46 65 46 66 / 6 2 11 50 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ NF/22
Area Forecast Discussion
National Weather Service Key West FL
959 PM EDT Fri Oct 11 2019 .DISCUSSION...In the middle and upper levels(700 to 200 mb), latest available satellite imagery overlaid with available model streamline analysis as of 900 pm, continues to depict a cold core cyclone that is moving east and is centered over Northern Minnesota, situated within a full latitudinal trough encompassing the the Upper Midwest, Central and Northern Plains, and the Northwestern United States, with zonal 50 to 75 knotters at 250 mb moving across from California to the Lower MS Valley where it splits into a narrow ridge axis extending northwards to Western Quebec, with a narrow southern trough axis over Florida. Just east of that is a regional scale negatively titled trough axis from Southern Canada to the NW Atlantic with a cyclone embedded in that near the Benchmark. Water Vapor imagery shows middle level dry air being advected across Southern Florida and the Keys. At the surface and in the lower to middle levels (Surface to 700 mb), latest available marine and land surface observations as of 900 pm, depicts Subtropical Storm Melissa, which as of 500 pm, was located near 38.2N 69.5W, ambling about with a slight southward movement at 3 mph. This storm is producing wind gusts to 50 mph across SE New England, mainly Cape Cod and the islands. West of that, positively oriented near 1025 mb surface ridging is positioned from Eastern New York States southwest down to near Atlanta. As a result, the 00Z sounding at Key West illustrated the developing surface pressure gradient associated with this synoptic pattern, with fresh northeast breezes developing above 950 mb up to about 650 mb, and total PWAT at 1.76 inches. .CURRENTLY...As of 900 pm, skies are partly cloudy across the entire Keys island chain and surrounding waters. Radar shows isolated small showers mostly confined to boundaries that have moved well south of the Reef and into the Florida Straits attm. C-man stations along the Florida Reef are already northeast between 15 and 20 knots, with gusts to 20 to 25 knots, as well as at Smith Shoal Light. Island sensors are around 15 mph. Temperatures across the islands are in the upper 70s to around 80 with dewpoints are in the mid 70s. .SHORT TERM...Tonight and Saturday, given the aforementioned MSLP gradient as represented in the synoptic pattern, local winds should begin to freshen across the islands and surrounding waters overnight. They have already begun to do so across the Eastern locations along the Reef as of this writing. Available non- hydrostatic models, BOTH HRRR and the local WRF indicate another surface-850 mb perturbation within the NE flow will move southwest across the islands after midnight. Given a moderately moist and unstable airmass, rain chances will continue to be above normal. Currently have middle of the chance for pops, 405, overnight and again during the day on Saturday. The increased convergence on Saturday would also allow for slightly more coverage of faster moving showers as well. No changes on this cycle attm. && .MARINE... Small Craft Should Exercise Caution tonight as northeast to east winds increase to 15 to 20 knots. Small Craft Advisory may be required Saturday across the Straits of Florida. && .AVIATION... VFR will be the predominant conditions tonight. Additional shower activity is developing as a night time wind surge moves in from the east. Most of the showers and isolated thunderstorms will stay over the Florida Straits with low confidence of showers skirting across the island terminals. For now will not include VCSH. Wind direction will continue to be favorable for a cloud line to develop in the late morning early afternoon hours of Saturday. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...Futterman Aviation/Nowcasts....LIW Upper Air/Data Collection......NB Visit us on the web at Follow us on Facebook and Twitter at: