Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/28/22

Area Forecast Discussion
National Weather Service Gray ME
1052 PM EST Sun Feb 27 2022 .SYNOPSIS... Arctic cold front exits to the S and E later this evening. It will be cold and blustery tonight with wind chills falling below zero. Wind chills will drop to 20 below zero or colder in the mountains tonight. High pressure will dominate the weather tomorrow before a quick hitting clipper system brings some light snow to the region Tuesday night. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... 1045 PM...arctic front and SHSN have cleared the CWA at this point with T/Tds falling quickly on gusty NW winds. May see a brief bout of upslope SHSN, once the dry air advection slows during the overnight. otherwise gusty winds should settle by midnight. 735 PM...Line of snow squalls mostly weakening as it exits the area, ans may see a few more run of the SHSN this evening, but these should end well before midnight as well, with the exception of some upslope SHSN in the mountains which will until after midnight, but should end before daybreak Monday. Winds stay gusty through about 02-03Z, but they will settle down a bit although still remain strong enough to produce wind chill, especially with rapidly falling temps. Low bottom out from -5 to zero in the N, to around 10 above in srn NH and coastal ME. Previously...Current radar shows areas of snow showers in the mountains with some returns downstream over the coastal plain of Maine. Area webcams and surface obs confirm snow showers activity in the mountains while downstream returns are likely still just virga. Farther upstream radar shows a well defined line of snow squalls across Upstate NY into NW Vermont. Observations and LSRs from BTV show this line of squalls has produced winds in excess of 40 MPH and visibility reduced to 1/4 mile. CAMs continue to paint a robust area with snow squall parameters of 3 to 5 across the northern two thirds of the area with parameter values dropping towards southern New Hampshire and the Maine coast, but still high enough to bring potential for snow squalls to these areas. Latest RAP analysis shows a slight downward trend in instability with the steepest low level lapse rates not making their way into southern New Hampshire. However, the HRRR and other CAMs remain steadfast in holding a line of heavy snow showers and squalls together as the Arctic front presses southeast through the area this evening. This line of heavy snow showers and squalls is expected to reach NW New Hampshire just after 4 PM and will be pushing south of the foothills between 5 and 6 PM and it is here where the best opportunity will be for sudden bursts of heavy snow, strong winds and visibility that could drop to less than 1/4 mile. Despite waning snow squall ingredients this line will approach the Maine coastline around 7 PM and the NH/MA border around 8 PM. Current temperatures along and south of the foothills are in the mid to upper 30s with temperatures expected to drop into the 20s with the frontal passage adding the concern for wet and slushy roads to freeze quickly this evening. Snow shower and squall activity will diminish after 8 to 9 PM with gusty northwest winds in the wake of the front. Temperatures will drop well below zero across the north and with gusty NW winds wind chills will drop below 20 below and have continued the Wind Chill Advisory for tonight into Monday morning. South of the mountains temperatures will drop into the single digits to near 10 degrees with wind chills below zero into Monday morning. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Monday will be cold and blustery as high pressure builds in from the west. Expect mostly sunny skies with NW winds gusting up to 30 MPH through mid day. Highs will be restricted to the single digits across the far north with mid to low 20s across the south. Winds will start to relax late Monday as high pressure moves near overhead. With high pressure cresting over the region Monday night radiational cooling will allow for temperatures to drop well below zero across the north and into the single digits across the south. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Overview: Near to below normal for much of the extended trending above normal by the weekend. Main trof axis overhead to east of the area will keep any precip rather light until larger trof digs to the west by the weekend. Impacts: Light snow accumulations are probable Tue evening/early Wed morning and may impact the evening and morning commutes. Forecast Details: Tue the clipper system approaches the area from the west. The primary forcing mechanism will be WAA at H8...fairly broad and uniform across the forecast area. This should translate to fairly uniform light snowfall amounts across the area as well. The exception will be around Casco Bay and points north. Lingering cold mid level temps will support ocean effect snow as flow returns. This may both increase the intensity and duration of snowfall for these areas and so I currently am forecasting higher amounts approaching Penobscot Bay. Forecast for late Wed into Thu is a little trickier. Model guidance suggestive of a follow up wave producing some lights snows as it slides south of the forecast area. 27.12z GFS shows more of a cold frontal passage...while its own ensemble has around half the members producing light snow. To me this suggests that there are still a couple scenarios on the table...and I will keep PoP at chance given the uncertainty. Deeper southwest flow develops across CONUS Fri and starts to edge into the Northeast by Sat. I expect gradually warming temps thru the weekend. Deeper moisture and stronger warm frontal forcing will also mean the threat for a more robust QPF event will become more likely by Sun. && .AVIATION /04Z MONDAY THROUGH FRIDAY/... Short Term...A arctic boundary will continue to push south late this afternoon bringing the threat for quick hitting snow showers / squalls. This could bring a rapid onset of IFR/LIFR conditions due to snow for most TAF terminals late afternoon/evening. MVFR and -SHSN may linger at KHIE through the first part of tonight with VFR expected for remaining terminals in the wake of the front tonight. Westerly winds will shift out of the NW tonight with gusts around 25 kts. VFR is expected monday into Monday night as high pressure builds in. Long Term...VFR early Tue will give way to areas of IFR or lower in SN. May see some local IFR conditions early in the day between PWM and RKD as ocean effect SHSN move onshore. VFR returns Wed in offshore flow. Another round of SN and IFR or lower conditions is possible Thu but is lower confidence than the Tue event. && .MARINE... Short Term...Arctic front crosses the waters this evening with westerly winds shifting out of the NW behind the front and Gale conditions expected into Monday morning. Arctic air pouring over the waters will also bring moderate freezing spray late tonight into Monday. High pressure builds in Monday from the west with SCA conditions lingering into Monday evening before subsiding Monday night. Long Term...Marginal SCA conditions possible ahead of approaching clipper system in southerly flow. This will shift to westerly behind the clipper and may continue around marginal SCA conditions into Wed morning. CAA across the waters Thu may bring another round of SCA conditions. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Wind Chill Advisory from 4 AM to 10 AM EST Monday for MEZ007>009. NH...Wind Chill Advisory from 4 AM to 10 AM EST Monday for NHZ001- 002. MARINE...Freezing Spray Advisory until 1 PM EST Monday for ANZ150>154. Gale Warning until 10 AM EST Monday for ANZ150>154. && $$ SYNOPSIS... NEAR TERM...Cempa/Schroeter SHORT TERM...Schroeter LONG TERM...Legro AVIATION...Legro/Schroeter MARINE...Legro/Schroeter
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
849 PM CST Sun Feb 27 2022 .UPDATE... Updated for evening discussion. && .DISCUSSION... As of 0200Z, clouds were clearing in the northwest with the back edge of the stratus deck roughly along the highway 82 corridor. Behind the clouds, winds will diminish and radiational cooling will allow temperatures to fall below freezing in the north and west. Temperatures in portions of the Delta area will drop to near the dewpoints and this will lead to some fog. With temperatures below freezing, some freezing fog could result in mostly minor ice accretion on elevated surfaces. Conditions will continue to be monitored overnight for any potential freezing fog warning possibility. Temperatures warm quickly after dawn with the help of full sun. /86/ Prior discussion below: Tonight & Monday... Tonight: As the SW-NE oriented trough axis & strong isentropic subsidence moves in this evening, clouds will quickly clear from NW- SE, as they are currently are in the NW Delta. This will help clear out of NW of the Natchez Trace by midnight & out of the region by daybreak. As shortwave ridge axis builds in through daybreak, sfc ridging will help temps fall below freezing for areas along & NW of the Natchez Trace & into the mid-upper 30s to the SE into the I-59 corridor. There are indications for some potential for patchy fog development, right around the MS River, due to good crossover potential. Light gradient N-NE wind may be able to limit that potential somewhat. However, low-end HREF probs, HRRR & NAM show indications of some better potential, so for now will introduce fog for areas along & N-NW of a line from Winnsboro to Vicksburg to Yazoo City to Greenwood. Due to temps falling below freezing, some of this could be patchy freezing fog. With more expected mist rather than dense fog & some gradient wind that could limit coverage/dense fog potential, will hold off any mention in the HWO. If trends continue in the direction of dense fog, future mention in the HWO & freezing fog advisory may be needed. Monday: Shortwave ridge axis will build through the area, with some increase in thermal warmth. With deep, dry air profiles (i.e. PWs only around a quarter inch) & efficient mixing & clear skies, highs will moderate near climo into the low-mid 60s. /DC/ Tuesday through next weekend... Overnight tomorrow night...temps warm slightly...remaining above freezing through the early morning hours. Overall, the weather quiets down a bit with weakly northwesterly flow aloft over the region. Temperatures moderate, with highs in the 60s Tuesday, starting a warming trend that will culminate in upper 70s/near 80 by Friday. Overnight lows running tandem will start in the lower 50s by Friday. High pressure ridging over the Gulf States and the Southeast keeps the weather quiet and the flow pretty light with some variability over the region through the end of the week. By Friday, an upper wave drops in over the west coast and into the desert SW, resulting in a pattern shift and a 500 mb ridge building in over the Mississippi River Valley, at least briefly. That same wave develops a surface low that moves into the Southern Plains for Saturday. Given the WAA shown in the ECMWF in the mid levels and the stronger southerly surface winds Saturday, temperatures may not be warm enough for the first part of the weekend. Also, the NBM winds seem far too low for Day 8...but that is also highly dependent on the evolution of the next storm system expected to bring precip/storms for the weekend. /HJS/ && .AVIATION... 00Z TAF discussion: MVFR to IFR ceilings persist this evening and will be slow to improve through the remainder of the evening. However, some improvement to VFR will be possible through the overnight hours and by daybreak all sites should be VFR. /28/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 31 63 35 68 / 0 0 0 0 Meridian 34 63 35 69 / 1 0 0 0 Vicksburg 30 62 33 66 / 0 0 0 0 Hattiesburg 37 65 35 70 / 0 0 0 0 Natchez 31 62 34 67 / 0 0 0 0 Greenville 30 60 35 65 / 0 0 0 0 Greenwood 30 61 35 65 / 0 0 0 0 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ LP