Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 160812 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 310 AM EST Mon Jan 16 2017 .SYNOPSIS... High pressure to the northeast will set up cold air damming over central NC through Monday before a low pressure system approaches the area midweek. && .NEAR TERM /THROUGH TONIGHT/... As of 928 PM Sunday... A 1030 MB surface high over the northern Mid-Atlantic States will build southward into the area overnight. 925-850mb southerly upglide atop the cooler airmass advecting into the region from the NE has and will continue to support patchy light rain overnight, eventually waning Monday morning. Precipitation will be vary light with mostly trace amounts. The isentropic lift will aid to initiate another cold air damming episode overnight. Min temps should vary from near 40 northeast to mid 40s southwest. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... As of 310 PM Sunday... Monday, ongoing CAD atop a quasi-stationary frontal zone extending across upstate SC and back into southwestern NC will maintain a low overcast deck through the morning, with patchy light rain and/or drizzle possible across the northern counties. Temperatures will be slow to recover, especially across the north half. An end to the spotty light precip and a gradually lifting of the ceilings will allow temps to rebound into the lower 50s across the south and the mid-upper 40s across the north. If ceilings lift sooner or dissipate, potential for afternoon temperatures to be 5-6 degrees warmer, primarily across the south. Monday night, expect variable cloudy skies to persist while another weak perturbation will approach from the west. This feature may trigger a patch or two of light rain and/or drizzle, mainly over the western Piedmont. Min temps in the low-mid 40s. && .LONG TERM /Wednesday through Sunday/...
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As of 310 AM Monday... This period will feature warm temps and alternating wet and dry days. Polar air will remain bottled up well to our north, affecting only eastern Canada and Maine, leaving NC in a mild pattern with low level thicknesses staying well above seasonal normals. A very wavy and progressive flow across the southern CONUS will bring bouts of unsettled weather reminiscent more of early spring than of the heart of winter. Wed/Wed night: Areas of rain should be ongoing Wed morning, ahead of a small but potent shortwave trough that moves from the Ohio Valley ESE across VA/NC Wed/Wed night. An occluded frontal system ahead of this wave will shift over and off the mid-Atlantic coast, dragging a cold front slowly SSE through the state late in the day. Mild WSW flow ahead of this front should equate to highs in the mid 60s to near 70 despite abundant cloud cover. Expect good chance to likely pops, weighted early in the day, exiting to the east in the afternoon. Cooler lows are likely Wed night with fair skies post- front, although lows will still be above normal, in the lower to mid 40s. Thu/Thu night: A brief dry period is expected as the front settles to our south and a weak continental high builds over the area from the west, beneath a prominent mid level ridge sitting between the aforementioned exiting wave and ahead of another strong low/wave shifting through the central and southern Plains Thu. Fair skies Thu with increasing clouds late Thu into Thu night. Highs in the upper 50s to lower 60s. Lows in the lower to mid 40s. Fri/Fri night: High coverage of rain appears likely to return by Fri morning, as the Plains low/trough tracks ENE, deamplifying but taking on a negative tilt as it crosses the Mid-South then Ohio Valley/mid-Atlantic region. Passage of this wave should draw the surface front back northward as a warm front, with another short period of shortwave ridging following for Fri night. Highs in the upper 50s to mid 60s and lows in the mid-upper 40s. Sat into Sun: The mid level ridging holds over the Southeast on Sat, along with a light SW low level flow into NC. Models hint at a potential secondary frontal zone along the Gulf Coast that would, if it occurs, provide a focus for convection, effectively shutting off any moisture influx into NC. As such, Sat should be a generally dry day, with temps once again above normal, peaking in the upper 50s to lower 60s. By Sun, however, the active southern stream culminates in a deepening low over the Southern Plains, Gulf States and Mid- South/W Ohio Valley, with a strong negatively tilted trough approaching our area from the W and SW. The op GFS and ECMWF differ a bit with timing but both indicate this general pattern, with a strong surface low over the mid Miss Valley, a possible occlusion moving into the western Carolinas, and warm frontogenesis across the Carolinas. This has the potential to bring a threat of strong storms late Sun into Sun night. Of course, at this far range, the details cannot be pinned down, and there is still plenty of uncertainty. But the op models do have support from the CFS, and the GFS and ECMWF are fairly close in solution at this range, very surprising considering that the pertinent features of this pattern are still well out over the western Pacific and SE Asia and should not, by all accounts, be very well sampled. Temps should remain above normal through the weekend. -GIH
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&& .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 1244 AM Monday... 24 Hour TAF period: MVFR ceilings beginning to show up across the CWA this morning and conditions are expected to continue to deteriorate with IFR conditions if not LIFR ceilings to begin to show up at least at the Triad sites if not all as in-situ cold air damming begins to set in across the NW Piedmont. expect light winds out of the northeast or east through the period. Ceilings are not expected to lift beyond MVFR levels in most locations on Monday with the exception of KRWI and possibly KFAY late in the day. Otherwise will maintain MVFR conditions through the end of the TAF period. Some light rain will also be possible. Long term: An active pattern will see several systems cross the area next week. While no winter precipitation is expected, adverse aviation conditions due to low ceilings and visibilities are expected. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Ellis NEAR TERM...CBL SHORT TERM...WSS LONG TERM...Hartfield AVIATION...Ellis is the U.S. government's official web portal to all federal, state and local government web resources and services.