Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 261545 AFDCTP Area Forecast Discussion National Weather Service State College PA 1145 AM EDT THU MAY 26 2016 .SYNOPSIS... A ridge of high pressure will set up shop over the western Atlantic for the next several days bringing warm and increasingly humid conditions to the region into the holiday weekend. Cooler and showery weather may arrive for Memorial Day. && .NEAR TERM /UNTIL 7 PM THIS EVENING/...
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Mid cloud deck has eroded to a large degree across much of the central mtns and susq valley late this morning...and mdt cu are developing across the ridges as sfc-based...and lowest 100mb ml cape increases to a few hundred j/kg. ml cape should ramp up further to 700-1000 j/kg during the mid to late afternoon hours as a weak sfc/upper trough (currently moving through central ohio) drifts across the Allegheny Front and Central Mtns of the state. this is where the last few runs of of the HRRR and WRF ARW paint the greatest chc for showers and isolated to scattered TSRA. The coverage and intensity of the convection should diminish this evening as this disturbance and sfc trough approaches the Lower Susq Valley. Will maintain high chc to low likely pops across the central and western part of the CWA...with slightly lower chcs for convection across the far east...as a result of the later arrival of the theta-e ridge and aforementioned trigger mechanism in the form of the sfc/upper trough. SPC does not even put us in the marginal risk. PWATs will be in the 1.25-1.5 inch range and the warm-cloud layer more than 10kft deep today. There could be some heavy small rainers since they will be moving slowly - but at least they will be moving today. That being said. rainfall is still expected to "average" one tenth of an inch or less in most places. However, locations seeing a briefly heavier few showers (or a TSRA) could see a quick one-quarter of an inch of rain. High temps should be a few degrees lower than Wednesday for most places. The NW mountains may struggle to climb out of the upper 70s.
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&& .SHORT TERM /7 PM THIS EVENING THROUGH 6 PM FRIDAY/... Precip chances get much lower after sunset, but a few cells may survive until close to midnight. Then the light wind overnight could allow for fog to form as the moisture/dewpoints will be much higher than the last few nights - especially after many places have some rain on Thursday. While there should be a lull in the showers later tonight and Friday morning, the CAPE gets high again in the afternoon - possibly much higher (maybe twice) than Thursday. However, even with CAPEs in the 2000J/kg range, the models generate only scattered convection. This may have more to do with a lack of forcing as there is no short wave to help convection along. Will hold the course with 30-40 POPs at this point with the better chance for a shower over the ridges. Once again, the showers should pop up over the mountains first - but may just rain themselves out of existence with almost no shear at all. What rain does fall could be heavy with almost zero storm motion and PWATs will still be above 1 inch. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... The large scale pattern has a decidedly summertime look and feel to it through the Memorial Day weekend and into next week with light winds aloft and a prevailing ridge across the northeast CONUS. Temperatures will average above normal with the core of the `hot` weather front-loaded Friday-Sunday before trending modestly toward late May/early June climatology. Precipitation risk early in the period should be characterized by diurnal convection with the highest probs occurring during peak afternoon heating, augmented at times perhaps by weak disturbances drifting through aloft. Max POP may be centered on or around Memorial Day as a weak shortwave suppresses heights as it passes by to the north and some interaction takes place with `tropical` system migrating toward the southeast U.S. coast. Latest NHC forecast says this area of disturbed weather has a 30% chance of cyclone formation in the next 48 hours. && .AVIATION /15Z THURSDAY THROUGH MONDAY/...
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High pressure over the region will result in widespread vfr conds with just a 6-10 kt southwesterly breeze developing and continuing through late this afternoon. An approaching weak upper lvl disturbance and subtle sfc trough, combined with an increasingly moist ssw flow, will produce sct shra/tsra during the aftn and early evening. Although vfr conds will predominate, a brief vis reduction is possible associated with a passing shra/tsra. Sct evening shra/tsra should become confined to taf sites kmdt and klns this evening before tapering off, as the disturbance passes east of the region. The focus will then shift to the potential of patchy late night fog under light and variable wind...especially in spots that receive rain this aftn/evening. A moist swrly flow ascending the mtns could also result in ifr cigs at KBFD late tonight, as latest mdl soundings and SREF prob data suggest. OUTLOOK... Fri...Early am low cigs possible. Isold pm tsra impacts possible. Sat-Mon...Isold pm tsra impacts possible.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo/Lambert NEAR TERM...Lambert/dangelo SHORT TERM...Dangelo LONG TERM...Steinbugl AVIATION...Lambert/Fitzgerald

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