Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
230 PM EST Monday Nov 30 2015
rain chances will slowly increase today as low pressure approaches
the region. Rain is expected to spread through the area Tuesday
and Wednesday before high pressure builds through the remainder of
Near term /through tonight/...
high pressure continues to shift further northeast this afternoon while
an upper low advances out of The Rockies and warm advection
begins across our region. Cold air damming across the eastern
zones has slowly begun to break as flow veers throughout the day.
Thus...freezing rain remains out of the forecast while precipitation
slowly progresses northward.
Rain chances increase overnight as the warm front approaches the
area amid a crossing shortwave. Continued warm advection is
prognosticated to keep precipitation in the form of rain through the
Temperatures tonight were tweaked using the lastest guidance
Short term /Tuesday through Wednesday/...
upper level split flow will help advance a series of shortwaves
from large upper low over the northern plains. The low pressure
system is prognosticated to occlude as it shifts towards the western
Great Lakes. With it...the warm and cold front passages will
support widespread showers through the period as moisture
increases in southerly flow. Have adjusted probability of precipitation and quantitative precipitation forecast slightly
based on latest guidance. Temperatures are to remain above normal
before the passage of the cold front.
Long term /Wednesday night through Monday/...
an upper low is prognosticated to cross the Great Lakes and upper Ohio
Valley region Wednesday night through Thursday morning with rain and snow shower
chances. Otherwise...building surface high pressure should bring
dry weather and moderating temperatures through early next week. The latest
guidance blend was used for the gridded forecast.
Aviation /19z Monday through Saturday/...
a shortwave embedded in SW flow and increasing low level moisture
ahead of developing upper Midwest low pressure are expected to
continue spreading MVFR ceilings north across the area through this evening. A
developing low level jet across central PA should be close enough to
result in a period of low level wind shear tonight at lbe and duj.
Deterioration to IFR and showers are expected Tuesday with the
approach of the low/S associated cold front.
Outlook...Tuesday night through Saturday/...
restrictions are likely through Thursday as the cold front and subsequent
upper low cross the region.