Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
1005 am EDT Sat Jul 30 2016
an upper level trough will influence the region through early
next week...bringing daily chances of scattered showers and
thunderstorms. Most of the time will be dry in any one location
however. High pressure will build over the northeastern United
States by mid to late next week.
Near term /until 8 PM this evening/...
Updated the forecast with base blend and the hrrrv1 quantitative precipitation forecast on top of
this. The cams probably have better clues to the uncertainty and
potential evolution of the convection. So the texture of the
forecast is based on the hrrrv1. The hrrrv2 and hrrrv1 show
similar solutions. Best rains to east and south. The ncar 3km efs
shows this same solution.
The cams seem to focus on rain in western in central areas with
the stuff on radar sweeping across the state between now and about
5 PM. Very little rain in the cams after 5 PM in west and central
areas. The cams also seem to clear out the southeastern steadier
rainfall by 7-8 PM. Nothing organized behind it.
The hrrrv1 has some steaks of of 1 to 2 inches of rain. Varies
when and where every run. Keeps heaviest rainfall to our east. The
hrrrv2 has lower quantitative precipitation forecast amounts with few locations over 1 inch. But
same general scenario.
We have the hrrrv2 feed on our research site now. Currently called
hrrrpara as NCEP is running it in parallel for testing before it
replaces the hrrrv1.
Short term /8 PM this evening through 6 PM Sunday/...
The hydrostatic models and ensembles are all we relative to the
cams after about 0600 UTC. The 3-hour gefs on a 0.5 km grid shows
sharper drying than the coarser resolution data grids.
I suspect our overnight pops are too high and the ncar efs has
only isolated showers over PA on Sunday.
We probably are to aggressive with the rain potential on Sunday
and we knocked down the blended quantitative precipitation forecast considerably. Of course the
hrrr versions do not cover this time period and the only good cam
efs runs only at 0000 UTC daily but shows considerably drier day
Sunday than the NCEP models.
Long term /Sunday night through Friday/...
diminishing pops into Monday as the upper level trough and
cyclonic flow slowly exits off the coast. Big ridge builds over
the central US and moves east to Ohio by Friday. This puts US into
a drier pattern with northwest flow. May see something move over the
ridge but then drop to the west and south of PA. Can't rule out
some afternoon clouds popping and maybe an isolated convective
cell over the higher terrain but that should be it. Temperatures
will start out in the normal range and warm to above normal toward
the end of the week.
Aviation /14z Saturday through Wednesday/...
Current issues for flying are the showers and rain over western
areas and the very humid air with haze and fog in the southeastern
The showers will move westward over the course of the day. Expect
MVFR and spotty IFR with the rain. There will be some embedded
thunderstorms so check the radar before takeoff.
The rain will not likely impact widespread areas in the east until
the afternoon. But the humid air will cause areas of MVFR with
haze and fog.
Most organized rain ends after midnight and patchy fog will be an
issue. Overall better flying weather on Sunday.
Outlook... sun- Monday...morning fog restrictions, then scattered
showers and isolated thunder. Tuesday- Wednesday...mainly VFR, but with
morning fog restrictions.