Dec, 9, 2007, system is back online. (restored after the motherboard [ABIT AB9 QuadGT] failure on Dec/4)
Next day 1300/1600 PST 3km forecasts are available around 1930 PST;
750m 1300 PST forecasts are also available around 2200 PST;
Forecasts result from model initializations with 0Z (and 12Z moring update)
data. Update times for 750m forecasts are spaced roughly 20
minutes for each 30 min increment.
Each update simply overwrites
the previous forecast, so while the model is still running two different
forecast times can have different dates.
Please check the forecast dates at the top of each plot for currency !
Links to Further Information:
Parameter descriptions
BASIC thermal forecast parameters
- a short and simple list of the parameters most important for thermal soaring
July 2002 SOARING magazine BLIPMAP article - a descriptive "first thing to read" for potential BLIPMAP users, giving an
overview of BLIPMAP predictions
Additional information
but intended for users of traditional RUC and ETA BLIPMAPs, not these RASP BLIPMAPs, so
allowances must be made
Overview
These forecasts are intended to help the
meteorology-minded pilot better evaluate soaring conditions. The
maps are particulalry useful to cross-country soaring pilots, since
they allow evaluation of conditions away from the home field.
Utilizing the forecasts can require some self-education (though that
can't be too hard since over 2000 US pilots actively use BLIPMAPs in
the US) as individualized assistance is not provided. At first
glance the website can seem intimidating since so many parameters are
forecast - but most are "supplemental" forecasts to be used as needed
and many users normally look only at the three or four they have found to be
most useful, such as the expected lift strength or the maximum (dry)
thermalling height or cloud potential/height forecasts, looking at
additional parameters only under special conditions.
How are RASP forecasts produced ?
RUC and ETA BLIPMAP forecasts are obtained by
post-processing forecast files output from NCEP prognostic models, so
horizontal and vertical resolutions are determined by those used in
those models. But here I am running a prognostic model myself,
so am able to specify the vertical/horizontal grid (though of course
subject to limits of practicality). A WRF (Weather Research and
Forecasting) model is being initialized and marched forward in time at
30 second time intervals to produce forecasts at 3 hr
increments. Initial and boundary conditions come from the
larger-scale models run by NCEP. To increase accuracy, forecasts are produced for both a
larger-domain coarse grid (12 km) and a smaller-domain fine grid (3
km) nested inside it, but only results for the latter are
displayed. To produce a 1300 PST 1km forecast, after the preceding forecasts are complete, the model
is re-initialized from the 1000 PST 3km forecasts and a 3km/750m nested-grid
forecast run for 3 hours.
Notes and Caveats:
() One is not supposed to believe all the details of these
forecasts, particularly since the small-scale structure is constantly
changing yet one a few snapshots at different times are shown.
Rather, one should be looking for patterns.
() Forecasts for points close to the boundary will be less
accurate than for those located nearer the center of the domain, due
to inevitable mis-matchings between the coarse and fine grids.
In particular, predictions of max/min BL vertical velocity are very
noisy and inaccurate near the boundary (particularly where boundary
condition problems exist). To remind users of this, a dotted
line marks the "frame" outside of which coarse-fine boundary
interaction problems are most prevalent.
