Monday, January 19, 2009

Snow Storm #6: Preliminary Verification

(updated below - Update II - Update III)

Preliminary storm-total snowfalls from CDUS41...PNS...and CF6 bulletins for Sunday.

Four new daily records.
PWM - 11.5" (11.2"; 1979)
CON - 10.3" (7.7"; 1994)
ORH - 8.2" (6.5"; 1948)
BGM - 3.8" (2.5"; 1978)

One daily record tied.
PVD - 7.5" (7.5"; 1948)

CAR SN:H2O was the only suspect report...given the low densities reported by most other stations. Storm-total snowfall amount looks reasonable in comparison to vicinity reports carried in the PNS; therefore...no adjustments indicated.

Please report errors in Remarks.
Final results and storm summary Tuesday evening.

UPDATE
Regarding PNS snowfall totals referenced in Remarks; The Local Climate Bulletin (CDUS41) is the primary source for snowfall verification data. The snowfall reports in the PNS do not always reflect the official data in the CDUS41.

The BOS PNS issued today @ 1:15 PM EST carries a 3.2" snowfall report for PVD valid @6:50 AM EST SUN...18 JAN. METARs show snow continued for another six hours 41 minutes. The 1751z METAR 6-group reported 0.52" liquid. The 4-group...which rounds to the nearest inch...increased from 3" to 7" between 12z and 18z.

The same holds true for BOS (PNS report time was 7:00 AM EST...18 JAN)...ORH (6:50 AM...EST 18 JAN) and BDL (6:50 AM EST...18 JAN).

Thanks to the poster 'Anonymous' for taking the time to eagle-eye the verifications.

UPDATE II
In Remarks...poster 'Anonymous' links to a WFO CAR summary report where BGR/s FSS reported a two-day snowfall of 11.2" @ 8:00 AM EST MON...JAN 19 and questions whether preliminary verification value of 4.4" is accurate.

The two-day storm-total liquid precipitation...as reported in METAR 6- and 7-groups... totaled 0.43"...of which 0.32" fell before the end of the verification period (11:59 PM EST SUN...18 JAN).

The density of 11.2" frozen precipitation from 0.43" of liquid precipitation is 26:1. If the same SN:H2O is applied to the 0.32" liquid observed during the verification period...an adjusted BGR snowfall total of 8.3" seems reasonable.

UPDATE III
Daily record tied @ MDT - 1.5" (1.5"; 1958)

3 comments:

Anonymous said...

http://forecast.weather.gov/product.php?site=NWS&format=CI&version=1&glossary=0&highlight=off&issuedby=BOX&product=PNS

pvd, orh, bos

Anonymous said...

orh

10.3" is "to date" and not for the date

http://www.weather.gov/climate/index.php?wfo=box

Anonymous said...

You really think BGR's total is accurate? I don't buy that one for a second. First, the CF6 lists 0.43" liquid equivalent, which would make it a 10.2:1 snow ratio. I don't understand how Bangor could get a 10.2:1 ratio farther inland than say PWM's 19.2:1 ratio closer to the coast or Boston's 25.1:1 ratio very close to the coast? (IMG:style_emoticons/default/huh.gif)

Then of course there's this http://www.erh.noaa.gov/car/News_Items/200...-19_item001.htm, which lists

BANGOR FSS 11.2 800 AM 1/19 COOP BGRM1

Granted there was some snow that fell after midnight, so 11.2" might be a little high depending if that's the storm total for the entire event. If it's the entire event, then I'd say 8.3" is a much more reasonable estimate for BGR than the 4.4" they listed. 4.4" really makes no sense at all to me.