Winter '17 / '18 - Snow Storm #3: Preliminary STP Verifications
Exceptions:
SBY
17-JAN CLI and CF6 bulletins carried 'MM' as daily snowfall at post-time. Intermittent light snow reported during the day between 1029 and 1527 ... twice reducing VSBY briefly to 2 1/2 SM for a total of 34 minutes. Tipping bucket data unhelpful. STP entered as Trace.
HYA
Estimated storm-total snowfall based on inverse distance weighting technique using vicinity STP reports from Barnstable county carried in PNSBOX.
BOS
All frozen precipitation. Low SLR due likely to 2M temperatures > 0°C.
PWM and CON
17-JAN CLI and CF6 bulletins carried 'MM' as daily snowfall at post-time. STPs from PNSGYX.
UPDATE 19-JAN-18 @ 3:15 PM EST
PWM/CON CLI and CF6 carry 5.9" and 2.5" ... respectively.
UPDATE 19-JAN-18 @ 10:15 PM EST
CON
The 17-JAN CLI snowfall report issued by GYX for CON is clearly in error given VCNTY PNSGYX
reports.
Inverse distance weighting using all VCNTY PNSGYX reports from Merrimack county in NH results in
a derived two-day STP of 4.3". The closest public report of 4.2" came from CoCoRaHS 1.7 MI SE of
CON.
The derived two-day STP of 4.3" was reduced for verification to 3.5" after applying an SLR of 13.6 to the 0.06"
liquid reported by ASOS prior to contest deadline. CON/s SLR was derived by inverse distance
weighting of SLRs from 'neighboring' NEWxSFC forecast stations (ORH [12.7] and PWM [14.6]).
Bottom line: Changing CON/s preliminary STP (5.6") to the verifying STP (3.5") flipped
forecaster rankings in the 4th / 5th and 8th / 9th slots along with changes to all Z-scores
(some better; some worse).
CON ... along with SBY ... have long been a troublesome stations.
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Stations observing at least:
Trace - 27
4" - 5 (19%)
6" - 1 (4%)
8" - 0
Max melt-water at RDU (0.49")
PWM - 0.41"
BGR - 0.37"
New daily records: 2
RDU - 5.9" (4"; 1946)
ORF - 2.5" (1.8"; 1911) [corrected station ID: h/t Roger Smith / Peter O'Donnell in Comments]
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Please report any errors in Comments along with a link to the correct data.
Final results for Snow Storm #3 delayed one day (conducting fermentation experiment FRI evening)
Expected post time: NLT SAT evening.
Posts
7 comments:
Concord's F-6 shows only 2.5" for January 17. I don't recall seeing such a large discrepancy between the PNS and F-6 before.
The CLI report carries 0.25" liquid and 2.5" frozen for an SLR of 10:1. Looks suspicious to me given PWM (ORH) SLR was 14.6 (12.7); however ... even at the higher SLRs ... CON STP is still < 4".
CON may have been in a hole ~15z during the storm's peak intensity with CIG and VSBY much higher than on the coast.
I can work up inverse distance weighting using VCNTY values from the PNS. One problem will be adjusting the reports to account for snowfall before the deadline.
Any other ideas?
TQ,
I am fine however you work it out. I was just surprised by the large difference between the PNS and climate report.
KCON STP - inverse distance weighting = 4.3" using all VCNTY PNSGYX reports from Merrimack county in NH. Closest station report was 4.2" came from CoCoRaHS taken 1.7 MI SE of CON.
Thoughts?
Daily record for ORF not ORH?
I think we are stuck with the CF6 value for CON, it seems low but that's their report ... one thing worth mentioning however, as I also have snowfall contests on the go, on rare occasions the CF6 values change after a few days. We saw that happen at DCA with the early December snowfall, and I think I've seen a couple of other minor cases. So CON may change down the road, who knows? -- Roger Smith
Having thought about the CON STP some more ... I tend to agree with Roger; it seems low but that/s their report.
CON/s 10:1 SLR is clearly unsupported by other data; however ... there have been more then a few instances over time where STPs for other stations indicate obviously bogus 10:1 SLRs but that/s been their report and we/ve use it.
I've certainly done myself no good with that suggestion. :) -- Roger
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