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IOP 1: 20 Jan 2001
IOP 2: 23 Jan 2001
IOP 3: 25 Jan 2001
IOP 4: 31 Jan 2001
IOP 5: 1 Feb 2001
IOP 6: 6 Feb 2001
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IOP 8: 10 Feb 2001
IOP 9: 11 Feb 2001
IOP 10: 12 Feb 2001
IOP 11: 17 Feb 2001
IOP 12: 18 Feb 2001
IOP 13: 21 Feb 2001
IOP 14: 24 Feb 2001
IOP 15: 25 Feb 2001
IOP 16: 1 Mar 2001
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2001 - Monterey, CA
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Program Status for 17 February 2001: IOP 11

Status | Observations | Forecast Discussion | Flight Plan | Aircraft Status | Soundings Status

Status
Saturday, February 17 P-3 flight, 1430 UTC take off.
Sunday, February 18 1600 PST flight.
Weather briefing at 1000 PST.
Monday, February 19 Possible P-3 flight.

Status | Observations | Forecast Discussion | Flight Plan | Aircraft Status | Soundings Status

Observations
2327 UTC At 35.49N, 123.04, 946 mb:
heading: 43deg , have descended to alt= 2000 ft

winds:195deg, 13kt
air temp: 9.1degC ,dewpt temp: 7.9degC

2253 UTC Sounding from 35.3N, 122.0W

Press(mb)    ht(m)    T(degC)  Td(degC)  ff(kt)  dd(deg)
1002.1       -SFC     12.0     10.5       -       -
1000          173     11.0      9.1      23      155
 925          821      7.6      6.0      22      180
 850         1514      4.0      2.4      21      190
 700         3070     -3.7     -8.7      32      195
 500         5564    -20.3    -23.0      42      215
2243 UTC at 34.43N, 121.91W, 465mb:
heading: 348deg at 20000ft

winds: 203deg, 41kt
air temp: -22.5degC, dewpt temp: -26.2degC

2242 UTC Sounding from 34.4N, 122.0W

Press(mb)    ht(m)    T(degC)  Td(degC)  ff(kt)  dd(deg)
1001.7       -SFC     12.8      11.1     21      145
1000          145     11.6      10.5     25      150
 925          794      8.4       6.5     23      180
 850         1488      3.6       2.7     24      195
 700         3048     -2.7      -8.5     31      185
 500         5562    -19.9     -22.1     45      205
2230 UTC Sounding from 33.9N, 123.2W

Press(mb)    ht(m)    T(degC)  Td(degC)  ff(kt)  dd(deg)
1001.7       -SFC     11.0      9.0       5      205
1000          141     10.2      7.9       6      225
 925          786      7.6      2.6      22      270
 850         1478      2.4     -0.2      21      250
 700         3030     -3.9     -5.2      33      180
 500         5561    -20.3    -22.3      39      190
2212 UTC Sounding from 33.4N, 124.5W

Press(mb)    ht(m)    T(degC)  Td(degC)  ff(kt)  dd(deg)
1001.6       -SFC     11.8      8.3      14      175
1000          135     10.6      7.8      15      175
 925          781      7.0      3.9      14      255
 850         1472      3.0     -2.4      12      270
 700         3020     -5.3     -8.7      18      210
 500         5559    -20.7    -24.1      48      195
2128 UTC Sounding from 35deg30minN, 123degW

Press(mb)    ht(m)    T(degC)  Td(degC)  ff(kt)  dd(deg)
1001.6        -SFC      10.6      9.0      3      150
1000          132       10.4      8.5      8      235
 925          778        7.8      7.6     14      185
 850         1472        4.2      4.0     30      185
 700         3026       -4.3     -4.9     33      190
 500         5560      -21.1    -23.6     40      200

2121 UTC Sounding from 34deg54minN, 123degW

Press(mb)    ht(m)    T(degC)  Td(degC)  ff(kt)  dd(deg)
1001.7      -SFC       10.8       9.2      9       270
1000         137       10.0       8.5     13       265
 925         783        7.6       6.7     12       175
 850        1477        4.4       3.4     25       180
 700        3034       -4.1      -5.5     33       200
 500        5561      -20.5     -23.6     40       200
2116 UTC Drop#2 made at 34.3N, 123W from 465mb (20000 ft) at 2115 UTC.

Heading for drop#3 at 35N, 123W Drop#4 will be at 35.5N, 123W

Cutting through what looks to be the storm triple point.

2115 UTC Sounding from 34deg24minN, 123degW

Press(mb)    ht(m)    T(degC)  Td(degC)  ff(kt)  dd(deg)
1001.7       -SFC      11.0      10.3       9      315
1000          141      10.0       9.3      10      295
 925          789       8.2       8.0      17      180
 850         1484       4.4       3.6      22      195
 700         3041      -3.7      -4.9      30      195
 500         5562     -19.5     -25.2      41      205
2109 UTC at 34.3N, 123.1W, 465mb:
heading to pt at 34.3N, 123W to make drop.

winds: 209deg, 50kt
air temp: -23.9degC, dewpt temp: -26.3degC

2101 UTC Sounding from 34deg24minN, 124degW

Press(mb)    ht(m)    T(degC)  Td(degC)  ff(kt)  dd(deg)
1001.6      -SFC        11.2      8.6
1000         135        10.2      7.7       11      150
 925         781         6.8      2.1       13      240
 850        1473         5.8     -0.2       24      215
 700        3024        -5.7     -7.5       31      220
 500        5590       -20.3    -23.8       57      205
2056 UTC At 34.4N, 124.4W, 465mb:
heading: 126deg at 20000 ft

winds: 201deg, 54kt
air temp: -24.3degC, dewpt temp: -27.4degC

Have climbed to 20000 ft to make drops.

2040 UTC Sounding from 34deg21minN, 124deg58minW

Press(mb)    T(degC)  Td(degC)  ff(kt)  dd(deg)
  925          7.6        -       17      220
  850          3.7      -4.5      20      246
  700         -4.1     -17.4      27      224
  500        -20.5     -23.2      51      190

2040 UTC Flying a "figure 4" around precip band centered on 34.5N, 123.5W, close to developing low. Will get some dropsondes into system.
2036 UTC Doppler Radar on P-3 showing band of 50 dBz max w/ tops at 6 km (20k ft).

This band is embedded in the lighter precip is about 60 miles wide. Low level jet info below. The south of Santa Cruz and Santa Cruz mntns will probably be most impacted by LLJ.

LLJ:
45kt at 180deg at 2000ft, mix rat.= 8g/kg
at 925 mb; 41kt, 191deg, air temp: 8.5degC, dewpt t: 8.5degC
at 900 mb; 40kt, 189deg, air temp: 7.2degC, dewpt t: 7.1degC

2000 - 1700 UTC

Here are s-band images during the cold rain. I think we had a frontal occlusion passage near 1830Z, after which the melting level has come down >300 m, the precip decreased in intensity briefly, the cloud layer briefly became more shallow, and the winds briefly decreased. During the last few minutes, the winds are picking up again, the rain is heavier, and the sfc temp continues to rise (i.e., static destabilization given decrease in melting level aloft). I suspect the warm rain is done for awhile,. In any event, the hour ending 19Z we had 0.36, and the hour ending 20Z had about .2 - .25" (haven't added it up yet).

1941 UTC
1905 UTC
1857 UTC
1851 UTC at 38.34N, 123.62W, 980mb:
heading: 233deg at 1000 ft

winds: 175deg, 23kt
air temp: 9.6degC, dewpt temp: 8.1degC

Planning to head south to sample rainband offshore in vicinity of Big Sur coast.

1806 UTC LLJ:
at 38.38N, 123.21W
winds: 165deg, 53kt at 930mb (~2200 ft)
mixing ratio: 7g/kg, air temp: 7.0degC
1750 UTC
1739 UTC at 38.74N, 123.57W, 988 mb
heading: 142deg at 700 ft

winds: 141deg, 42kt
air temp: 9.1degC ,dewpt temp: 8.1degC

AXBT dropped at 1738UTC at 38.8N,123.6W

1733 UTC at 38.97N, 123.80W, 987 mb:
heading: 146deg at 700 ft

winds: 143deg, 44kt
air temp: 9.0degC ,dewpt temp: 8.3degC

1729 UTC LLJ:
At 39.05N, 123.96W
winds: 153deg, 50kt,at 940mb
mixing ratio: 6.8g/kg
1716 UTC at 38.59N, 123.42W, 814 mb:
heading: 329deg at 6000 ft

winds: 184deg, 31kt
air temp: 0.5degC ,dewpt temp: -0.1degC

About to make AXBT drop.

1704 UTC at 38.45N, 123.55W, 985 mb:
heading: 88deg at 800ft

winds:148deg, 43kt
air temp: 8.6degC ,dewpt temp: 8.2degC

Mixing ratios at/near 8 g/kg within the low level jet.
During spiral down: saw 45kt jet at 940mb level from the south, mixing ratios up to 8 g/kg.

1700 - 1100 UTC
1659 UTC Sounding from CZD:
T(C)    Alt (m)   p(mb)
  0      1908      804
 -3      2488      748
 -8      3386      667
-13      4204      599
-22      5568      500
1642 UTC at 38.2N, 123.96W, 987mb:
heading: 82 deg at 750 ft

winds: 163deg, 42kt
air temp: 10.2degC, dewpt temp: 9.6degC

1632 UTC At 38.1N, 124.2W, 877 mb:
heading: 349deg at 4000 ft

winds:190deg, 22kt
air temp: 4.6degC , dewpt temp: 1.3degC

1610 UTC
1608 UTC at 38deg17minN, 123deg47min, 988 mb:
heading: 222deg , at 700 ft

winds: 148deg, 39kt
air temp: 9.9degC ,dewpt temp: 9.7degC

1545 UTC at 38deg44minN, 123deg7minW, 678mb:
heading: 178deg at 10000ft moving to pt 11

winds 181deg, 42kt
air temp: -7.1degC, dewpt temp: -9.7degC

1500 UTC at 38deg14minN, 123deg12minW, 989mb:
(heading:346deg, moving to pt 4 at 750ft)

winds: 141deg, 36kt
air temp:8.4degC, dewpt temp: 8.1degC

LLJ: max 40kt at 2000ft 6.6g/kg

1450 UTC
1450 UTC Sounding from BBY:

T(C)    Alt (m)   p(mb)
  0      2052      790 
 -3      2647      733
 -8      3197      683
-13      3838      629
-21.6    5561      500
1430 UTC at 36deg0minN, 122deg26minW, 991 mb (1000 ft):

winds: 152deg, 39kt
air temp: 11.2degC, dewpt temp:3.5degC

1352 UTC Sounding from BBY:

T(C)    Alt (m)   p(mb)
  0      2052      790
 -3      2647      733
 -8      3305      674
-13      3928      622

500mb -21.9 C 5567 m

1234 UTC Sounding from CZD:

T(C)    Alt (m)   p(mb)
  0      2012      795
 -3      2389      758
 -8      3280      676
-13      4054      611

500 mb -21 C 5565 m

Status | Observations | Forecast Discussion | Flight Plan | Aircraft Status | Soundings Status |

Forecast Discussion
Forecast discussion for 17 February 2001

1445 PST:
IR satellite imagery depicts N30.06/W123.73 north to SFO Bay. Lower temp cloud top area continues to shrink with lowest readings in the -35/-38C range. Cloud top temps of -43C west of Santa Cruz and into North SFO Bay. While flow is south-to-north, eastward progression of the system reamins quite slow and averaging only 25Kts over the last 8 hours. Some orographic enhancement of cloud cover now showing up over the Southern sierra Nevada and light shower activity into the South SAC Valley.
Gudgel

1415 PST:
IR Satellite imagery at 22Z shows dimishing area of lower temps at cloud top from N29.45/W123.87 north to N39.0/W123.2. Still some readings at -45C, especially west of Golden Gate and southwest of Monterey Bay, but generally warming elsewhere. Very little activity west of W124.5.

Strongest radar returns over the Santa Cruz Mountains at 38dbz otherwise generally 20dbz along depicted line 60 south of Santa Cruz northward into N-Central California.

Rain reports: Yorkville 1.22"/Venado 1.04"/Cazadero 1.63"
Gudgel

1320 PST:
IR Satellite imagery depicting the area of lowered temps at cloud top from N35/W124.0 south to N30.2/W124.2 beginning to show signs of stretching out and no longer blossoming. Rain echoes in the flow pattern pretty much parallel to CA coast flowing northward with only a slight eastward movement of the band (approx 10Kts). Acknowledge reports from PACJET P3 about 50dbz echoes southwest of Santa Cruz in the just offshore band. No apparent development behind the slowly eastward moving band with the back edge from N30/W126 north to N44/W126.

Precip totals as of 1300 PST: SFO Trace / Crescent City 6-hr 0.22" / Arcata 6-Hr 0.13". Venado storm total as of 1300 PST at 0.92".
Gudgel

1245 PST:
Satellite imagery as of 2030Z (1230 PST) depicting lowering temps at cloud tops in areas centered around N34.7/W123.38 and N32.99/W124.12 embedded in line from N39.14/W121.86 SSW to N30.0/W124.97 and apparently associated with frontal position. Widespread area of low temps along California coast north of Point Reyes from N37.62/W124.51 N to N45.07/ W124.73. Onshore radar showing area of 30dbz about 30NM SW of SFO in N-S band of rain.

Rain reports indicate over 0.68" at Venado in the last 12 hours with Yorkville getting 0.88". Ukiah has had 0.14" in the last hour.
Gudgel

1215 PST:
Heavy Rain reported at Santa Rosa with 40dbz echo in the area. Higher reflectivity line from ground radar N39.1/W122.82 extending SSW to N36.4/W122.92 with general dbz values of 20-25...areas of 30-40dbz. Gusts here at Monterey 14-21knots from 180 degs. IR imagery at 1952Z depicting low temps at cloud top from N38.63/W120.09 SSW to N30.1/W122.89: another at N38.44?W122.51 SSW to N30.2/W124.78 with the aforementioned area of enhancement in this line around N32.34/W124.53 and extending NNE to N35.83/W123.22.

Rain at Cazadero now over 1" storm total. Santa Rosa rain 0.06" in the last hour Wind 26008KT / Ukiah 0.16" Wind 19015KT / Arcata 0.03" Wind 14011KT.
Gudgel

1150 PST:
Satellite Imagery at 1930Z depicts quickly expanding area of cold cloud tops (-44C) centered at N32.20/W124.68 and moving NNE (15 deg T.N.) approximately 30knots. Most notable in just the last 2 hours. This area acts as south anchor of a line beginning to show lowering cloud top temps extending northward to N35.75/W123.1.
Gudgel

1140 PST:
Buoy #59 at 19Z: Wind 260/18G26 Air Temp 51F/Sea Temp 54F Press 1007.5 Wave 13 Feet, Data 14 Seconds

IR Satellite showing at area of weak PVA enhancing southern end of line centered N31.35/W125.03 streaming NNE at 25kts up the existing of current front/rain location off California Coast.
Gudgel

1100 PST:
Morning Brief just concluded.
Precip reports as of 1000 AM PST: Crescent City 0.06" / Arcata 0.07" / Ukiah 0.03" / and Santa Rosa 0.04". Cazadero 0.22" in the last 2-hours (16-18z).

Radar depicting band of precip centered N41.72/W124.07 south to N39.3/ W123.77 with strongest echoes around N40 at 40dbz but echoes generally in the 20-25dbz range. Another band of echoes extending just offshore centered N38.08/W123.29 south to N36.57/W123.33 with echoes 20-25dbz.
Gudgel

0930 PST:
Last Hourly Rain Reports: Crescent City 0.07" / Arcata 0.05" / Ukiah 0.08" / Santa Rosa Trace / Cazadero 0.30" (2-hour 14-16Z) with a surface temp of 6.2C and wind southeast at 10-12Kts.

Area of brightest echoes (values 45-50dbz) on coast in N-S line from N40.76/ W124.39 south to N39.94/W124.26; and aligning with colder cloud tops at 1715Z (0915 PST). Another N-S line of instability enhancement beginning to show up on IR satellite imagery along W127.40 at N40. Eastward movement about 15-20kts.
Gudgel

0845 PST
A line of narrow and currently weak instablity behind onshore band beginning to show up on satellite IR imagery as of 1630Z orientated along N-S line at W127.7 (between Lightning strike depicted at N40.9/W127.71W (and also the farthest south point of lower cloud top temp at -32.5C).
Gudgel

0830 PST:
Southern extent of cold air appears to be around N39.3 with the leading edge reaching W132.0. Back edge of surface coldfront continuing to slow with latest 6-hour average around 17knots east component. At 1600Z, back edge from N40.0/W126.38 southward to N34.19/W126.91 and then southwest...highest echoes around 40 maybe 45dbz at coast at N40. Another high cloud band (cloud top temps -32C in the north to -47C over SFO Bay) back edge line from N40.38/W122.5 south to West SFO Bay to N36.64/ W122.65 at 1600Z...Highest radar echoes with this band appear to be 30dbz at N38.84/W122.52.

Precipitation totals last hour: Crescent City 0.05" / Arcata 0.01" / Ukiah 0.08" / Santa Rosa 0.02" / No Rain at SFO but a trace at Oakland. Cazadera precip 0.17" in the last hour (14-15Z).
Gudgel

0730 PST:
Precipitation at Cazadero started accumulating at about 0340 PST. Total as of 0700 PST was 0.26"...Crescent City 0.03" last hour/ Arcata Trace/ Ukiah 0.07" / Santa Rosa 0.02" / Shelter Cove had 0.42" in last 15 hours (once/day report) / No Rain yet at SFO.

Composite Radar Reflectivity showing two bands along coast north of SFO Bay. First band centered along N41.0/W124.63 to N38.88/W124.40 with echoes primarily in the 20-25dbz range...one area of 40dbz at N40.3/ W124.47. The other band onshore roughly entered at N41.04/W124.13 south to N39.31/W123.85 with echoes 40dbz elongated along N40.82/W124.16 to N40.14/W123.84.
Gudgel

0630 PST Report:

1330Z IR satellite imagery depicts back edge of surface frontal band north-south alignment along W127.5 and separated from large area of upper cloud shield that has moved ahead with back edge along W126.0. Some upper cloud top temps of -38.0C over surface edge farthest north at N39.0 and extending southward with enhancement south of N35.0. Some Farallon Islands light drizzle/light rain as of 0600 AM PST. Surface front appears to have slowed significantly based on back edge movement of 20 knots over the last 7 hours. Light rain reported at Crescent City with 0.01"; Arcata not raining but trace of rain last hour; Ukiah light rain and 0.01"; Santa Rosa not raining but trace in the last hour. Gudgel

Status | Observations | Forecast Discussion | Flight Plan | Aircraft Status | Soundings Status

Flight Plan
Monterey - Pt. 1 3,000 ft w/ porpoises 500-5,000 ft.
Pt. 1-2-3 Frontal module 500 - 18,000 ft.
Pt. 3-4-5 Full blocking stack 500 - 5,000 ft.
Pt. 5-6 5,000 ft.
Pt. 6-7 Partial blocking stack 500 - 5,000 ft.
Pt. 7-8-10-7 Blocking stack along coast 500-5,000 ft.
Pt. 7-11 Fly MVA to pt. 11 and spiral up to 12,000 ft.
Pt. 11-7 Fly 12,000 ft to Pt. 7 and spiral down to 500 ft.
Pt. 7-12 3,000 ft with porpoises 500-5,000 ft.
Pt. 12-13-14-15 Frontal module 500-20,000 ft.
Pt. 15-16 750 ft.
Pt. 16,17,18 Spiral to MVA and then go to Pt. 18
Pt. 18-19 MVA + 5,000-7,000 ft
Pt. 19-20 750 ft. with porpoises 500-6,000 ft.
Pt. 20-21 750 ft. with porpoises 500-6,000 ft.
Pt. 21 - Monterey Return to Monterey.

Status | Observations | Forecast Discussion | Flight Plan | Aircraft Status | Soundings Status |

Aircraft Status
Saturday, February 17 0600 PST take off.
Sunday, February 18 1600 PST flight.
Monday, February 19 Possible flight.

Status | Observations | Forecast Discussion | Aircraft Status | Soundings Status |

Sounding Status
17 February
Bodega BaySoundings starting at 12Z continuing with event.
CazaderoSoundings as event develops.
OaklandSoundings requested at 15, 18 and 21Z.
RenoNo special soundings requested.
18 February
Bodega BaySoundings as event develops.
CazaderoSoundings as event develops.
OaklandSoundings requested at 3Z.
RenoNo special soundings requested.
19 February
Bodega BaySoundings as event develops.
CazaderoSoundings as event develops.
OaklandSoundings requested at 9, 15, 18 and 21Z.
RenoNo special soundings requested.