MODIS and GOES Fog Products During Significant Moisture Return January 18-22

After an arctic outbreak in early January (8-11) sea surface temperatures in the bays and nearshore waters dropped into the upper 40s and lower 50s.

MODIS SST at 0700 UTC 20 January.

Moisture return to South Texas Sunday night January 18th in the form of stratus when a low-level jet developed. The GOES fog depth product was valuable in monitoring the evolution of the clouds and the different heights as evident in this loop.

GOES fog depth loop from 0615 to 1331 UTC 18 January 2010.

MODIS fog product at 0843 UTC 18 January.

A stratocumulus deck was persistent along the Coastal Bend into the night hours of January 19th.  However, shortly after sunrise dense sea fog moved inland along the Coastal Bend during Tuesday morning January 19th.   The fog gradually dissipated by the afternoon and temperatures warmed into the 70s.  Sea fog often occurs in the bays and near-shore waters when warm air and dewpoints exceed the sea surface temperatures enhancing a low-level inversion.  Particularly challenging was the timing of the sea fog during Tuesday morning and then the formation of a stratus layer Tuesday night and Wednesday morning, January 20th, precluding low visibilities.  The stratus developed over the Coastal Bend as a low-level jet and stronger pressure gradient was present.  GOES and MODIS imagery depicted these events.

Low cloud base product from 0115 to 1115 UTC 20 January depicted the high ceilings with the stratus versus fog.

MODIS fog product at 0417 UTC 20 January.

Fog depth product from 0600 to 0801 UTC 20 January.

Observations for KNGP (Naval Station Corpus Christi)

20 Jan 7:56 am	65	64	97	SSE	6	2.00	BR	OVC003	1006.6	29.73	29.717
20 Jan 6:56 am	65	64	97	SSE	6	5.00	BR	OVC003	1007.0	29.74	29.727
20 Jan 6:08 am	64	64	100	SSE	7	5.00	BR	OVC004		29.71	29.697
20 Jan 5:56 am	64	64	100	S	9	5.00	BR	OVC006	1005.8	29.71	29.697
20 Jan 5:20 am	64	64	100	SSE	10	6.00	BR	BKN006 OVC027		29.71	29.697
20 Jan 5:05 am	64	64	100	SSE	13	6.00	BR	FEW006 SCT012 OVC027		29.71	29.697
20 Jan 4:56 am	65	64	97	SSE	12	6.00	BR	SCT006 BKN012 OVC027	1005.8	29.70	29.687
20 Jan 4:46 am	64	64	100	SSE	14	6.00	BR	FEW008 BKN012 OVC027		29.71	29.697
20 Jan 4:16 am	64	64	100	SSE	14	6.00	BR	FEW004 OVC029		29.71	29.697
20 Jan 3:56 am	64	64	100	SSE	12	5.00	BR	BKN004 BKN031	1006.2	29.72	29.707
20 Jan 3:46 am	64	64	100	SSE	13	5.00	BR	BKN004 OVC031		29.72	29.707
20 Jan 3:17 am	64	64	100	SSE	13	6.00	BR	SCT002 OVC031		29.73	29.717
20 Jan 2:56 am	65	64	97	S	12	5.00	BR	OVC002	1007.0	29.74	29.727
20 Jan 2:29 am	64	64	100	SSE	12	4.00	BR	OVC002		29.75	29.737
20 Jan 1:56 am	65	64	97	S	8	6.00	BR	OVC004	1007.9	29.77	29.757
20 Jan 12:56 am	65	65	100	SSE	8	5.00	BR	OVC004	1008.3	29.78	29.767
19 Jan 11:56 pm	65	64	97	S	9	7.00		BKN004 OVC015	1008.8	29.79	29.777
19 Jan 10:56 pm	65	65	100	S	10	3.00	BR	OVC002	1008.8	29.79	29.777
19 Jan 10:53 pm	64	64	100	S	10	2.50	BR	OVC002		29.79	29.777
19 Jan 10:40 pm	64	64	100	S	13	1.75	BR	OVC002		29.79	29.777
19 Jan 10:25 pm	64	64	100	S	12	4.00	BR	OVC002		29.79	29.777
19 Jan 10:05 pm	66	64	94	S	15	6.00	BR	BKN004 OVC023		29.79	29.777
19 Jan 9:56 pm	65	65	100	S	14	6.00	BR	SCT004 OVC023	1008.8	29.79	29.777
19 Jan 9:35 pm	64	64	100	S	13G20	4.00	BR	OVC002		29.79	29.777
19 Jan 9:19 pm	64	64	100	SSE	14	2.00	BR	OVC002		29.78	29.767
19 Jan 8:56 pm	64	64	100	SSE	17	1.00	BR	OVC002	1008.3	29.78	29.767
19 Jan 8:27 pm	64	64	100	SSE	16	1.00	BR	OVC002		29.78	29.767
19 Jan 8:10 pm	64	64	100	SSE	12	0.75	BR	OVC002		29.79	29.777
19 Jan 7:56 pm	65	65	100	SSE	14	2.00	BR	OVC002	1008.6	29.79	29.777
19 Jan 7:44 pm	64	64	100	SSE	13	4.00	BR	OVC002		29.79	29.777
19 Jan 6:56 pm	63	63	100	SSE	9	0.25	FG	OVC002	1009.0	29.80	29.787
19 Jan 6:15 pm	64	64	100	SSE	15	0.50	FG	OVC002		29.78	29.767
19 Jan 6:08 pm	64	64	100	SSE	15	3.00	BR	OVC002		29.79	29.777
19 Jan 6:02 pm	64	64	100	SSE	13	6.00	BR	BKN004		29.79	29.777
19 Jan 5:56 pm	65	64	97	SSE	16G22	7.00		SCT010 SCT250	1008.6	29.79	29.777

The stratus decreased across the region Wednesday night and Thursday morning when winds diminished.  Dewpoints in the mid 60s and clear skies led to ideal conditions for radiational fog over inland areas and the reformation of sea fog.  Early Thursday morning a combination of very dense sea fog and radiational fog formed with visibilities down to 1/16 mile in many locations in the Coastal Bend.  A period of offshore flow developed Thursday morning allowing for rapid clearing and warm temperatures.

Observations for KNGP.  Depiction of the worse dense fog of the year followed by clearing.

21 Jan 11:56 am	69	59	70	N	8	10.00		CLR	1008.2	29.77	29.757
21 Jan 11:06 am	61	61	100	N	6	3.00	BR	SCT001		29.79	29.777
21 Jan 11:02 am	61	61	100	N	7	2.00	BR	BKN001		29.79	29.777
21 Jan 10:56 am	60	60	100	N	7	0.25	FG	BKN001	1008.7	29.79	29.777
21 Jan 9:56 am	58	58	100	NNW	8	0.06	FG	VV001	1008.6	29.79	29.777
21 Jan 8:56 am	57	57	100	N	6	0.06	FG	VV001	1007.9	29.77	29.757
21 Jan 7:56 am	57	57	100	N	5	0.06	FG	VV001	1006.8	29.73	29.717
21 Jan 6:56 am	57	57	100	N	6	0.06	FG	VV001	1006.1	29.71	29.697
21 Jan 5:56 am	58	58	100	N	3	0.25	FG	VV001	1005.6	29.70	29.687
21 Jan 5:42 am	57	57	100	CALM		0.25	FG	VV001		29.70	29.687
21 Jan 5:32 am	57	57	100	CALM		<0.25	FG	VV001		29.69	29.677
21 Jan 4:56 am	58	58	100	N	3	0.25	FG	VV001	1004.9	29.68	29.667
21 Jan 3:56 am	59	59	100	N	7	0.25	FG	VV001	1004.7	29.67	29.657
21 Jan 2:56 am	59	59	100	CALM		0.25	FG	VV001	1004.0	29.65	29.637
21 Jan 1:56 am	60	60	100	S	6	0.25	FG	VV001	1003.5	29.64	29.627
21 Jan 12:56 am	61	61	100	SSW	5	0.25	FG	VV001	1003.3	29.63	29.617
20 Jan 11:56 pm	61	61	100	S	14	0.25	FG	VV001	1003.3	29.63	29.617
20 Jan 10:56 pm	62	62	100	SSE	8	0.25	FG	VV001	1003.0	29.62	29.607
20 Jan 10:18 pm	63	63	100	SSE	7	0.25	FG	VV001		29.64	29.627
20 Jan 10:06 pm	64	64	100	S	6	0.75	BR	OVC001		29.65	29.637

However, the weak offshore flow again led to the formation of very dense fog Thursday night through Friday morning.  The fog again reduced visibilities down to 1/16 of a mile making it the most significant fog of the season for coastal areas.  The fog lifted into stratus and was very slowly to dissipate in coastal areas Friday afternoon as onshore flow prevailed.  This loop of the GOES fog products revealed the advection of fog from south to north across South Texas.

GOES fog depth 0501 to 1045 UTC 22 January 2010 depicting the advection of fog.