Update the IMS pre-processing time and IMS snow data format (#1228)

This PR updates the IMS snow data pre-processing time from being the 18z
to the 00z cycle, and also changes to assimilate the IMS snow data in
ascii format from the operational dump.

This PR contributes to
NOAA-EMC/global-workflow#2779

parm/snow/obs/lists/gdas_snow.yaml.j2

@@ -3,7 +3,7 @@ observers:
 {% include 'snow/obs/config/adpsfc_snow.yaml.j2' %}
 {% include 'snow/obs/config/snocvr_snow.yaml.j2' %}
 {% set cycle = current_cycle | strftime("t%Hz") %}
-{% if cycle in ['t18z'] %}
+{% if cycle in ['t00z'] %}
 {% include 'snow/obs/config/ims_snow.yaml.j2' %}
 {% endif %}
 {% endfilter %}

parm/snow/prep/fims.nml.j2

@@ -4,7 +4,7 @@
   otype = "{{ CASE }}_oro_data",
   jdate = "{{ current_cycle | to_julian }}",
   yyyymmddhh = "{{ current_cycle | to_YMD }}.{{ current_cycle.strftime('%H') }}",
-  imsformat = 2,
+  imsformat = 1,
   imsversion = "1.3",
   fcst_path = "{{ DATA }}/bkg/"
   IMS_OBS_PATH = "{{ DATA }}/obs/",

parm/snow/prep/prep_ims.yaml.j2

@@ -2,7 +2,7 @@ calcfims:
   mkdir:
     - '{{ DATA }}/obs'
   copy:
-    - ['{{ COM_OBS }}/{{ OPREFIX }}ims{{ current_cycle | to_julian }}_4km_v1.3.nc', '{{ DATA }}/obs/ims{{ current_cycle | to_julian }}_4km_v1.3.nc']
+    - ['{{ COM_OBS }}/{{ OPREFIX }}imssnow96.asc', '{{ DATA }}/obs/ims{{ current_cycle | to_julian }}_4km_v1.3.asc']
     - ['{{ FIXgfs }}/gdas/obs/ims/IMS_4km_to_{{ CASE }}.mx{{ OCNRES }}.nc', '{{ DATA }}/obs/IMS4km_to_FV3_mapping.{{ CASE }}_oro_data.nc']
 ims2ioda:
   copy: