diff --git a/codebase/superdarn/src.bin/tk/tool/map_addhmb.1.17/map_addhmb.c b/codebase/superdarn/src.bin/tk/tool/map_addhmb.1.17/map_addhmb.c
index 2d3d1f70b..a5366eae6 100644
--- a/codebase/superdarn/src.bin/tk/tool/map_addhmb.1.17/map_addhmb.c
+++ b/codebase/superdarn/src.bin/tk/tool/map_addhmb.1.17/map_addhmb.c
@@ -54,7 +54,7 @@ struct CnvMapData *map[3];
 struct GridData *grd[3];
 
 
-int latcnt[36];
+int latcnt[46];
 
 struct OptionData opt;
 
@@ -112,7 +112,7 @@ int main(int argc,char *argv[])
   float latdef=62;
 
   float latref=59;
-  int nlat=36;
+  int nlat=46;
 
   float bndstep=5;
   int bndnp;
diff --git a/codebase/superdarn/src.lib/tk/hmb.1.0/include/map_addhmb.h b/codebase/superdarn/src.lib/tk/hmb.1.0/include/map_addhmb.h
index 5816ee3ff..517fd7c3b 100644
--- a/codebase/superdarn/src.lib/tk/hmb.1.0/include/map_addhmb.h
+++ b/codebase/superdarn/src.lib/tk/hmb.1.0/include/map_addhmb.h
@@ -25,9 +25,9 @@ along with this program. If not, see <https://www.gnu.org/licenses/>.
 
 /* the boundary array sizes correspond to the grid within which the HMB boundary
  * is searched for when determining the HMB from the data: [24 MLT hours]
- * and [36 Geomagnetic Latitudes, ranging from 40 to 76 degrees] */
-extern float bndarr[24][36];
-extern float lathmb[36];
+ * and [46 Geomagnetic Latitudes, ranging from 30 to 76 degrees] */
+extern float bndarr[24][46];
+extern float lathmb[46];
 
 struct hmbtab *load_hmb(FILE *fp);
 void make_hmb(void);
diff --git a/codebase/superdarn/src.lib/tk/hmb.1.0/src/hmb.c b/codebase/superdarn/src.lib/tk/hmb.1.0/src/hmb.c
index 748e27b64..777ac9c82 100644
--- a/codebase/superdarn/src.lib/tk/hmb.1.0/src/hmb.c
+++ b/codebase/superdarn/src.lib/tk/hmb.1.0/src/hmb.c
@@ -48,10 +48,10 @@ along with this program. If not, see <https://www.gnu.org/licenses/>.
 #include "map_addhmb.h"
 
 float latref=59;
-int nlat=36;
+int nlat=46;
 
-float bndarr[24][36];
-float lathmb[36];
+float bndarr[24][46];
+float lathmb[46];
 
 #define HMBSTEP 50
 
@@ -104,7 +104,7 @@ struct hmbtab *load_hmb(FILE *fp)
   ptr->time=realloc(ptr->time,sizeof(double)*cnt);
   ptr->median=realloc(ptr->median,sizeof(float)*cnt);
   ptr->actual=realloc(ptr->actual,sizeof(float)*cnt);
- 
+
   return ptr;
 }
 
@@ -137,7 +137,7 @@ void add_hmb_grd(float latmin,int yr,int yrsec,struct CnvMapData *map,
 
   /* We should do something about the hemisphere here */
 
-  for (lat=latmin+0.5;lat<90;lat++) {  
+  for (lat=latmin+0.5;lat<90;lat++) {
     nlon=(int) (360*cos(lat*PI/180)+0.5);
     lstp=360.0/nlon;
 
@@ -157,9 +157,9 @@ void add_hmb_grd(float latmin,int yr,int yrsec,struct CnvMapData *map,
       bfac=(90-latmin)/(90-latref);
       del_L=bfac*5.5;
       latx=latmin;
-      if ((mlt>=11) && (mlt<=19)) 
+      if ((mlt>=11) && (mlt<=19))
         latx=latmin+del_L*(1+cos((PI/8)*(mlt-11)));
-      else if ((mlt<11) && (mlt>=5)) 
+      else if ((mlt<11) && (mlt>=5))
         latx=latmin+del_L*(1+cos((PI/6)*(11-mlt)));
 
       if (lat<=latx) {
@@ -172,7 +172,7 @@ void add_hmb_grd(float latmin,int yr,int yrsec,struct CnvMapData *map,
 
     off=map->num_model;
     map->num_model+=c;
-    if (map->model==NULL) 
+    if (map->model==NULL)
       map->model=malloc(sizeof(struct GridGVec)*map->num_model);
     else map->model=realloc(map->model,sizeof(struct GridGVec)*map->num_model);
 
@@ -207,7 +207,7 @@ void make_hmb()
 
       mlt=m;
 
-      lathmb[n]=n+40.0; /* The +40.0 means we start making the grid used by the iterative HMB-finding algorithm at geomagnetic latitude of 40 degrees. */  
+      lathmb[n]=n+30.0; /* The +30.0 means we start making the grid used by the iterative HMB-finding algorithm at geomagnetic latitude of 30 degrees. */
       latmin=lathmb[n];
 
       bfac=(90-latmin)/(90-latref);
@@ -263,12 +263,12 @@ void map_addhmb(int yr, int yrsec, struct CnvMapData *map, int bndnp,
     if (map->hemisphere==1) {
       if ((mlt>=11) && (mlt<=19))
         map->bnd_lat[i]=latmin+del_L*(1+cos((PI/8)*(mlt-11)));
-      else if ((mlt<11) && (mlt>=5)) 
+      else if ((mlt<11) && (mlt>=5))
         map->bnd_lat[i]=latmin+del_L*(1+cos((PI/6)*(11-mlt)));
     } else {
-      if ((mlt>=11) && (mlt<=19)) 
+      if ((mlt>=11) && (mlt<=19))
         map->bnd_lat[i]=-latmin-del_L*(1+cos((PI/8)*(mlt-11)));
-      else if ((mlt<11) && (mlt>=5)) 
+      else if ((mlt<11) && (mlt>=5))
         map->bnd_lat[i]=-latmin-del_L*(1+cos((PI/6)*(11-mlt)));
     }