2000Z, the forecast calls for scattered thunderstorms with rain  developing and a few becoming severe; the CB clouds have  tops at flight level (FL) 450 or 45,000 feet MSL.  It should be noted that when information is given in the area  forecast, locations may be given by states, regions, or specific  geological features such as mountain ranges.  Figure 13-8  shows an area forecast chart with six regions of forecast,  states, regional areas, and common geographical features.  Inflight weather advisories, which are provided to en route  aircraft, are forecasts that detail potentially hazardous  weather. These advisories are also available to pilots prior  to departure for flight planning purposes. An inflight  weather advisory is issued in the form of either an AIRMET,  SIGMET, or convective SIGMET.  AIRMETs (WAs) are examples of inflight weather advisories  that are issued every 6 hours with intermediate updates  issued as needed for a particular area forecast region. The  information contained in an AIRMET is of operational  interest to all aircraft, but the weather section concerns  BOSS WA 211945  AIRMET SIERRA UPDT 3 FOR IFR AND MTN OBSCN  VALID UNTIL 220200  AIRMET IFT…ME NH VT MA CT RI NY NJ AND CSTL  WTRS FROM CAR TO YSJ TO 150E ACK TO EWR TO  YOW TO CAR OCNL CIG BLW 010/VIS BLW 3SM  PCPN/BR. CONDS CONT BYD 02Z THRU 08Z  Each AIRMET bulletin has a fixed alphanumeric designator,  numbered sequentially for easy identification, beginning with  the first issuance of the day. Sierra is the AIRMET code used  to denote IFR and mountain obscuration; Tango is used to  denote turbulence, strong surface winds, and low-level wind  shear; and Zulu is used to denote icing and freezing levels.  An AIRMET includes forecast of moderate icing, moderate  turbulence, sustained surface winds of 30 knots or  greater, widespread areas of ceilings less than 1,000 feet  and/or visibilities less than three miles, and extensive  mountain obscurement.  phenomena considered potentially hazardous to light aircraft  and aircraft with limited operational capabilities.  Inflight Weather Advisories  AIRMET  Example:  Figure 13-8.  Area forecast region map.  13-11  South  D e l t a A r e a  NW  NE  North  Central  SW  SE  NW  NE  Ozarks  B o t  H e l  SW Missouri  Lakes Area  Lake of the  Ozarks Area  Extreme  SRN  IL  SW  SE  C e n t $_{r}$a l  NW  NE  NW  NE  SW  SE  C e n t r a l  $_{I}$o w a  SW  SE  Extrm  SE  NW  NE  Northeast Lakes  Region  Upper Mississippi Valley  A r r o w h e a d  L a k e S u p e r $_{i}$o r  S h o r e l $_{i}$n e  WRN Upper MI  Cntrl  Upper MI  ERN Upper MI  D o $_{r}$P e n i s u l a M a c k i n a c A r e a  N R N H i g h l a n $_{d}$s  The  Thumb  S a g i n a w  V a l l e y  Grand  Valley  I r i s $_{h}$H i l $_{l}$s  N e a r L a k e  M i  Ex trm N  NW  NE  SW  SE  N e a r O h $_{i}$o R $_{i}$v e r  SW  SE  West  N C n tr l  Northe rn  South ern  Cntrl East NE  West  Middle  East  A p a l c h i a $_{n}$M o u n t a i n s  SE  NE NW  A l$_{o}$ n g  O h i $_{o}$R $_{i}$v e r  Extr m NW  S W R N  So ut he r n  W Cn trl  E Cn trl  N  Th ir d  S Th ir d  N e a r La k e E r $_{i}$e  Lee  Lake  Erie  L o w e r G r e a t  L a k e s B a s $_{i}$n  E x t r m N W  Alleg heny  Plate au  N W  S W  S C n t r l  N E  S E  N C n t r l  L e L a $_{k}$e  O n t a r $_{i}$o  N R N  SRN N E  E a s $_{t}$e r n  S h o e  Coastal  Waters  N E NW  S W  S E  C o a s ta l P lain N E  S E  P i e d m o n t W e s t  Mtns  of  SC  C o a s t a l P l a i n  N W M t n s H i l l s o f  A l a b a m a  W e s t  C n t r l  E a s t  C n t r l  E x t r m  S E  Ex tr m  So uth ern  Ge org i a  M o b i l e  A r e a  FL  W  85  E x t r m N o r t h  N o r t h  C e n t r a l  A p a l c h e B a y  S o u t h  E x t r m  S o u t h  Upper  Keys  Lower Keys  G u l $_{f}$S t r e a m  Florida Straits  Coastal  Waters  C a t s k i l l  M t n s  E C n t r l  Cape Cod  C o a s $_{t}$a $_{l}$P $_{l}$a $_{i}$n s  Huds on V alley  Mohawk  Valley  W e s t o f  C a t k i l l s  A d ir on da ck M tn s  Champlain  Valley  G r e n  M t n s  N of Catskills  Wh it e M tns  N W  N E  C o a s $_{t}$a $_{l}$S e c t $_{i}$o n S E  S W  MN  IA  MI  IL  IN  MO  AR  LA  MS  AL  TN  GA  FL  SC  NC  VA  MD  DC  NJ  OH  WI  WV  PA  NY  ME  VT  NH  MA  RI  CT  Coastal Waters–from  coast outward to the  flight information  region border  SW  SE  Nort hern  N E M t n s  Central  S t r a it$_{o}$ f J u a n D e F u c a  Olympic Mtns  Sa cr am en t o  Va lle y  Nort hwes t  North  Centr al  South  Centr al  Lower  Rio  Grande  Valley  Lower  Coastal  Plain  M $_{i}$d C o a s $_{t}$a l  P $_{l}$a $_{i}$n  U p p e r C o a s $_{t}$a l  P $_{l}$a $_{i}$n  Northwest  Texas  P u g e t  S o u $_{n}$d  C a s c a d $_{e}$M t $_{n}$s  C a s c a d e M t n s  o $_{f}$C a s c a d $_{e}$s  Mtns  NE WA  Columbia  Basin  Interior  Valley  Co lu mb i a G org e  B $_{l}$u e  M $_{t}$n s  W a l $_{l}$o w a  M $_{t}$n s  M t n s o f  N E O R C o s t a l R a n g e  W i l a m e t e V a l e y  Coast and  Costal Valley  H i g h P l a t e a u  E a s t S l o p e s  WA  OR  S h a s t a  i s k i y o u s  N E C A  NRN  Sierra  Mtns  Coa stal  Mtns  and  Valle ys  S a n J o a q u i n  V a l l e y  S R N  i e r r a  M t n s  C o a s t a l M t n s a n d V a l l e y s  W e s t e r n N v a d a  E a s t e r n N e v a d a  Coastal  Areas  Death  Valley  Lake Tahoe  Lake  Mead  Lake  Mojave  M o j a v e  D e s e r t A n t e l o p e V a e y C o a s t a l R a n g e  SRN  Deserts  Santa  Barbara  Channel  Santa Monica  Bay  C o a s t a l P l a i n  Gulf of  Santa Catalina  C o a c n e ll a d I m p e ri a l V a ll y s  Great  Basin  C o l r a d o  R i v e r  V a l e y  G i l a r i v e r V a l l e y  M o g o l o n R i m  C h i r c a h u a  M t n s  White  Mtns  Little  Colorado  Valley  G r a n d C a n y o n  F o u r  C o r n e r s  A r a  E x tr m S W  U i n t a B a s i$_{n }$ S Cntrl  Mtns  Great  Salt  Lake  W as at ch M tn s  W e s t C e n tr a l V a ll y s  S a n J u a n $^{M}$t n s  NW  Cntrl  Colorado  Mtns  S o P l a t t e V a l l e y  NE  Palmer Lake Ridge  or Divide  Eastern Plains  Lo we r A rka ns as  Va lle y  SE  S a n L u i s V a l e y  No rt h  Pa r k  R i o  G ra nd e  Va lle y C o n t i n e n $_{t}$a $_{l}$D $_{i}$v $_{i}$d e  S a c r e m e n t o M t n s  S a n g r $_{e}$D $_{e}$C r i s t o  M t n s  E a s t e r n  N e w M e x i c o  Ea ste rn P lai ns  Gr ee n R ive r  Ba sin  So  Ce ntr al M tn s  SW  WY  L a r a m i e M t n s  N P l a t e R i v e r V a l e y SE  WY  B l ac k H ill s  NE  W Y  Big  Ho rn  Mt ns B i g  H or n B as i n W i n d R i v e r M t n s  T e t o n  M n s  S n a k e R iv er V a l $_{l}$e y  C e n tr a l M t n s ( S a w o t h )  Y e ll o w s t o n e P a r k  B i t t e r r o o t R a n g e  F l a t h e a d V a l l e y  East  Slopes of  Cont Dvd  SWRN  Mtns  F or t P ec k  R es er vo i r  W in d R ive r  Ba sin  E  of  Co nt  Dv d  P e c o s  R i v e r  W es t o f Pe co s  B i g B e n d A r a  Ea st  of Pe co s  So uth we st  Panh andle  Northeast  Sout heas t  Coastal Bend  Southwest  Southeast  Panh andle  Northeast  High Plains  Flint  Hills  Marais des Cygnes Basin  Kansas River Valley  Blue River Valley Lower Republican Valley  C h e y n e R i v e r  James  River  NE Lakes Region  Rosebud  Country  Pine  Ridge Area  Big Bend Reservoir  North of  Black  Hills  L a k e L e w i s a n d  F r a n c i s C a s e C l a r k  Dame  Reservoir  Missouri  Slope  Souris River Valley  Sand Hills  Central Nebraska  Nebraska pan Handle  P l a tt e  R i v e r  B a s $_{i}$n  SE  NE  CA  NV  ID  MT  ND  SD  NE  KS  OK  TX  WY  UT  CO  AZ  NM  L a k e P o w e l l  Red River Valley  Lower Mississippi Valley  CHI  Chicago  BOS  Boston  MIA  Miami SFO  San Francisco  SLC  Salt Lake City  DFW  Dallas/Fort Worth  Lake Mich Shoreline 