Mid-South Probabilistic Quantitative Precipitation Forecast (QPF)



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NWS Memphis Weather Forecast Office

NWS - Mid-South Probabilistic Quantitative Precipitation Forecast (QPF)
County Warning Area [CWA]: MEG
Regional NWS Weather Office: Memphis, TN

000
FXUS04 KWBC 210650
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
249 AM EDT SAT OCT 21 2017


PRELIM DAY 1 QPF DISCUSSION
VALID OCT 21/1200 UTC THRU OCT 22/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...NORTHWEST INTO THE NORTHERN ROCKIES...

AN IMPRESSIVE AND LONG DURATION ATMOSPHERIC RIVER EVENT WILL
IMPACT THE PACIFIC NORTHWEST THROUGH THE DAY 1 PERIOD. RAINFALL
RATES THIS MORNING WILL INITIALLY BE LIGHT IN THE BROAD WARM AIR
ADVECTION REGIME WITH LOW LEVEL FLOW NOT IDEALLY SITUATED INTO THE
TERRAIN. HOWEVER BY THIS AFTERNOON RAINFALL RATES WILL INCREASE AS
LOW LEVEL FLOW TURNS MORE WESTERLY AND OROGRAPHIC ASCENT IS THUS
MAXIMIZED. THE ATMOSPHERIC RIVER AXIS WILL FLUCTUATE A BIT TO THE
NORTH THIS AFTERNOON AND THEN BACK SOUTH TONIGHT...WHICH WILL
SHIFT THE HEAVIEST RAINFALL RATES FROM OR EARLY TODAY...INTO WA
THIS AFTERNOON/EVENING AND THEN BACK SOUTH INTO OR BY LATER
TONIGHT.

THE ANOMALIES ASSOCIATED WITH THIS EVENT ARE QUITE IMPRESSIVE. LOW
LEVEL WESTERLY FLOW...INTEGRATED MOISTURE TRANSPORT...AND PWAT
VALUES...WILL ALL BE NEAR THEIR CLIMATOLOGICAL MAXIMUM VALUES FOR
AT LEAST A PORTION OF THIS EVENT. THUS THE IMPRESSIVE RAINFALL
TOTALS SEEN IN THE GUIDANCE ARE LEGITIMATE. ANTICIPATE PRETTY
WIDESPREAD 0.25" IN AN HOUR TOTALS ACROSS THE WESTERN WA/OR
TERRAIN...WITH RATES MAXIMIZING NEAR 0.75" IN AN HOUR IN THE MOST
PRONE UPSLOPE REGIONS. RAINFALL TOTALS THROUGH 12Z SUNDAY SHOULD
BE IN THE 4-6" RANGE OVER MUCH OF THE WA/OR COASTAL RANGES AND THE
CASCADES...WITH ISOLATED AMOUNTS AS HIGH AS 6-8"...WITH 1-2" MORE
COMMON OUTSIDE OF THE TERRAIN. THIS ATMOSPHERIC RIVER EVENT WILL
HAVE A PRETTY GOOD INLAND EXTENT...THUS ANTICIPATING 1-2" THROUGH
12Z SUNDAY INTO PORTIONS OF THE NORTHERN ROCKIES AS WELL...WITH A
GOOD PORTION OF THIS FALLING AS RAIN AS SNOW LEVELS RISE THROUGH
THE DAY.

OVERALL MODELS ARE IN VERY GOOD AGREEMENT WITH THIS EVENT. WPC QPF
THUS FOLLOWS CLOSE TO A MULTI MODEL CONSENSUS WITH MORE WEIGHTING
GIVEN THE TO THE HIGHER RES GUIDANCE. IN GENERAL CHANGES FROM
CONTINUITY WERE MINIMAL.


...FLORIDA...

NO SIGNIFICANT CHANGES EXPECTED TO THE CURRENT POST FRONTAL EAST
NORTHEASTERLY LOW LEVEL FLOW REGIME ACROSS FL DAY 1.  SCATTERED
SHOWERS LIKELY TO CONTINUE OFF THE WESTERN ATLANTIC AND ACROSS THE
PENINSULA THIS PERIOD. SOME HIGHER PWAT AIR BEGINS TO LIFT
NORTHWARD OUT AHEAD OF THE TROUGH TO THE WEST...AND THIS MAY FOCUS
SOME HIGHER RAINFALL AMOUNTS NEAR THE FL KEYS...ALTHOUGH CURRENT
INDICATIONS ARE THAT THE HEAVIEST TOTALS REMAIN SOUTHWEST OF THE
KEYS.


...SOUTHERN PLAINS INTO THE MS VALLEY...

A MID/UPPER LEVEL TROUGH AXIS WILL PUSH INTO THE PLAINS THROUGH
THE DAY TODAY...WITH A COLD FRONT STEADILY PROGRESSING EAST AS
WELL. WILL HAVE PLENTY OF MOISTURE AND INSTABILITY ACROSS THE
PLAINS AND MS VALLEY OUT AHEAD OF THESE FEATURES...WITH PRETTY
GOOD MOISTURE TRANSPORT SEEN AS WELL. THUS THE COMBINATION OF
DIURNAL HEATING...FALLING HEIGHTS AND STRONG SURFACE CONVERGENCE
ALONG/NEAR THE FRONT...WILL LIKELY ALLOW FOR WIDESPREAD CONVECTION
ALONG THE FRONT EXTENDING FROM IA SOUTHWEST INTO TX. OVERALL THE
FRONT AND TROUGH WILL REMAIN PROGRESSIVE THROUGH THE DAY 1
PERIOD...WHICH SHOULD MEAN THE CONVECTION SHOULD ALSO BE STEADILY
PUSHED EAST. THIS FORWARD MOTION SHOULD CAP THE MAGNITUDE OF
RAINFALL AMOUNTS THAT CAN BE EXPECTED. HOWEVER THE ANOMALOUS PWATS
IN PLACE AND THE EXPECTED WIDESPREAD NATURE OF CONVECTION WILL
STILL SUPPORT SOME HEAVY RATES AND A BROAD AREA OF 1-2" EXTENDING
FROM PORTIONS OF KS/MO SOUTH INTO TX.

DO HOWEVER THINK THERE IS SOME OPPORTUNITY FOR BRIEF TRAINING OF
CONVECTION...ESPECIALLY THIS AFTERNOON AND EVENING DURING THE
FIRST SEVERAL HOURS OF THE EVENT. MEAN WINDS ARE PARALLEL TO THE
FRONT...SO COULD IMAGINE THAT WE SEE SOME REPEAT CONVECTION FOR A
PERIOD ACROSS NORTHEAST TX INTO EASTERN OK/KS...BEFORE THE
CONVECTIVE LINE ORGANIZES AND PROPAGATES MORE QUICKLY OFF TO THE
EAST. THUS DO THINK SOME ISOLATED 2-4" AMOUNTS ARE POSSIBLE IN
THESE AREAS.

OVERALL MODELS ARE IN GOOD AGREEMENT WITH THIS SYSTEM. WPC THUS
USED A BLEND OF THE ECMWF/GFS/UKMET ALONG WITH VARIOUS HIGH RES
SOLUTIONS TO GENERATE QPF. THIS RESULTS IN A SLIGHT INCREASE IN
AMOUNTS FROM OUR PREVIOUS FORECAST...BUT GENERALLY ONLY MINOR
CHANGES IN THE AXIS. ONE AREA OF UNCERTAINTY IS THE SOUTHERN
EXTENT OF CONVECTION ACROSS TX. THE VARIOUS HIGH RES GUIDANCE SHOW
A WIDE RANGE OF SOLUTIONS. TENDED TO LEAN THE FORECAST TOWARDS THE
HRW ARW2 OVER THIS AREA...AS DO THINK THAT THE CONVECTIVE LINE HAS
A GOOD CHANCE OF EXTENDING FURTHER SOUTH INTO TX THAN IS
ADVERTISED BY SOME OF THE OTHER MODEL SOLUTIONS.

CHENARD


GRAPHICS AVAILABLE ON THE WEB AT
WWW.WPC.NCEP.NOAA.GOV/QPF/QPF2.SHTML

24HR QP VT 22/12Z
 0.01 524262 527246 532232 537215 540210 540203 540200 537185
      534181 531175 528168 524163 520158 518155 514153 510150
      507145 503141 499138 495136 493133 489129 484124 477122
      473120 467119 462122 459126 453129 447129 442133 437138
      434140 429139 425135 422135 421138 415150 411164 415176
      414184 417189 419196 415200 415215 409227 406229 399229
      397231 396235 396242 400248 406251 423266 427279 428289
      429292 433294 437294 441294 444296 445302 448306 449309
      453310 457308 467301 483286 485284 488287 492292 494296
      497298 500300 504299 509297 513291
 0.01 515892 515876 514874 511872 507869 499865 494856 492850
      491848 488848 483851 478852 477855 477861 476873 474879
      468880 463881 459882 447884 440885 434883 428878 419873
      412865 402871 396874 394876 389876 384877 382880 381884
      379884 373886 365890 360892 356894 348901 345905 341910
      337913 333906 330908 326908 322907 320905 319898 322893
      321888 318883 314881 307876 305871 301872 299874 294881
      289878 284874 279865 277861 274859 271863 269869 269872
      266873 261875 255881 254892 255899 257904 260911 264917
      270926 273929 275933 282940 285944 286947 285951 278955
      268960 266964 269968 276976 278978 276982 272986 288020
      299022 302023 303026 307025 311021 315016 318011 320007
      322004 325007 327012 329014 334011 340004 343000 346997
      358998 361996 365992 372984 377978 382976 389971 397964
      401961 403959 405962 405969 407973 417978 421980 428981
      432979 438978 445977 451974 457969 462967 468965 477961
      486957 494952 497947 502945 507944 511939 514934 514921
      513914 514908 515892
 0.01 495100 496094 494091 488086 486084 483080 480074 477071
      474071 472072 474074 480079 481083 481090 479092 479097
      482098 487101 491106 493107 494102 495100
 0.01 497990 495985 491984 489982 485982 479982 467981 463984
      458988 450992 445993 439995 429999 420005 413010 408013
      404019 402023 402028 403030 407031 409029 412029 433024
      456020 475012 482007 485001 488000 490998 493998 495995
      497990
 0.01 471108 470105 468105 465104 462101 460101 460104 461106
      463109 464112 465114 466114 466110 468108 469110 471108
 0.01 457120 455115 454111 455105 456101 453095 450092 445095
      439095 437096 433095 430091 427091 427095 429100 428103
      425104 424107 424111 420116 423121 423129 429130 433126
      436122 438121 442122 444124 446124 451119 453121 457120
 0.01 412071 412070 410068 408068 407067 405067 403067 405068
      406070 408070 410071 412071 412071
 0.01 317815 317811 316807 312800 311795 312792 311788 308784
      302781 299784 297788 292789 285786 279784 276784 273785
      265786 259786 256785 244792 241791 236791 227795 225797
      226800 229806 231828 234835 238841 242848 247854 253857
      258854 264849 268842 270835 267828 263821 262817 263813
      271810 279809 288812 291814 293818 298822 300824 304824
      306828 309831 311831 312824 317815
 0.25 531213 532209 532203 530195 526182 522172 519166 512163
      507158 504153 499147 495143 492137 481127 474125 470124
      468130 468138 472143 462138 459134 457136 453136 452140
      449143 448147 444147 440147 435149 432151 431155 435162
      437167 437171 437176 434182 431184 427184 424186 426189
      431190 433197 436203 437206 436208 434213 431213 427213
      425215 422219 420224 426230 408233 404238 402242 404244
      408243 410246 417251 430256 433257 434260 437267 440275
      446280 451280 457278 466271 470267 472266 476266 485271
      489275 494281 500286 505287 511284 518273 520269 522264
      522258 522254 519245 516237 514230 511223 507218 504212
      503207 503201 505197 508198 513202 518207 521211 524214
      529216 531213
 0.25 485230 484228 482227 482226 481229 482230 483232 485230
 0.25 491874 491871 491868 491866 491865 490863 489861 488861
      487862 486864 486865 485866 485869 486871 486874 486876
      488878 489877 490876 491874 491874
 0.25 459197 460195 459193 459192 458191 456190 455191 454194
      454196 453196 453198 452201 453202 454201 455201 456200
      458200 458199 459197
 0.25 468915 467907 464902 460899 454899 447902 442905 429907
      427904 424897 422896 418897 414899 409896 403896 392903
      388905 385906 381905 380901 378900 372901 361905 355910
      350913 341919 337922 333926 315941 312944 309950 305954
      302957 296960 293965 292973 290981 288985 289994 291999
      295002 300014 306015 307013 308009 309003 313998 322995
      328991 333995 335996 339996 344993 349991 353992 355996
      357996 360994 364990 367984 371979 377975 392963 401956
      407953 414951 423946 429945 432945 438943 443940 452932
      462927 468915
 0.25 445116 446114 446111 445109 444106 442104 441104 439105
      437105 435106 434107 433109 434112 435112 436113 437112
      438112 439112 440113 441115 442115 443117 445117 445116
 0.25 427208 426207 424206 423207 424208 425210 425211 426211
      427209 427208
 0.25 312930 311924 310919 308917 303913 301907 296903 292897
      289891 284887 274882 268882 266885 265888 267893 271898
      275903 278910 282914 288918 299918 303918 307919 308924
      309930 312930
 0.25 300811 300808 300806 298805 296806 295807 296809 297810
      297811 299813 300811
 0.25 290929 290928 288928 288929 290929 290929
 0.25 265802 265796 262792 258791 253794 251797 246800 242802
      237805 236808 234814 234820 235828 237832 242835 246835
      249831 253822 254818 258813 263805 265802
 0.50 519268 520263 520257 517249 511233 503215 496197 494194
      495188 498178 501177 503180 506187 511194 517196 521198
      524198 523184 504165 496162 491156 489152 491148 493146
      492142 490137 485132 482129 478129 475129 472127 471130
      471133 470137 474140 482142 483145 481147 478147 473149
      469146 464142 459142 456143 453152 446153 439151 436152
      434155 444171 446178 444181 441183 440188 442192 446198
      450198 452194 453188 454186 457187 467185 473180 477177
      479181 479185 475192 469195 464200 457203 451209 444213
      437213 434216 431217 424220 423224 425226 431231 432235
      430237 424236 418233 413233 410235 408237 410240 416246
      423250 428252 432252 436255 442261 445263 449263 453262
      458260 463257 469255 474256 478257 484261 490268 495275
      501281 506282 510279 513277 515275 519268
 0.50 495244 494240 491235 489231 487227 484225 481224 479226
      481231 485233 487233 491235 493240 495244 495244
 0.50 464171 464169 464168 463166 462165 462163 463161 462158
      461158 460157 458158 458160 457162 456163 455164 454166
      454169 455171 455172 456173 458173 459172 460171 462171
      463171 464171
 0.50 461913 460907 454908 449910 444910 433915 428916 424914
      420910 417906 413904 407905 397910 385914 381913 378909
      368907 362909 358911 348917 335932 318947 311954 305960
      300964 297970 293981 292985 292991 295996 298994 302990
      304988 307990 308993 311993 318992 327988 330988 334992
      336994 339993 343990 355985 363981 371976 380969 389962
      397956 404950 409945 414945 417942 414940 418937 424935
      432931 438928 441925 445921 448919 450920 454922 457920
      461913
 0.50 443111 443108 442107 441108 440110 442111 443111
 0.50 259809 259807 259805 259803 258801 257800 255800 254802
      253804 253806 253808 254810 255811 256811 258810 259809
 0.50 252812 250806 248804 244805 241808 238810 237816 236820
      237826 239830 242832 245829 247827 248821 248816 251813
      252812
 1.00 515269 515267 515265 515264 515261 514260 513259 512260
      511262 511265 512267 512268 513270 514271 515269
 1.00 508248 509242 508237 505228 500218 498212 495208 491201
      487198 482197 474200 466206 461205 457207 455211 448214
      441214 437216 425223 432229 436232 436235 434237 417242
      424247 429249 433248 436248 438249 443252 449253 454252
      461250 469249 479249 484252 488257 492263 498270 502273
      504271 503267 500258 496249 491241 478229 477225 477222
      479221 488224 498243 503248 506249 508248
 1.00 491170 490167 488163 484156 482154 477153 473153 470150
      464150 462148 460150 461154 463156 468163 469166 473165
      479167 480165 483166 485169 489170 491170
 1.00 463178 463175 459175 458176 456177 453176 452173 450171
      449170 449173 452176 453178 453182 455184 457184 459182
      462181 463178
 1.00 439229 438228 437228 438231 439229
 1.00 411931 410928 406927 400931 396932 394931 391928 388927
      386928 376936 370939 365938 366933 369926 370923 370918
      368916 364916 355918 350922 346927 341933 337939 327947
      322952 315956 310960 307967 308973 311975 314976 317974
      322974 324976 328976 332975 334976 336980 337985 342986
      348983 355979 359974 361972 365970 372968 378965 385961
      393951 403944 408938 411931
 1.00 245823 245821 245819 244817 244816 243815 242814 242815
      242817 243817 242818 242819 242821 242823 243824 245824
      245823
 1.50 504241 503233 500227 494212 486201 480202 473203 468208
      461208 457212 450215 438216 436219 436222 442228 441246
      447248 453248 460246 466244 479244 481243 484245 488253
      491259 495265 498266 499263 497254 493248 490242 480234
      476228 475225 476220 491222 495235 499241 503242 504241
 1.50 484161 483159 483158 482156 481155 480155 481158 482159
      482160 483162 484161
 1.50 470158 470156 469155 469153 468155 469155 470158 470158
 1.50 462178 461176 461175 459176 458177 457178 456179 457181
      459181 460180 461180 462178
 1.50 435228 435227 434225 433225 432224 431222 429221 427222
      426223 427224 428224 430225 432226 433227 435228 435228
 1.50 428242 427242 426241 424239 423238 421237 419237 418236
      416236 415236 414238 415240 417240 419241 420243 422245
      423245 425244 426244 427244 428242
 1.50 388949 388938 386933 382936 377941 368945 362949 359952
      355954 357936 352934 347935 340941 335946 330954 330960
      332962 336965 337969 340979 342982 346982 352977 357967
      362962 367962 372963 375963 378961 384954 388949
 1.50 318967 319964 319962 319960 317959 316959 314960 312961
      311962 310964 310965 310966 310969 312971 314971 316971
      317969 317968 318967
 2.00 501238 501237 500235 500234 498232 498231 498232 498233
      499235 501238 501238
 2.00 496262 497260 496258 496257 495254 493253 492253 490252
      490253 491255 491256 492258 493259 494261 495262 496262
      496262
 2.00 488244 487241 485240 485243 486245 488245 488244
 2.00 490219 490214 488209 487205 482203 475204 467209 460210
      457213 453214 449216 446216 441216 439217 439221 441224
      445228 450228 452231 445233 441235 439238 440242 443245
      446245 451245 458243 466241 469240 474241 480242 480238
      479233 476230 472228 470226 471223 476219 480219 486220
      490219
 2.00 461178 461177 459177 459179 461178 461178
 2.00 424241 423239 421239 420240 421241 421243 422244 423243
      424243 424241
 2.00 378949 378947 377946 375946 373946 372947 371947 370948
      368949 368950 366952 365954 365956 366958 368958 370957
      371956 372956 373956 375954 377952 378949
 2.00 350967 349964 346962 344960 346956 348949 349944 346941
      342942 340945 336949 334957 336960 339961 343962 342965
      342970 344973 348971 350967
 3.00 486215 486210 483207 478207 474209 472211 469211 464211
      461213 458215 454215 451217 447218 442218 443223 446226
      451224 455223 458226 459229 457231 450233 444236 441238
      442241 445241 452242 459239 466237 464226 476217 482217
      486215
 3.00 479238 479236 478233 477233 476232 474231 474232 473232
      471233 471236 472237 473238 475239 477240 479239 479238
 4.00 477238 478235 477235 476234 474234 474235 475237 477238
      477238
 4.00 481213 481212 479211 477211 476211 475212 474213 473214
      473215 475215 477216 478215 480214 481213
 4.00 472216 470215 467212 464214 461214 459216 456216 454216
      453221 455222 458224 460226 462226 464224 466224 467225
      469220 471218 472216
 4.00 464236 465234 464232 462233 462236 463236 464236
 4.00 460237 460235 459234 457233 455233 453234 452235 451235
      450235 448235 447236 446238 447240 449240 451240 452240
      453239 454239 456239 457239 458239 460238 460237
 5.00 470218 470217 469215 468214 467214 466214 466217 466218
      468220 469218 470218
 5.00 463223 464221 463218 461218 459218 457218 456217 454218
      455221 457223 458223 460224 462225 463223
 5.00 458237 458236 457235 455235 454235 455237 456238 458237
      458237
 5.00 452238 451236 450235 448236 447236 448238 449239 451238
      452238
 6.00 462223 462221 460221 459221 457220 456219 457221 457222
      458222 460223 462223 462223

$$

Mid-South Probabilistic Quantitative Precipitation Forecast (QPF) from: NOAA-NWS