Skip Navigation Links 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
The Weather Prediction Center



Follow the Weather Prediction Center on Facebook Follow the Weather Prediction Center on Twitter
NCEP Quarterly Newsletter
WPC Home
Analyses and Forecasts
   National High & Low
   WPC Discussions
   Surface Analysis
   Days ½-2½ CONUS
   Days 3-7 CONUS
   Days 4-8 Alaska
   Flood Outlook
   Winter Weather
   Storm Summaries
   Heat Index
   Tropical Products
   Daily Weather Map
   GIS Products
Current Watches/

Satellite and Radar Imagery
  GOES-East Satellite
  GOES-West Satellite
  National Radar
Product Archive
WPC Verification
   Medium Range
   Model Diagnostics
   Event Reviews
   Winter Weather
International Desks
Development and Training
WPC Overview
   About the WPC
   WPC History
   Other Sites
Meteorological Calculators
Contact Us
   About Our Site is the U.S. Government's official web portal to all federal, state, and local government web resources and services.
Hawaii Extended Forecast Discussion
(Caution: Version displayed is not the latest version. - Issued 1228Z Mar 22, 2018)
Version Selection
Versions back from latest:  0   1   2   3   4   5   6   7   8   9   10   
Abbreviations and acronyms used in this product

Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
828 AM EDT Thu Mar 22 2018

Valid 00Z Fri Mar 23 2018 - 00Z Fri Mar 30 2018

An upper low initially near 35N/175W is shown by all
model/ensemble guidance to move southeastward over the next few
days, passing north of Hawai'i over the weekend, with an
associated surface front passing through the islands as well. A
surge high high precipitable water values (near 2.00 inches) ahead
of the front will support the development of widespread convection
and potentially heavy rainfall. The heaviest rainfall should focus
across the western islands Fri-Sat and then across the eastern
islands by Sun. While the GFS and ECMWF both show agreement on the
timing of the system, convective/mesoscale differences affect the
precise distribution of heavy rainfall. The 06Z GFS shows
potential heavy rains across the western islands Fri-Sat night,
but then an extensive area of convection farther south seems to
serve to cut off more extensive convection across the eastern
Islands. Meanwhile, the ECMWF keeps the entire Hawaii'an chain
under a threat for heavy rainfall. ECENS probabilities suggest
there could be some credence to the GFS idea, with probabilities
of heavier amounts showing a slight reduction across the eastern
islands. At this time, confidence in the convective details is low
so either scenario seems possible.

After Monday, models/ensemble show general agreement that heights
will rise across Hawai'i with drier air advecting across the
state. Low-level flow during this time period should be very light
through mid-week, with light easterlies resuming by late next
week. A trough should begin to amplify along 175W by late next
week, but at this time ensembles suggest that upper ridging should
remain relatively strong across Hawai'i at least through Fri,
keeping the chances for any widespread convection at bay.